250 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Electric Warm-Stage, for Use with the Microscope, combined 

 with a Nernst Lamp to Illuminate the Microscope. — H. C. Ross gives 

 the following description of this apparatus (figs. 48 and 49) exhibited at 

 the December Meeting. 



"With the assistance of Engineer-Lieut. Fielder, R.N., I have in- 

 vented an electric warm-stage, which has the following advantages : — 

 (1) As it fits on top of the slide, it can be slipped on or off without alter- 

 ing the focus. (2) It can be used with the highest powers of the Micro- 

 scope and with the Abbe condenser. (3) It does not interfere with the 

 movements of the mechanical stage, the warm-stage moving backwards 

 and forwards with the slide. (4) It requires no attention, for so long as 

 the current is running through it, so long will the temperature of the 

 centre of the slide be 9r ' 



3/°C. 



Fig. 48. 



" The apparatus consists of a box of ebonite, about the same length 

 as but a little wider than an ordinary slide, and it is three-eighths of an 

 inch thick. There is a gap in the centre 1 in. square, to allow for the 

 cover-slip and objective of the Microscope. 



" Pressed into the ebonite box is a coil of wire, which offers a standard 

 resistance to the electric current, and this again is covered in by a sheet 

 of mica — the mica surface being in contact with the slide. Two wires 

 connect the warm-stage with the main electric light circuit. Two brass 

 clips are supplied with each apparatus, so that the warm-stage can be 

 clipped on to the slide if desired. 



" That the temperature of the centre of the slide can be maintained at 

 37° C, it is necessary that there should be a certain amount of resistance 

 on one of the wires connecting the apparatus with the light circuit, which 

 resistance varies according to the voltage. In the first apparatus I made, 



* C. Reichert (Vienna), Catalogue No. 25 (Mikroskopie, 1904) pp. 12-13. 



