122 Scientific Intelligence. 
placed in front of the lens, pointing out the parts which alone could be 
embraced in a correct perspective view of it, and what parts the large 
lens or mirror would moreover receive and transmit rays from, to be 
jumbled in the photographic picture with that which would alone give 
a correct idea of the object as seen. e showed from the now famil- 
cumference of the aperture, the effect of the combination of the mat 
ginal pictures was most distinctly exhibited and demonstrated, by halos 
extending round the true image, and the sharp cross lines ruled on the 
object and shown in the image with the small lens, but all confused 2 
that with the surrounding apertures. i 
10. On a Rock-Crystal Lens and Decomposed Glass found in Nine 
veh; by Sir Davin Brewster, (Proc. Brit. Assoc., Atheneum, No 
1298.)—Sir David said that he had to bring before the Section ap ob 
ject of so incredible a nature that only the strongest evidence could 
render the statement at all probable :—it was no less than the finding 
of a rock-crystal lens, in the treasure-house at Nineveh, where " 
had for centuries lain entombed in the ruins of that once magnificent 
city. lt was found in company with several bronzes and other 
of value. He had examined the lens with the greatest care and 
taken its several measurements. It was not entirely circular i ™® 
aperture, being 1,8,ths inches in its longer diameter and 1,4,ths me? 
in its shorter. Its general form was that of a plano-concave lens; - 
light,—ihis was badly polished and scratched. The eonvex face 
the lens had not been ground ina dish-shaped tool in the manner 1 
which lenses are now formed, but was shaped on a lapidary’s whe*’ 
or in some such manner. Hence it was unequally thick, but its ¢* 
treme thickness was ths of an inch, its focal length being 44 inehe* 
S eaeae 
