US2822726A - Microtome - Google Patents

Description

Feb. 11, 1958 JI.""BLUM 2,822,726

MIICROTOME 7 Filed April 8 1955 6 Sheets-Sheet 1 44 1;), I 144 1 I a2/ INVENTOR 0:5, 54 an! ATTORN Y J. BLUM MICROTOME Feb. 11, 1958- Filed April 8, 1955' 6 Sheets-Sheet 2 QQN \R \RN INVENTOR- @755: 54 a w ATTORNEY "Feb; I1, 1958 J. BLUM MICROTOME Filed April 8, 1955 6 Sheets-Sheet 3 mQ W9 k ion-T mmv wE N R W. E E

w mm J. BLUM MICROTOME Feb. 11, 1958 6 Sheets-Sheet 4 Filed April s, 1955 hwy INVENTOR 70:5; 510M mRW ATTO

J. BLUM MICROTOME F eb. 11, 1958 6 sheets-Sheet 6 Filed April s, 1955 INVENTOR T 3 D7 c7555,- 45; 0M BY United grates PatentO Mrcaorolvm Josef Blum, Norwalk, Conm, assignorto Ivan Sorvall, Inc., Norwalk Conn, a corporation of New York Application April 8, 1955, Serial No. 500,110 3? Claims. (CI. 8840) 'Ihis-invention relates to microtomy and more particularly to an improved machine for producing ultra thin sections of tissues for both optical and. electronmicrosr copy.

The purpose of the-present invention is to provide an proved microtome instrument th'at'is rugged, easy to operate, practically maintenance free, and which is capa Me of producing ultra thin sections of biological tissues in order of from $4 to /2 micron of exceptional quality,

and uniformity.

The instrument of the present invention embodies an extremely reliable and accurate means for advancing the specimen to the knife; a collet type chuck which is adapted to hold the specimen firmly at any desired angle and. to provide facility for rotating or changing, the specimen;. stage which provides for and a knife holder mounting fine'and coarse adustment of specimen.

A salient feature of the present invention is the novel means for passing the specimen against the knife in only one direction and providing a return stroke for the speci men that bypasses the knife, thereby minimizing static friction and eliminating damage to the specimen.

A further feature of the microtome of the present invention is the provision of compensating spring suspensions for all the moving mechanical components which the stage relative to the precludes readjustment of parts under normal conditions so as to render the instrument practically maintenance free throughout its long life.

There are also provideda number of spherical balls for use'in critical pivotinglocations so as to provide high precision support for the moving members which are articulated, retracted or indexed with the minimum amount of pressure.

A novel adjustable knife holder is also provided which is adaptable for versatile adjustment and which permits lateral movement of the knife without any change of preset angle.

An important feature of the knife holder is the provision of a three point mounting structure which permits the utilization of an irregular or broken piece of glass as a knife.

Means are also provided in the instrument of the present invention to automatically retract the control pawls from gear teeth on return strokes of the advancing mechanism, thereby preventing chattering and eliminating.vibrations that might otherwise introduce errors in the functioning ,of the machine.

Another novel feature of the present invention is the provision of simple means for resetting the advancing mechanism without disassociating any of the parts in such a way as to require subsequent re-adjustment.

Still other objects and advantages of the invention will be apparent from the specification;

The features of novelty which. are believed toibe characteristic of the inventionzare set forthherein and will best be understood, both aszto :theirfundamentalprinciice Patented F eh. I 1,. 15358 and the means for moving the speciment relative-to the knife;

Fig. 4 is anenlargedview, partly broken away, partly" in section, taken on the line 4-4 of Fig. 5,- and partly in. phantom outline, of therear portion of the microtome' showingthe mounting for the rear portion of the specimen armand the advancing mechanism for the'arm;

Fig; 5 is a'side view taken on line 5-5 of Fig. 4;

Fig. 5A is. a schematic representation of a portion of theadvancingmechanism in oneposition;

Fig. SB'is aschematic representation of saidadvancing mechanism in a second position;

Fig. 6 is a'greatly enlarged side view taken along line 6-6 of Fig; 4; partly in section, partly in elevation and partly in phantom" outline;

Fig. 7 is a top view ta-kenalong lme 7-7'of Fig. 6;

Fig. 8 is'a view, partly in section, .takenalong line 8-8 of Fig. 3

Fig. 9 is a fragmentary enlarged view, partly. in section, taken along line 9-9 of Fig. 8; I

Fig. 10 is a view taken alongline 10-10 of-Fig. 3;

Fig. 11 is an exploded view, partly in: section of. the k'nife'holder shown in Fig. 8;

Fig. 12 is an enlarged side view, partly in sectiomof the mounting means for the cutting knife;

Fig. 13 is a view, partly in section andpartly inphantom' outline, taken along line 13-13 of Fig.3;

Fig. 14 is an enlarged bottom view of amidportionof the base casting of the instrument showing the castingstructure as well as a bottom view of, a portion of the advancing mechanism; and L Figs. 15 through 20 area series ofenlarged viewsof the pawl, ratchet and cam elements whichform partof the advancing mechanism, several of thesefigures beingpartly broken away and partly. in phantom outline.

Referringvnow to the drawings in detail, the microtcme of the present invention is mounted on a base-generally designated 31, made of a castingof light weight but strong There is also provided a pair of platform-rails 41and 42, rail 41 being cast integrally. on. the. tops of walls 32 and 33 and coextensive therewith,.rail 42 being; castintegrally with the tops of, walls34 and 35 and coexten sive therewith; The topsurfaces of rails-:41. and 42 arelapped. flat and accommodate the superstructure of the machine.

Base 31 may optionally be provided with ears43 at; the lower edges of walls 32 and 35 with suitable vertical.

apertures 44 for the insertionofbolts for rigidly mounting-the-machine on a suitable tableor platform; (Figs.

3 prene, felt, or the like, as shown in Fig. 8. Mounted on rails 41 and 42 is a support frame, generally designated 51, having side walls 52 and 53, respectively, rear wall 54 and a floor 55 secured to rails 41 and 42 by suitable means, such as bolts, or the like, not shown. (Figs. 1, 2 and 4.) i

The top of frame 51 has'a pair of forwardly extending substantially parallel arms 58 and 59 (Figs. 1 and which form the support means for the compound pivoting assembly to be described hereinbelow. Near the forward end of shoulder 58'there is a vertical lateral slot 61 (Fig. 2), the lower end of which terminates in a collar 62 which encircles horizontal pin 63. (Figs. 2 and 4.) Pin 63 is secured within collar 62 by means of horizontal screw 64 threadably extending across slot 61. The inner vertical surface of support .pin '63 has a bearing recess for seating pivotball 65. r

The outside vertical surface of shoulder 59 has a horizontal elongated recess, 71 (Figs. 1 and 5) within which a fiat leaf spring 72 lies, the rear portion of the spring being secured to thevertical'wall of the recess by means of screws 73. i

The forward end of shoulder 59 has a horizontal transverse clearance hole 74 (Fig. 4) over which the forward end of leaf spring 72 extends. The forward end of leaf spring 72 has a bearing recess for seating pivot ball 76. In some embodiments therecess may alternatively be substituted by a pierced hole provided its diameter is smaller than that of ball 76.

The mechanism for advancing the speciment block towards the microtome knife is mounted pivotally between balls 65 and 76. (Fig. 4.) The advancing mechanism comprises a U-shaped yoke, generally designated 80, having. upwardly extending arms 81 and 82. Arm 81 has a horizontal socket rod 83 secured therein, the outer end of said rod having a bearing recess which accommodates ball 65. Arm 82, on the other hand, has a horizontal socket rod 85 mounted fast therein and extending into aperture 74 and rotatable freely therein. A bearing recess 86 on the outer vertical wall of socket rod 85 is adapted to accommodate ball 7 6. Yoke 80 is freely pivotable between shoulders 58 and 59 on spherical balls 65 and 76, the loading on the suspension being provided by the tension on the forward free end of leaf spring 72. Yoke 80 has a downwardly extending lever leg 87 whose function will be described hereinbelow.

