Practical navigation, or, An introduction to the whole art : containing the doctrine of plain and spherical triangles : plain, mercator, great-circle sailing, and astronomical problems : the use of divers instruments ... : sundry useful tables in navigation, and a table of 10,000 logarithms, and of the logarithm-sines, tangents, and secants / by John Seller.

  • Seller, John, active 1658-1698.
Date:
1694
Catalogue details

Licence: Public Domain Mark

Credit: Practical navigation, or, An introduction to the whole art : containing the doctrine of plain and spherical triangles : plain, mercator, great-circle sailing, and astronomical problems : the use of divers instruments ... : sundry useful tables in navigation, and a table of 10,000 logarithms, and of the logarithm-sines, tangents, and secants / by John Seller. Source: Wellcome Collection.

    28/532 (page 14)
    | ESAnfo, This mutt be folved by the Reverfe Rule of Three, and mutt be thus fated. | Months. Tb. Months, ee 7 ———~ 400 = ———— 1 Where ’tis plain that more requires lefs3 that is, though the third Number be more than the firft, yet it requires a leffer Number to anfwer unto it than the fecond: Therefore you muft multiply 400 by 7, and it is 2800, which divided by 12 (the third Number) makes 2 33 tb. and 4 1b remaining, the 12 part of whichis 6 5.84, So the Anfwer to the Queftion is, That I mu lend him 2 33 Ib. 6 s. 8 d, for 12 Months. The Operation, Months Ib. Months. 7 GOO nn T 2 ns 4, Which being reduced by 20 the Shillings in one Pound, and ig is 80 Shillings; which being divided by 12. produceth 6s, and 8 remaining, which is 25 of a Shilling, or.8 Pence. |