THE LANTERN MICROSCOPE. 267" 



II. 



THE LANTEEN MICEOSCOPE. 



WE need not describe in detail the Lantern Microscope. The only 

 importance it has for science consists in the fact that the 

 magnified image of an object can thus be exhibited to several 

 spectators at once, which is advantageous in public lectures. Its 

 applicability is, however, limited to objects which can be seen 

 distinctly with the compound Microscope and low powers ; fine 

 structural details that require more powerful objectives are not 

 reproduced distinctly enough in the image to enable them to be- 

 demonstrated to the uninitiated. This is especially true when the 

 illumination is effected by electric light, or by Drummond's lime- 

 light, both of which are much inferior to sun-light in intensity. 

 Moreover, the employment of this instrument is accompanied by 

 conditions which materially diminish its practical value. We 

 consider demonstrations are more satisfactorily made with the 

 Microscope proper than by the indistinct images of a photo-electric 

 or gas Microscope. A relatively favourable impression has been 

 made upon us hitherto by the results obtained with low-power 

 objectives only particularly the enlargements of photographs- 

 upon glass. 



The objectives of the lantern Microscope are constructed 

 precisely like those of the compound Microscope, except that 

 the lenses are not usually cemented together with Canada balsam,, 

 because this method of union might be injured by the heat 

 produced by the illumination. Mohl states that he has employed 

 ordinary objectives for the solar Microscope without injuring 

 them, and that Plcessl has found no inconvenience arise from 

 cementing the lenses together. 



The mechanical arrangement of the illuminating apparatus 

 varies, of course, according to the source of light employed, 

 We think it unnecessary to enter into the details of construc- 

 tion, as the devices in use at the present time are described in 

 most of the text-books of Physics, and are scarcely within our 

 province. 



