224 



SCIENCE. 



[Vol. XII. No. 301 



Now, what is wanted is a cell with, say, the same storage-capa- 

 city and weight, — even with the same rate of depreciation, — but 

 which has a normal rate of discharge and charge of four or five 

 times that of the present type. We could then use from l,ooo to 

 1,500 pounds of battery on a car, — enough to make one or two 

 round trips, — reduce the total weight of the car to 9,000 pounds, 

 decrease the investment and cost of renewal three or four times, 

 and allow the present car bodies and tracks to be used without any 

 considerable alteration. Under these circumstances (and there is 

 no doubt the conditions will be sooner or later attained), street-car 

 traction by secondary batteries would be an assured and immediate 

 success for any ordinary condition of grade. 



Dr. von Waltenhofen's experiments are of interest in this con- 

 nection, because of the very rapid discharges to which he subjected 

 the Farbaky-Schenck cell, with apparently excellent results as to 

 efficiency and freedom from harmful effects. The cell in question 

 had seven positive and six negative plates, weighing 47 pounds, the 

 total weight of the cell being about 60 pounds. It was constructed 

 with a view to discharging it at 100 amperes, — five times the nor- 

 mal rate. The plates of this type of storage-cell have been de- 

 scribed in this journal. They are of a modified 'grid' form, the 

 holes being filled with a mixture of red lead and coke, or other 

 porous material, moistened with sulphuric acid. 



The cell was first completely charged, and then discharged at a 

 rate of 100 amperes, until the potential difference at the terminals 

 fell from 1.87 to 1.78 volts. The capacity was 166 ampere hours. 

 Then the cell was charged at 20 amperes, and discharged at 100 

 ampferes as before, but only 100 ampere hours were put in. 88 

 ampere hours were returned, giving an efficiency in ampere hours 

 of 88 per cent. In total energy the efficiency was 77 per cent. It 

 is evident, however, that these figures are much higher than would 

 be obtained if the cell was fully charged. In another experiment 

 the discharge-rate was increased to 200 amperes, the cell was 

 charged with 200 ampere hours, and the output was about 130 

 ampere hours, — a current efficiency of 65 per cent, with a total 

 efficiency of from 45 to 50 per cent. It is stated that neither of 

 these discharges injured the cell in any way. A current of 300 

 amperes was then tried, and the cell kept up its potential difference 

 reasonably well for about fifteen minutes. As to the effect the au- 

 thor says, " Whether this great over-exertion has been injurious to 

 the accumulator, Messrs. Farbaky and Schenck do not state; but 

 our experiments have shown that the cell can be discharged with- 

 out injury at 200 amperes." 



The author compares the performance of several types of cells, 

 from which we get the following data : — 



Farbaky and Schenck. — Capacity per pound of plate, 3.5 am- 

 pere hours ; discharge-rate per pound, 2.1 amperes ; total efficiency, 

 TJ per cent (.'). 



Reckemaun. — Capacity per pound of plate, 4.1 ampere hours ; 

 discharge-rate per pound, .37 of an ampere; total efficiency. Si per 

 cent. 



Juh'e?i. — Capacity per pound of plate, 4.2 ampere hours; dis- 

 charge-rate per pound, .42 of an ampere ; total efficiency, 83.5 per 

 cent. 



Tiidof {at a practical discharge-rate). — Capacity per pound of 

 plate, 1.3 ampere hours; discharge-rate per pound, .33 of an am- 

 pere ; total efficiency, 68.6 per cent. 



These figures of Dr. von Waltenhofen for the Farbaky-Schenck 

 accumulator mark an advance, and an advance that is in the right 

 direction ; but it is greatly to be regretted that the most important 

 fact that is brought forward, namely, that the cells are not injured 

 by such high discharge-rates, rests on a bare assertion, and no 

 figures are given to show that a number of such discharges extend- 

 ing over a considerable period have been attempted. 



New Method of producing Electric Currents. — C. 

 Braun, in the Berzchte der Berliner Akademie, describes a new 

 method of producing electric currents. A wire of nickel is twisted 

 into a spiral, and the two ends are connected with the terminals of 

 a sensitive galvanometer. When the spiral is suddenly pulled out, 

 there is a deflection of the galvanometer ; and, when it is compressed, 

 there is a deflection in the opposite direction. The direction of the 

 ■current in a connected wire is determined by the direction of the 

 twist as looked at from the end to which the wire is connected. 



