April 13, 1888.] 



SCIENCE. 



177 



motive draws a gross load of i8 tons, in addition to passengers 

 and its own weight, at an average speed of 6 miles per liour : with 

 12 tons load, its speed is 9 miles per hour. 



The generating dynamos are chiven from a turbine at about one- 

 third the distance from the Bessbrook end of the line. The weight 

 of the motor-cars is distributed as follows : — 



Tons. Cwt. Qrs. 



Car body 3 6 i 



Leading truck .... i 17 2 



Rear " i o o 



Motor and : 



The current is conveyed to the car through a central rail insulat- 

 ed on blocks of paraffined wood, returning through the earth and 

 track. The gearing is first from the motor-axle through a spur- 

 gear to a countershaft, then from the countershaft to the car-a.xle 

 by a chain gearing. The total cost of the line and equipment, in- 

 cluding two locomotive cars, was ^2,500. The cost of running per 

 train mile has been 4.2 d. 



During the discussion, Mr. Lineff brought forward a comparison 

 between the cost of conductors and accumulators for electric trac- 

 tion. He assumes the interest and depreciation of conductors at 

 ten per cent ; of accumulators, at thirty per cent ; representing over- 

 head conductors by A ; underground by B, and batteries by C. 



tion in buildings where a high candle-power is desired, and where 

 the irregularities of arc-lamps are objectionable. The voltage used 

 is 100; the amperes, 20. 



The Gibson STORAGE-B.A.TTERY. — In this cell the plates are 

 made by fixing peroxide of lead in perforations in a lead plate. In 

 the ordinary ' grid ' form of storage-battery plate the holes are of an 

 hour-glass form, — smallest in the middle, — the contraction pre- 

 venting the plug of active material from falling out. This has the 

 disadvantage that the pressure caused by the gradual corrosion of 

 the grid has a tendency to break the plug in the middle and force 

 it out. To remedy this, M. Godot invented a plate in which the 

 hole was largest in the middle, and smallest at the surface. The 

 objection to M. Godot's plate is in difficulty and cost of manufac- 

 ture. In the Gibson form the holes go square through the plate : 

 in them are put capsules of peroxide of lead in the form of a paste. 

 The capsules only fit loosely in the holes, and extend beyond the 

 surface. Plates thus prepared are passed between rollers set at 

 such a distance apart that they press the capsules to the level of the 

 surface of the plate, at the same time flattening the lead slightly, 

 and causing the edges to overlap the holes, thus keeping the active 

 material in. The method seems a decided improvement over that 

 of M. Godot to accomplish the same purpose : very possibly, if 

 tried with the best possible form of plate, it will be an improvement 





Length of 

 Line. 



Two Cars. 



Four Cars. 



Si.x Cars. 



Eight Cars. 



Ten Cars. 





A. 



B. 



c. 



A. 



B 



C. 



A. 



B. 



C. 



A. 



B. 



C. 



A. 



B. 



C. 



in 



lile 



200 



1,500 



2,400 



j 22s 



1.525 



4,800 



250 



1,550 



7.200 



275 



1,575 



9, 600 



300 



1,600 



12,000 



fS/t3£i 



liles 



400 



3,000 



2,400 



450 



3,050 



4,800 



500 



3,iao 



7,200 



550 



3.150 



9,600 



600 



3.200 



12,000 



3 





600 



4.500 



•2,400 



675 



4iS75 



4,Soo 



7S0 



4.650 



7,200 



825 



4,7=5 



9,600 



900 



4,800 



12,000 



4 





800 



6,000 



2,400 



900 



6,ic-o 



4,800 



r.ooo 



6,200 



7,200 



>,I0O 



6,300 



g,6oo 



t,20O 



6,400 



12,000 



Mr. Lineff assumes that each car needs three sets of storage- 

 cells, l| tons in each set, at £(30 per ton ; and the cost is increased 

 three times in the table to allow for three times the depreciation as 

 compared with conductors. The increased cost of cars and motors 

 for the accumulators is taken at fifty per cent of their value. In 

 reality there would be required but two sets of cells per car, while 

 the increased cost of each car could hardly be the ^135 assumed. 

 The comparison, then, is hardly fair to the accumulators. Instead 

 of the ^400 per car assumed, ^250 would be a fairer price, the 

 cost of the cells being taken at ;£6o per ton. As it stands, 

 in a line four miles long the accumulators would be cheaper for 

 five cars or less, as compared with underground conductors, while 

 the overhead wire would cost less than either for any number of 

 cars. If the lower estimate given be assumed, then the cost of 

 underground conductors and accumulators will be the same on a 

 four-mile line when about nine cars are run. Any increase in the 

 length of the line favors the storage-battery : an increase in the 

 number of cars favors the underground conductor. Still in this 

 estimate there is not included any consideration of reliability and 

 flexibility, and in these the storage has many advantages over any 

 other system. It will be seen, however, that the overhead conduct- 

 or is cheaper than either of the other plans, and in the smaller 

 towns and the suburbs of cities it will probably be generally 

 adopted. 



High Candle-Power Incandescent Lamps. — An English 

 firm, Clark, Chapman, Parsons, & Co., are manufacturing incan- 

 descent lamps of candle-powers up to 1,000 candles. They con- 

 sume about 2 watts per candle, and have a life of 800 hours. It is 

 very possible that the life and efficiency of these lamps will be im- 

 proved, in which case they will be active competitors with arc-lamps 

 for street-lighting. If the intensity of 1,000 candles is honestly 

 measured, and gives the average of the light in all directions, then 

 the efficiency is about half that of the ordinary arc-lamp. The price 

 of the incandescent lamps is not given ; but we may suppose that 

 the cost of renewal will not be much in excess of that of the car- 

 bons used in the arc-lamps, while the attendance will cost little or 

 nothing. The lamps would seem to have a wide field for applica- 



on the ordinary 'grid ' type. It hardly seems probable, however, 

 that it will improve either the efficiency of the battery or storage 

 capacity, although it might increase the rate of discharge and the 

 life of the plate. 



Magnesium in Prim.ary B.atteries. — M. Hein has been in- 

 vestigating the value of magnesium as a positive element in pri- 

 mary batteries. The electro-motive forces are high as compared 

 with results ordinarily obtained ; but there are the objections that 

 magnesium is expensive (it is worth from a dollar and a half to two 

 dollars a pound), and the resistance of the solutions of magnesium 

 salts is greater than that of the ordinary solutions used. 



Positive 

 Element. 



Solution. 



Negative 

 Element. 



Solution. 



Electro- 

 motive 

 Force. 



Magnesium 



Dilute sulphuric acid 



Zinc 



Dilute sulphuric ?cid 



.S76 







Copper 



Sulphate of copper 



2.03 





Sulphate of magnesium 



" 



L( U .1 



1.93 



Magnesium 



Dilute sulphuric acid 

 Sulphate of magnesium 

 Chloride of magnesium 



Carbon 



Dilute nitric acid 



2.888 

 2.863 

 2.910 



Magnesium 



Bichromate solution 

 Dilute sulphuric acid 

 Sulphate of magnesium 

 Chloride of magnesium 



Carbon 



Bichromate solution. 



2.952 

 2.980 

 2.901 

 2.970 



Magnesium 



Chloride of ammonia 

 Chloride of magnesium 



Carbon and 



manganese 



dioxide. 





2.219 

 2.334 



