46 



SCIENCE. 



[Vol. XII. No. 286 



run in a conduit between the tracks, and the cars make connection 

 with it by a grip passing through a slot in the conduit. There are 

 several objections to this system. One of the most serious is the 

 initial cost, the conduit alone costing from §50,000 to $80,000 per 

 mile of single track. The conduit must be made large, it is diffi- 

 cult to clean, the pressure is liable to distort it and close the slot ; 

 its depth — varying from two to three feet — is liable to interfere 

 with steam, gas, or water pipe. A break in the cable will suspend 

 the entire traffic on the line. A broken strand is apt to foul the 

 grip and pile one car on another, as has happened in Philadelphia. 

 The efficiency of the system is not over twenty to twenty-five per 

 cent, while to guard against accident the engine outfit is usually 

 from two to four times that required at any time. Any extension 

 of a cable line is expensive because the length of the cable is fixed. 

 The speed of the cars is limited to that of the cable, so there is no 

 chance for them to catch up if they get behind time ; the motion, 

 too, is uneven and unpleasant. 



For electric traction Mr. Sprague claims the following advan- 

 tages. It will do the work more satisfactorily and at a less cost 

 than horses ; on levels and up and down grades electric-motor cars 

 can be run much faster than horse-cars ; they can be gotten under 

 way and stopped much more quickly; the equipment will occupy 

 thirty-five per cent less space than horse-cars, the horse space 

 being saved, and this fact, together with the ability to back when 

 necessary and to quickly gain headway, enables an electric car in a 

 narrow and crowded street to work a passage through where horse- 

 cars would be stopped. Electric cars can be run more safely on 

 down grades, since if the brake-chain breaks the car can be con- 

 trolled by the motors, reversing when necessary. The motion of 

 an electric car is smooth, and its starting and stopping are easy ; 

 the cars are clean, they can be lighted and heated by electricity; 

 the streets are cleaner, and objectionable stables are not needed. It 

 becomes feasible to operate branch lines, and also combinations of 

 grades, curves, and ill-conditioned streets, that would be prohib- 

 itory to any other system. 



To the objections that have been urged against electric systems, 



— that an extended system cannot be operated by electricity, that 

 the lines may break down, that a large number of cars cannot be 

 operated simultaneously, especially when bunched up, and that 

 armatures and brushes burn up, — Mr. Sprague opposes his own 

 very extensive experience, especially in the case of the Union Pas- 

 senger Railroad in Richmond, where all of these difficulties have 

 been met and overcome. 



Before giving the details of the Richmond road. Mr. Sprague ex- 

 plained from curves some important points in the theory of electric 

 motors for traction work. Discussing the different methods of 

 gearing the armature of the motor to the axles of the car wheels in 

 order to reduce the velocity, he concludes that there is only one 

 good way, which is to centre the motor on the axle, suspending it 

 flexibly from the car body or truck, and driving the axle by gearing 

 with one or two reductions according to the nature of the service. 



Taking up the methods of supplying the current to the motors, 

 from storage-batteries on the cars, from overhead wires, or from 

 wires in a conduit underground, Mr. Sprague first discusses storage 

 batteries. These he considers as extremely promising for surface 

 traction, but at the present state of development the excessive 

 weight, the depreciation and cost, lack of capacity, and the space 

 taken up in the car, make their success problematic. The weight of 

 the car is so great — almost 20,000 pounds for a loaded car — that 

 many of the tracks now in use would have to be rebuilt for them. 



The difference in cost between an overhead and conduit system 

 is mainly in the cost of the conduit, $25,000 to §30,000 a mile. The 

 latter has the advantage that there are no overhead obstructions, 

 and it can therefore be used in streets where the former is not per- 

 mitted. Its disadvantages are cost, possibilities of leakage, and 

 difficulty in cleaning and repair. 



The overhead system is cheap, easily insulated and repaired ; if 

 properly constructed it need not be unornamental nor dangerous, 



— in fact the electrical pressure should not be great enough to en- 

 danger life. Mr. Sprague recommends this system for suburban 

 districts, for comparatively narrow streets, for all streets operating 

 under an elevated railroad structure, or where the tracks are near 

 a sidewalk. 



