SHIP-BUILDING. 



By the preceding eftimate, we find the 74-gun fhip, PI. I. 

 weighs, when brought down to her load-water-line, 2810 

 tons 745 pounds, that is to fay, wherv fitted for fea, with 

 fix months' provifions on board. It may now be known, 

 with fome degree of certainty, if the upper water-line on 

 the fheer-draught, Plate I., be properly placed, only by 

 reducing the immerfed part of the bottom into cubic feet ; 

 for, if the 74-gun fhip, when brought down to the load- 

 water-line, weighs 2810 tons 745 pounds, the quantity of 

 water difplaced mull alfo be 2810 tons 745 pounds, or 

 6,295,145 pounds. Now a cubic foot of falt-water being 

 fuppofed to weigh 64,375 pounds, we (hall therefore 

 find, that if we divide 6,295,145 by 64,375, the quotient 

 will be 97,788 folid feet, which is the contents of that 

 volume of water which fhe mufl difplace correfponding to her 

 weight. 



D'tfplacement or Capacity. 



The iblid contents of a (hip's bottom, were it any regular 

 figure, might be eafily calculated geometrically ; but as its 

 curves are fo various, the following rule, by approximation, 

 may be near enough for practice. 



Take the half-breadths of every other frame, and double 

 them, from 26 to O, in the half-breadth plan upon the upper 

 water-line ; then find the fum of thefe, together with half 

 the foremoft frame O, and aftermoft frame 26. Now, the 

 frames being equidiftant, multiply that fum by 1 1 feet, 

 the diftance between every other frame, and the produft is 

 the area of the water-hne contamed between the frames 

 26 and O ; then find the area of that part of the water-line 

 afore O, and abaft 26, by taking the half-breadth of every 

 timber, and proceed as before, and multiply by 2 feet 

 9 inches ; find alfo the area of the ftem, knee, and gripe, 

 before the foremoll-timber, alfo the area of the llern-polt and 

 rudder abaft the after-timber ; then thefe areas being added 

 to the firll found, will be the area of the furface of the 

 whole water-line. Note, the thicknefs of the bottom plank, 

 as taken in that direftion, mull be added. 



The areas of the other water-lines may be found in the 

 fame manner : then the fum of all thefe areas, except the 

 uppermoft and lowermolt, of which only one-half of each 

 muft be taken, being multiplied by 3.6 feet, the diftance 

 between the water-lines (thefe lines in the Iheer-plan being 

 alfo equidiftant from each other), and the produft will 

 be the folid content of the fpace contained between the 

 lower and upper water-lines. 



Add the area of the lower water-line to the area of the 

 upper fide of the keel ; multiply half that fum by the 

 diftance between them, the produft will be the folid content 

 of that part between the lower water-line and upper edge 

 of the keel. 



The foHd contents of the keel muft be next found, 

 by multiplying the area by its depth ; then the fum of 

 thefe folid contents v/ill be the number of cubic feet con- 

 tained in the immerfed part of the bottom, below the upper 

 water-line. 



The reafon of the above rule will be obvious, by refer- 

 ring to the article STEREOiviETRY ; for there, to find the 

 folid contents of any irregular body, the area of the fur- 

 faces muft be taken by ordinates ( and fuch are the joints 

 of the frames of a fliip), and thofe furfaces multiplied by 

 the' depth or depths (and fuch are the water-hnes), which 

 give the folid contents required. 



The application of this rule, in finding the cubic feet 

 contained in the bottom of the 74-gun ftiip, below the 

 upper water-line in Plate I. 



7 



Area of the Upper Water-Line. 

 f frame 26 is 43 ft. 8 in. the half of which is 



L frame O is 46 ft. 2 in. the half of which is 



X by the diftance between the frames 



Area between 26 and O - - - - 5794 



526 

 1 1 



■ frame 26 is 43 ft. 8 in. the half of which is 



timber 27 ----- - 



frame 28 ----- - 



timber 29 ----- - 



frame 30 ----- - 



timber 3 1 - 

 frame 32- 

 timber ^3- 



frame 34 ----- - 



timber 35 ----- - 



frame 36 ----- - 



timber 37 is 5 ft. 



2 in. the half of which is 



Ft. 

 21 



43 

 42 

 41 

 40 



38 

 37 

 34 

 32 

 27 



19 



2 



X by the diftance between the timbers 



Area of the poft and rudder 



Area abaft 26 - . . - 





*i 



the half of which is 



■ frame O is 46 ft. 2 in. 



timber P - - 



frame Q - - 



timber R - - 



frame S - - 



timber T - - 



frame U - - 



timber W - - 



frame X - - 



timber Y - - 

 half the ftem 



X by the diftance between the timbers 



Ft. 

 23 

 45 

 43 

 41 

 38 

 36 

 3' 

 26 



19 



10 



o 



Area of the knee 



Area before O - 

 Area abaft 26 - - 



Area between 26 and.O 



Area of upper water-line 



In. 



10 

 2 

 2 

 O 

 O 



6 



o 



10 



I 



2 

 2 



7 



In. 

 I 

 2 

 2 

 8 



10 



o 

 8 



3 



4 



8 



10 



7721 



10 

 Area 



