BENJAMIN FRANKLIN. j^ 



cated a noxious quality to the air, and that the atmosphere 

 was poisoned by effluvia emitted from the body. 



Franklin's interest in matters of health and sanitation is 

 further illustrated in the provision made in his will in behalf of 

 a water supply for Philadelphia ; in his experiments in ventila- 

 tion and his efforts to improve our means of keeping ourselves 

 warm ; and by frequent references in his letters to matters of 

 health. He had very definite ideas in regard to disease and 

 its cause, which in many points went against the medical theo- 

 ries of the day. Some of these were emphatically expressed 

 in his paper on colds. In a letter on the treatment of hospital 

 patients* he recommended light covering and abundance of 

 fresh air, declared that the idea that perspiration was better 

 under thick clothes was fallacious ; and expressed himself con- 

 vinced from certain experiments of what he had before sus- 

 pected, that " the opinion of perspiration being checked by 

 cold is an error, as well as that of rheum being occasioned 

 by cold. But this is heresy here, and perhaps may be so with 

 you. I only whisper it, and expect you will keep my secret. 

 Our physicians have discovered that fresh air is good for 

 people in the smallpox and other fevers. I hope in time they 

 will find out that it does no harm to people in health." 



With singular prevision of what science was to develop, 

 Franklin wrote to Priestley in 1774, almost at the date of the 

 birth of modern chemistry : " That the vegetable creation 

 should restore the air which is spoiled by the animal part of 

 it looks like a rational system, and seems to be of a piece 

 with the rest. We knew before that putrid animal substances 

 were converted into sweet vegetable when mixed with the 

 earth and applied as manure ; and now it seems that the same\ 

 putrid substances, mixed with the air, have the same effect. 

 The strong thriving state of your mint in putrid air seems to 

 show that the air is mended by taking something from it, and 

 not by adding to it." To this he added another heresy in 

 those times that he did not believe the woods were unhealthy. 



Another prophecy is embodied in Franklin's views on the 

 progress of storms. He ventured the theory in 1747 f that 

 though the course of the wind in storms is from northeast to 



* To Mr. Leroy, from London, 1773. 

 f In a letter to Jared Eliot. 



