CENTRAL SCIENTIFIC CO., CHICAGO, U. S. A, 353 



No. 8022. No. 8925. 



S922. MICROTOME, Spencer Rotary, intended for the most accurate and careful work. An inclined 

 plane feed, which is independent of the up-and-down movement on the perpendicular support, 

 overcomes the inaccuracies inherent in other rotary microtomes. The provision of an accurate 

 and reliable feed mechanism, combined with the utmost rigidity of parts, make this instru- 

 ment the most precise and accurate for laboratory or research work. Sections may be cut 

 of any definite thickness, each section having the same thickness. 



The feed mechanism is composed of a rigid bearing, on which the feed block is moved by an 

 accurate screw, cut with two threads to the millimeter; it is -revolved by a ratchet feed wheel 

 with 250 teeth; each tooth represents therefore a movement forward of the object of one 

 micron. The feed is so arranged that it can be set for sections of any thickness, from 1 

 micron to 60 microns, by turning the knurled button at the back of the case until the number 

 representing the desired thickness appears opposite the indicator at the small opening in the 

 side of the case near the balance wheel. The total excursion of the feed is 37 mm, allowing 

 a sufficient range for cutting a complete series of a very large object without the necessity 

 of a break due to resetting the knife and feed mechanism. 



The up-and-down stroke of the object clamp is 50 mm which permits the cutting of very large 

 sections and gives sufficient stroke for celloidin cutting. The clamp may be held at its upper 

 limit for orienting or trimming the block by pushing in a pin. The object may easily be 

 rotated. 



The knife is fastened by two clamps, each of which clamps the knife at the back and along IVt 

 inches of the edge as well. It may be turned to any desired angle, and the clamps may also 

 be moved toward one another to bring them as near to the ribbon as desired to gain addi- 

 tional rigidity. When the clamps are thus drawn together, the knife may be moved so that 

 practically all of the cutting edge can be used before the necessity of resharpening. The 

 adjustment screws provide for knives of different widths. The whole knife support is adjust- 

 able to and from the object, and is very easily and conveniently clamped in any location by a 

 lever connected with an eccentric cam. 



The whole of the feeding mechanism is covered, protecting the wearing parts from dust and 

 presenting a very neat appearance. The top of the case is hinged to the lower part, permit- 

 ting it to be easily opened. The balanct wheel is grooved, so that the instrument may be 

 run by a motor. The whole microtome is finished in crystal black, alcohol-proof enamel. The 

 smaller parts are heavily nickel-plated. 



When desired, the microtome is provided with an adjustable knife support which is especially 

 adapted to celloidin sections. The knife holder of this support is adjustable from a horizontal 

 position through 55 upward. Complete with one knife, handle and back for sharpening, and 

 with three object disks $130.00 



8923. KJMJ_t'; HOLDER for Xo. 8922, for celloidin sections 15.00 



8924. KNTFE HOLDER, Adjustable, for No. 8922, permitting the entire block carrying the knife to 



be shifted 1 !> inches either way from center 10.00 



8925. RIBBON CARRIER. Spencer Cylindrical, for use with No. 8922, consisting of an aluminum cyl- 



inder mounted in an aluminum frame, under the base of which are small rollers, rolling in 

 the direction of the long dimension of the frame. The end of the ribbon adheres to the evl- 

 inder, which is slightly turned by the knurled heads shown in the illustration as the ribbon 

 lengthens. At the same time, the cylinder and frame are gently pushed forward on the rollers 

 to place the ribbon on the cylinder in a long spiral. The cylinder has flanges at the ends so 

 that when it is removed from its bearings and placed on a sheet of paper on the table, the 

 sections of the ribbon are not injured. When in this position each turn of the spiral may be 

 cut and one turn after another, each approximately 8 inches long, may be spread out in order 

 on the paper. The cylinder is 4% inches long, 2% inches in diameter, and mounted so as to 



bring it as close as possible to the microtome knife 8.00 



S926. TABLE fur Xo. S922, complete with motor and speed regulator, all enclosed. Length, 38 inches; 

 width, 26 inches; oak finish. 



Xo A B C D 



A.C. D.C. 



For volts 110 220 110 220 



Each 80.00 98.75 75.00 93.75 



