He compiled a Dictionarium Britannicum: a more complete universal etymological English dictionary than any extant, bearing the date 1730, but supposed to have been published in 1721. This was a great improvement on all previous attempts, and formed the basis of Dr Johnson's great work. Bailey, who was a Seventh Day Baptist (admitted 1691), had a school at Stepney, and was the author of Dictionarium Domesticum and several other educational works. He died on June 27 1742.