[1] During the course of his career, he also operated a popular navigation school for merchant mariners, and published a variety of almanacs during the American Revolution period.
Daboll had little formal education but mastered mathematics quickly while earning a living as a cooper.
Daboll did so, beginning in 1771, under the alias "Edmund Freebetter",[4] before switching to publishing almanacs and registers under his own name.
[2] For the most part, they contained common almanac material:[5] "lunations; eclipses of the luminaries; aspects; judgment of the weather; rising, sitting and southing of the seven stars; sun and moon's rising and sitting; festivals, and other remarkable days; courts; roads" The textbook Daboll's schoolmaster's assistant: being a plain, practical system of arithmetic, adapted to the United States was published in 1799, and updated with Daboll's Schoolmaster's assistant, improved and enlarged being a plain practical system of arithmetic: adapted to the United States in 1814.
Its popularity was based, in part, on its practicality:[6] "We were taught arithmetic in Daboll, then a new book, and which, being adapted to our measures of length, weight, and currency was a prodigious leap over the head of poor old Dilworth, whose rules and examples were modelled upon English customs."
[7] In 1811, at the invitation of Commodore John Rodgers, Daboll instructed midshipmen on the frigate President.