Prussia 1.89 per 1000
Belgium 2.8 "
England 4.5 "
Staffordshire 7.3 "

This statement shows that more care is wanted in this last-named county especially, as I find that the yield of coal in Belgium is half as much as in England.  Long working in the dark, if one may so speak, is a cause of serious detriment to the sight, and the worker also suffers much from constantly inhaling the small black dust, which in course of time affects the lungs, causing what is known as “miner’s asthma.”  Without going further into the unhealthy nature of the miner’s work, it may be interesting to mention something of the actual process, and having myself been an eye-witness of it, I will explain it as shortly as I can.  The workers having arrived at the pit-mouth at their proper hours—­for the pit is worked by shifts, and consequently is generally worked day and night—­the first operation is for each to procure his lamp from the lamp-keeper, receiving it lighted and locked; this is found to be necessary, as from the small light given by the Davy-lamp the men are often tempted to open them, and some are even, so foolhardy as to carry their lamp on their cap and a candle in the hand, and hence a terrible explosion may take place.  A few words on the Davy-lamp, which came into use about sixty years ago, may not be out of place here.  This safety-lamp of the miner not only shows the presence of gas, but prevents its explosion.  It is constructed of gauze made of iron-wire one-fortieth to one-sixtieth of an inch in diameter, having 784 openings to the inch, and the cooling effect of the current passing through the lamp prevents the gas taking fire.  If we pour turpentine over a lighted safety-lamp, it will show black smoke, but no flame.  Provided with his lamp, the miner takes his place with others in the tub, which conveys him with great rapidity to the bottom of the shaft.  Here landed, he takes his way to the workings, some of these, in large pits, being two miles from the bottom of the shaft.  To a novice this is not easy, as you have to walk in a crouching manner most part of the way.  Once there, he begins in earnest, and drives at his pick for eight hours, the monotony only relieved by his gathering the products into small railway waggons or tubs to be removed.  This is done mostly by boys, but in the larger mines by ponies of the Shetland and other small breeds.  The tubs are taken to a part of the mine where, if one may so speak, the main line is reached, and then formed into trains, and taken to the shaft by means of an endless rope worked by an engine in the pit.  In accomplishing all this work, great care has to be taken that the current of air is not changed or stopped.  This is effected by means of doors placed in various parts of the mine, so as to stop the current and drive it in the required direction.  These doors are kept by boys, whose duty it is to open and close them for the passage of the coal tubs.  Those boys are