To illustrate the advantages of electricity for certain classes of 

 traction work, Mr. Sprague proceeded to describe the equipment 

 and operation of the Richmond street railroad, a description of 

 which has appeared in this journal. The road is a difficult one,, 

 practically impossible for horse traction. There are grades of over 

 ten feet in a hundred, and curves of small radius on heavy grades. 

 The total trackage is twelve miles, the equipment is forty cars. 

 Each car axle is geared to a motor of y-J-horse power, capable of 

 working up to 15-horse power if required. The motors are out of 

 sight, and are practically noiseless. The system used is the over- 

 head. The power station is in the middle of the line, and is pro- 

 vided with boilers and engines of 375-horse power. In distributing 

 the current a main conductor is taken along the line of track, either 

 on the poles or underground, and is connected at intervals to the 

 overhead working conductor, from which the current is taken. 

 This allows a small overhead wire, and a break in it will not inter- 

 rupt the traffic on the line. The return circuit is through the car- 

 wheels to the rails and the earth. This road has been running 

 long enough to allow reliable figures as to the expense being ob- 

 tained. It is found that the cost of power is §1.48 per car day, the 

 car making eighty miles, and of material, labor, and depreciation,. 

 §1.98 per car day ; the total being §3.46 per car day, or 4.32 cents 

 per car mile. This is to be compared with the ten cents a car 

 mile that horses cost, and in the latter estimate there is no allow- 

 ance for depreciation of cars, etc. At present there is a saving in 

 this line of §125 a day as compared with horses. The passengers- 

 carried are over 10,000 per day. 



Passing to the application of electricity on a larger scale, Mr. 

 Sprague considers the problem of the elevated roads. At present 

 steam engines weighing 22i tons, with a capacity of 185-horse 

 power are used. For a proper service the number of cars should 

 be increased at certain hours, but the weight of the locomotive will 

 not give traction enough for the desired increase, and the strength 

 of the structure will not allow an increase in its weight. As to the 

 energy used, 59 per cent is employed in starting. 24 per cent in 

 lifting, 17 per cent in traction; the average horse power is 70.3. 

 Mr. Sprague's substitute for the locomotive is a car with an electric 

 motor geared to each axle. In stopping and in going down grades 

 he will brake by making his motors into dynamos, feeding current 

 into the line for the other trains, thus recovering a part of the 

 energy lost in starting and in going up grade. The motors are to- 

 have a collective capacity of 300-horse power, and the car will be 

 used for passengers : at each end of it will be a compartment for 

 the motor men. 



Mr. Sprague's ideal railroad system for New York is as follows : 

 There would be four tracks from the Battery up Broadway to 

 Twenty-third street ; thence diverging in two divisions, each still 

 with four tracks, one along the line of Madison Avenue to the 

 Harlem River ; the other following Broadway and running up the 

 line of the Boulevard and Tenth or Eleventh Avenue. Two tracks- 

 would be for express, two for way traffic : they would be in two- 

 tiers, the former below the latter. Electric cars are to be used, 

 the current delivered from an overhead wire ; express speed, thirty 

 miles, way trains, twelve miles per hour. This system is to be sup- 

 plemented by surface cars operated by electricity. 



These are the main points in Mr. Sprague's paper, which will be- 

 discussed in the fall meeting of the Institute of Electrical Engi- 

 neers. 



MENTAL SCIENCE. 



Experiments in Thought-Transferrence. 



The English Society for Psychical Research has definitely ac- 

 cepted the theory of telepathy, or a mode of communication be- 

 tween mind and mind other than that through the recognized 

 channels of sensation. A portion of the evidence upon which 

 they found that belief is of an experimental nature, and it is this 

 portion that is most apt to arouse the attention of scientific men ;: 

 it is this portion, too, that is certain to bring to light obscure phases 

 of mental action, irrespective of the answer it may yield as to the 

 possibility or inipossibilily of ihought-transferrence. In the last 

 issue of the Proceedings of the English Society (June, 1S88), M. 

 Charles Richet, well known as a physiologist, and editor of the- 



