The seaman's practice : containing a fundamental problem in navigation, experimentally verified: namely, touching the compass of the earth and sea, and the quantity of a 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. 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 /