SCIENCE. 



[Vol. XIII. No. 324 



been pretty extensively employed for lighting, and lately experi- 

 ments have been made with a view to their adoption for street-car 

 work. A car in Brooklyn equipped with these cells has made over 

 eighty miles with one charge, — a record which has not been 

 equalled; although the distance a car can go does not determine 

 the value of the battery used, since the very important question of 

 weight should enter, and in this case the weight is over five thou- 

 sand pounds. The Detroit cells have been recently tested at the 

 Johns Hopkins University, and a few figures as to their perform- 

 ance will be of interest. Taking a cell with 15 plates, of which the 

 total weight is 80 pounds, the following results were obtained : 

 charge rate, 15 ampferes ; discharge rate, 20 amperes; storage 

 capacity, about 220 ampere hours ; efficiency, between 75 and 80 per 

 cent. This cell, after experiments at normal charge and discharge 

 rates had been made, was charged at a rate of from 75 to 85 am- 

 peres, and discharged at over 250 ampdres ; and this was done a 

 number of times. At the end of the tests there were no signs of 

 deterioration, which, considering the rough usage to which the cell 

 had been subjected, speaks well for their durability, although the 

 length of the experiments was not sufficient to test their length of 

 life under normal conditions. 



The Magnetic Properties of Nickel. — Professor Ewing, 

 whose researches on the magnetic properties of iron are so well 

 known, has examined the magnetization of nickel under various 

 conditions. He finds that nickel behaves very much as iron does 

 when submitted to a magnetizing force. The permeability, or 

 magnetic conductivity, is small at first, then increases to a maxi- 

 mum, then decreases again. The maximum value of the induction 

 obtained was 5,380, so that nickel is about one-quarter as magnetic 

 as iron. When a piece of nickel was heated to redness and then 

 allowed to cool slowly in the air, its permeability increased. On 

 stretching a piece of nickel, its permeability decreased rapidly. 

 For example : a certain specimen of wire had a value of the maxi- 

 mum magnetic susceptibility for no load, of 15. With a load of 13 

 pounds, this was reduced to 2.6, while at 26 pounds it was but .95. 

 On submitting specimens to compression, the reverse effect was 

 found: as the pressure increased, the magnetic susceptibility in- 

 creased from 5.6 at no load, to 29.0 at a load of 45 pounds per 

 square millimeter. 



A Challenge to the Westinghouse Company. — Mr. 

 Harold P. Brown has issued a challenge to the Westinghouse 

 Electric Lighting Company, to a competitive test of the apparatus 

 of that company against a corresponding continuous-current plant. 

 Each company is to provide a plant capable of furnishing 650 

 lights. These are to be sent to the Testing Bureau of the Johns 

 Hopkins University, where they are to be tested for efficiency. The 

 loser is to purchase the winning plant, which is to be presented to 

 the university ; and he is also to pay all of the expenses of the test. 

 If the Westinghouse Company desires it, they may use one of the 

 Westinghouse engines, while Mr. Brown will employ for the con- 

 tinuous-current plant some other make of automatic high-speed 

 engine. If the Westinghouse Company does not accept the chal- 

 lenge, Mr. Brown will consider himself at liberty to purchase an 

 alternating plant and have the test made. It is to be hoped that 

 the test will be made, as systematic knowledge of the performance 

 of alternating apparatus is wanting, although the marked success 

 of the system speaks well for its efficiency. 



The Conductivity of Mica at High Temperatures. — 

 W. H. Schultze, m Wiedeman7i s Annale7i, describes a number of 

 experiments on the conductivity of mica at high temperatures. It is 

 well known that the conductivity of glass increases rapidly with the 

 temperature, a fact which in many cases is a serious inconvenience. 

 The results of Mr. Schultze's experiments are, that while mica 

 split parallel to the planes of cleavage shares with glass the prop- 

 erty of becoming a better conductor as the temperature rises, yet 

 the conductivity reaches a maximum, and after that diminishes 

 until at very high temperatures it becomes infinitely small; so that, 

 comparing glass and mica, it is seen that even at high temperatures 

 the latter is the better insulator. 



