Page:Popular Science Monthly Volume 27.djvu/734

714 thought the hay the naked little fellows were lying upon too rough for their tender skins, and put wadding in its place. "But, with a sneer of contempt for the stupidity of men in such matters, Anna Maria promptly cast out the wadding and bumped her progeny upon the hay again." In washing them, "she would roll them over and over with her paws, and lick them till the sparks flew, and they would utter plaintive little squeaks." But they throve splendidly. "Every night this graceful couple gamboled about my table while I read or wrote. It was a delight to me to watch them at their toilet or eating the food which they held in their delicate little paws. . . . When tired of play, they would clamber up to my shoulder and slumber, huddled together like two love-birds." Anna Maria at last died of a cold, and her place was supplied by a new female, whose chief peculiarity was that as soon as she had a family she would bite off her babies' heads."

Cannibalism among Rats.—Mr. W. Mattieu Williams believes that rats are, upon occasion, voracious cannibals, devouring one another by wholesale and without mercy. Being troubled beyond endurance by these pests, and getting no relief from dogs, ferrets, and cats, and fearing poison, he tried the effects of stuffing the holes with broken glass. "This was successful, and some curious results accompanied the clearance. At first, there were streaks of blood on the kitchen-floor in considerable quantity, and distributed all over it. These appeared on several mornings. At about the same time, and subsequently, much scampering and screaming was heard beneath. This was followed by a rapid reduction of the number of the enemy. My theory," says Mr. Williams, "is, that when any one rat was wounded by the glass, the scent of blood excited the voracity of the others, and a cannibal struggle occurred; that this continued till extirpation followed—the more fighting, the more bloodshed and the more cannibalism." Mr. F. W. Halfpenny partly confirms this view in "Science Gossip," where he says that the black rat is still to be met with at most of the London docks; that the Norway or sewer rat not only kills its victim, but devours it. He describes skins of freshly killed black rats turned inside out, and found in various drawers, boxes, etc., and states that this treatment of their victims is usual with rats. As an experiment, Mr. Halfpenny gave the carcass of a white rat to one of the black and white variety. It was eaten, only a few bones of the head remaining attached to the everted skin.

Coal-Dust in Fire-Damp Explosions.—The Royal Prussian Fire-damp Commission has carried out a series of experiments in the Royal Coal-Mine near Neunkirchen, the results of which go far to confirm Mr. W. Galloway's theory of the agency of coal dust alone, and in conjunction with firedamp, in propagating explosions in mines. At the mine in question is a blower of firedamp at a depth of 131 yards below the surface, which gives off 0·9 cubic foot of gas a minute. For the experiments cannon were planted at the closed end of a horizontal gallery 167 feet long, having a branch 38 feet long, starting at a distance of 93 feet from its closed end. The branch gallery was closed at both ends with two-inch planking. One gun was fired when the gallery was free from fire-damp and from coal-dust; the flame of the shot was a little over 13 feet long. In a second experiment the floor of the gallery was strewed with coal-dust 1·17 inch thick for a length of 65 feet. The shot gave rise to a loud detonation, and the resulting flame filled the gallery to a distance of 88 feet. The inner planking of the branch gallery was broken. In the third experiment the gallery-floor was strewed with coal-dust for a length of 130 feet. The flame traversed the whole length of the gallery with great velocity, and came out at the open end to a distance of 16 feet, or 183 feet in all. It also emerged from the branch gallery to a distance of several yards. The outer partition of this gallery was broken into small fragments. For the fourth experiment, the partitions in the branch gallery were replaced, coal-dust was strewed on the floor for a distance of 65 feet, and a volume of 35 cubic feet of fire-damp was introduced and completely diffused. The firing of the shot produced a flame 190 feet long, accompanied by a report like a thunder-clap. The inner brettice of the