The sea-man's practice : Containing a fundamental problem in navigation, experimentally verified: namely, touching the compass of the Earth and sea, and the quantity of degree in our English measures. Also an exact method or form of keeping a reckoning or journal at sea, in any kind or manner of sailing. With certain tables and other rules used in navigation. As also the plotting and surveying of places: the latitude of the principal places in England: the variation of the compass: the finding of the currents at sea, and what allowance is to be given in respect of them. By Richard Norwood, reader of the mathematicks.