212 HOSACK ON THE LAWS OF CONTAGION. 



contagious vapour."* In fact, these fires, he adds, appeared to relume 

 that of the contagion ; " they heated the air, already rendered suffocating 

 by the heat of the season and climate ; the pestilential poison became 

 more active, and the disease acquired new force. "f 



The plague of Aleppo, in 1760, 1761, and 1762, might also be cited 

 upon this occasion, as well as many others, both anterior and subsequent 

 to that period, to show that the epidemic influence of this disease is 

 chiefly dependent upon the atmosphere into which it may be introduced. 

 I cannot, however, pass over, without comment, the plague which the 

 British and French troops suffered during the celebrated expedition to 

 Egypt in 1300 and 1801, inasmuch as it will show that this disease, even 

 in its native climate, is governed by the same laws of communication 

 which have been observed when it has been introduced into other coun- 

 tries. 



We are accordingly told, by the learned Dr. Wittman,| " that the 

 disease is more prevalent at Rosetta than in any other town, or part of 

 Egypt; he adds, "the streets of Rosetta are extremely narrow and very 

 dirty. The crowded manner in which the inhabitants live together 

 would appear sufficient, in a stagnant state of the atmosphere, in most 

 of their towns, to generate pestilential or malignant diseases. The very 

 few comforts and conveniences which fall to the lot of the poorer class 

 of the natives in Egypt, by far the most numerous, would lead one na- 

 turally to expect great mortality when the plague prevails among 

 them. Dreadful examples are seen annually to happen." In another 

 part of the same work, he is still more explicit on this point, showing 

 that the plague " doe3 not always possess the same activity and force;" 

 and the necessity, as he expresses it, of some " powerful agent to put 

 the contagion into action, and to give it its full force" He then asks, 



» Bertram!, p. 94i + Jbid. p. 75. \ Travels in Egypt, p. 525. 



