April 2-], 1888.] 



SCIENCE. 



2or 



by a number of electric tramways at present in operation. The 

 only question is, will considerations of safety and aesthetics allow 

 the current to be economically conveyed to the cars ? For instance : 

 in the Sprague Electric Railway in Richmond, using an overhead 

 conductor, it is costing for power about Si. 70 per day per car, the 

 cars averaging over eighty miles. This is for only twenty cars. 

 When the full complement is running, the cost will be reduced, 

 probably to about $1.50 per car per day. This cost is to be com- 

 pared with the $5 or §6 that must be allowed per car per day for 

 horses, at an average of, say, 60 miles per car per day. If the 

 overhead system could be used, then, in all of our cities, there 

 would be no doubt as to the results as far as street-car traction 

 ^oes. When it comes to ordinary railroad-work, the state of af- 

 fairs is very different. The question is, shall we substitute for 

 steam, used directly, a power which is in the first place derived 

 from steam, and which suffers the losses due to at least two trans- 

 formations before it is utilized in driving the train ? As far as mere 

 economy of power-production goes, the question is easily answered : 

 the efficiency of a stationary steam-plant is greater than that of a 

 locomotive-engine; and the cost of a horse-power delivered to the 

 driving-axles of the train by the electric motor would not be more 

 for coal, attendance, and depreciation, than the same power from 

 the locomotive, even after allowing for all the losses in the differ- 

 ent transformations. The advantages of the electric motor are 

 these: the driving-machinery is the simplest that it is possible to 

 conceive of; the armature of the motor would be fitted directly on 

 the car-axle, while the field-magnets would rest on the truck. Each 

 axle would have its motor, and in a train every second or third car 

 would be a motor-car. One advantage of this has been pointed 

 out, first, probably, by Prof. George Forbes. Taking a six-car 

 train, we would have the traction, not of four wheels, but of six- 

 teen, supposing two motor-cars. This will enable us to make any 

 speed that safety will allow, to start quickly, and to take at high 

 speeds, grades that at present are inadmissible. In fact, we can 

 dispense with a great deal of the graduig that makes the construc- 

 tion of railroad-lines so costly. Again : on the down grades we 

 can make our motors into dynamos feeding current into the line, 

 — a plan due, I think, to IMr. Sprague, — instead of wasting energy 

 by braking the wheels ; and we can in the same way brake the 

 cars when stopping. The advantages, then, are great simplicity, 

 increased traction, allowing an increase of speed and a decrease in 

 the cost of constructing the road, recovery of energy on down 

 grades and in stopping. As compared with city electric tramways, 

 such as are now in use, railroads would have the advantages of 

 simplicity, in not requiring any gearing between the motor and car- 

 a.xle, and in allowing any economical means of conducting the 

 current to the car, and the employment of high electro-motive 

 forces. There is one great disadvantage, however, that the future 

 may remove, but which at present is serious. A station supplying 

 any portion of the line will have to have a capacity equal to the 

 maximum work that will be required of it at any time, while the 

 mean work might be very much less than this. As the maximum 

 may differ from the average work five or six times, we would have 

 to equip stations of five or six times the present capacity of the 

 locomotives, at a cost that would throw the balance in favor of the 

 present system, unless there happened to be very considerable 

 sources of natural power along the line. The remedy for this — a 

 remedy which cannot be at present applied — is in equipping the 

 stations with storage-batteries ; charging them when the required 

 power is below the average, drawing from them when it is above. 

 We may say, then, that, with long-distance direct lighting and 

 electric tramways, electric railways wait the development of a more 

 perfect storage-battery to be successful. 



Electric Phenomena provoked by Radiation. — Very 

 lately considerable attention has been attracted to the effect of light 

 on the phenomena of electrical discharge, the light generally in- 

 creasing the effects, allowing discharge where it would not other- 

 wise occur. In the Philosop/iical Magazine for April, Professor 

 Righi gives a preliminary account of some interesting experiments 

 he is trying in the same field. Two metals, one in the form of a 

 disk, the other a net, are placed opposite one another. One of the 

 metals. A, is connected with one pair of quadrants of an electrom- 

 eter ; the other metal is connected with the other pair and the 



earth ; and the needle is charged. If A is illuminated, a deflection 

 is obtained which reaches a maximum in a time which is shorter 

 the nearer the irradiating source and the larger the surface of the 

 metals. The sun's light does not produce this effect in a marked 

 way : the magnesium light is more active ; the voltaic arc gives the 

 best results. It is probable that the ultra-violet rays are the most 

 active. Four of these ' photo-electrical cells ' are connected in 

 series, and gi\'e the same results as ordinary cells in series on open 

 circuit. 



