3o8 



SCIENCE. 



[Vol. XI. No. 282 



universal, and where they will make the distribution of electricity 

 for lighting on a large scale better able to compete in price with 

 gas. 



The Magnetization of Watches. — With the rapid intro- 

 duction of dynamo-electric machines and electric motors, there has 

 arisen an inconvenience that is not only felt by those who work in 

 electric-lighting stations, but which is likely to affect the public 

 generally. Steel is usually used in the quick-moving parts of 

 watches ; and when this, for any reason, gets in a strong magnetic 

 field, it becomes magnetized, greatly changing the rate of the watch, 

 and making it irregular. '' It is possible to demagnetize a watch that 

 is affected in this way ; but it is a troublesome process, and is not 

 a permanent safeguard. To avoid this trouble, non-magnetic bal- 

 ances are being rapidly introduced ; and, although those made at 

 present are more costly than steel, yet they add but little to the 

 total cost of the watch, and make it reliable under all conditions. 

 Probably the first to make an alloy that would possess the proper- 

 ties of hardness and elasticity without being magnetic, was Pail- 

 lard. He has described several alloys that may be used ; and 

 watches made with balance-wheels and hair springs of these alloys 

 have stood the most severe tests, with success. The most impor- 

 tant component in the alloys is palladium. The other components 

 are copper and iron, for one of the alloys ; viz. : — 



Palladium 50 to 75 parts 



Copper 20 '^ 30 



Iron S " 20 " 



Another alloy is, — 



Palladium , . . . , 65 to 75 parts 



Copper IS " 25 " 



Nickel I '^ 5 '" 



Gold I " 2}i " 



Platinum 3< '' 2 " 



Silver 2 " 10 " 



Steel I " 5 " 



These alloys, especially the latter, are almost free from magnetic 

 properties. Balances that are to be compensated for temperature 

 are either made of two segments of alloys of different composi- 

 tions, having different rates of expansion ; or the segments are one 

 of alloy, the other of silver. Since attention has been called to 

 Paillard's methods, quite a number of manufacturers in this country 

 and England have experimented on the subject, and are now mak- 

 ing non-magnetic watches ; and it is probable that at an early day 

 the majority of the watches sold will be made to resist the action 

 of magnetic fields. 



Conductivity of a Vacuum. — M. Foeppl has experimented 

 on the conductivity of a vacuum by an ingenious method. He 

 made an induction-coil whose secondary circuit consisted of a 

 glass tube 7 millimetres external diameter, 4.2 millimetres internal 

 diameter. The ends of this coil were connected to a second coil 

 so arranged as to form a galvanometer, within which was a magnet 

 suspended by a cocoon-fibre. The glass tube forming the secon- 

 dary circuit was coiled in two layers of 18 turns ; the primary coil 

 was 24 centimetres long, and was composed of twelve layers of 

 seventy-two turns of wire. With a current of 22 amperes in the 

 primary, making and breaking the circuit, M. Foeppl could not dis- 

 cover any deflection of the needle when there was a vacuum in the 

 secondary tube, even when the degree of rarefaction was changed 

 through a somewhat wide range. He calculates from his experi- 

 ments that the resistance of such vacuums as he used could not be 

 less than 3 x 10^ times that of pure copper. This experiment bears 

 directly on the question as to whether a perfect vacuum would be 

 a perfect conductor or a perfect insulator, since the effect of the 

 electrodes used to introduce the current into vacuum tubes is 

 avoided. While it has, to within a short time, been admitted that 

 a tube in which there is a very perfect vacuum will not admit the 

 passage of electricity, it has been held by some that the result is 

 due to an enormous resistance at the surface of the electrodes, not 

 in the vacuum itself. This experiment disproves this view ; at 

 least, for the degrees of rarefaction employed. The wonderful in- 

 fluence of light on electric discharges that is being now investigated 

 by so many experimenters would possibly have influenced the results 

 of M. Foeppl's experiments, if they had been tried in the presence 

 of some intense source of light. 



