bU« 



SUMMARY OF CURRENT RESEARCnES RELATING TO 



Fig. 148. 



if the milleil head of tbo fine-adjustment bo graduated, tlie thickness of 

 the licjuid hxycr is easily ascertained. 



The third tube (fig. 148) is less simple than the foregoing, but it is 

 constructed so that it gives the thickness of the liquid layer at once. It 

 consists of (1) a metal tube, the lower end closed by glass, while the 

 upper end is expanded ; (2) of another tube to dip into the former and 

 closed at the lower end by glass. But the 

 latter tube, instead of being screwed to the 

 Microscope, is screwed to an arm, the upright 

 of which is fixed to the edge of the first or 

 outer tube, so that by turning the inner tube 

 round it sinks or rises, and thereby produces 

 a thinner or thicker layer of fluid. The 

 depth of the liquid is measured by means of 

 a millimetre scale marked on one side of the 

 upright. The head of the internal tube almost 

 touches this scale, and hence it is easy to read 

 ofi" the number of millimetres the tube has 

 risen or fallen. This procedure is facilitated 

 for fractions of millimetres by dividing the 

 upper surface of the disc into 10, and each 

 of these divisions into two parts, by which a 

 tenth or twentieth of a millimetre is given. 



In order that the instrument may be more 

 easily cleaned and fixed at zero, the upright 

 is made in two pieces, the outer being fixed 

 to the inner tube, and the inner one to the 

 outer tube. I'he two pieces are kept tight 

 by a binding-screw. When a liquid is to be 

 examined, the outer piece is withdrawn, and 

 the milled head of the other turned until 

 the zeros of the two scales coincide ; the tube is then slipped in so 

 that the two glasses at the lower extremities are in apposition. The 

 binding-screw is then tightened up. This position evidently corresponds 

 to the thickness 0. 



Weiss, D.—X7eber das FleiscM'sche Hamometer. (On the FleiscLl Hpemometer.) 



Pnigcr Med. Woc/ie7ischr., XIII. (1888) p. 20. 



C4) Photomicrography. 



Burstert's Photomicrographic Apparatus.* — Dr. H. Burstert's appa- 

 ratus is shown in fig. 149. The camera A is attached to the wooden 

 stand L R S, the end of the expanding bellows bein?? also fixed to the 

 piece W which carries the Microscojie, the stage m, and the illuminating 

 apparatus fed. W slides in a blot on R, and may be adjusted to any 

 desired distance from the focusing plate. The various parts of the illu- 

 minating apparatus are made to slide upon an iron bar screwed to W, so 

 that they may be adjusted independently. 



The whole apparatus is set at any desired inclination by means of 

 the chain K and leg S, and it may be used vertically or horizontally. In 

 the latter case the mirror / is removed, and replaced by the source of 



* Jescrich, P.. ' Die Mikrophotographie,' 8vo. Berlin, 1888, pp. 98-9 (1 fig.). 



