Closely connected with his faith in air-baths was his opinion that people seldom caught cold from exposure to air or even to dampness. He wrote letters on the subject and prepared notes of his observations. These notes are particularly interesting and full of curious suggestions. The diseases usually classed as colds, he said, are not known by that name in any other language, and the name is misleading, for very few of them arise from cold or dampness. Indians and sailors, who are continually wet, do not catch cold; nor is cold taken by swimming. And he went on enumerating the instances of people who lived in the woods, in barns, or with open windows, and, instead of catching cold, found their health improved. Cold, he thought, was caused in most cases by impure air, want of exercise, or over-eating. “I have long been satisfied from observation, that besides the general colds now termed influenzas (which may possibly spread by contagion, as well as by a particular quality of the air), people often catch cold from one another when shut up together in close rooms and coaches, and when sitting near and conversing so as to breathe in each other’s transpiration; the disorder being in a certain state. I think, too, that it is the frouzy, corrupt air from animal substances, and the perspired matter from our bodies, which being long confined in beds not lately used, and clothes not lately worn, and books long shut up in close rooms, obtains that kind of putridity which occasions the colds observed upon sleeping in, wearing, and turning over such bedclothes or books, and not their coldness or dampness. From these causes, but more from too full living, with too little exercise, proceed, in my opinion, most of the disorders which, for about one hundred and fifty years past, the English have called _colds_.” Much of this is true in a general way, for medical practitioners have long held that all colds do not arise from exposure or draughts; but they do not admit that colds can be taken from turning over old books and clothes, although the dust from these might make one sneeze. John Adams and Franklin while travelling together through New Jersey to meet Lord Howe, in 1776, discussed the question of colds, and the former has left an amusing account of it. The taverns were so full at Brunswick that they had to sleep in the same bed. Franklin insisted on leaving the window wide open, and discoursed on the causes of colds until they both fell asleep.