NOTES. 



863 



diate of Arkansas and Tennessee to that 

 of New Jersey. A radius of from 18 to 

 24 takes in the marine tertiaries of the 

 East and the West; one of 24 marks 

 the main outlines of the continent; while 

 one of 36 takes in the extreme points 

 of the continent in all directions. The 

 rule is applied with almost literal simi- 

 larity to the other continents. Professor 

 Owen furthermore maintains that the west- 

 ern Alps became a dynamic focus at about 

 the beginning of the Cenozoic period, and 

 that Monte Rosa is nearly the center of the 

 dry land of the globe, whence a great circle 

 of immense seismic activity may be traced 

 nearly parallel with the Asiatic continental 

 trend to the Himalayas and thence around 

 to the Andes and the South American earth- 

 quake-region. Another great circle is nearly 

 parallel to the North American trend, and 

 includes the volcanoes of Central America 

 and the geysers of Iceland, and incloses 

 and probably aids to heat our Gulf Stream. 



Valne of Disinfectants. Dr. George M. 

 Sternberg, surgeon in the United States 

 Army, has reported upon the results of ex- 

 periments he has made with various disin- 

 fectants and vaccine virus, the conclusion 

 drawn from which is that chlorine, nitrous 

 acid (nitrogen dioxide), and sulphurous acid 

 (sulphur dioxide), are reliable disinfectants 

 in the proportion of one volume to one hun- 

 dred volumes of air. Probably a consider- 

 ably smaller proportion of these disinfect- 

 ants would be efficient in destroying the 

 potency of thin layers of virus in a moist 

 state, or of virus exposed to the action of 

 the disinfectant in an atmosphere saturated 

 with moisture. Experiments with carbolic 

 acid, on the other hand, " show that the 

 popular idea, shared perhaps by some phy- 

 sicians, that an odor of carbolic acid in the 

 sick-room or foul privy is evidence that the 

 place is disinfected, is entirely fallacious, 

 and, in fact, that the use of this agent as a 

 volatile agent is impracticable, because of 

 the expense of the pure acid and the enor- 

 mous quantity required to produce the de- 

 sired result." 



A Selenium Photometer. M. Leon Ti- 

 dal has devised a photometric apparatus 

 of selenium, for measuYing the intensity of 

 natural or artificial light by means of an 



action purely physical and mechanical, and 

 in a manner analogous to that by which we 

 measure the temperature and the amount of 

 atmospheric pressure with the thermometer 

 and the barometer. The difference in con- 

 ductibility which results from the action of 

 light on selenium produces deviations in the 

 needle of the galvanometer which corre- 

 spond in extent with the intensity of the 

 luminous source. In this manner we may 

 determine, at a glance, the intensity of light 

 at any instant. The principle is applied to 

 the construction of meteorological photom- 

 eters, for which elements of selenium of 

 equivalent conductibility are provided, to 

 be substituted for each other as their molec- 

 ular condition becomes modified ; the plates 

 may be restored to their normal condition 

 by heating them, and used again. This in- 

 strument may be employed for the rapid and 

 visible record of the instantaneous changes 

 in luminous intensity, at all heights and 

 depths, the observer reading the indications 

 of the galvanometer at the place which may 

 be most convenient for him. 



NOTES. 



Tb~e American Public Health Association 

 will hold its tenth annual session at India- 

 napolis, Indiana, October 17th to 25th. Pa- 

 pers will be presented on the different ac- 

 tion of disease in the white and black races, 

 the removal of excreta, heredity, sanitary 

 associations, vaccination, intermittent fever 

 in New England, sanitary organization, cat- 

 tle-disease, etc., etc., with reports of com- 

 mittees on the prevention of venereal dis- 

 ease, compulsory vaccination, the manage- 

 ment of epidemics, statistics, cattlc-diseascs, 

 National Museum of Hygiene, incorporation 

 of the Association, and necrology. 



The American School of Classical Studies 

 at Athens, Greece, under the direction of a 

 committee of the Archaeological Institute of 

 America, is to be opened on the 2d of Octo- 

 ber. Its object is to promote the study of 

 classical literature, art, and antiquities, by 

 graduates of American colleges, and to 

 prosecute and aid original and co-operative 

 research in those subjects. The school is 

 open, free of fees, to bachelors of arts, 

 properly recommended from co-operating 

 colleges. Nine colleges in New England, 

 New York, New Jersey, and Baltimore, have 

 contributed annual subscriptions of $2,250, 

 most of them for ten years, in aid of the 

 school. 