Positioned between the upwardly extending arms 82, 83, of yoke 80, is an arm support pivot block 91 in the form of a rectangular casting having a generally rectangular central aperture 92. Mounted on each vertical outward surface of pivot block 91 is a leaf spring 93 having a central bow94 that bulges outward and is spaced apart from its respective vertical wall of the pivot block. In the intermediate portion of each bow 94 is a bearing recess or aperture adapted to seat balls 95 and 96, respectively, which are also seated in respective recesses 97 and 98 in the inner vertical faces of socket rod 83 and socket rod 85, respectively.

Bows 94 of springs 93 normally urge outwardly against balls 95 and 96 and provide a preloaded tension therefor, thereby eliminating back lash or lost motion in the pivoting action of pivot block 91 relative to yoke 80. The horizontal axes of balls 65 and 76 are aligned with each other, the common axis line being spaced slightly apart vertically from the common horizontal axis line of balls 95 and 96. This is graphically illustrated in Fig. 5A which shows generally the relative positions of balls 76 and 96. As the bottom of yoke 80 moves forward it pivots on balls 65 and 76, whereby balls 95 and 96 are carried forward to a predetermined fractional extent of the movement of yoke 80. Since pivot block 91 is suspended between balls 95 and 96, its movement is coextensive with that of the balls. The purpose of this compound pivoting mechanism will be elucidated hereinbelow. Each of the respective upper and lower horizontal bars of pivot block 91 has a vertical central aperture. The two apertures are axially aligned with each other and accommodate a pivot pin 101 rotatable therein on its longitudinal axis. The top and bottom faces of pin 101 are exposed through the respective apertures and have hearing recesses 102 and 103 which accommodate balls 104 and 105, respectively. Balls 104 and 105 are seated in suitable bearing recesses in the central portions of leaf springs 106 and 107, respectively, mounted on the top and bottom faces respectively of pivot block 91. Leaf springs 106 and 107 each have a pair of lateral ridges 108 formed on each side of the ball seating location whereby the central bowed section of said springs are adapted to preload balls 104 and 105 in order to prevent lost motion in the rotation of pivot pin 101 and to prevent back lash thereof.

Mounted fast upon pivot pin 101 is horizontal specimen advancing bar 111 which is adapted to swing in'a horizontal plane relative to pivot block 91 within certain limits. Bar 111 extends to the forward parts of the machine and at its end there is mounted the specimen holder which will be described hereinbelow.

In order to advance the specimen at the forward end of bar 111 toward a cutting knife, the requisite motion is imparted by the motion of pivot block 91 whose suspension pointsballs. 95 and 96--are displaced by the pivoting action of yoke 80. See Figs. 5A and 5B. Advancing bar 111 is also capable of independent vertical pivoting motion on balls 95 and 96, independently of the motion of the pair of balls 95, 96 relative to the pair of balls 65 and 76. Hence, the three sets of pivots described provide for forward, backward, horizontal, and vertical motions of the forward end of the bar, and accordingly, thecorresponding motions of the specimen as well.

Mounted on the rear end of bar 111 is a stud 112 whose outer end is engaged by one end of a downwardly extending spring 113 whose other end is anchored on horizontal stud 114, mounted in rear wall 54 of frame 51. (Fig. 5.) One purpose of spring 113 is to pull down upon the rear end of bar 111 in order to eliminate back lash in the motion of the bar. A more detailed description of this action will he provided hereinbelow.

There will now be described the means for moving the specimen at even increments toward the cutting knife:

Dowuwardly extending lever leg 87 of yoke 80 which moves freely within a longitudinal slot in floor 55, is arranged to engage a mechanism by which it is moved in a forward direction, As shown in Figs. 5, 6, 7 and 14, the advancing mechanism comprises a horizontal rotatable screw 120, having a plurality of buttress saw-tooth threads 121, and supported at its axial points by means of balls 122 and 123 that are seated in bearing recesses 124 and 125, respectively, in the opposite ends of said screw. Rear ball 122 is seated in bearing recess 126 on stud 127 connected to bracket 128 which is attached to the lower edge of wall54 of frame 51 and which extends downward into aperture 129 in wall 36 of base 31. (Fig. 1.) Ball 123 at the forward end of said screw is seated in a bearing recess in vertical leaf spring 131 whose upperend is connected rigidly between anchor block 132 attached to a forward portion of the floor 55 of frame 51.

Spring 131 has adequate strength and is biased with sufiicient tension toward the rear of the machine to provide asecure mounting for screw between balls 122 and 123. Spring 131 also has sufficient resilience to provide for temperature compensation by accommodating the expansion of contraction of screw 120 as well as to provide an anti-backlash seating for the screw, and to prevent any lost motion that might otherwise be incurred as in previous mechanical arrangements.

Pivotally'rnounted' on the lower end of lever leg 87 of yoke 80 is an H-yoke generally designated 135, having a cross bar 136, a pair of. rearwardlyextending legs 13? and a pair of forwardly extendinggarms l38r See Figs:- 5, 6, 7 and 14. Legs 137 engagethe-respective endsof:

pivot pin 139 extending transversely through'leg 87.

Yoke 135 extends forwardly-and generally horizontally of the bottomof legr87 being from leg 87, a portion recessed at 140 yoke.

to permit the vertical motion of said rider. block 144 has a channel 145 within which pin141; is accommodated. The bottom of'block144 is serrated; in the form of buttress saw teeththat mate precisely.

with threads 121 on screw 120.,

It will be noted that by virtue of the spring mounting width of channel .145, said-block swivelling action, while at theof block 144 and of the is capable of a limited same time it is relative to yoke reedom to accommodate itself to threads 121.0n screw prevented from moving longitudinally.

120 without causing any longitudinal motion on the part of the lower end of leg 84 relative to said screw, thereby:

preserving the accuracy of the specimen advancingmechanism'.

Threadably secured into cross bar'136 is a:pin-141- into the area below the-space 135. Thus, the blockis. provided .with.

Rider block 144 is urged downward upon threa'dsf121 by means of vertical pressurepin 147 mounted'slidably. in vertical slot 148 in leg87. A captive spring149 (Fig.. 4) within slot 148, causes the lower end 'of pin .147, extending through recess 140, to bear downward upon cross bar 136' of H-yoke 135, maintaining the teeth of block 144 in intimate engagement with'the threads 121 on screw 121). Thus, the rotation'of screw '120 causes rider block 144 to move forward or backward depending upon the direction of rotation of the screw whereby leg 87 of yoke 80 is caused to move forward'or. backward as desired.

The lower part of yoke '80 is normally urged rearward-' ly by means of spring 151 (Fig. 5), one end of which is connected to hook 152 mounted in yoke 80, the other end of which is 153 mounted on the forward surface connected to hook of wall 54'of'frame 51. The action of spring 151 also urges rider block'135 rearwardly and enhances the engagement of its'teeth with threads 121 on screw 120, thereby eliminating backlash or lost motion on the part of the screw action.

While the teeth of rider block 144 are in engagement with the threads of lead screw 120, spring 151 is prevented from urging the lower end of yoke 80 backwards towards frame 54. When, however, it is desired rapidly to retract the lower end of the yoke backward in order to start a new cutting cycle, rider block 144 may be lifted from screw threads 121 by means of forwardly extending curved slide rod 155 that is mounted pivotally on bracket 128' by means of screw 156.

As shown in Figs. 6 and 7, slide rod 155 is operated by arm 157 of bell crank 158 whose pivot pin 159 extends through walls 32 and 33 of base 31. The outer end of pivot pin 159 has a handle 160 which can be manipulated manually to move inner arm 157 upwardly thereby moving rod 155 upwardly tobear against pin 161 extending outwardly from one of the forward .arms 138 of H-yoke.

When rod 155 bears upwardly against pin 161,.H-yoke. from threads 121against the action of. ressure pin 147, thereby pivoting H-yoke upwards and' 135 is lifted free permitting spring 151 todraw the lower end of--yoke 89 pivotally toward the back of the machine. Thus,. the operator may automatically reset the advancingk mechanismback to itsstarting Qposition by merely de-.

the rear 'surface' of vanced accordingly by this toward the cutting knife to slice tissues ofthe desired pressing; handles 160 on the: outside of. themachine (Fig: 1).-

In order to prevent crank arm 157 from dropping. too: far, asupport pin.1 62 mounted in and extending inwardfrom-wall'33 (Fig. 7) serves as a stop for crank-158 when handle 160 is released, thereby permitting 'rod 155. tofall' by gravity and to remainsupported in--its inop=- erative position upon-arm 157, as shown in Eigs.6 and 7. Rod 155 may be curved in a suitable manner in:- order to provide a smooth lifting action for pin-1610f yoke 135.

