ZOOLOGY AND BOTANY, MIOROSCOPY. ETC. 



459 



second lamp supplied for illuminating opaque objects from both sides of 

 the instrument, so as to avoid the influence of shadows. The whole of 

 the circles in which the various parts of the instrument revolve are 

 graduated to degrees so that the observer may be able to tell the angle 

 at which any effect has been produced in order that it may be at once 

 obtained again. 



The substage and mirror are attached to the prism-box, and move with 

 it. The mirror can also be detached and applied to the centre of the base. 



The stage can be raised and lowered to compensate for the different 

 thicknesses of the slide. 



Universal Projection Apparatus for Mineralogical Purposes.* — Dr. 

 F. J. P. van Calker's apparatus is announced under the title of " Universal 

 projection apparatus for the representation of microscopical images of thin 

 slices of rocks with and without polarization, of the phenomena of thick 

 and thin crystal plates in parallel and convergent polarized light, of tension 

 phenomena, of the difference between parallel and oblique extinction, the 

 phenomena of pleochroism and microchemical reactions." It is, however, 

 nothing more than a stand with a brass ring, through which crystallo- 

 graphic, optical, and microscopical apparatus are pushed. 



Culpeper's Simple and Compound Microscopes (Wilson's form).— The 

 Microscope shown in fig. 97 (simple) and fig. 98 (compound) would appear 



Fig. 97. 



to have escaped the notice of the writers who have treated of the history 

 of the construction until quite recently .| It was designed and made by 

 Edmund Culpeper whose name is generally known in connection with the 



* Zeitschr. f. Krystallogr., xii. (1886) pp. 55-8 (1 pi.)- . . 



t Society of Arts Cantor Lectures on the Microscope, by J. Mayall, junr. (reprint m 

 collected form), 1886, pp. 34-5 (2 figs.). 



2 H 2 



