181 
A paper was read “ On the Casting, Grinding, and Polish- 
ing of Specula for Reflecting Telescopes, Part I,” by James 
Nasmyth, C.E., Corresponding Member of the Society. 
In this, the first part of his paper, the author describes in 
considerable detail the methods and processes by which he 
produces speculum metal of the best quality, and casis, 
anneals, and rough-grinds a speculum of ten inches in 
diameter, his descriptions being illustrated by drawings of 
the apparatus he employs. In the second part of the paper 
he will describe the processes of fine-grinding, polishing, and 
figuring ; and will give directions for the general manage- 
ment and use of reflecting telescopes. His instructions are 
based upon the results of thirty years’ experience in the art 
of working specula, and will, he believes, enable any zealous 
amateur to make for himself, at a moderate cost, a really 
good and useful reflector. 
PHOTOGEAPHICAL SECTION. 
April 12th, 1866. 
Dr. J. P. Joule, F.R.S., &c., Vice-President of the Section, 
in the Chair. 
A paper was read entitled “Note on the First Use of 
Hyposulphite of Soda in Photography,” by A. Brothers, 
F.R.A.S. 
