74 
on the heated side, and, after passing across the fine glass 
index, descend on the other side. It is also evident that the 
sensibility of the instrument may he increased to any required 
exteut, by diminishing the directive force of the magnetic 
needle. I purpose to make several improvements in my 
present instrument, but in its present condition the heat 
radiated by a small pan, containing a pint of water heated 
30°, is quite perceptible at a distance of three yards. A 
further proof of the extreme sensibility of the instrument 
is obtained from the fact that it is able to detect the heat 
radiated by the moon. A beam of moonlight was admitted 
through a slit in a shutter. As the moon (nearly full) 
travelled from left to right the beam passed gradually across 
the instrument, causing the index to be deflected several 
degrees, first to the left and then to the right. The effect 
showed, according to a very rough estimate, that the air in 
the instrument must have been heated by the moon’s rays a 
few ten-thousandths of a degree, or by a quantity no doubt 
the equivalent of the light absorbed by the blackened surface 
on which the rays fell.” 
E. W. Binney, F.R.S., the President, said that of late years 
considerable attention had been devoted to the examination 
of the beds of sand and gravel found in the valleys formed since 
the deposition of the till or boulder clay. Sir Charles Lyell, 
in his valuable work on the Geological Evidences of the 
Antiquity of Man, has given us many facts connected with 
these valley gravels, especially relating to the terraces of the 
higher and lower level gravels found in the valley of the 
Somme, in which the flint instruments have been met with. 
As these two deposits are seen in the neighbourhood of Man- 
chester, he wished to direct attention to all excavations that 
were being made in them, in order that any remains or 
implements which might be met with should be preserved. 
Doubtless many interesting specimens have perished, owing 
to the parties finding them being ignorant of their value. Many 
