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



ship Carnarvon from the island of Fernando Po, having " a 

 crew of seven European seamen, two free negroes, one Kroo- 

 man, one captain and two mates. Two of the seamen were 

 ill of fever, Owen Williams and C. Hall. On Sunday, Ja- 

 nuary 23, one of the sick seamen died. On January 26, 

 three of the healthy men, namely, the steward, the second 

 mate and a seaman, were taken ill of fever. January 27th, 

 a seaman taken ill of fever. The weather calm, with light 

 winds ; the island still in sight ! January 30, another seaman 

 taken ill of fever. The steward died. February 4, the cap- 

 tain taken ill. John Williams died. February 6, the chief 

 mate taken ill of fever. February 7, Smith, seaman, died." 

 Here there was doubtless a high dew-point, and the tempe- 

 rature was not, as in tiie instances of Cook and Perouse, raised 

 much above it by fires. It would be very easy to give ample 

 additional evidence of the pernicious effects of damp air at 

 sea far beyond the influence of vegetable efllluvia. 



But it may be thought that, if warm and damp air is suf- 

 ficient to produce fevers, the sea between the tropics would be 

 found more unhealthy than the land, which is known to be 

 contrary to experience. To this it may be replied that the 

 ordinary cool current of air that flows from the poles to the 

 equator is in general sufficiently dry even over the sea to pre- 

 vent that part from being very unhealthy, or at least as much 

 so as the hot and moist valleys between the tropics. Captain 

 Basil Hall in his fragments of voyages says : " As we ap- 

 proached the equator the thei'mometer fell from 82° in the 

 day to 79° or 80° at night. The symptoms of change of cli- 

 mate became daily more manifest. Every skylight and stern- 

 window was fastened wide open, and every cabin scuttle 

 driven out that a free draught of air might sweep through the 

 ship. The seamen and marines dined on the main deck that 

 the lower deck might be kept as cool and as airy as possible 

 against the sultry and feverish night season. We generally 

 exposed a dozen buckets full of sea-water on the gangway at 

 8 or 9 o'clock in the evening, and these being allowed to 

 stand till the morning, 4 or 5 o'clock, became so much cooler 

 than the sea by the evaporation during the night, that the 

 shock was unspeakably grateful." 



Here we perceive that evaporation was going on actively 

 on the surfaces of the water in the buckets, the dew-point 

 must therefore have been considerably below the tempera- 

 ture ; yet even here we find the night season desci'ibed as 

 sultry and feverish, though the temperature was then a few 

 degrees lower than it was during the day : this could arise 

 only from the dew-point being then a little nearer to the tern- 



