ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



305 



from the battery enter and leave at p n respectively. The former is 

 connected, through the arm /, with 7 spiral German-silver wires Ji i 

 of different thickaesses, contained in the vfooden base, which act as a 

 rheostat to increase or diminish the intensity of the current received 

 by the lamps. By means of the arm / the current can be made to 

 pass through any one (1-7) of the wires until the proper degree of 

 illumination is obtained. At the other end the wires are, by the arm g, 

 put in connection with any one of the three wires I, II, or III. These 

 are connected with the end of the treble wire r c, and from the latter 

 point are led separately either to the large or small lamp or to the 

 stage B, where (at d) the current is made use of for heating purposes.* 

 The wire from n is in communication with the foot of the Microscope, 

 the latter thus serving as a conductor for the return current. 



A simpler form of Microscope is show^n in fig. 49 A (with photo- 

 micrographic camera B attached). The lamp I is beneath the stage, 

 replacing the mirror, and is put in communication with the battery 



Fig. 50. 



Fig. 51. 



Fig. 52. 



f-K+o d 



f^ ^e 



G by the wires p n, p' n' and s. The piece r is for raising or 

 lowering the lamp without having to touch it when hot ; {d is the 

 milled head for the coarse adjustment, and / g the trunnions on which 

 the body-tube and also the stage are inclined). 



For a separate lamp Dr. Stein uses the stand fig. 50, which is 

 practically identical with that of Mr. Stearn.f 



The lamps used by Dr. Stein are shown in figs. 51 and 52 and are 

 identical with the Swan lamps in use in this country. A is the small 

 lamp with its spiral socket B, and C the larger lamp. (The connecting 



* Dr. Stein's -warm-stage arrangement will be described in a subsequent 

 number of the Journal in connection with a summary of the various warm-stages 

 which have been suggested. 



t Loc. cit. 

 Ser, 2.— Vol. V. X 



