142 Miscellaneous Intelligence. 
A camera with several adjustments for producing stereoscopic pic- 
tures was described at the recent meeting of the British Association by 
Mr. A. Claudet (see page 124 
Brewster gives the following directions for drawing on a plane the 
dissimilar representations of solids for the stereoscope (Phil. Mag. [4]; 
iii, 16): 
value, but c’ will lie on the left side of C. Calling E the distance 
between the two eyes, and / the height BC of the solid, we shall: have 
AB: iat Ce and Cc= ‘a 
» which will give us the results in the 
2AB 
following table, AC being =8 and E=2¢ inches :— 
Height. Height. 
=h, AB. Ce. Bosh... AB. Ce. 
1 7 0-279 inch. 5 3 2-088 inch. 
2 6 0:4166 “« 6 2 B79 ae 
3 5 | eS 7... 1 8°78 25: 
4 4 125... 8 0 Infinite. 
If we now wish, by directing the axes of the eyes beyond MN to b, 
to ascertain the value of Ce’, which will give different depths d of the 
hollow solids corresponding to different values of Cd, we shall have 
Ab: sad :Ce' and Cc’'— 
; which, making AC8 inches as before, 
2AB 
will give the following results :— 
Depth. Depth : 
Cb=d. Ad, ce’. Cb=d. Ab. Cel 
1 9 0-139 inch. 7 15 0-58 inch. 
2 10 0-25... 8 16 0-625 . 
3 11 0-34. 9 17 0-662 - 
4 12 04166 “* 10 18 0- 2 
5 13 4 “a ll 19 0-723 
6 i4 0-535 + 12 20 0-15: i 
The values of h and d, when the excentricities Cc, Cc’, as we may oe 
! Coe eae 
them, are known, will be found by the formule h=srR and d=543 
As Ce is always equal to Ce’ in each pair of figures or dissimilar a 
tures, the depth of the hollow solid will always appear much grealé 
than the height of the raised solid one. When Ce and Ce’ are ea 
0-75 h: d=3: 12, and when they are both 0-4166, h:d=2:4 
when they are both 0-139 h: d=0-8: 1-0. ' ; 
3. Pseudoscope of Wheatstone, (Phil. Mag. [4] iii, 151.)—As - 
instrument conveys to the mind false perceptions of all external obje¢ 
the author calls it a Pseudoscope. It consists of two reflecting prisms, 
