May 1832. macacu — malaria. 77 



dangerous a place as the fatal Macacu within reach. I ques- 

 tioned every one of the party, especially the second lieutenant 

 and master, as to what the three who perished had done dif- 

 ferent from the rest ; and discovered that it was believed they 

 had bathed during the heat of the day, against positive orders, 

 and unseen by their companions ; and that Morgan had slept 

 in the open air, outside the tent, the night they passed 

 on the bank of the Macacu. 



As far as I am aware, the risk, in cases such as these, is 

 chiefly encountered by sleeping on shore, exposed to the air on 

 or near the low banks of rivers, in woody or marshy places 

 subject to great solar heat. Those who sleep in boats, or under 

 tents, suffer less than persons sleeping on shore and exposed ; 

 but they are not always exempt, as the murderous mortalities 

 on the coast of Africa prove. Whether the cause of disease is 

 a vapour, or gas, formed at night in such situations, or only a 

 check to perspiration when the body is peculiarly affected by 

 the heat of the climate, are questions not easy to answer, if I 

 may judge from the difficulty I have found in obtaining any 

 satisfactory information on the subject. One or two remarks 

 may be made here, perhaps. — The danger appears to be incurred 

 while sleeping ; or when over-heated ; not while awake and 

 moderately cool ; therefore we may infer that a check to the 

 perspiration which takes place at those times is to be guarded 

 against, rather than the breathing of any peculiar gas, or air, 

 rising from the rivers or hanging over the land, which might 

 have as much effect upon a person awake, as upon a sleeper. 

 Also, to prevent being chilled by night damp, and cold, as 

 well as to purify the air, if vapour or gas should indeed be the 

 cause of fever, it is advisable to keep a large ffre burning while 

 the sun is below the horizon. But the subject of malaria has 

 been so fully discussed by medical men, that even this short 

 digression is unnecessary. 



To return to the narrative. Mr. Bynoe consulted with the 

 best medical advisers at Bahia, and afterwards at Rio de J aneiro, 

 and he and I had the melancholy satisfaction of knowing that 

 the best had been done for his patients. 



