April 26, 1889.] 



SCIENCE. 



.19 



treme contagiousness of diphtheria from person to person is well 

 known, and the virus adheres tenaciously to objects on which it 

 happens to alight. The clothing of a patient, even when the dis- 

 €ase is of the mildest form, his bedding, the furniture of his room, 

 and the objects which he handles, may for weeks afterward com- 

 municate the disease. Dr. Sternberg, in his recent Lomb Prize 

 essay, also mentions the fact that all damp, foul places, such as 

 sewers, cellars, and ill-ventilated spaces under floors, afford condi- 

 tions favorable for the development and propagation of the diph- 

 theritic virus. The virus, once received, may be propagated in 

 such a place for an indefinite time ; and, ascending in the vapors 

 which arise from this culture-bed, it is liable to communicate the 

 disease to any one who inhales it. Thus in New York City prior 

 to 1850, although foul sewers and unsanitary conditions existed, 

 there was no diphtheria ; but in the decade following 1850 this 

 disease was introduced. The germ made its way into the sewers 

 under ground ; and now, wherever sewer-gas escapes into the 

 domiciles of the city, it carries with it the diphtheritic poison. 

 The amazing vitality and power of propagation of this virus are 

 apparent when we reflect that it has permanently infected the New 

 York sewers, so that children in all parts of the city are constantly 

 falling ill with the disease. 



The Bacillus of Tuberculosis.— According to M. Moule, 

 domestic fowls are frequently the subjects of tuberculosis, the dis- 

 ease often involving the abdominal organs. Paie de foie gras is 

 sometimes almost a pure culture of tubercle bacilli. Dr. Squire of 

 the London Epidemiological Society states that the bacillus of tuber- 

 culosis may enter the body (I) by inoculation through a cut or 

 scratch ; (2) by means of the genito-urinary mucous membrane ; 

 (3) by the product of conception, and by direct hereditary transmis- 

 sion ; (4) by the mucous membrane of the alimentary canal ; (5) by 

 the mucous membrane of the respiratory tract, and by the air-cells 

 of the lungs. The possibility of infection through the alimentary 

 tract assumes importance from the prevalence of tuberculosis in 

 animals which are used as food, and from the e.xperimental proof 

 of the infectiousness of the milk of tuberculous cows. The pres- 

 ent state of knowledge on the subject points very strongly to the 

 necessity for careful inspection of cattle kept for dairy pur- 

 poses, and for precautions in using the milk, and possibly also the 

 flesh, of diseased animals. 



The Contagiousness of Tuberculosis. —The New York 

 Board of Health has passed the following resolution : Resolved, 

 that Drs. T. M. Prudden, H. M. Biggs, and H. P. Loomis, the 

 pathologists of this department, be and are hereby requested to 

 formulate a brief and comprehensive statement regarding the con- 

 tagiousness of tuberculosis in man, stating therein the evidence of 

 the same, and recommending, in the briefest possible manner 

 practicable, the simplest means of protection from its influence. 



Lead-Poisoning. — At a meeting of the Practitioners' Society 

 ■of New York, Dr. Kinnicutt, the president, reported two cases of 

 lead-poisoning occurring from an unusual source. The first pa- 

 tient was admitted to St. Luke's Hospital, suffering from lead colic 

 and " wrist-drop." He had been employed as a florist ; and on 

 investigation by Dr. Vaughan, the house-physician, it was found 

 he had been in the habit of biting off the ends of the tinfoil used as 

 wrappers for hand bouquets. The tinfoil used for this purpose con- 

 tained as much as eighty per cent of lead. There was no history 

 of other sources of lead-poisoning. The second patient was ad- 

 mitted to the hospital, suffering from lead colic, and presenting a 

 typical blue gum--line. He had been in the habit, for several weeks, 

 of drinking beer from bottles which, he said, were cleaned by his 

 employer with lead shot. Dr. R. F. Weir recalled the fact that 

 several cases of lead-poisoning, some years ago, had been traced to 

 the use of a popular brand of chewing-tobacco which was wrapped 

 in tinfoil. Dr. Dana referred to some cases of poisoning which 

 had been traced to the consumption of certain beverages coming in 

 bottles with so-called patent stoppers. He said that he had re- 

 cently had two Chinese patients in his hospital service, both of 

 whom were suffering from lead-poisoning. He was unable to trace 

 the source of the poisoning. 



