COMPOSITE PORTRAITS, STEREOSCOPIC MAPS 265 



for me by my cousin, long since dead, R. Cameron 

 Galton, in the Proceedings of the Royal Geographical 

 Society [18] of that year. I cannot fully understand 

 why stereoscopes do not hold a higher position in popu- 

 lar estimation than they do ; it may be partly due to 

 two causes to the fact that the two eyes are unequally 

 operative in a larger proportion of persons than might 

 be supposed, and to the cost and unwieldiness of the 

 usual stereoscope. Compound lenses give better and 

 wider images than plain ones, but for common 

 purposes I find that plain ones, mounted as in an eye- 

 glass, serve quite well enough. Those I generally 

 use are cheap things, mounted in a strip of wood. 



I wished to obtain a map that should have the 

 effect of a model, so suitable models were procured 

 and photographed stereoscopically. The result was 

 a perfect success. An unexpected result occurred 

 when a pure white plaster cast was treated in this 

 way, for it wholly failed to give the required appearance 

 of a solid, but if grains of dust were sprinkled over it, 

 much more if names were written on it, the stereo- 

 scopic effect appeared in its full strength. Good models, 

 and therefore stereoscopic maps made from them, 

 give a far better idea of a mountainous country than 

 any ordinary map can do, however cleverly it may 

 be shaded. Map-makers might well pay some at- 

 tention to stereoscopic maps and to providing cheap 

 eyeglasses with which to view them. 



