That ships may be well rigged, it is necessary, in the first place, that the fore stay and main top mast stay should be in a right line, and, in like manner, the main and mizen top mast 'stay. The fore stay may end on the bowsprit, between one-third and two-fifths of its length from the small end; secondly, that the top sails should be of similar figures, or at least, that their sides should be of the same cut: thirdly, that when the ship is seen, at one or other of the extremi ties, the shrouds and the breast back stays should ap pear parallel: this depends partly on the breadth of the channels, which ought to be regulated in a man ner conducive to this end. To accomplish it, the length of the head of the main mast, from the under side of the trestle trees, which is 5 of the length of 36 the mast T, the cap of the fore mast should be lower than that of the main mast, by a quantity 2.22 for frigates, and 2 for barks. The cap of the mizen mast should be on a level with the main top.
If the length of the main top mast be denoted by S, the length of the mizen topmast will be 1.3 ST for 5 frigates, and 1.316 for barks, supposing the length of the pole to be in the same proportion, as for the other top masts. If it be longer, that difference is added.
The head of' the mizen mast ought to be that of the fore mast that of the main mast. The length of the fore top mast should also be of that of 1 the main; the heads of these masts or of their 17 length. The length of the top gallant masts to the stop should be 0.5, the length of the top mast. The length of the main yard 0.52 X the length of the ship from the stem to the stern post for frigates; and the main top sail yard 0.79 x the length of the main yard. For barks, supposing their extreme length 1., the 20 length of the main yard will be 0.6 the length of the main top sail yard 0.81 X the length of the main yard. The main top gallant yard = 0.7 x the length of the main top sail yard. All the yards of the fore 9 mast of those of the main mast.
Again, Chapman informs us, that the proportion or the mizen top sail yard to its mast, is equal to the proportion of the main top sail yard to the main top mast. The cross jack yard = 1.22 the length of the mizen top sail yard for frigates, and = 1.18 x this length for barks. The sprit sail yard = fore top sail yard; the sprit sail top sail yard = fore top gallant yard. The girth of the yard arms is of their length for the lower yards, and those of the top gallant yards; but 7 for the top sail yards.
The distance of the centre of gravity of the fore 4 mast from the perpendicular at the stem is of the 2 length. The centre of the main mast is behind the middle of the ship. The distance of the centre of the mizen mast front the perpendicular at the stern = 0.132 x by the length of the ship.
The main mast should rake aft one foot in thirty; the mizen mast double the rake of the main mast; the fore mast should be perpendicular, and the elevation of the bowsprit above the horizontal plane, should be about four feet for frigates, and three for barks, in a length of seven feet.
With respect to the diameter, experience has shown that if the respective lengths of the main mast, main yard, and main top mast in feet be denoted by L, R and S, the diameter of the main mast in inches will be tt s o ; that of the main top mast ; the diameter 13 4.63 1 , of' the fore mast less than that of the main mast; and that of the fore top mast 20 less than that of the main top mast. The diameter of the top gallant mast = 0.3 x their length reckoning to the stop. The diameter of the bowsprit should be a mean of the diameters of the main and fore masts; the diameter of the jib boom 4 that of the main top mast; the 2 diameter of the mizen mast tnat of the main mast; and the diameter of the mizen top mast that of the main top mast.
Again, the diameter of the main yard, and that of the fore yard in inches = 0.25 X length of the yard; that of the top sail yards = 0.23 x also by the length of the yards; that of the top gallant yard = 6 of their length. The diameters of the sprit sail yard, and cross jack yard = 0.21 the length. The diameter of the sprit sail top sail yard = that of the main top gal lant yard. The diameter of the mizen peak is an inch for four feet in its length. The studding sail booms have two feet greater length than half the yard, and their diameter in inches is 5 their length in feet.
The depth of the main trestle trees in inches is the fourth of the height of the top mast in feet, less half an inch; the thickness of the fore trestle trees is 15 less than that of the main trestle trees, and the mizen of the main; the thickness of the top mast cross tree 5 is 7 that of the trestle trees of the respective tops. The breadth of the said trestle trees and cross trees is 7 5 4 or of their depth. The thickness of the caps is 4 .
of the diameters of the top mast.