A. J. Drexel, the banker, is about to found an industrial col- 

 lege for women at Wayne, Penn., at a cost of $1,500,000. 



NOTES AND NEWS. 



Some interesting experiments were made March 22 near 

 Dartford with the Maxim Nordenfelt quick-firing and automatic 

 guns. As described in Eiigineering, the first weapon fired was 

 the Maxim automatic gun of .45 caliber, and with this 334 rounds 

 were fired in twenty-sev.en seconds. A comparative test was then 

 made between ordinary rifle-powder and the new Maxim smoke- 

 less powder. A cartridge containing 85 grains of black powder, 

 and others containing 55 grains of the new powder, were fired. 

 The last-mentioned cartridges gave a slightly greater velocity, and 

 at the same time produced extremely little smoke. Among the 

 other guns tried was an automatic six-pounder, which has a drop- 

 ping block like the Sharpe's rifle. It requires only two men to 

 work it, one man firing and the other loading. Every thing about 

 the gun is fixed save the gun itself, which is placed inside a jacket, 

 which latter is also fixed. There can be no danger of escape of 

 gas or from a hang-fire. The gun, on being fired, recoils about 4i 

 inches, and then returns to its original position. The cartridge- 

 case is not ejected till the gun has travelled some little distance on 

 its return journey. The act of putting in the new cartridge pushes 

 forward the ejectors and releases the block, which rises and closes 

 the breech. If great rapidity is required, one man on a saddle with 

 a butt to his shoulder aims and fires, while a man on each side 

 puts in the cartridges. If only one gunner is left unkilled, a single 

 man can work the gun in the following manner : having laid the 

 gun and fixed the trigger in a firing position by a bit of wood or 

 string, he simply puts in cartridge after cartridge, the gun on each 

 occasion going off as the cartridge is pushed forward. It can be 

 fired, with two men to load, sixty times a minute. 



— The kaolin and pottery clays of Texas are beginning to at- 

 tract considerable attention. There have been representatives of 

 several of the different Northern and Western potteries through 

 the State during the last few weeks, looking up the ordinary pot- 

 tery clays as well as the kaohn of Edwards and adjoining counties. 

 The deposits of these materials are abundant, and of such quality 

 that they are certain to be brought into market at an early day. 



— An English correspondent of the American Field writes that a 

 new gunpowder, the invention of Mr. Hengst, has recently been 

 tested at the Royal Gunpowder Factory, Waltham Abbey, Eng- 

 land, and the results point to it as a promising substitute for black 

 powder for military and sporting purposes. The new powder is 

 prepared from straw, which is pulverized, chemically treated, and 

 finished in granular form for use. It is claimed for this powder 

 that it is smokeless, flameless, practically non-fouling and non- 

 heating, and that both the recoil and the report are less than those 

 of black powder, with superior penetrative power. From the pow- 

 erful character of this explosive, which, weight for weight, is 150 

 per cent stronger than gunpowder, and is not explodable by con- 

 cussion, it is probable that in a compressed form it will be found to 

 be applicable to blasting-purposes^. 



— President Patton says that after June i the Princeton College 

 will have added to its permanent endowment fund $250,000 through 

 the kindness of many old and some new friends. 



— Mrs. Eliza A. Clark of Cleveland has given $100,000 to the 

 Cleveland College for Women, a department of the Western Re- 

 serve University. One-half the amount is to be expended in erect- 

 ing the Clark Hall of Liberal Arts. 



— The committee on science and art, of the Franklin Institute, 

 has recommended the following awards : of the John Scott legacy 

 medal and premium, to Thomas A. Edison of Orange, N.J., for his 

 invention of the mimeograph, an improved duplicating system and 

 apparatus ; of the Elliott Cresson medal, to Edward Alfred Cow- 

 per of London, England, and J. Hart Robertson of New York, for 

 their invention of a system of facsimile telegraphy, called " The 

 Writing Telegraph ; " of the John Scott legacy medal and premium, 

 to A. A. Marks of New York, for his improvements in artificial 

 limbs ; of the John Scott legacy medal and premium, to Thomas 

 Shaw of Philadelphia, for his mine-inspector's gas-testing appara- 

 tus I and of the John Scott legacy medal and premium, to Roman 



