DRAWING WITH THE MICROSCOPE. 149 



being possessed by the optical part, the instrument is 

 just as perfect and manageable without its stage as with it, 

 and may be used upon any large body whatever > which will 

 be found a great convenience. This construction also 

 gives great facilities for demonstrating all sorts of test 

 objects, as well as for verifying and proving the nature of 

 bodies inspected (a subject which is as yet understood 

 by few observers.) 



With respect to the exhibition of larvae, &c. in the 

 solar microscope, it may be observed generally, that what- 

 ever object-glass shews them well in a compound aplanatic, 

 with the assistance of the body and eye-glasses, will shew 

 them unassisted in the solar instrument, because the dis- 

 tance to which the rays are suffered to diverge does the 

 work of the compound body in giving the necessary 

 amplification, which it is the peculiar property of this 

 instrument to effect to a vast extent, without altering the 

 size of the field of view. A solar microscope may in fact 

 be defined in its optical principle as a mere object-glass, 

 forming an image on a skreen, instead of the space in- 

 cluded in the field bar of a compound body. 



C. R. G. 