It hasbeen found advantageous to provide that block 144 be made of a suitable resilientplastic material such as the one presently known as Teflon, orthevlike. Although such materialsare resilient, they havesuflicient toughness to preserve their'shape, and this particularly= is important when it is necessary to provide block 144 with serrations to mate evenly and repeatedly with threads 121on screw 120. Also, such a material is advantageous in the event ofaccidents, for should block 144 bounce-or otherwise strike against screw 120, there would be no damage-eitherto the screw threads or to the block because of such a contingency.

In order to prevent any damage to the yokeby the action of spring 151, there is 5) connected to the. rear end of the slot in floor 55'offrame 51 by means of screw 164 whose head is recessed from the forward surface-of saidfstop in order that it is not impinged upon. by leg 87 of yoke 80. Stop 163 maybe-madeof a suitable resilient material such as rubber or neoprene, to absorb any shock caused by the sudden backward movement and contact of leg 87 with saidstop.

The spatial relationship between stop. 163, the lower leg 87 of yoke 80, and rider block-144may be so arranged. that when yoke has been retracted to its rearwardmost position, and rod has been permitted to move down-, ward by releasing handle of bell crank 158, rider block' 144 will be lowered into engagement with at least. a few turns of threads 121 on lead screw 120-so thatthe action of moving the specimen forward may be resumedupon rotation of screw 120.

By means of a mechanism to. be described hereinbelow, horizontalspecimen advancing. bar 11-1v ismoved vertically upon pivot balls 95 and 96-by manually operated. mechanical means to cause the specimen to pass against the cutting knife, and to bypass the knife on its return. stroke. Coordinated amechanism for rotating the lead screw apredetermined. amount in order to predetermineddistance so that the specimen will be adsame predetermined distance:

thickness.

This rotating mechanism comprises a horizontal arm. 171 (Figs. 1, 2, 4, and 5) whose rearward end is connected by press fit into pivot block 91 and which extends.

forwardly in the same general directionas bar 111 whosepivotal motion it duplicates.

171 by means of pin 174 is a lower end of which is pivotally connected to pin 176 mounted between the lateral arms 178 of yoke 179. Yoke Pivotally connected to arm 179 is freely pivotable around horizontal stationary'shiftv mounted fast by means of set 181 (Figs.-6 and 7) which is screw 182 to downwardly extending leg-183 'of. block:132. With each upward and downward stroke of rod-175, yoke- 179 reciprocates pivotally around shaft 181.

Mounted substantially parallel to shaft 18-1 and fixed fast within arms which shaft longitudinal axis rear end of shaft which is adapted ratchet wheel 188 mounted fast on screw 120 by means of set screw 189, the rotation the rotation of screw 120.

178 of yoke 179 is bushing 184 through extends, said shaft beingrotatable on its 185 and rotatable therewith is pawl 136.

provided a stop 163 (Fig..

with the movement of bar 111 is:

advance said bar longitudinally a descending lift rod 175, the

within said bushing. Mounted on the to engage teeth 187 on the periphery. of.

of said ratchet wheel causing...

' Mounted on the forward end of shaft 185 and rotatable therewith is a second pawl 191 which coacts-withthe periphery of limiting disc 192. Disc 192 is fixed by suitable means, such as press fitting or otherwise, to bushing 193 that is mounted around and is rotatable relative to shaft 181, the latter shaft being positioned coaxially relative to screw 1 20. Limiting disc 192 has substantiallythe same diameter as ratchet wheel 188 except for a portion of its periphery that is recessed to form a cam surface19f4.

See Figs. 6, 7 and 15.

A wire 195 is coiled around end of the wire being connected to of yoke 179, and the rearward end tended over the top of pawl 186 to limit th outward movement of said pawl and, accordingly, of pawl 191. Since pawls 186 and 191 are fixed fast upon shaft 185, the rotational movements of all three of'said elements are integral with each other.

By observing Figs. 15 through 17, it will be noted that while both pawls 186 and 191 are mounted fast upon shaft 185 and rotate therewith, the operative points of the respective pawls are radially offset from each other by a prescribed distance. Whenever the point of pawl 191 is urged into recess 194 of limiting disc 192, the point of pawl 186 is engaged with teeth 187 of ratchet wheel 188. See especially Figs. 15 and 18. When, however, pawl 191 is rotated outwardly from cam 194 and rides on the outer periphery of limiting disc 192, shaft 185 is rotated, causing pawl 186 to rotate therewith and to disengage from teeth 187 of ratchet wheel 188, as can be seen in Fig. 16, for example.

Assuming that limiting disc 192 is in afixed termined position, reciprocal motion of rod 175, moving yoke 179 pivotally around shaft 181, cam 191 will be moved inward and outward at certain predetermined times as determined by the rise portion of cam surface 194, and therefore it'will control the motion of pawl 186 to cause the latter to engage and disengage the teeth 187 of ratchet wheel 188. This control by pawl 191 over pawl 186 predetermines the position at which pawl 186 will engage teeth 187 of ratchet wheel 188, and the duration of said engagement, thereby predetermining the amount of rotation that will be effected upon ratchet wheel 188, and accordingly, screw 120. The degree of rotation of screw 120 with each reciprocating cycle of lift rod 175 determines the distance by which bar 111 is advanced thereby determining the thickness of the specimen tissue that will be cut, as will be described in greater detail hereinbelow.

Fig. 18 shows a typical preselected position of limiting disc 192 whereby cam 186 will be engaged with ratchet wheel 188 for substantially the full amount of the stroke of lift rod 175. Fig. 16 shows a preselected position of disc 1 92 whereby cam 186 will be engaged with wheel 188 for a very minor portion of the duration of the stroke of rod 175. Any intermediate positions for disc 192 may be preselected by the operator as will be described below.

Each cycle of reciprocating action of lift rod 175 is intended to cause the alternate engagement and disengagement of pawl 186 with ratchet wheel 188, the period of said engagement causing screw 120 to rotate a predetermined radial distance for advancing the specimen to the tissue cutting knife. This action requires a reciprocating radial motion on the part of pawls 186 and 191, and this is accomplished by means of a curved friction spring 201 bushing 184, the forward the rearward arm 178 of said wire being expredeattached on the forward end of shaft 185 and rotating therewith. (Figs. 7, 14.)

Spring 201 extends laterally between and is frictionally engaged jointly by limiting disc 192 and a friction disc 202, the latter being attached by suitable means, such as press fit or otherwise, to bushing; 193 and rotatable therewith. As can be observed from Fig. 19, when rod 175 moves upward to move arms 178 of yoke 179 upward, the frictional resistance of spring 201 between discs 192 and 202, which at the momcntare stationary, will it will be seen that upon the vertical.

cause shaft 185 and pawls 186 and 191 to rotate toward their respective cooperating elements, namely ratchet wheel'188 and limiting disc 192, whereby said ratchet wheel will be engaged and rotated for a distance equivalent to the distance which pawl 191 has traversed within cam recess 194 of limiting disc 192. Thus, the upward stroke of rod causes the rotation of screw 120 for advancing the specimen to the tissue cutting knife.

On the downward stroke of rod 175, the frictional resistance of spring 201 between stationary discs 192 and 202 will cause shaft to rotate and cause pawls 186 and 191 to rotate promptly outward from the peripheries of their respective coacting elements, namely ratchet wheel 188 and limiting disc 192. See Fig. 20. This action is also useful for rapidly disengaging pawl 186 from ratchet teeth 187 thereby preventing the pawl from bouncing on, or rubbing against, said teeth during the return stroke, which actions might otherwise introduce undesirable characteristics of wear and inaccuracy into the apparatus. During the downward stroke of rod 175, screw 120 remains stationary.

During the downward stroke of rod 175, the outward movement of pawl 186 is limited by the rearwardly extending end of wire 195, and in this manner spring 201, which rotates with shaft 185, is prevented from escaping from between discs 192 and 202. Obviously, on the upward stroke of rod 175, spring 201 cannot escape from between said friction discs because the inward rotational motion of pawls 186 and 191 is limited by their coacting elements.

