63 
General Meeting, December 30th, 1879. 
J. P. Joule, D.C.L., LL.D., F.RS., &c., President, in the 
Chair. 
Mr. Thomas Ward, Brookfield House, Northwich, and 
Mr. J ohn Bell Millar, B.E., Assistant Lecturer in Engineer- 
ing, Owens College, were elected Ordinary Members of the 
Society. 
Ordinary Meeting, January 13th, 1880. 
J. P. Joule, D.C.L., LL.D., F.B.S., &c.. President, in the 
Chair. 
The Badiograph,’’ by D. WiNSTANLEY, F.B.A.S. 
I have described already one of the several arrangements 
which I have devised for the automatic registration of the 
solar radiance.* The instrument in question places a lead 
pencil on a sheet of paper and writes down therewith when, 
and for how long, the sun may chance to shine, but it makes 
no record of th.e intensity of his rays. I will now ask your 
attention to the description of another and much more per- 
fect apparatus, one which continuously records the inten- 
sity of thermal radiation to which it is exposed. This 
instrument I have called the ‘"radiograph.” It consists 
essentially as follows : — A difierential thermometer of which 
the stem is circularly curved is mounted concentrically 
upon a wheel of brass in a groove cut with that object for 
* Proceedings of Manchester Lit. and Phil. Soc., Nov. 18th, 1879. 
Peoceedings — Lit, & Phil. Soc.. — Vol. XIX. — No. 7. — Session 1879-80. 
