E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Mizentop, maintop, foretop.
Service in these masts has nothing whatever to do with age or merit. A top is a platform fixed over the head of a lower mast, resting on the trestle-trees, to spread the rigging of the topmast.
The mizenmast is the aftermost mast of a ship; the foremast is in the forward part of a ship; the mainmast is between these two.
He was put into the mizentop, and served three years in the West Indies; then he was transferred to the maintop, and served five years in the Mediterranean; and then he was made captain of the foretop, and served six years in the East Indies; and at last he was rated captains coxswain in the Druid frigate.Capt. Marryat: Poor Jack, chap. i.