Notices respecting New Books. 55 
Edinburgh, so fine that the square inch contains 13,200 aper- 
tures. 
‘<I haye tried cylinders of the size necessary for the colliers, 
in explosive atmospheres contained in large glass vessels ; the 
light given by a cylinder of seven inches high and two inches in 
diameter in the fire-damp mixed with 12 of air, is nearly as 
bright as that of the lamp in common air, and eyen the least 
brilliant flame would enable the miner to find his way, and, I 
think, would be sufficient for him to work by when he was very 
near it. The light is much increased by hanging within, from 
the top of the cylinder, a small cage of platiua or iron wire; this 
becomes ignited by the flame, and gives a steady red light im the 
midst of it ; and 1 have never had an explosion in employing it. 
“*6 The cheapness of the wire-gauze safe-lamps or guards for 
candles, will be an additional reason for bringing them into com- 
mon use; for the dearest of them can hardly cost more than 
one shilling. 
“They have the advantage of guarding the light from loose 
materials falling from the roof of the mine; there is no danger 
of their being broken; and td prevent them from being bent, 
they may be covered with a frame without, constructed of a few 
pieces of thick wire. The gauze should be made into the form 
of cylinders by double joinings sewn together through the double 
part by a wire of small diameter ; any aperture larger than that 
of the gauze-wire should be most carefully guarded against, and 
the cylinders should be tried in a vessel filled with an explosive 
mixture before they are used in the mine. A coating of oxide 
is soon formed upon the brass; but in my limited experience 
this has appeared to defend the interior from the action of air, 
and to render the wire durable: if, however, it should be found 
that this does not hold good in the mines, thicker or plated 
wire may be adopted, or double cylinders, or, at all events, as the 
top of the cylinder is principally exposed to heat, this may be 
double. 
“ With the wire safe-lamp or guarded candle the miner may 
explore all parts of the mine where explosive mixtures exist, and 
the state of the flame will show him the degree of contamination 
of the air. As the fire-damp mixes with the air the flame will 
enlarge. When the fire-damp has reached its explosive point 
his cylinder will be filled with flame; but the flame of his wick 
will appear within the flame of the fire-damp. As the inflam~ 
mable gas increases in quantity the fame of the lamp will disap- 
pear, and the flame in his cylinder will become paler ; and this 
ought to be a signal to him to leave that part of the workings. 
For when the flame of the fire-damp is extinguished, though the 
D4 air 