The amount of rotation of ratchet wheels 188, and accordingly screw 120, to be caused by pawl 186 is determined by the position of limiting wheel 192 and the radial relationship of its recessed cam 194 relative to screw 120. The position of limiting cam 194 may be adjusted by means of gear wheel 205 attached fast to bushing 193, whereby said gear wheel rotates co-radially with limiting disc 192 (Figs. 4, 6 and 7).

It will be noted that gear wheel 205, friction disc 202 and limiting disc 192 all rotate co-radially with each other on bushing 193, which rotates freely around shaft 181. The longitudinal movement of bushing 193 is prevented by end collar 206 mounted fast by means of a set screw or otherwise to shaft 181.

The peripheral teeth of gear 205 are engaged by a worm 207 (Figs. 4, 7) attached by means of set screw 208 to shaft 209 which extends laterally and is rotatably supported in sleeve bearing 210 extending laterally through walls 32 and 33 of base 31. Mounted on the outer end of shaft 209 which extends outside of wall 32 (Figs. 1, 4 and 14) is a knurled knob 211 which may be grasped and rotated manually by the operator.

Knob 211 has a flange 212 having a graduated scale printed or etched thereon which indicates the thickness of the tissue that it is desired to cut. A plate 213 having an index line is mounted on the outer surface of wall 32 adjacent flange 212 so that the latter may be set in the desired position. As knob 211 is rotated, worm 207 rotates gear 205 thereby rotating limiting disc 192; and the latter may be set at any desired position as indicated by the graduated scale on flange 212 that has been suitably calibrated relative to the cam recess 194 and ratchet teeth 187. By this means the operator can set the instrument to cut tissues of a desired thickness by simply rotating knob 211 to the requisite indicated point on the calibrated scale of flange 212.

The means for controlling the cyclic motions of specimen advancing bar 111 relative to its compound pivots are mounted upon a vertical frame, generally designated 221, attached by bolts 222 to rails 41 and 42 intermediate'the front and rear of the machine (Figs. 1, 2, 3 and 13). Frame 221 comprises a pair of vertical posts 223 and 224, to the front edges of which is connected guide plate 225 by means of bolts 226 or the like. In

9 some embodiments guide plate 225 may be separated from posts 223. and 224 by spacers 227, while in other embodiments it may be flush with 'or cast integrally with the front of posts 223 and 224.

Guide plate 225 has a central aperture 228 through which bar 111 extends, the contours of aperture 228 being designed to determine the path described by said bar as it is moved through the cutting cycle.

The means of providing mechanical motion for bar 111 comprises an operating wheel 231 having a handle 232 which is grasped manually by the operator to rotate the wheel. See Figs. 1, 2, 3 and 13. Wheel 231 is mounted upon a shaft 233 which extends rotatably through horizontal bushing 234 (Fig. 13) mounted through post223 of frame 221. Mounted on and rotatable with the inner end of shaft 233 is a crank disc 235 secured to said shaft by means of set screw 236 in hub 237 of said disc.

Connected near the outer periphery of crank disc 235 is a stud 241 upon which is mounted laterally extending crank pin 242 to which is pivotally mounted the lower end oflink 243, which is adapted to articulate loosely around said pin. Threadably inserted into the upper end of link 243 is a turnbuckle 244 whose upper end is threadably engaged by the lower end of link 245, the upper end of which is loosely articulated with a horizontal pin 246 mounted horizontally between the legs 247 of yoke 248 mounted around bar 111. The upwardly extending arms 251 form a clamp around bar 111 which may be tightened and loosened by means of shoulder screw 252 extending freely through one of the arms and threadably engaging the other arm.

By rotating turnbuckle 244 it is overall length of the linkage possible to adjust the between crank wheel 235 and bar 111. The articulating connections at .the ends .of said linkage permit not only vertical motion, but horizontal motion as well, on the part of bar 111 within the limits of guide aperture 228, the purpose of which will be described hereinbelow.

The forward end of bar 111 has an axial aperture 255 into which is secured, by press fit or otherwise, shaft 256 of substantially cone shaped socket 257. See Fig. 3. Socket 257 accommodates ball 258 secured therein by cap 259 threadably engaging the outer periphery of said socket. .through central aperture of cap 259 is shaft 261 of chuck body 262 having a tapered internal aperture which accommodates a plurality of removable chuck jaws 2'63 arrayed annularly within said chuck.

A knurled compression ring 264 threadably engages the outer periphery of chuck body 262, the annular shoulder 265 of said ring being adapted to urge jaws 263 further into the aperture of chuck body 262 when ring 264 is tightened thereon. This action reduces the space between the gripping faces of jaws 263 which thereby tighten their grip upon specimen block 266. Specimen 267 is embedded in block 266 by means well known in the art.

By virtue of the jaw structure within chuck 262, the aperture size is adjustable, thereby ensuring a firm positive grip on the specimen block along its entire length. The ball and socket means for attaching the chuck 262 to bar 111 permits angular adjustment of the specimen 267 to provide its proper orientation relative to the cutting knife. The ball and socket means provides for angular aswell as radial adjustment or the specimen.

The knife holding assembly and stage therefor are located at the front portion of the machine and are positioned on horizontal platform 271 which is movable back and forth upon rails 41 and 42 of base 31. See Figs. 2 and 3. Each of the inner vertical walls of rails 41 and 42 has a longitudinal horizontal channel 272 and 273, respectively, positioned opposite each other and within which anchor plate 274 is movable longitudinally. See

Mounted fast in ball 258 and extending forwardly .272 and 273 until the desired .causing eccentric cam .285 thereby urging platform 271 aperture 295 by shoulders 298 of ..Figs.,8 and 10. Extending through plate 274 is vertical lock rod 275, the upper end of which is inserted into aperture 276'in substantially the'center of the bottom surface of platform 271. Aperture 276 issufiiciently deep to permit vertical movement of rod 275 therein. The lower end of rod 275 isthreadably engaged by nut 277, while spring 278, coiled around rod 275, urges plate 274 downward from platform27l, the width ofchannels 272 and 273 being great enough to permit a slight vertical movementon thepart-ofplate 274.

Aperture 276 is intersected at right angles by horizontal aperture 279 bored-throu-gh the sideofplatform 271 and accommodating lever spindle 28 1 therein. The outer end of. spindle .281 has ahandle 282 for manual rotation thereof. Spindle 2:81 is keyed'into position in platform 271 toprevent longitudinal movement by means of-vertical set-screw 2.83threadablyinserted through the top of the --.platform, the :lowerendf of said screw engaging annular keyway 2 8 4recessed in the peripheryof spindle 281.

diameter. andihasthe form of a circular circular aperture-2 36 in vertical rod 275.

Plat forml27 1 maybe adjustably 'moved alongrails 41 and 42,,.anc'hor..pl-ate 2'74 moving therewith in channels I I position is determined, after which.handle282 is operated to rotate lever spindle 281 to force rod 275 upwards,

surfaces ofrails 41 and -42 untila locking condition occurs between platform 27 1 and base 3 By rotating handle 282 in theopposite direction, the platform is released from the locked position,'this action being assisted by spring 278, and the platformcan then berelocated' in another ,position onrails 41 and 42 to be locked again inanother desired position. I

Positioned on the top surface of platform,271'is*kr1ife holder stage 291 having a smooth bottom'su-rface movable freely upon the top surface of platform 271. 2, 3, 8 and 9. The top of platform 271 has arec'essd See Figs.

longitudinalkeyvvay 292 which accommodates 'key293 of vertical lock rod 29:4 which extends upward into andis "movable vertically in aperture 295 in the central portion of stage 271. A captive spring 296 isrposition'edwithin above :rod 294' and normally urges Jsaid'i rod downward. Key 293 has a pair of outwardly extending flanges '297 whichare limited in theirupwa'rd movement keyway 292 thereby 'Ilimitin'g the .upwardmovemen't of'l'ock rod 294. The vertical dimension of -keyway292 is sufficient to permita slight vertical movement on the-part of rod 294.

