890 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



At tho short ends of tho instrument aro fitted two plates R and 

 R', which are connected by a middle vertical plate S, 1 cm. thick, 

 which serves to carry tho object-holder. On one side is a wedge- 

 shaped cleft /, ascending 5 per cent. ; on this the object-carrier or 

 slido X is supported. The object-carrier xyzz' somewhat resembles 

 that of Gottscbau, but is modified in detail. As a coarse adjustment 

 is of great advantage, Gottschau's clamp arrangement is so modified 

 that the screws themselves act as axes. The screw w, which allows 

 the pincers to move vertically in a plane parallel to the middle wall, 

 fits into a dovetailed tenon moving upwards and downwards 2^ cm. 

 in a groove in the carrier; turning the screw raises the pincers 

 vertically. 



The long microtome-screw T for raising tho slide lies parallel to 

 and outside the middle vertical wall. Its supporting points are at U 



and V. It traverses a middle piece, which is united to the carrier, 

 and is worked by means of two dovetailed parts which through the 

 screw can be pushed up the inclined plane in a slit (ascending 5 per 

 cent.) in the middle piece. Backlash is avoided by a special ar- 

 rangement of two tightening screws A A at V. The screw is turned 

 by a milled head 2 with ten divisions. One turn pushes up the slide 

 1 mm., raising the object 0*05 mm. A small spring catch clicks for 

 every thickness of 0*005 mm. The middle piece W through which 

 the long micrometer-screw passes, opens by means of a horizontal 

 joint /a v, and is kept fastened by the screw £. Any inequality in the 

 motion of the long lever screw is prevented by means of a spring it, 

 which presses the jointed divisions fx v together. A thick screw (14 mm. 

 diameter) is chosen, because it is easier to work and less liable to 

 bend. On the middle wall S a millimetre scale 20 cm. long is 

 screwed on at Y with a vernier Z. Measurements as fine as 

 0*005 mm. are made by means of a vernier fixed to the carrier. 



Weigert's Immersion Microtome for large Sections.*— Prof. C. 

 Weigert has adapted the Gudden microtome for cutting sections 



* Zeitschr. f. Wiss. Mikr., ii. (1885) pp. 326-33 (2 figs.). 



