Early Diary of John Adams, volume 1 Previous document in volume April 6th. 1754. Next document in volume April 9 1754. April 8th. 1754. JA April 8th. 1754. Adams, John April 8th. 1754. The Theory of simple machines and in particular of the inclined plane, of the wedge and screw, and other machines compounded of these simple ones, finish’d.