172 Transactions.—Miscellaneous. 
Art. XII.—On a “ Direct-vision Solar” E. ye-piece for large Telescopes. 
By H. Srey. 
[Read before the Otago Institute, 12th October, 1875.} 
When coloured glasses are placed before the eye-piece of telescopes in 
solar observations, they intercept a certain portion of the heat, but this can 
only be by their absorbing it; in absorbing the heat they necessarily gga. 
become heated, and when used with telescopes of greater aperture than two — 
inches, they are liable to fuse or crack, thus endangering the eye-sight of 
the observer. 
The screens here exhibited were devised originally for the purpose of 
observing the Transit of Venus, in December last. 
In their construction, advantage is taken of the transparency of thin 
films of the metals, a film of silver being precipitated on glass, by Liebig’s, 
or other methods, and then guarded by another glass. These films are 
chosen, so that part thereof is nearly transparent, and the other part nearly 
opaque, and by a sliding method, a suitable part can be brought over the 
field of view of the telescope so as to be adapted to the varying intensity of 
light, arising from clouds, ete. One of these films is on plane glass; the 
other is on a convex glass, which is guarded by a concave one. These dark 
screens appear to give excellent definition, and, being of a neutral tint, they 
allow of seeing the sun as a white globe on a black ground. In using them, 
the mirror side is turned towards the sun, and “light and heat being 
reflected in sensibly equal proportions,” their excess is reflected back, while 
sufficient light is transmitted through the film to admit of proper illumin- 
ation, after the telescope has magnified the image. Testing these films for 
safety, under a large condenser, they resisted the heat, while colored 
glasses, even if only lightly colored, were instantly cracked. 
»for by merely sliding the screen, it can be 
adjusted to the varying illumination without removing the eye. 
Arr. XTII.—4n account of the Maori House, attached to the Christchurch 
Museum. By James W. Stack. 
[Read before the Philosophical Institute of Canterbury 5th August, 1875.] 
This house was designed and the carving and scrolls executed by Hone 
Taahu, of the Ngatiporou tribe, who named it Hau-te-ana-nui-o Tangaroa. 
(The sacred great cave of Tangarca—the Polynesian Neptune). 
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