140 Miscellaneous Intelligence. 
the eye-holes 24 inches. Below at middie is a handle for holding it. 
The two pictures to be viewed (one drawn as the object would appear 
a short distance off to the left eye, the other, as to the right eye, and 
the two on one piece of paper, the requisite distance apart) are placed 
against the back piece be. On looking through the eye-pieces, the two 
pictures are superimposed at the middle point between them, and are 
seen as one; the several objects appear at their proper distances, 12 
advance of one another; moreover every part stands out in bold relief, 
heads looking like stationary, etc. This superposition of the two pic 
(3.) In a third kind, (the reflecting stereoscope,) the rays of light are 
bent by reflection from plates of black glass; common glass covered 
impose the two in this mode of viewing them. The reflecting stere” 
Scope Is most easily adapted to eyes of different focal distances, and 
also to pictures of different sizes. The semilenses have the advantage 
of magnifying the pictures. ; 
(4.) Another of Brewster’s stereoscopes is the Total Reflexion Stere?- 
scope. The left eye looks through a prism (fig. 5) from L, and sees 
i i ing 
, ei 
pictures produces no appreciable injury to the effect. It is essential that 
the angles of the prism ABC and ACB should be equal. If t 
ces AB and AC are made convex by annexing to each a plano-con 
lens, this kind of stereoscope then magnifies the objects seem. 
