494 



SCIENCE. 



[Vol. VII., No. 174 



the same number of days in March, there was a re- 

 duction representing the saving of 290 lives, and 

 this not taking into account an increase in the 

 population of more than 3,000 souls. 



In March the largest number of persons suc- 

 cumbed to disease on the 31st, there being on 

 that day 137 deaths recorded ; on the 30th of 

 April the maximum limit was reached, amounting 

 to but 124 deaths. 



The deaths of children under five years of age 

 during March were 1,221, and in April but 1,075 ; 

 and yet diarrhoeal diseases carried off in April 56 

 persons, and only 32 in the preceding month. 

 Scarlet-fever caused a mortality of 49 this month, 

 as compared with 42 in March. The lines in the 

 chart representing scarlet-fever and the diarrhoeal 

 diseases, which for two months have nearly coin- 

 cided, now begin to diverge, and the separation 

 will be more and more marked as the season ad- 

 vances. The increase of deaths from diarrhoeal 

 diseases appears to be pretty evenly distributed 

 throughout the month, and not very perceptibly 

 increased in any one period over another. The 

 largest number of deaths from diseases of this 

 nature in any one day was 5, on the 22d. The 

 week in which this occurred was characterized by 

 high temperatures, 81°, 74°, 74°, 81°, 84°, and 83° 

 being the maxima for six consecutive days be- 

 ginning with the 19th ; and during this period there 

 were 16 deaths from this class. The next largest 

 number of deaths was 4, on the 11th inst.; and on 

 six consecutive days of that week the maxima 

 reached by the thermometer were respectively 70°, 

 52°, 64°, 68°, 69°, and 67°, and the recorded deaths 

 were 14. 



This is an interesting comparison, and would 

 seem to show that there are other influences at 

 work in the causation of diarrhoeal diseases than 

 an elevation of temperature at one part of the 

 day. On these days, when the thermometer was 

 ranging from 74° to 84° in the afternoon, it was 

 at other parts of the day much lower, sometimes 

 as low as 48°. It is the high temperature con- 

 tinued throughout the greater part of the twenty- 

 four hours, and repeated day after day, as occurs 

 in July and August, which produces such fearful 

 ravages among the inhabitants of the large cities. 

 Especially is this destructive influence marked 

 when the air is laden with moisture. A study of 

 the accompanying chart will show, that, at the 

 time when these high temperatures occurred, the 

 air was comparatively dry ; on the 23d inst., when 

 the maximum temperature was 84°, the humidi- 

 ty was but 60, saturation being 100. That this is 

 an important element in the problem is not to be 

 overlooked. It is a matter of common experience 

 that a temperature of 90° with a dry atmosphere 



can be more comfortably borne than one of 80° 

 with the air saturated with moisture. In the one 

 case evaporation from the body is rapid, resulting 

 in a cooling of the surface ; in the other it is 

 impeded, or seriously interfered with. 



Consumption and diphtheria show for April, as 

 compared with March, a slight decrease in mor- 

 tality. 



The mean temperature for the month was 52.87°, 

 that for March having been 37.60°. The maximum 

 was on the twenty-third day, the thermometer 

 then registering 84°. This is the highest recorded 

 in the month of April since 1871. 62° was the 

 highest point reached by the mercury during 

 March : its lowest point in that month was 8°, 

 while during April at no time was it more than 

 two degrees below freezing. 



While the number of days upon which rain fell 

 was but seven, rather less than the average for a 

 considerable number of years, yet the total 

 amount of water which fell was 3.85 inches, con- 

 siderably above the average amount for the same 

 period. On the 4th of the month one-quarter of 

 an inch of snow fell, and three-quarters of an inch 

 on the day following. In the corresponding 

 month of 1885, there were several flumes of snow, 

 the amount being too small to accurately measure. 

 Snow is not a frequent visitor in the month of 

 April : in the year 1870 it fell to the depth of two 

 inches and a half ; in 1875 no less than thirteen 

 inches and a half are recorded ; and in the years 

 1882 and 1883 there was in each one half -inch. 

 With these exceptions, no snow has fallen in April 

 during the past fifteen years. From a meteoro- 

 logical point of view, April, 1886, was an excep- 

 tional month. 



SYMPATHETIC VIBRATIONS OF JETS. 1 



After a brief historical notice of the observa- 

 tions of Savart, Masson, Sondhauss, Kundt, La- 

 conte, Barret and Tyndall, Decharme, and Ney- 

 reneuf, on the sympathetic vibrations of jets and 

 flames, the author described his own experiments. 

 Attention was directed to the subject by the 

 accidental observation that a pulsating air-jet 

 directed against a flame caused the latter to emit 

 a musical sound. The pitch of this sound de- 

 pended solely on the rapidity of the jet-pulsations, 

 but its intensity was found to increase in a re- 

 markable way with the distance of the flame from 

 the orifice. In order to study the phenomenon, 

 air was allowed to escape against the flame from 

 a small orifice in the diaphragm of an ordinary 

 telephone, the chamber behind the diaphragm 



1 Abstract of paper read before the Royal society, 

 April 28, by Chichester A. Bell. 



