546 
hardly divest ourselves of the unpleasant feeling that they 
arise from causes which ought to be preventible.* 
The subject will divide itself into two parts : Firstly, the 
scientific principles involved in Mr. Ansell's method of 
detecting foul air ; and, Secondly, a description of the instru- 
ments which he has invented, and the way of using them. 
And here let me say a word for the claims which abstract 
science has upon the attention of those who call themselves 
" practical men," because they ignore science until the day 
of its fruition has arrived. But just as certainly as a tree 
must pass through various stages of growth, yielding leaves 
and flowers before its ultimate object of bearing fruit be 
accomplished, so is it an ordinary necessity that a knowledge 
of the laws governing matter shall precede the application 
of those laws to industrial improvements. It becomes, 
therefore, the interest of those who look only to technical 
results to encourage the cultivation of that higher science 
which is one essential to the production of those results. 
Professor Tyndall, speaking on this subject, has referred 
to the steam engine, electric telegraph, &c, and he goes on 
to say : " Remember that these are but new things ; that it 
is not long since we struck into the scientific methods which 
produced these extraordinary results. We cannot for an 
instant regard these as the final achievements of science, but 
rather as an earnest of what she is yet to do. They mark 
our first great advances upon the dominion of Nature. 
Animal strength fails, but here are the forces which hold the 
world together, and the instincts and successes of man assure 
him that these forces are his when he is wise enough to 
command them." 
* The official returns of accidents to persons employed in coal mines for the 
years 1865 and 1866 have been issued since this paper was read. 
18G5. 1866. 
Lives lost by accidents in England, Wales, and Scotland . . 984 1,484 
Persons employed per life lost 321 216 
Tons of coal raised per life lost 100,519 67,877 
