STATE OF HEALTH AND DISEASE. 
clxxiii 
improved the diet of the men. Another deviation from the usual allowance 
was the employment of good flour instead of biscuit, by which the crews 
were furnished with a daily supply of well-fermented bread. When to this 
was added a liberal proportion of lemon- juice, pickles, vinegar, fyc., it was 
reasonable to hope that the exciting cause would not acquire any consi- 
derable activity, unless a very strong predisposition prevailed. 
Of the remote predisposing causes to which we were exposed from the 
peculiarity of our situation, a cold and vitiated atmosphere was the most to 
be dreaded. It is true there was little to be apprehended from the effects 
of the external air, for during the winter months, which constitute three- 
fourths of the year, the atmosphere is pure, clear and dry ; its mean tempe- 
rature considerably below zero of Fahrenheit, and rarely undergoiiig : any 
very sudden change. The clothing of the men was found adequately warm 
to protect them from the severest cold experienced, which they were enabled 
to confront not only with impunity, but with a degree of profit and 
pleasure. 
In the interior of the vessels the state of the air was necessarily very dif- 
ferent. To economise and preserve a tolerable degree of heat below, it was 
necessary to keep the hatchways continually covered ; the rarefied air which 
escaped by the flues being replaced through the crevices, and by the occa- 
sional opening of the hatchways. In this way, although the renewal of pure 
air, was abundantly frequent to maintain healthy respiration, the air was sel- 
dom of sufficient temperature to carry off the vapours which floated between- 
decks. These were deposited upon the cold sides of the ships, overhead, 
and in the bed-places, in icicles, which, by alternately thawing and freezing, 
kept up a dampness that for some time proved a source of danger, de- 
manding continued attention to obviate its pernicious influence on the health 
of the crews. 
Personal uncleanliness was another evil against which it was difficult to guard. 
The smoke with which the air was loaded attached itself to the persons and 
clothing of the men in such quantity as to cause great inconvenience; toler- 