Aperture 295 isintersected at right angles by horizontal aperture 301 bored through the side ofstage 291 and accommodating'ther'ein lever spindle 302. The outer end of spindle 302 has a handle 303'for manual rotation thereof. -Sp'indle 302 is key'ed into position in stage 291 to prevent longitudinal movement by means of vertical set screw 304threadably inserted through the bottom of stage'291, the'uppe'r end of said screw engaging annular keyway'305 recessed 'in the periphery of spindle 302. V

Theinne'r'e'nd' of spindle 302. is reducedsomewhat in diameter and has the form ofa circular cam .306 whose axis is displacedv from'theaxis of spindle 302, thereby providing an eccentric which is inserted horizontally into cooperating circular aperture 307 in lock rod 2944. Upon rotation of spindle 362, eccentriccam 306 causes the upward movement'oflock rod .294, forcing flanges 297 upward against shonlder's 29$, thereby urging stage 291 downward upon platform 271 until they are locked together. Upon rotating lever 302 in the opposite direction, lock rod 294 is lowered, this action being assisted by spring 296, thereby releasing the grip between stage 291 downward against the top 3) at the rear end of which is mounted upwardly extending bracket 312 whose upper portion is substantially coextenrsive with the base portion of stage 291. Bracket 312 has :a pair of recesses 313 in the front face thereof which :accommodate the respective ends of a pair of springs 314 which extend forwardly into corresponding horizontal apertures 315 in stage 291. Springs 314 normally urge :stage 291 forward from bracket 312.

Mounted on the front end of platform 271 is a pair of brackets 316 between which is mounted pin 317 which gpivotally supports adjustment bar 318. A short portion of bar 318 extends upward from pin 317 and the larger portion of said bar extends downward below said pin. Ihreadably inserted through the lower end of bar 318 is thumb screw 319 having a knurled head, the inner end of said screw bearing against downwardly extending bracket 1 321 connected to platform 271. Threadably inserted through the upper end of bar 318 is a thumb screw 322 having a knurled head, the inner end of said screw bearing against the forward vertical face of stage 291. Screw 322 serves as a coarse adjustment for the stage 291 relative to platform 271, while screw 319 serves as a fine adjustment means for the stage relative to the platform.

After platform 271 has been locked in position relative to base 31, it is necessary to adjust the knife to a position which is critical relative to the specimen. Hence, lever 303 of spindle 302 is rotated in a manner to permit free movement of stage 291 relative to platform 271, subject only to the action of springs 314 for a coarse adjustment. Screw 322 is rotated until an approximated position of coarse adjustment is reached, after which screw 319 is rotated to provide a fine adjustment to the precise position that is desirable for the knife, at which point lever 302 is rotated to lock stage 291 to platform 271, as described hereinabove.

The casting of stage 291 has an upwardly extending boss 325 that terminates in a split collar 326 whose longitudinal month 327 is formed by upper lip 328 and lower lip 329. See Figs. 2. 3 and 8. Positioned in vertical coaxial apertures in lips 328 and 329 and movable vertically therein is grip bolt 331, the lower end of said bolt bearing against the upper end of captive spring 332 in aperture 333 of lower lip 329 and which normally urges bolt 331 upwards.

Aperture 333 is intersected at right angles by horizontal aperture 335 in lower lip 329 which accommodates lever spindle 336, to the outer end of which is attached operat ing handle 337. Fig. 2. The inner end'of spindle 336 is reduced in diameter and has the form of a circular cam whose axis is displaced from the axis of spindle 336, thereby providing an eccentric which is inserted horizontally into mating aperture 338 in bolt 331 (Fig. 3).

Inserted horizontally in collar 326 is a cylindrical sleeve 340, having a longitudinal slot 341 (Fig. 11), and which is locked into position therein by turning spindle 336, causing bolt 331 to move downward to constrict month 327 thereby reducing the diameter of said collar which now grips the sleeve tightly. When lever 336 is rotated in the opposite direction, bolt 331 is moved upward assisted by the action of spring 332 whereby collar 326 is loosened to release sleeve 340.

While sleeve 340 is movable longitudinally within collar 326, the rotation of the sleeve relative to the collar is prevented by key 342 .(Fig. 3) extending longitudinally upon the outer periphery of the sleeve and riding in longitudinal mating keyway 343 in the inner periphery of the collar. Although key 342 and keyway 343 are shown in Fig. 3 as being intermediate the top and bottom of sleeve 340 and collar 326, respectively, the illustration in Fig. 8 shows the key and keyway at the top of the collar and sleeve respectively, in order more clearly to illustrate the action thereof. Of course, the key and keyway may be arranged in any other suitable position.

Longitudinally inserted into sleeve. 340 and fitting smoothly therewith is block 344 (Figs. 3, 8 and ll) secured into said sleeve by means of pressure plate 345 enclosing the outer end of the sleeve. Pressure plate 345 has an aperture 346 through which shoulder screw 347 extends and threadably engages aperture 348 in said block. Screw 347, which has a knurled head 349 for manual operation, causes a tight locking action between block 344, on the one hand, and pressure plate 345 and sleeve 340, on the other hand, the pressure plate being provided with an annular cam 351 which bears against a mating annulus 352 on one end of' sleeve 340; The

other end of sleeve 340 has an angular edge 353 which mates with and bears against an annular recess 354 on a flanged annular extension 355'on block 344. By loosening screw 347, block 344 may be adjustably rotated within sleeve 340 and subsequently locked therein in any desired position.

The internal diameter of sleeve 340 is slightly greater than the outside diameter of block 344 whereby the latter is freely movable longitudinally and radially within the former. When the assembly of block 344 and sleeve 340 are locked in position in collar 326, slot 341 permits the internal diameter of sleeve 340 to be reduced thereby assuring that the gripping action of collar 326 will be transmitted throughsplit sleeve 340 to block 344.

Flange 355 has a pair of extensions 356 and 357, respectively, which together form a holder for knife 358. Bottom extension 357 has a pair of studs 361 which serve as a support for one or two edges of the knife, while upper extension 356 has an obliquely downwardly extending threaded aperture 362 accommodating screw 363 having a knurled head 364 for manual operation, the end 365' of said screw being adapted to bear upon another edge of the knife. (Fig. 12). Studs 361 and the end 365 of screw 363 serve as a three point foundation for a knife which may be formed of a broken piece of glass.

Knife 358 may be cut from window glass or the like, having a suitable thickness, such as inch, for example,

substantially in the shape of a rhomboidal equilateral parallelogram with the cutting edge 366 having an acute angle, such as 45, for example. It is evident, however, that in cutting a piece of glass, its contour may be somewhat irregular and, therefore, the provision of a threepointfmounting-studs 361, screw point 365permits firm support and wide latitude of adjustment for the knife to bring its cutting edge to its optimum cutting position.

In order to provide additional rigidity to the mounting of knife 358, there is provided pressure plate 371 which is movable laterally between extensions 356 and 357 toward the outside vertical face of said knife, and which bears against it. and urges its opposite vertical face against the end of block 344. Plate 371 has a central aperture which accommodates shoulder screw 373 which rotates freely therein, the head of the screw being recessed below the clamping surface of the plate.

Pressure plate 371 is mounted on the inner end of stud screw 374 having a central longitudinal aperture 375 threadably engaged by screw 373. Stud screw 374, having a knurled head376 for manual operation, is threadably inserted into end plate 377 which in turn is secured to extensions 356 and 357 by means of screws 378. Thus, the rotation of screw 374 in stationary end plate 377 will cause pressure plate 371 to move laterally between extensions 356 and 357, whereby knife 358 may be released from, or tightened into, the knife holder. The provision of lateral adjustment of pressure plate 371 permits the knife holder to accommodate itself to knives of difierentthicknesses. It is understood, of course, that knife 358 may be made of suitable steel materials other than the glass knife that has been described.

.Qnce'knife 358 is tightened into its mounting in knife block 344, and while screw 347 is loose, the block is rotated within sleeve 340 until the cutting edge 366 is in lever spindle 336 has been rotated to loosen collar 326, sleeve 340 containing the knife mounting assembly may be moved laterally in respect of specimen 267 to the optimum cutting position, after which lever spindle 336 is rotated in the opposite direction and collar 326 tightened around sleeve 340, thereby locking the knifeholder as' sembly in position.

