104 



POPULAR SCIENCE MONTHLY. 



some unknown point in the tube, and to 

 remove the obstruction it was desirable 

 to locate its position as closely as pos- 

 sible before digging down to the pipe. 

 This was satisfactorily accomplished by 

 firing a pistol at one end of the tube; 

 its report was echoed from the obstruc- 

 tion, and indicated its position by the 

 time required for the transmission of 

 the sound. The pistol was fired in a 

 hole in the side of the pneumatic tube 

 near the end, which was capped and 

 had a rubber-hose connection to the re- 

 cording apparatus. The end of the rub- 

 ber hose terminated in a chamber closed 

 by a diaphragm about five inches in 

 diameter, which had a stylus attached 

 to it. A cock in the middle of the rub- 

 ber hose was partly closed to reduce the 

 force of the explosion on the diaphragm, 

 and the pistol was fired. The sound- 

 wave immediately produced a move- 

 ment of the diaphragm, causing the sty- 

 lus to make a mark on the record dia- 

 gram. The hose cock was then fully 

 opened, and when the sound-wave had 

 traveled to the obstruction and been re- 

 flected back it again moved the dia- 

 phragm, and caused the stylus to make 

 a second mark on the diagram. The 

 lapse of time had been automatically 

 recorded on the same diagram, so to 

 determine the distance it was only 

 necessary to note the exact interval of 

 time between the direct and reflected re- 

 ports, divide it by two, and multiply the 

 quotient by the velocity of sound under 

 the existing conditions." The obstruc- 

 tion was indicated at 1,537 feet from 

 the diaphragm. Excavations were made 

 at this place, and the carrier was found 

 nearly at the calculated point. The 

 limits of distance at which this method 

 is applicable have not yet been deter- 

 mined, but Mr. Batcheller, the engineer 

 of the Pneumatic Tube Company and 

 the deviser of the above ingenious ex- 

 pedient, has found that in a tube 43.3 

 inches in diameter a pistol shot will 

 vibrate a sensitive diaphragm at a dis- 

 tance of 65,129 feet; decreasing the di- 

 ameter of the tube decreases the dis- 

 tance over which the pistol shot will act. 



Diseased Meat in Paris.— The po- 

 lice of Paris, says the Lancet, have just 

 laid hands on a vast fraudulent organi- 

 zation for evading the precautionary 

 measures drawn up by the authorities 



for inspecting the meat distributed for 

 consumption in the suburbs of Paris. 

 Both for Paris and the suburbs all ani- 

 mals destined for food have to be killed 

 in public slaughterhouses, where the 

 strictest watch is kept by the municipal 

 veterinary surgeons, who forbid the de- 

 livery to the butchers of any meat 

 which exhibits the slightest suspicious 

 signs. Elaborate regulations have been 

 laid down as to the various diseases 

 which render meat unfit for the food of 

 man, and naturally enough tuberculosis 

 is the complaint most rigorously watched 

 for. The swindlers who have been ar- 

 rested made up a vast organization 

 which used to buy up from the farms of 

 the eastern provinces and even in Ger- 

 many such animals as, owing to disease, 

 would have been refused for slaughter 

 at the abattoirs, and, moreover, they 

 bought them dirt cheap. These animals 

 were then conveyed in regular herds to 

 a small place near Paris and killed in 

 sheds built at the bottom of an old 

 quarry. Under cover of night the meat 

 was taken away by the accomplice 

 butchers and resold in the various sub- 

 urban shops. In connection with this 

 clandestine slaughterhouse the firm had 

 a kind of cemetery, where those animals 

 were buried the meat of which was too 

 bad for even the swindlers to risk its sale 

 in the market. Ivry was the place where 

 the fraud was discovered, and the offi- 

 cial inquiry shows that the organiza- 

 tion was singularly complete. It is ex- 

 traordinary that the slaughterhouse, 

 which was in full work, should never 

 have attracted the attention of the vil- 

 lagers, but it must be remembered that 

 all killing was done by night and that 

 the slaughtermen were all Germans who 

 did not understand a word of French, 

 and were therefore unable to engage in 

 imprudent conversation with the neigh- 

 bors. 



How Aluminum is made. — In a 

 paper read before the Manchester Junior 

 Electrical Engineers, J. H. Henderson 

 describes the two commercial methods 

 of making aluminum: The agent which 

 has made aluminum a commercial prod- 

 uct is electricity. This is how electroly- 

 sis produces it (by one successful meth- 

 od) : In a metal, carbon-lined crucible 

 having two carbon electrodes, one of 

 which acts as anode and the other as 