Windmills forElectric-Lighting. — Some time ago the pos- 

 sibilities of windmills for domestic electric-lighting were mentioned 

 in this journal, and lately the experiment has been practically tried. 

 Professor Blyth read before the Glasgow I^hilosophical Society a paper 

 on the subject, in which he describes an experiment which he made 

 last summer, — the lighting of a cottage in which he spent his va- 

 cation by a dynamo driven by a windmill, and charging a storage- 

 battery. The windmill used was an old-fashioned type, with four 

 arms at right angles to each other, each of them thirteen feet long. 

 There was no especial regulating-device. The dynamo was belted 

 directly to the fly-wheel of the mill, and charged twelve cells of 

 storage-battery which supplied the incandescent lamps in the cot- 

 tage. Professor Blyth had never used more than ten lamps at 

 once, but he could have used more. With a good breeze, enough 

 electricity could be stored in half a day to supply light for four 

 evenings of three or four hours each. The lamps used were of 8- 

 candle power. When charging, the current passed through a cut- 

 out that would disconnect them from the dynamo when it ran be- 

 low a certain speed : so the windmill could be allowed to run all the 

 time, charging the battery when the wind happened to be strong 

 enough. The current had been used to run a light turning-lathe, 

 and Professor Blyth had begun to make a light carriage to be run 

 by the stored electricity. The paper opens to us a field for inge- 

 nuity, comfort, and amusement in our homes. Windmills much 

 superior to that described can be readily purchased, a small dyna- 

 mo can be bought or built at little cost, and storage-batteries can 

 be purchased or made. With them we could light our house eco- 

 nomically ; our light would be better, cooler, and healthier than gas 

 or coal-oil lamps ; while the current could be utilized for running 

 fans, sewing-machines, etc. Indeed, to the average American, with 

 some spare time and some small ingenuity, the amusement and in- 

 struction of such a plant would more than pay for its expense. 



HEALTH MATTERS. 

 Cremation of Garbage. 



The important subject of garbage-cremation, and the recent 

 advances made in this method of disposing of this waste material, 

 are admirably summed up in the following extract from the Sani- 

 tary News: — 



An indorsement of the method of disposing of kitchen waste, 

 recently inaugurated in Chicago, was pronounced before the sec- 

 tion on State medicine at the Cincinnati meeting of the American 

 Medical Association, Tuesday, May 8, by Dr. J. Berrien Lindsley 

 of Nashville, Tenn. Dr. Lindsley 's paper was an exhaustive r^- 

 sum^ oi the present status of garbage-cremation. He gave two or 

 three examples showing the great quantity and variety of polluting 

 material occurring without pause in the limits of a city. 



Baltimore, August, 1887, estimated by police census, had a popu- 

 lation of 437,155. The amount of night-soil delivered at the dumps 

 for the year ending Dec. 31, 1887, was 51,107 loads, or 10,221,400 

 gallons. Probably more than half the inhabitants use water- 

 closets which carry off an equal amount. 



The dead animals, etc., removed during the same year, were : — 



Total number of dead animals 25,249 



" " '' fowls 9,079 



" " fish 23,574 



*' " cart-loads of dead fish, vegetable and other offal re- 

 moved from various docks ... 1,067 



" '' pounds of decayed meat condemned 1,495 



" " dozens of eggs condemned 607 



Richmond, population 100,000. The report of contractor for re- 

 moval of garbage or kitchen refuse, year 18S7, shows total number 

 of loads carried off 2,680, equal to 72,200 bushels. 



Memphis, population 62,335. Number of loads of garbage re- 

 moved in 1887 was 29,120. 



These examples were selected at random. To keep the city 

 clean is the principal work of municipal governments, and requires 

 more expenditure of money than all other objects combined, ex- 

 cepting schools and police. 



The city filth naturally falls into four main subdivisions, — street- 

 sweepings, night-soil, dead animals, and garbage. The latter 

 alone concerns us at present. The definition of garbage is refuse 