First, the cutting edge of the knife is sighted horizontally relative to the specimen while rotating block 344 within sleeve 340, and when the knife is aligned horizontally with the specimen, the block is locked in position Within the sleeve by tightening screw 347. During this first operation sleeve 340 is prevented from rotating by reason of the engagement of key 342 with keyway 343 in collar 326. Next, the operator sights the knife vertically while moving the assembly of sleeve 340 and block 344 laterally within collar 326 until the knife and the specimen are in vertical alignment at which point the knife assembly is locked in collar 326 by rotating spindle lever 336 by means of handle 337.

In operation, specimen block 266, in which specimen 267 is embedded, is mounted in chuck 262 of the specimen holder. Ball 258 is adjusted in socket 257, either radially, or angularly, or both, in respect of bar 111 to provide the optimum position for the specimen relative to cutting edge 366 of knife 358. Platform 271 is secured in position by manipulating handle 282 of lever 284, and the position of stage 291 relative to platform 271 is adjusted by means of the coarse and fine adjustment screws 322 and 319, respectively, after which handle 303 of lever 302 is manipulated to lock the stage to the platform. The cutting angle and the position of cutting knife 358 is adjusted by horizontal and vertical sighting of cutting edge 366 relative to specimen 267 as described hereinabove.

Specimen 267 is then oscillated past cutting edge 366 of knife 358 by the operator grasping handle 232 and rotating wheel 231; thereby causing the crank and'linkage connection between said wheel and bar 111 to move the latter in a path determined by the contours of aperture 288 in guide plate 225.

Referring to Fig. 13, specimen advancing bar 111 is shown in the process of moving downward in a vertical path whereby the specimen is moved past and against the cutting edge of the knife. After a slice of tissue has been cut from the specimen, cutting bar moves downward diagonally toward the left, after which it moves upward in a second vertical path thereby causing the specimen to bypass the cutting knife. A second diagonal cam edge of aperture 228 causes bar 111 to move upward to the right to a starting position, after which the cutting cycle is repeated.

In order to ensure a straight line motion in the vertical transit bar 111 in passing the specimen across knife 358, a starting recess A is 228, which is offset to the right from vertical edge B of said aperture. When bar 111 is caused to move downwardby the crank linkage, described hereinabove, bar 111 moves slightly toward the left as it emerges from recess A, and moves downward along edge B against which it is biased by the residual friction engendered between balls 1041and 105 upon pivot rod 101, said balls being spring biased upon the ends of said rod by spring blades 106- and 107 mounted on pivot block 91. See Fig. 5.

After the slicing action has taken place, bar 111 moves diagonally downward to the left along edge C of aperture 228 until it reaches recess D which is slightly olfset from vertical return edge E. The relationship of recess D to edge E provides for the same biasing action as recess A performs for the bar in respect of its transit along edge B. The return path of bar 111 is defined by aperture edge E provided at the top of aperture 7 whereby the specimen bypasses the knife at a safedistance, after which cutting bar 111 is returnedalong the upwardly extendingdiagonaledgeiG of aperture 228 to" its'o'riginal positoin in recess-A."

It will be remembered marine linkage" between crank disc 235 and bar 111 is loosely articulated at its upper and lower ends. See'Fig'. 13 anddes'criptio'n-above. This was provided in order to pe'rmit bar 111'to rotate pivotally within guide plate'225whose plane is substantially perpendicular to the plane" 'ofrotation of crank pin 242. In order to take up the slackthatsucha linkage entails, the downward pull of' spring113 (Fig. 4) continually urges the forward end'of bar 111 upwards, thereby obviating'any play that might otherwise existbetween pin 242 and link 243, and between link 245 and pin 246, respectively.

in previous microtomes, static-friction engendered by the motion of the specimen holder andits whole assembly has introduced aberrations into the advancing mechanism which has caused undesirable variations in the tissue slicing operation. In the microtome of the present invention, however, static friction has been reduced, if not eliminated entirely, by havingthe bar 111', mo'v'ing principally only at its forward end, describe a virtually circular motion, thus avoiding the complete stop' and reversal actions that are characteristic of other instruments. At the same time this circular motion of bar 111, and, accordingly, of the specimen holder enables the tissue specimen to bypass the knifeedge on the return stroke, thus eliminating possible damage to the tissue block and the specimen embedded therein.

The'apparatus of the present invention provides this bypass action by means of the novel pivot action whereby the specimen on the forward end of bar 111 is moved in a virtual circular plane while the rear end of the bar is based in a bearing ball pivoting assembly which ensures; dimensional stability without sa'ciificingany degree of accuracy and of flexibility of operation.

The specimen is advanced Each 360 linkage near the forward end of the bar.

Lever arm 171 moves with bar 111 and lifts rod 175,' on each upward stroke, thereby causing ratchet wheelfi 188 to rotate a predetermined radial distance, depending; upon the pre-selection made on knob 211, as described Upon rotation of ratchet wheel 188, screw' 120 is likewise rotated the same distance to cause the:

advance toward the cutting knife. It will' hereinabove.

desirable to prevent the pawl from bouncing or chatter ing on said teeth in its returnstroke so as to eliminate any vibrations that might otherwise be imparted to the specimen.

In one typical embodiment, ratchet wheel 188 has teeth 187, while threads 121 of screw have a thread I one complete revolution of ratchet wheel 188 advances block 144 a distance of 0.5

pitch of 0.5 mm. Therefore,

mm. If cam disc 192 were arranged to permit pawl 186 to engage teeth 187 of wheel 188 at such a position whereby said wheel would be advanced the radial space of only 144 would advance only one tooth, then rider block 0.005 mm.

Referring to the compound pivot mounting of cutting". bar 111, the common horizontal axis of balls 65"and 76 is spaced apart vertically from the common horizontal axisof balls 95 and-.96, as is schematically illustrated in.

toward the cutting knife in minute increments whereby extremely thin tissues are cut. turn of wheel 231 moves bar 111 through one complete cutting cycle by means of the'connecting rod:

is bypassing the knife. When bar 186 moves Fig. 5A. In the embodiment referred to, these two horizontal axes are spaced apart by 0.025". If the overall length between pivot point 139 of yoke 80 and leg 87 and the pivot mounting on balls 65 and 76 is 5", and the transmitted force is applied to balls 95 and 96, which serve as the pivot point for bar 111 and which are ofiset from balls 65 and 76 by 0.025, it can be seen that a reduction ratio of 200:1 is obtained.

Assuming that ratchet wheel 188 is advanced radially by a distance of one tooth on the periphery of said wheel, and rider block advances 0.005 mm., since the forward motion of bar 111 is only 5 of the motion of rider block 144, as illustrated schematically in Fig. B (where for purposes of clarity of illustration, the block actually has been displaced by a greater number of turns on screw 120), the specimen, attached to the forward end of bar 111, advances toward knife edge 366 by of 0.005 mm., or 0.000025 mm., which is equivalent to 0.025 micron, or micron. I

It is apparent that the thickness of tissues to be cut in multiples of a micron may be predetermined by manipulating knob 211 to rotate cam disc 192 thereby permitting pawl 186 to engage peripheral teeth 187 of ratchetwheel 188 at distances indicated on the calibrated scale 212on knob 211 in order to provide a greater amount'of rotation on screw 120 to cause bar 111 to advance the proportionately greater distance toward the cutting knife.

Although the axis of the pivot mounting forbar 1 11 of balls 95 and 96 has been described as being slightly below the axis of the pivot mounting of yoke 80 on balls 65 and 76, it will be understood that the positions of these respective axes may be reversed in some embodiments provided the direction of the screw threads 121 is reversed on screw 120 with a corresponding reversal of the'other cooperatin gparts. In either case, the combination of yoke 80 and leg 87, acting as a lever, provide the means for advancing the specimen to the cutting knife. g

In the specification, I have explained the principles of my invention, and the best mode in which I have contemplated applying those principles, so as to distinguish my invention from other inventions; and I have particularly pointed out and distinctly claimed the part, mode or combination which I claim as my invention or discovery.

While I have shown and described certain preferred embodiments of my invention, it will be understood that modifications and changes may be made without departing from the function and scope thereof, as will'be clear to those skilled in the art. 7

I claim:

1. A microtome comprising a base, a cutting knife mounted on said base, a first frame mounted on said base,

a second frame mounted on said first frame and pivotable' vertically relative thereto, advancing means mounted on said second frame and pivotable horizontally relative there to, and a specimen mounted on the outer end of said ad vancing means extending towards said knife, said advancing means and said specimen being movable in all lateral directions relative to said knife.

