Sometimes rats are the cause of accidents. Some years ago an explosion occurred at a mine in Wales, when several men lost their lives. There was one pit which was known to be full of explosive gas, and the men were warned to be very careful of their movements with their lamps. A lamp, in which the glass was surrounded with iron netting, was placed on a shelf in the part of the mine where the men were at work. The miners were a few yards away, when they noticed half a dozen rats clambering about the lamp, and saw them tip it over. It fell from the shelf and struck a lump of coal. A hole was made through the wire gauze, the lamp was broken, and a terrible explosion of gas followed. To the here-related accidents, we feel obliged to add a thrilling and fatal adventure of two Pennsylvania miners, which occurred in the vicinity of Scranton, Pa., on the 23d of April, 1877:— In calculating the cost of coal, there is one important item which is never taken into consideration by capitalist or consumer, and that is the loss of life and limb incurred in the work of digging “dusky diamonds” and preparing them for market. A glance at the list of deaths and accidents published monthly in the local papers, is sufficient to send a thrill of horror through the stoutest heart; but familiarity soon makes us partially indifferent to such matters, and it is only when some thrilling calamity occurs, such as the Avondale or West Pittston disaster, that we are fairly aroused to the perils incident to the work of mining. We know but little of these things, unless we see an occasional account of it in the newspapers, and even then we can but faintly realize the mishaps that befal, from day to day, in the way of fire-damp explosions, falling roofs, and the innumerable other death-dealing agencies that lurk in the depths of the coal mine. [Sidenote: FEARFUL FALL OF A ROOF.]