592 
at liberty to resort to the expedient of suspending weights 
from the ends of the levers which would avail him, and thus 
control would be lost. 
2nd. It may be objected that if the driver is wishful to add 
to the pressure and elude detection by the pressure gauge, he 
can do so by shutting off its communication with the boiler. 
To prevent this, it is intended so to construct the cock com- 
municating with the boiler that it can never entirely shut off 
the communication. 
For the better and more easy comprehension of this 
improvement, a pressure gauge, constructed upon this 
principle, was exhibited. 
OBSERVATIONS ON THE BEST MODE OF WORKING AND 
VENTILATING COAL MINES. BY J. BRAKENRIDGE, ESQ., 
OF SANDAL HALL, WAKEFIELD. 
This Paper, which was illustrated by means of a large 
diagram of a coal mine worked upon the principle which it 
recommends, was prepared for the last meeting of the 
Society, at Barnsley, when Mr. Carter, of Halifax, read his 
paper upon the subject of ventilating mines. Having, however, 
mistaken the day of the Barnsley meeting, I consented to 
read this Paper now. Soon after the dreadful explosion at 
Lund-hill, in February last, I addressed a letter to Sir 
George Grey ; and the present Paper is an elaboration of 
that letter. The following are the principal points of the 
Paper : — 
The late fearful explosion at Lund-hill Colliery, with the 
awful destruction of human life and property caused thereby, 
furnishes another solemn warning to all interested in mining 
operations, or having the management of coal mines; and 