2. A microtome comprising a base, a cutting knife mounted on said base, a supportmeans mounted on'said base, a frame, a first pivot mounting connecting "said frame to said support means for pivoting motion inone direction, specimen advancing means, a second pivot mounting connecting one end of said advancing'means to said frame for pivoting motion in a 90- direction relative to the first pivoting motion, both of said pivot mountings together forming a compound pivotmounting for said advancing means whereby the other end of said'advancing' means may be moved laterally in all directions.

3. A microtorne comprising a base, a cutting knife mounted on said base, a support means mounted on said base, a frame, a first pivot'mounting connecting said frame to said support means for pivoting motion in one direction, specimen advancing means, a second pivot mounting connecting said advancing means to said frame for pivoting motion in a direction relative to the first pivoting motion, both of said pivot mountings togther forming a compound pivot mounting for said advancing means whereby the outer end of said advancing means may be moved laterally in all directions, each of said first and second pivot mountings comprising a pair of balls, and spring loading means in which said balls are seated.

4. 'A microtome comprising a base, aknife mounted on said base, a support means mounted on said base, a lever pivotally connected to said support means, a frame, a first pivot mounting connecting said frame to said lever for pivoting motion in one direction, specimen advancing means adapted to hold a specimen on its outer end, a second pivot mounting connecting said advancing means to said frame for pivoting motion in a 90 direction relative to the first mentioned pivoting motion, both of said pivot mountings together forming a compound pivot mountingfor saidadvancing means whereby the outer end of said means may be moved lateraly in all directions, the first pivot mounting being slightly spaced apart from the fulcrum of said lever whereby the movement of the latter causes the outer end of said advancing means to move toward said knife.

5. A microtome comprising a base, a knife mounted on said base, a support means mounted on said base, a lever pivotally connected to said support means, a frame, a first pivot mounting connecting said frame to said lever for pivoting motion in one direction, advancing means adapted to hold a-specimen on its outer end, and a second pivot mounting connecting said advancing means to said frame for pivoting motion in a 90-direction relative to the first mentioned pivoting motion, both of said pivot mountings together forming a compound pivot mounting for said advancing means whereby the outer end of said means may be moved laterally in all directions, the first pivot mounting being spaced apart from the fulcrum of said lever whereby the movement of the latter causes the outer end of said advancing means to move toward said knife, each of said first and second pivot mountings comprising a pair of balls.

6. A microtome comprising a base, a knife mounted on said base, a support means mounted on said base, a lever pivotally connected to said support means, a frame, a first pivot mounting connecting said frame to said lever for pivoting motion in one direction, advancing means adapted to hold a specimen on its outer end, a second pivot mounting connecting said advancing means to said frame for pivoting motion in a 90 direction relative to the first mentioned pivoting motion, both of said pivot mountings together forming a compound pivot mounting for said advancing means whereby the outer end of said means may be moved laterally in all directions, the first pivot mounting being spaced apart from the fulcrum of said lever whereby the movement of the latter causes the outer end of said advancing means to moved toward said knife, each of said first and second pivot mountings comprising a pair of balls, and spring loading means in which said balls are seated.

7. A microtome comprising a base, a knife mounted on said base, a support means mounted on said base, a lever, one end of said lever being in the form of a yoke, the yoke portion of said lever being pivotally connected to said support means, a frame, afirst pivot mounting connecting said frame between the arms of said yoke for pivotaing motion in one direction, advancing means adapted to accommodate a specimen on one of its ends, a second pivot mounting connecting the other end of said advancing means to said frame for pivoting motion in a 90 direction relative to. the first mentioned pivoting motion, both of said pivot mountings together forming a compound pivot mounting for said advancing means whereby the specimen end of said means may be moved laterally in all directions, the first pivot mounting being Spaced apart from the fulcrum of said lever whereby the movement of the latterncause s the .specimenend of said advancing means to move toward'said knife.

8. A microtomecomprising a base, a knife mounted on said base, a support means mounted on said base, a lever, one end of said lever being .in he form of a yoke, the yoke portion of said lever being pivotally connected to said supportmeans, aframe, a first pivot mountingcbnnecting said frame between the arms ;of said yoke for pivoting motion in one direction, advancing means adapted to accommodate aspecimen on one of its ends, and a second pivot mounting connecting the other end of said advancing means to saidfr'a'me for pivoting motion in a 90 direction relative to the first mentioned pivoting motion, both of said pivot mountings tQgether forming a compound pivot mounting for said advancing means whereby the specimen end of said means maybe moved laterally in all directions, the first pivot mounting being spaced apart from'the'fulcrum of said leverwhereby the movement of the latter causes the specimen end of said advancing means to 'move toward said knife, the pivotal connection of the lever to the support means and the first and second pivot-mountings each comprising a pair of balls.-

9. A microtome comprising a base, a knife mounted on said base, a support means mounted on said base, a lever, one end of said lever being in the form of a yoke, the yoke portion of said lever being pivotally con nected to said support means, a frame, a first pivot mountingconnecting said frame between the arms of said yoke for pivoting motion in one direction, advancing means adapted to accommodate a specimen on one of its ends, a second pivot mounting connecting the other end of said advancingmeans to said frame for pivoting motion in a 90 direction relative to the :first mentioned pivoting motion, both of said pivot mountings together forming a compound pivot-mounting for said advancing means whereby the specimen end of said means may be moved laterally in all directions, the first pivot mounting being spaced apart from the fulcrum ofsaid lever whereby the movement of the latter causestbe specimenend of said advancing means to move toward said knife, the pivotal connection of the lever to the support-means and the first and second pivot mountings each comprising a pair of balls, and a spring loaded mountingfor each of said pairs of balls. r

10. A microtome comprising a base, aknife mounted on said base, asupportmeans mounted on said base, a specimen holder adapted to accommodate a specimen on its outer end, a compound pivoting connection on the other end of said specimen holder connecting the latter of said support means whereby said specimen maybe moved in all lateral directions relative to said knife, a guide plate mounted on said ;base an aperture in said plate through which the outer end of said specimen holder extends, the contours of said guide plate causing said specimen holder to carry said specimen past said knife in one direction only and to bypass the specimen around said knife during the remainder of the motion of said specimen holder.

11. A microtome comprisinga base, a knife mounted on said base, a support means mounted 'onisaid base, a specimen holder adapted to accommodate a specimen on its outer end, a compound pivoting connection on the other end-of said specimen holderconneoting the latter to said support means whereby'said specimen maybe moved in all lateral directions relative to sa-id knife, a guide plate mounted on said-base, an aperture in said plate through which the outer end of said specimen holder extends, the contours of said guide plate causing said specimen holder to carry said specimen past said knife in one direction only and to bypass the specimen around said ,knife during the remainder of the motion of said specimen holder, means for moving said compound pivoting connection towards said knife, (and means for moving said specimen tholder in cycles within said aperture.

1'8 l-2.- A- microt ome comprising a base, a knifemounted on saidbase, a support means mounted on "said base, a specimen holder adapted to accommodate a specimen-on its outer end, a plurality of spring loaded balls forming a compound pivot mounting on the other end of said specimen holder connecting the latter to 'said support means whereby said specimen may-be moved in all lateral directions relative to said knife, a guide .plate mounted on Said'base, n aperture injsaid plate through which the outer end of said s ecimen holder e xtends, the contours of said guide plate causing said specimen holder to carry said specimen past said knife in .one direction only and to" bypass the specimen around said ,knife during the remainder ofthemotion of said specimen ho1der,'m;eans for moving said compound pivot mounting towards said knife, means for moving. said specimen holder in cycles within said aperture, said spring loaded piqvt mounting being adapted to provide a biasing action to urge said I holder toward the edges of said aperture.

