Extract from Thomas Jefferson to Thomas Mann Randolph, 18 Apr. 1790 [Quote]
my method is to make two observations a day, the one as early as possible in the morning, the other from 3. to 4. aclock, because I have found 4. aclock the hottest & day light the coldest point of the 24. hours. I state them in an ivory pocket book in the following form, & copy them out...