The practice of inoculation justified. [electronic resource] : A sermon preached at Ingatestone, Essex, October 12, 1766, in defence of inoculation. To which is added, an appendix on the present state of inoculation; with observations, &c. By Robert Houlton, M.A. chaplain to the Earl of Ilchester, and officiating clergyman at Mr. Sutton's. Published by general request