13. A microtome comprising a" base, support means mounted on said base, a lever pivotally connected to said support means, a frame, a first pivot mounting con? necting said frame to said lever for pivoting motion in one direction, advancing means adapted to accommodate a specimen on oneof its ends, a second pivot mounting connecting the other end 'ofsaid advancing means to 'saidframe for pivotingmotion in a" direction relative tothe first mentioned pivoting motion, both of said pivot mountings together forming a compound pivot mounting for said advancing means whereby the specimen end of said means may be moved laterally in all directions, the first pivot mounting being spaced apart from the fulcrum of said lever whereby the movement of the latter causes the-specimen end of the advancing means to move toward a cutting knife, a screw mountedlongitudina'lly relative to said advancing means in saidba'se, thread mejanson saidscrew and on the thrust end of said leverinterengaging to causesaid lever to move in accordance with the rotationof said screw. a V c i 14. A'microtome according to claim 13 whereinsaid interengaging screw thread means comprises buttress threads, andfurthercomprising spring means connected between said lever and said support means whereby said thread interengaging means areurgedtogether to obviate backlash and lost motion. v a

'15. A microtome according to clai1n14, and further comprising means for disengaging said intereng'aging thi'ead means. T i

16. A micro ome according to claim 14, and further comprising a pair of balls, in which the respective ends first. pivot mounting connecting one end of said lever .to

holding a specimen on the advancing means, means the other senditof men is .passed across sard knife during one portion ;.of' 7 said oscillation and bypasses the knife laterally during another portion of said oscillatio 19. A microtome accordingto claim 18, and further comprising means oscillating withsaid oscillating means and operative toca'use the movement ofsaid levero y I during thefportion .of oscillation'of said advancing me when thes-pecimen bypasses the knife;

- 2.0. Amicrotome comprising a'knif'e, a specimen'liold freely movable portion of said 7 er, a lever to which said holder is pivotally connected, said lever being adapted to move said specimen holder toward the knife, a screw mounted substantially parallel to said specimen holder, a yoke mounted pivotally on the thrust end of said lever, a rider block mounted on another portion of said yoke, threads on said block adapted to mesh with the threads on said screw, spring means bearing upon said yoke to urge said block into engagement with said screw, and means adapted to disengage said block from said screw against the action of said spring means.

21. A microtome comprising a knife, a specimen holder, a lever to which said holder is connected, said lever being adapted to move said specimen holder toward the'knife, a screw mounted substantially parallel to said specimen holder, means pivotally connected to said lever for engaging the threads of said screw whereby the rotation of said screw causes said lever to move, means adapted to oscillate the specimen holder laterally relative to the cutting knife, a ratchet wheel mounted fast onsaid screw, and means oscillating synchronously with the lateral movement of the specimen holder and adapted to engage said ratchet wheel and move the latter within a predetermined distance.

22. A microtome comprising a knife, a specimen holder, a lever to which said holder is connected, said lever being adapted tomove said specimen holder toward the knife, a screw mounted substantially parallel to said specimen holder, means pivotally connected to said lever for engaging the threads of said screw whereby the rotation of said screw causes said lever to move, means adapted to oscillate the specimen holder laterally relative to said knife, a ratchet wheel mounted fast on said screw, means oscillating synchronously with the lateral movement of the specimen holder and adapted to engage said ratchet wheel and move the latter within a predetermined distance, and means for adjusting the position at which oscillating means engages said ratchet wheel whereby the degree of rotation of said screw is controlled.

23. A microtome according to claim 22, and further comprising a pawl connected to said oscillating means and adapted to engage the teeth on said ratchet wheel during one movement of said oscillating means and to disengagev from the teeth of said ratchet wheel during the return movement of said oscillating means.

24. A microtome comprising a knife, a specimen holder, a lever to which said holder is connected, said lever being adapted to move said specimen holder toward the knife, a screw mounted substantially parallel to said specimen holder, means pivotally connected to said lever for engaging the threads of said screwwhereby the rotation of said screw causes said lever to move, means adapted to oscillate the specimen holder laterally in all directions relative to said knife whereby the specimen is passed across the cutting edge of the knife during one portion of its motion and bypasses the cutting knife during another portion of its motion, a ratchet wheel mounted fast on said screw, means oscillating synchronously with the movement of the specimen holder, a pawl on said synchronous oscillating means adapted to engage said ratchet wheel, means connected to said pawl for determining the distance within which said pawl engages said ratchet wheel whereby the degree of rotation of said screw is controlled, and means connected to said pawl for disengaging said pawl from said ratchet wheel during a portion of the motion of said synchronous oscillating means, said pawl being arranged to engage said ratchet wheel only when the specimen bypasses the knife.

25. A microtome according to claim 24 wherein said means for determining the distance within which the pawl engages the ratchet wheel comprises a cam dis, a cam surface on said disc, a second pawl connected to said first mentioned pawl and adapted to engage said cam 20 disc whereby said first pawl is caused to engage and disengage said ratchet wheel.

26. A microtome according to claim 25, and further comprising means for rotating said cam disc thereby controlling the distance during which said first pawl engages said ratchet wheel.

27. A microtome according to claim 26, and further comprising a spring connected to both of said pawls, a friction disc mounted coaxially relative to said cam disc, said spring being engaged frictionally between both of said discs whereby during a portion of the movement of said synchronous oscillating means the first mentioned pawl is caused to disengage promptly from the teeth of the ratchet wheel.

28. In a microtome, a mechanism for advancing the specimen toward the knife comprising a lever, a pivot mounting for said lever near one end thereof, a specimen holder connected pivotally to said lever, the pivotal connection between said specimen holder and said lever being slightly displaced from the first mentioned pivot mounting, and a screw engaged by the other end of said lever, the rotation of said screw causing the specimen holder to be advanced.

29. A mechanism according to claim 28 wherein said pivot mounting and pivotal connection each comprise a pair of balls.

30. A mechanism according to claim 29, and further comprising a spring loading for each of said pairs of balls.

31. In a microtome, a mechanism for advancing the specimen toward the knife comprising a lever, apivot mounting for said lever near one end thereof, a frame pivotally connected to said lever for movement in one direction, the pivotal connection between said frame and said lever being slightly displacedfrom the first mentioned pivot mounting, a specimen'holder pivotally connected to said frame for movement in a direction relative to the movement of said frame, and a screw engaged by the other end of said lever, the rotation of said screw causing the specimen holder to be advanced, the combined pivot mountings of said frame and said specimen holder permitting the free end of said specimen holder to be moved substantially in any desired lateral direction.

32. A mechanism according to claim 31 wherein each of said pivotal mountings comprises a pair of balls.

33. A mechanism according to claim 32, and further comprising a spring loading for each of said pairs of balls.

34. A microtome comprising a knife, a specimen holder, a lever, said specimen holder being pivotally connected near one'end to said lever whereby its other end may be moved laterally in any desired direction, a specimen on said other end of the specimen holder, a screw mounted substantially parallel to said specimen holder, means on said lever for engaging the threads of said screw to cause the specimen holder to move the specimen toward the knife, means adapted to oscillate the free end of said holder laterally relative to the cutting knife, a guide plate, and a guide aperture in said plate through which the specimen end of said holder extends, the contours of said guide plate being arranged tocause the specimento pass in one direction only across the cutting edge of theknife and to bypass the knife in the remainder of its movement.

35. A microtome according to claim 34 wherein the means'adapted to oscillate the freeend of said holder comprises a crank, a loosely articulated link connected between said crank and said holder near said specimen and spring'm'eans mounted on said holder for taking up the slack in saidlink.

36. A microtome according to claim 34, and further comprising spring loading upon the pivotal connection of the specimen holder to said lever whereby said holder 21 is caused to be urged against the edges of said guide aperture.

37. A microtome comprising a knife, a specimen holder assembly, means for moving said assembly toward said knife, a chuck for gripping the specimen, and a ball and socket joint by which said chuck is connected to said assembly whereby the specimen may be adjusted in position rotatably or an'gularly in respect of the cutting edge of the knife.

38. A microtome comprising a knife, a chuck adapted to hold a specimen to be cut by the knife, a holder in the form of a bar, one end of said bar having a pivot mounting whereby the other free end of said bar is movable laterally in any desired direction in respect of the knife, and a ball and socket joint by which said chuck is connected to the free end of said bar whereby the specimen may be adjusted in position rotatably or angularly in respect of the cutting edge of the knife.

22 39. A microtome according to claim 38, and'further comprising means for rotating the free end of said bar to cause the specimen to pass across the cutting edge of the knife during one portion of its motion and to bypass the cutting edge of the knife during another portion of its motion, and means for moving said bar toward said knife in predetermined increments only when the specimen is bypassing the knife.

References Cited in the file of this patent UNITED STATES PATENTS

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