HEALTH MATTERS. 

 Portagiousness of Consumption. 



1-N a recent jjaper presented to the Medical Press Association of 

 St. Louis, Dr. William Porter discusses the ' portagiousness of 

 phthisis.' He prefers the word ' portagious,' because it conveys 

 a more exact idea of the manner of transmission of phthisis than 

 either ' contagious ' or ' infectious.' In his paper the term ' phthisis ' 

 is used to denote that class of disease to which belongs the large 

 majority of cases of slowly progressive pulmonary inflammations ; 

 i.e., chronic tubercular phthisis. 



Dr. Porter propounds the following question : ' Have we reason- 

 able evidence that the products of, or emanations from, a phthisical 

 subject may be carried to, received by, and cause like disease in, 

 one previously free from phthisis ? ' The answer to this question he 

 thinks must be answered in the affirmative, and quotes the follow- 

 ing experiments as sustaining this view. In experiments made by 

 Tappeiner in 1883. tuberculous sputa being inhaled by eighteen 

 healthy animals, tubercles in both lungs, and pleura, were after- 

 wards found in seventeen. That record of Koch's work found in 

 the second volume of the ' Imperial Health Reports,' shows, that, 

 after the inhalation of material from phthisical cavities, the rabbits 

 and guinea-pigs under observation had, within twenty-eight days, 

 tubercles throughout the lungs of all, and in the liver and spleen 

 of some. The carefully conducted investigations of Cadeac and 

 Mullet, recently published, show, that while no positive result was 

 obtained from compelling rabbits and guinea-pigs to inspire air ex- 

 haled by phthisical patients, yet when air was used collected from 

 near the beds of hospital inmates, the air presumably carrying par- 

 ticles of sputa, two out of twelve guinea-pigs acquired tubercle. 



The writer refers to some experiments which he made, to deter- 

 mine this point. " Three healthy guinea-pigs were selected. One 

 was inoculated with phthisical sputa, and placed in a small box 

 with one of the others. The third was confined in a box in an ad- 

 joining room. They were cared for alike, and had similar food. 

 In four weeks the first one died, and the examination showed tuber- 

 cle in the lungs, and a large cheesy gland near the point of inocu- 

 lation. Three weeks after, the second animal sickened and was 

 killed. I found small granulations scattered through both lungs, 

 at some points aggregated ; and in the right lung were two nodules, 

 having a soft cheesy centre. The third guinea-pig, examined three 

 months later, had no evidence of tubercle or other disease." 



The only experiment upon a human subject was made by Drs. 

 Demet, Pararky, and Zailories, of Syra, in Greece, who inoculated, 

 with sputa from a phthisical patient, a man whose history afforded 

 no suspicion of tubercle, and whose lungs were healthy, but who 

 had gangrene due to femoral embolism, and who would not permit 

 amputation. In three weeks, auscultation revealed evidences of 

 disease at the right apex. Thirty-eight days after the inoculation, 

 the man died from gangrene, when it was found that the upper 

 right lobe had seventeen small tubercles and two granulations in 

 the apex of the left lung. 



In an inquiry into the transmissibility of phthisis, made by the 

 Collective Investigation Committee in London, two hundred and 

 sixty-one answers were received from physicians in family practice, 

 affirming the proposition that phthisis may be communicated from 

 the sick to the well ; and evidence was given in proof of the state- 

 ment. One hundred and ninety-two observers recorded cases 

 where both husband and wife became phthisical, in one hundred 

 and thirty cases there bemg no phthisis in the family of the one to 

 whom the disease was thought to have been transmitted. 



Some of these cases were very interesting. Dr. Spriggs of Great 

 Bedford instanced the case of Miss R., aged 48. a dressmaker, who, 

 living in rather a lonely cottage at C, Bedfordshire, had three ap- 



