684 
B ritish A ssociation. 
[October, 
22nd and 24th, 1879, the real paths of all of which had to 
a greater or less degree of certainty and closeness been ap- 
proximately ascertained. A description of the past year’s 
aerolites was also given. The expected return of Biela’s 
comet to its perihelion in the present year, leading a shower 
of shooting stars to be looked for on the 27th of November 
next, is to be taken advantage of to report next year on 
meteor showers. 
The Report of the Committee on Instruments for Detect- 
ing Fire-Damp in Mines was read by Professor G. Forbes, 
F.R.S.E. Two new instruments have been constructed : 
the one of a large size, and worked by an eleCtric battery ; 
the other was small, portable, easily worked, and it answered 
all the purposes for which it was required. Both instru- 
ments were founded upon the faCts that sound travels 
quicker in light gases than in dense ones, and that air 
which is contaminated with fire-damp is lighter than pure 
air. The velocity of sound in different qualities of air was 
compared by noting the lengths which must be given to a 
brass tube to cause it to resound to a tuning-fork. The 
accuracy of the instrument was such that the percentage of 
fire-damp could be determined with an error of considerably 
less than one per cent. The committee had descended the 
Wharncliffe Silkstone Colliery, in the neighbourhood of 
Sheffield (this pit has a depth of 200 yards), and were 
taken to a disused part of the mine where it was known 
there was a blower. Gas in sufficient quantities were found, 
and the instrument registered gas with more readiness than 
the Davy lamp. But the greatest quantity registered was 
6 per cent, or twelve times the smallest quantity which the 
indicator detects. From the experiments they could assert 
that this instrument was capable of detecting and measuring 
fire damp even in small quantities. 
The paper which, perhaps, attracted the most attention 
in Section A was that by the Rev. S. Earnshaw, M.A., on 
“ Etherspheres as a Vera Causa of Natural Philosophy.” 
In defining the term “ ethersphere,” Mr. Earnshaw said all 
space not filled by matter is pervaded by ether, so that 
every atom of matter is surrounded by ether, but this is not 
what is included in the word “ ethersphere.” If any portion 
of space be rendered void by ether from any cause whatever, 
that space has become void of the repulsive forces which 
were centered within it, and that, consequently, when these 
forces are taken away the medium outside the space will 
draw closer towards that space ; and if the space be 
occupied by an atom of matter, the density of the sur- 
