288 Miscellaneous Intelligence. 
the most important points in North America. We hope to hear that 
active efforts have been made for the } iar toate of such an Institu- 
tion and we shall cordially wish it succ 
The self-regisiering magnetical iathcitioite that have been success- 
fully used in Canada by Capt. Lefroy, are peculiarly excellent and 
exact in their records, and it is very desirable that similar instruments 
should be introduced at Washington, Cambridge, and other o 
ries in the United States 
3. The Total- Reflexion Stereoscope ;* by Sir Davin Brewster, 
(Phil. Mag., [4] ili, 20. .)—This form of the stereoscope requires only & 
small prism and one iagram, or picture of the solid, as seen by oné 
eye; the other diagram, or picture which is to be combined with it, be- 
instru- 
ing created by total aginte from the base of the prism is i 
ment is shown in fig. 1, where D is the picture of a cone as seen by 
the: left eye L, and ABC | is the prism, whose base BC is so large that 
when the eye is placed close to it, it may see, by reflexion, the whole of 
the diagram D. The angles ABC, ACB must be equal, but may be of 
any _mngsiade, Great accuracy ‘in the equality of the angles is not 
nd a prism constructed by a lapidary out of a fragment of 
thiek pl pall glass the face BC being one of the surfaces of the plate, 
— answer the purpose.t When the prism is aed at abe, fig. oe 
end of a conical tube LD, and the diagram D, at the other ene © 
tures 2 formed C one reflexion, we as combine pve dissimilar a 
into a raised cone, as in the figure, or into a hollow one, if the pict 
at D is turned round 180°. 
dete Pte m aba, pe BO, 
weft sc the ay rier er ‘a Bed, ‘te. + ithe re paral cides BO 
aces of the. 
only, the work of the pulang f the plate-glass, and inclined faces Be 