ELECTRICAL NEWS. 



Ayrton and Perry's Secohmmeter and Secohm Stand- 

 ard. — In default of a full description, we have to content our- 

 selves with the announcement that Professors Ayrton and Perry 

 will shortly put a standard secohm on the market as an accessory 

 to their secohmmeter. The advantage of such a standard is evi- 

 dent, since it reduces the manipulations with the secohmmeter to a 

 very few simple ones, and dispenses with the use of a speed-coun- 

 ter, or tacheometer, for absolute determinations with the mentioned 

 instrument. This standard secohm will be used much in the same 

 way as any standard resistance would be used in the Wheatstone 

 bridge; in fact, the secohmmeter is nothing more than a very 

 nicely constructed double commutator. Descriptions of the sec- 

 ohmmeter proper appeared in several of the electrical papers some 

 time since. Nothing, however, was said about the use of this in- 

 strument. Through James W. Queen & Co., the sole agents for the 

 Ayrton and Perry instruments, we have received a full description 

 explanatory of the mode of using the secohmmeter for determining 

 absolutely, or comparing, the co-efficients of self-induction. This 

 description will be found on another page. 



Topeka Electric Railway. — The Topeka Rapid Transit 

 Railway, the equipment of which has just been finished by the 

 Thomson-Houston Electric Company, was put in operation on 

 April 3. This road is said to be the longest in the world (14 miles, 

 20 miles of track). The trial trip was made on Wednesday, April 

 3, with four cars filled with invited guests, including the managers 

 and chief officials of the Topeka City Street Railway and the East 

 and West Side Circle Railways, and was satisfactory. The elec- 

 trical apparatus consists of six 30-horse-power Thomson-Houston 

 generators. The residents of Topeka are enthusiastic, and it is 

 predicted that ere long electricity will be in general use on all the 

 street-railways in the city. 



Earthing Lightning-Conductors by Means of Gas 

 and Water Pipes. — In the Elektroteclmische Zeitschrift (vol. 

 XX. p. 473), A. VoUer has an article on the above subject, an ab- 

 stract of which appears in the Journal of the Instiiution of Elec- 

 trical Engineers, No. 77. It is generally assumed that the path of 

 the discharge follows only the line of least resistance, and no attention 

 has been paid to the fact, on which Mr. VoUer insists, that the di- 

 rection of the discharge is chiefly influenced by the state of electric 

 potential of the buildings in closest proximity to the charged cloud. 

 The better the connection of the metallic masses in buildings is 

 with the earth, the higher will be the potential of the induced elec- 

 tricity, and the greater likelihood is there of a discharge taking 

 place between the cloud and the points in question. Since the 

 general introduction of gas and water pipes into our houses, it is 

 these which offer the least resistance between the roofs and earth. 

 Hence, if a charged cloud should pass over such a house, the gas 

 and water pipes must be at a higher potential, and there is much 

 greater probability of the lightning entering the house through 

 them than at any other point : in other words, it is more likely that 

 the discharge will take place through the pipes than through the 

 lightning-conductor ; and, if the lightning-rod is not connected to 

 the pipes, the discharge will find its way somehow to the latter, 

 causing destruction in its path. At the request of the Hamburg 

 fire insurance companies, Mr. Voller undertook to inspect cases 

 of lightning-strokes, and to ascertain the point struck, as well as 

 the path followed. A great many interesting cases investigated 

 are duly recorded, but some general results only can be reproduced. 

 It generally happened, that, when the building struck was unpro- 

 vided with a lightning-conductor, the lightning struck some part 

 of the roof or walls, found its way to the gas and water pipes, and 

 then passed harmlessly to earth. In the few cases where lightning 

 struck a building fitted with a lightning-conductor, the discharge 

 jumped over from the conductor to the pipes. In fifteen cases 

 which were specially investigated in the years 1884 and 1S88, after 

 the lightning had done more or less damage at the point where it 

 struck, and in the immediate neighborhood, it was found that in 

 nine cases the discharge made its way to earth through the water- 

 pipes, in two cases through the gas-pipes, in two cases through 

 rain-pipes, in one case probably through the lightning-conductor of 



