Miscellaneous Intelligence. 989 
we wish to make a microscopic stereoscope of this form, or to 
magnify the drawings, we have only to cement plano-convex lenses, 
the requisite focal length, upon the faces AB, AC of the prism, or 
ae 
imperfection arising from the difference of paths in the reflected and 
direct pencils, ‘This difference is so trivial, that it might be corrected 
4. Notice of a Chromatic Stereoscope; by Sir Davin Brewster, K.H., 
PRS.,V.P.R.S,. Edin., (Phil. Mag., [4] iii, 31.)—In the year 1848, I 
‘ommunicated to the British Association, at Swansea, a brief notice of 
the Principle of this instrument.* : ape 
We look with both eyes through a lens, about 24 inches in diame- 
ter or Upwards, at an object having colors of different refrangibilities, 
Such as the colored lines on a map, a red rose among green leaves, or 
any scarlet object upon a blue ground, or in general any two simple 
**lors not of the same degree of refrangibility, the to colors will ap- 
” 
are 'mages of different colors being thus separated, the eyes unite 
e 43 in the stereoscope, and the red image takes its place nearer 
observer than the blue one, in the very same manner as the two 
Ph Portions of the dissimilar stereoscopic figures stand up in relief 
wi; distance from their more remote portions. The reverse of this 
Vill take Place if we use a concave lens, or if we turn the refracting 
8 of the two prisms inwards. ; 
* See Report of the British Association at Swansea, 1848, Trans. of Sect., p. 48. 