It is stated that the effects cannot be accounted for by induction. 

 A heating or cooling of the wire as a whole produces the same 

 effects. If the wire is annealed, it loses its power of giving a cur- 

 rent, but regains it again on being stretched. The effect is not 

 large enough in diamagnetic bodies to be observed with any cer- 

 tainty. It seems to exist in iron and steel, but other effects make 

 the observations difficult. If these effects exist at all, and are not 

 due to induction, they are probably caused by the different strains 

 on the outside and inside of a spire of the wire. It is stated that 

 if the wire be magnetized the effect is greatly augmented. 



Some Curious Incandescent Lamp Phenomena. — The Elec- 

 trical World publishes a letter from F. J. Crouch describing some 

 curious effects obtained with incandescent lamps, both of whose ter- 

 minals were joined to the circuit of an alternating-current dynamo. 

 The circuit of the dynamo is made through a resistance of about 2,000 

 ohms (the electro-motive force is not stated). To the leads on one 

 side of the resistance are attached both terminals of some Bern- 

 stein incandescent lamps, whose bulbs are immersed in tumblers of 

 salt water. From the other side of the resistance, and therefore at 

 a potential differing greatly from that of the lamps, wires are 

 brought to the tumblers and dipped in the water. " Now, when 

 the dynamo is started, the light appears, and the light-waves pass 

 through the glass." The light is described as "similar to that of 

 the glow-worm or firefly. With three Bernstein lamps, I obtained 

 a beautiful moonlight effect, sufficient to read by in a large room." 

 Another interesting phenomenon has been brought out in a series 

 of letters to the same paper. It is found that incandescent lamps 

 in the vicinity of belts or apparatus giving considerable statical dis- 

 charges have a very short life. The writer has tried a few experi- 

 ments to verify this. On holding near a Weston lamp (no volts) 

 the end of a wire connected with a Holtz machine, if the lamp be 

 burning and the machine is turned rapidly, the filament will break 

 in from one to five minutes. In the first lamp experimented on 

 there was a very marked vibration of the filament, being more vio- 

 lent when the negative pole of the Holtz machine was presented. 

 This lasted for perhaps a minute, when the filament broke. Some 

 other lamps were experimented on in which there was no vibration 

 of the filament that could be noticed ; still they broke in a short 

 time. The effect is of some practical importance in paper and 

 other mills, and the life of the lamps can be greatly increased by 

 putting over the bulb a wire netting connected with the earth. If 

 the net be made of polished wire, — German silver, for instance, — 

 there will be little or no loss of light. 



BOOK-REVIEWS. 



Literature in School. By HORACE E. SCUDDER. Boston and 

 New York, Houghton, Mifflin, & Co. 16"^. 15 cents. 



Of the many reforms now being urged in school matters, one of 

 the most commendable, and one which appeals to the best sense of 

 the community, is that which urges the replacing of the literary 

 mess now offered to the child in the usual school-reader by works 

 of literature which have won for themselves a place. In this 

 movement Mr. Horace E. Scudder of Cambridge has taken and is 

 taking a leading part. Not only has he written forcibly and well 

 on the subject, but he has himself prepared various editions of 

 standard works fit for use in the school-room. In the present pam- 

 phlet Mr. Scudder prints his address on the subject of ' Literature 

 in Common-School Education," read before the National Edu- 

 cation Association at its meeting in San Fra.ncisco in July last, and 

 his two papers on ' Nursery Classics ' and ' American Classics ' 

 respectively, which have recently appeared in the Atlantic Monthly. 

 Mr. Scudder points out that literature has a field and an office of 

 its own, and, unless it is recognized in the school, the place which 

 it should take must remain unfilled. Literature gives expression to 

 the spiritual and non-material wants of man, and must be brought 

 , into the foreground to counterbalance the tyranny of materialism, 

 which bids fair, unless checked, to increase year by year. Mr. 

 Scudder does not mean by the reading of literature in school the 

 critical study of great authors. To urge that, would be to place a 

 weapon in the hands of his opponents ; but he says (p. 31), " The 

 place, then, of literature in our common-school education, is in 



