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THE POPULAR SCIENCE MONTHLY. 



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 pro- 

 geny 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. "Ev- 

 ery 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 

 frhat as soon as she had a family she would 

 bite off her babies' heads." 



Cannibalism among Rats. Mr. W. Mat- 

 tieu 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, fer- 

 rets, and cats, and fearing poison, he tried 

 the effects of stuffing the holes with broken 

 glass. " This was successful, and some cu- 

 rious 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 

 sereaming was heard beneath. This was 

 followed by a rapid reduction of the num- 

 ber 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 con- 

 tinued till extirpation followed the more 

 fighting, the more bloodshed and the more 

 cannibalism." Mr. F. W. Halfpenny partly 

 confirms this view in " Science Gossip," 

 wkere 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 de- 



scribes 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-Dnst 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 fire- 

 damp, in propagating explosions in mines. 

 At the mine in question is a blower of fire- 

 damp at a depth of 131 yards below the 

 surface, which gives off 09 cubic foot of 

 gas a minute. For the experiments cannon 

 were planted at the closed end of a horizon- 

 tal 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 plank- 

 ing. 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 dis- 

 tance of 88 J- feet. The inner planking of the 

 branch gallery was broken. In the third ex- 

 periment the gallery-floor was strewed with 

 coal-dust for a length of 130 feet. The 

 flame traversed the whole length of the gal- 

 lery 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 ex- 

 periment, the partitions in the branch gal- 

 lery 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 



