Knowledofe. 



With which is incorporated Hardwickc's Science Gossip, and the Ilkistrated Scientific News. 



A Monthly Record of Science. 



Conducted bv Wilfred Mark Webb, F.L.S., and E. S. Grew, M..\. 



JUNE, 1 'J 11 . 



A SCIENTIFIC USE FOR THE STEREOSCOPE. 



By A. H. STUAKT, B.Sc, F.R.A.S. 



Students whose geometrical studies have been these the latter are undoubtedly the easiest to make 



confined to the geometry of two dimensions and the cheapest to produce. 



frequently find considerable difficult\- when problems The most elementary knowledge of jierspective is 



in three dimensions are presented to them. Ordinary all that is required to make stereosco})ic drawings of 



Figure 1. 



drawings afford very little help and there remain all the usual problems in solid geoinetry. Figure 1 

 onlv two methods b\- which assistance may be shows a simple method of drawing a cube in 

 offered, viz., models and stereoscopic drawings. Of perspective. A figure is. drawn for each eye, the 



205 



