January ii, 1889.] 



SCIENCE. 



31 



then goes on to say that " the best storage-battery that has been 

 devised is very wasteful as a source of motive power, yielding at 

 most but forty per cent of the power applied." Now, nothing 

 could be further from the truth than this statement. There is prob- 

 ably not a storage-battery at present on the market that will not 

 yield eighty per cent of the power applied. Almost any person of 

 electrical knowledge and experience knows this to be a fact ; and, 

 if further proof be necessary, it will afford me much pleasure to 

 have you send an expert, at my expense, to the electric station of 

 the Julien Electric Traction Company, 85th Street and Madison 

 Avenue, this city, to verify for himself the truth of this statement. 

 He can there see for himself the number of watts the battery re- 

 ceives from the dynamo ; and, if the battery does not discharge 

 over eighty per cent of the watts so received, you are welcome to 

 publish the fact to the world. 



The next objection the writer raises to the storage-battery sys- 

 tem is, that it is " excessively heavy and bulky, making it necessary 

 to carry about three times the load of an ordinary car." Now, 

 " the load of an ordinary car " (i6-footcar) is 3 tons: consequently 

 a storage-battery car would have to carry 9 tons of battery, if we 

 are to believe the writer. Now, Car No. 3 of the Julien Electric 

 Traction Company, at present running on Fourth and Madison 

 Avenues in this city, carries Just 120 elements, or cells, of battery, 

 each element weighing exactly 27 pounds, or 3,240 pounds ; or, 

 with the trays and containing-boxes, 3,600 pounds, — a little over 

 I J tons, instead of 9 tons, as the writer would have us believe. Let 

 me add, in connection with the weight of a storage-battery car, 

 what every engineer knows, that in a locomotive (which the 

 storage-battery car is), to have adhesion, you must have weight. 



The 120 cells above referred to contain 52 horse-power hours, 

 and will carry that car over the streets of New York, without being 

 recharged, for a distance of at least thirty-six miles, and carrying 

 over four hundred passengers in all. If the Hauss Electric Rail- 

 way is now doing equally acceptable and economical work, it would 

 be very interesting for the public to know it. The writer omitted, 

 by the way, to state where the Hauss electric system may be seen, 

 and what practical experience, if any, it has had. 



The writer goes on to say that the storage-battery system re- 

 quires a special car to be built, to provide the necessary space 

 beneath the seats to receive the battery. This is equally untrue. 

 Car No. 3, above referred to, is an old horse-car, and was altered 

 at an expense of about two hundred and fifty dollars for its present 

 purpose. The alteration required is the lifting of the car-body 

 some five inches above its present position. 



The next objection the writer has to the storage-battery is, that 

 it " has a life of only two years of constant service, and it is sub- 

 ject to the danger of short-circuiting, which at once destroys its 

 usefulness." The remark as to short-circuiting is very amusing. 

 Am I to understand that the motors constructed by the Hauss 

 Electric Railway (if they do actually construct any) are not subject 

 to the danger of short-circuiting.' If so, we must assume that 

 their usefulness is destroyed. Now, we all know that the experi- 

 ence of every electric railway in the country is that the electric- 

 railway motor has the same tendency to short-circuit that the most 

 peevish mule has to kick. If the short-circuited motors of 1888 

 were made a pile of, we should not need to go to Egypt to see a 

 pyramid. The fact is, that, since the fifteenth day of September 

 last, up to the present moment, we have not short-circuited a bat- 

 tery in our street-car service, although our cars have run in that 

 time in passenger-service some seven thousand miles. This 

 storage-battery short-circuiting is a thing of the past. The cells 

 are at present so connected that short-circuiting is impossible ; for 

 the connector would be blown out of position by an excessive cur- 

 rent, and thus save the battery. We should be pleased to have 

 you verify this at our station in this city. The writer gives our 

 battery "only two years of constant service." We thank him for 

 that concession, for we only ask six months' constant service in 

 order to compete with the cost of horse-traction. He probably 

 forgets that the material in the battery is not destroyed when the 

 "usefulness " of the battery ends, but is again made over into bat- 

 tery by a process so cheap as to compete favorably with the main- 

 tenance of horses. 



One word more, Mr. Editor, and I have done. Our 18-foot cars. 



Nos. I and 2, now in the service of the Fourth and Madison Ave- 

 nue lines, in this city, run from 86th Street and Madison Avenue 

 to the Post-Office, and back, — a distance of twelve miles, — on an 

 expenditure of less than fifteen horse-power hours of energy, and 

 frequently carry over two hundred passengers on the round trip. 

 This seems almost too good to be true ; but you would do us a 

 favor by inspecting the records at our station, and verifying this 

 statement for yourself. With storage-battery traction there can be 

 no mistaking the amount of energy expended ; for we know the 

 number of horse-power hours that are put into the battery, and of 

 course the number of miles such charge will carry the car. Now, 

 for the information of the public, we think it but fair that the Hauss 

 Electric Railway should tell us how far fifteen electrical horse- 

 power hours has carried one of their cars. The comparison would 

 be very interesting. Wm. Bracken. 



New York, Jan. $. 



The Soaring of Birds. 



In a recent number of Science (xii. p. 267) I notice an article 

 under the above heading. It seems to me that we have not yet 

 got to the bottom of the matter, and that the true explanation of 

 the phenomenon is still simpler. Imagine a piece of paper floating 

 in the air. The wind takes it, and carries it along horizontally with 

 its own velocity. After it has assumed the velocity of the wind, there 

 is but one force acting on it ; namely, the vertical one due to its own 

 weight. Imagine now a bird under the same circumstances. In- 

 stead of travelling with the wind, as everybody who has watched a 



soaring bird knows, he travels round and round in circles, each one 

 a little higher than the last, and each one a little farther along in 

 the direction towards which the wind is blowing. Now, when he 

 travels with the wind, he attains nearly its velocity, and then turns 

 and travels against it, rising rapidly at the same time, till he is- 

 nearly stationary, or perhaps is even going a little backwards, rela- 

 tively to the ground. He then turns and travels with the wind 

 again, either moving along horizontally, or perhaps dropping some- 

 what nearer the earth, until he attains his original velocity, when 

 the cycle is repeated. Comparing his motion with that of the pa- 

 per, we find that he does not move along so fast : there must, there- 

 fore, be some compensating advantage obtained, in order to use up 

 the surplus energy derived from the wind. 



In the above figure let H represent the direction of the wind, and 

 A the position of the bird. Let AB represent the force due to his 

 weight, and AD the mean force exerted on him by the wind, owing 

 to the fact that he does not move along as fast as the surrounding 

 air. Combining these, we get the resultant force AC acting upon 

 the bird. Now construct the plane EF perpendicular to the line 

 AC. The bird may then move anywhere in this plane without 

 losing energy. He cannot move to the right of it, but he may 

 move to the left, and thus gain energy. Practically he will move 

 in a spiral about the line AG, thus slowly dropping from the plane 



