192 



SCIENCE. 



[N. S. Vol. I. No. 7. 



kind of insect) and he concludes that 

 " Hemimerus belongs to the Orthoptera, 

 constituting a separate family very closely 

 allied to the Forficulina." He shows from 

 his dissections that the insect is viviparous, 

 bringing forth one young at a time. 



THE COOLING OF HOSPITALS. 



De. Moeeill Wyman, of Cambridge, Mas- 

 sachusetts, has published in the Proceedings 

 of the American Academy of Arts and 

 Sciences, Vol. 30, page 482, an interesting- 

 paper giving the results of some experiments 

 made in the Cambridge Hospital, in which 

 the air admitted to the wards in warm 

 weather was cooled by passing it through 

 pipes in which cold water was circulating, 

 these pipes being the same as those used for 

 warming the air in the winter by the circu- 

 lation of hot water. In one experiment the 

 external temperature was at 83° F.; there 

 was no wind and the patients were suffering 

 from the heat. The temperature of the 

 water as it entered the cooling pipes was 

 57 to 58 degrees. An electrical fan 36 inches 

 in diameter, making five hundred revo- 

 lutions a minute, forced about 10,200 cubic 

 feet of the warm outer air through these 

 pipes into the ward, which contained 21,000 

 cubic feet. In an hour the ah entering the 

 ward was at 71° F., and the comfort of the 

 patients was manifestly improved. But 

 the cooling surfaces were not only the ten 

 cooling coils of 30 square feet each, but also 

 the four walls of the air chamber beneath 

 the ward, being about 3,300 square feet of 

 surface, and it is estimated that the cooling- 

 power of the coUs was about one-tenth that 

 of the walls. A month later the heat of 

 the external atmosphere was greater and 

 the fan was more constantly in motion; the 

 temperature of the air chamber had in- 

 creased, and that of the water had risen to 

 70°. The quantity of water required for 

 the circulation was large and expensive, and 

 it was therefore shut off. But the same 



amount of ventilation was continued, th^ 

 air passing thi'ough the air chamber. During 

 the summer the ward temperature gradually 

 rose until it diii'ered but little from that of 

 the open air. Nevertheless, the comfort 

 given to the patients and nurses was im- 

 mediate and decided, and there was a 

 decided feeling of freshness and freedom 

 of air. 



Dr. Wyman points out that we can do 

 little towards lowering the temperature of 

 the air in hot weather in the volumes re- 

 quired for the ventilation of a hospital. It 

 is a question of the rate of evaporation 

 fi-om the perspiring surface, which is gov- 

 erned in a great measure by the velocitj' of 

 the air coming in contact with that surface, 

 and this is a factor which by art it is possible 

 to control. If we try to cool the air before 

 it enters the ward, it must be remembered 

 that air absolutely humid, when brought 

 into contact with warmer air also saturated, 

 will cool the latter, which will approach 

 dew-point, and if its moisture is condensed 

 into visible vapor will give out heat. 

 " Evaporation consumes heat, condensation 

 liberates heat." " To give comfort dui'ing 

 the excessive heats of summer the sick re- 

 quu"e three or four times the air needed for 

 satisfactory ventilation in winter. It re- 

 quired 400,000 cubic feet an hour for our 

 sixteen patients, and yet while this large 

 quantity was passing through the ward it 

 was only known, except at the registers, by 

 the accompanying sense of freshness and 

 pleasant coolness ; it was never felt as a 

 draught." 



" The experience of the Cambridge hos- 

 pital leads to these two conclusions : first, 

 that fresh air directly from the open, in 

 the quantity and manner there supplied, 

 can be made to give great comfort to 

 the sick during the heats of summer ; and, 

 secondly, that previous cooling of the 

 air so supplied is difficult and practically 

 useless." 



