Mr. T. Hopkins's Observations on Malaria. 115 



the same. But the dew-point the same as the temperature 

 even at 60°, with a stagnant atmosphere, might seriously check 

 evaporation from the human body, though not to the same 

 dangerous extent as the higher dew-point in the Campagna 

 of Rome. 



Captain Cook and others experienced the unhealthy in- 

 fluence of hot and damp air at sea, far removed from the sup- 

 posed seats of poisonous effluvia from decaying vegetable sub- 

 stances, and also found the benefit of heating and drying the 

 air. In Cook's Voyage from 1772 to 1775, p. 9, it is stated 

 that, " in latitude S" north, August 20 to 27th, the thermo- 

 meter generally at noon kept from 79° to 82°. On the 27th 

 spake with Captain Furneaux, who informed us that one of 

 his petty officers had died. At this time we had not one sick 

 on board, though we had everything of the kind to fear from 

 the rain we had had, which is a great promoter of sickness in hot 

 climates. To prevent this I took every necessary precaution 

 by airing and drying the ship with fires made between decks, 

 smoking, &c. &c. ; neglect of these seldom fails to bring on 

 sickness, but more especially in hot and wet weather." And 

 in page 291, vol. ii. " Care was taken to keep the ship clean 

 and dry between decks. Once or twice a-week she was aired 

 with fires. I had also frequently a fire made in an iron pot 

 at the bottom of the well, which was of great use in purifying 

 the air in the lower part of the ship." Sir J.Pringle in his ac- 

 count of Cook's sanatory precautions, says, that " some old 

 ships were more healthy than the new ones, because the 

 former having their galley in the forepart of the orlop, the 

 chimney vented so ill, that it was sure to fill every part with 

 smoke. This was a nuisance for the time, but, as he thought, 

 abundantly compensated by the extraordinary good health 

 of the crews." Perouse, when proceeding from the northern 

 part of the Pacific to the Equator, and in the latitude of 10° 

 north, writes thus: "The heat was suffocating and the hy- 

 grometer had never indicated more iiumidity since our de- 

 parture from Europe. We weie breathing an air destitute 

 of elasticity ! which joined to unwholesome aliments dimi- 

 nished our strength, and would have rendered us almost in- 

 capable of exertion if circumstances had required it. I re- 

 doubled my care to preserve the health of the crew during 

 this crisis produced by too sudden a passage from cold to heat 

 and moisture. 1 ordered the ship to be dried and ventilated 

 between decks." A high dew-point, no doubt, was here the 

 cause of the illness, and the drying was merely heating the 

 air so as to carry the temperature much above llie dew-point. 

 On the 20th of January the brothers Lander sailed in the 

 I 2 



