it out because they are of little use any further because that will reach farr enough for the length of any Rising line of any Ship whatever If any be desirous to convert any of the following numbers into inches he may do it by Dividing by 12. Thus I think I have spoken enough to the Ingenuous concerning the singular use of the Tables or of this way of Working by Segments o Circles CHAP. XII Concerning Measuring of Ships 60 20 1200 10 120100 I Shall say something concerning it the Shipwrights have to themselves a custome of measuring at London or on the River of Thames thus they multiply the length of the Keel into the bredth of the Ship at the broadest place taken from outside to outside and the product of that by the half bredth this second product of the multiplication they divide by 94 or sometimes 100 and according to that division the quotient thereof they are paid for so many Tuns as suppose in the former draught being in length 60 foot and 20 foot broad 60 being multiplyed by 20 the bredth produce 1200 that 1200 being again multiplied by 10 the half bredth produce 12000 if you divide by 100 you need do no more than cut off the two last figures toward the right hand which shall be the answer and rendreth the Ship to be 120 Tuns but if you divide the sum 12000 by 94 you wil have 127 2 3 of a Tun very neer but this cannot be the true ability of the ship to carry or lift because two ships by this rule of equall breadth and length shall be of equall burthen notwithstanding the fulness or sharpness of those Vessels which may differ them very much or the one ship may have more timber than the other in her building so shall carry less than the other But the true way of measure must be by measure of the body and bulk of the ship underwater for if one ship be longer in the floor than another of the same bredth and length she shall be more in burthen than the other as a Flemish ship shall carry more than a French or Italian Vessell of the same length and bredth Therefore I say the measure of the ship being known by measuring her as a piece of timber may be measured of the same form to the draught of water assigned her the weight of the same body of the same water that the ship swimmeth in shall be the exact weight of the ship and all things therein loading rigging victuals included therein then if the ship be measured to her light mark as she will swim at being lanched the weight of so much water being taken or substracted from the weight of the water when she is laden the residue shall be the weight that must load her or her ability of carrying called her burden by this means you may know the weight of the ship light and what she will carry to every foot of water assigned to her which cannot be done by no general rules in Arithmetick because of their great irregularity according to the differing minds of Shipwrights you may if you please first measure the content of the Keel and Post and Stem-rudder all of it that is without the Plank and under the water line and note it by it self then measure the body of the ship in the Midships made by the square made of the multiplying of the depth of the water line and the bredth then you may find the content of the want by the circular part of the ship under water being narrower downward and substract this from the whole content of the squared body of the depth of the Water-line and bredth of the ship and this shall be the solid content of that part of the ship I mean in solid foot measure of 1728 inches to the foot then proceed to the fore part or the after part of the ship and to 3 or 4 Timbers more find the mean bredth at the narrowing aloft at the water-line and alow at the floor and the mean depth and measure that piece of the ship as I told you of the middle part of the Ship and so measure the whole Ship by pieces and add them together and so many feet as it maketh so many feet of water shall be the weight of the said ship and the reason may be considered thus there is a ponderosity in warer but there is a greater in the ayre onely to the heaviest of things and there is a ponderosity in water it self but not so much as in other things more solid as in Iron Suppose a Gun or an Anchor of Iron it sinketh in the water but yet it is not so heavy in the water as in the ayre by the weight of so much water as shall make a body of the same water equal to the body of the Gun or Anchor in magnitude which weight substracted from the weight of the Iron body weighed in the ayre and so much must be the weight of it in the water Again if a body be lighter in weight than water of the same bigness it hath an ability of lifting in the water and can lift or carry so much as is that difference as a piece of cork or wood of firr-trees being lighter than water it swimmeth on the face of the water and refuseth to be depressed without more weight added to it Thus a ship being a concave body is made capable of lifting according to the greatness or littleness of this concavity respect being had to the greatness of the Timber put into it or the nature of it all which maketh a ship swim deeper or lighter in the water I have proved by the Thames water that fresh Water is lighter then salt water so then salt water being heavier than fresh causeth that a ship swimmeth deeper in the fresh water than in salt I shall not need to say any thing more concerning the mesauring for it will be understood by those that have any Judgment in the mesuring of triangles the matter it self being but a nicity rather than usefll I only touched it to shew those that are so curious minded which way they may accomplish their desires I shall forbear to give examples because it will much increase my Treatise and augment the Price which might prove more prejudicial to youngmen than advantagious CHAP. XIII Concerning the Masts of Ships FRom the length and bredth is gained the Mainmasts length and all the other Masts as wel as yards is derived from thence and there is different proceedings in this case according to the largeness of the Ships thus the main Masts of small Ships to be three times as long as the Ship is in bredth as a ship of 20 foot broad by the same rule must have a Mast of 60 foot long Others for greater Ships add the bredth to the length and to that the half bredth which some they divide by 5 and the quotient is the number of yards as a ship 114
the Scale and the first diagonal line is one inch the second is 2 and the third 3 inches and so to Six The way to demonstrate the Scale you see is very easie Draw Seven lines parallel to each other and of what length you please to retain what number of Feet you please then beginning at the top set off with the compasses the length of your Feet both allow and aloft then draw lines thwart the parallel lines to every foot of the Scale and set numbers to them beginning at the second foot 1 and to the third 2 to the fourth 3 and so forward leaving the first Foot to be divided into Inches by the Diagonall lines as you see in the foregoing Scale CHAP. III. Concerning the drawing your Draught upon Paper HAving fitted your Scale ready draw a line to represent the Keele of the Ship as you see in the draught following of 60 foot long by the Keele and 20 foot broad the streight line that representeth the Keele is marked with A B. Then draw a line underneath of equall length to signifie the bottome of the Keele Then next you may proceed to the Stern-post as the line A C will signifie the foreside or the inside thereof racking the one quarter of his length aft and for the length of the Stern-post it must be directed to the built of the Ship as whether she be to be a deep Ship or a shallow Ship so that the draught of the water ought to be respected first and then the lying of the Ports for the convenience of Ordnance for that the upper transome of the Buttock commonly is just under the Gun-Room ports to the upper edge of the said transome we understand the length of the Stern-post although if the Stern-post were continued to the height of the Tiller and another Transome fard there for the Tiller to run on it would steady the quarters of the Vessel very much and do good service The Stern-post being drawn we may proceed to draw the Stem which in the following Draught is not so much racked as was the old proportion of England which was the whole breadth of the Ship for then it should be 20 foot but it is no more then 15 foot just ¾ of the breadth for too much racke with the Stem doth a great deale of damage to any Ship if we consider that in this small Vessel had we given 5 foot more Racke all the weight of the Ships Head and Boltspreet Foremast Manger Halsps Brest-hooks aloft had been so much farther forward where there would have been want of Bodie to lift it so that it must of necessity be detriment to the Vessel when she saileth against a head sea and a great strain to her Now it will be very good to spend as much of this racke as we can under the water for it will help the Ship to keepe a good Winde by giving her something more Body in the water Next draw the Water-line in the following draught signified by the pricked line it is drawn to 9 foot height afore and to 10 foot height abaft from the upper edge of the Keele and higher abaft then afore for the most Ships saile by the Sterne and also for that the Guns should lie something higher abaft then afore from the water Then proceed to hanging of the Waals and here you see the lower Waalle drawne from the head of the Sterne-post to signifie that it should lie against the end of the Transome that the Transome Knees might be bolted to the Waals without board to one foot and an halfe under the Water-line a little before the middle of the Water line and at 9 foot high on the Stem and the next Waale parallel to the lower Waale one foot and an half asunder so that the upper Waale will lie just at the waters edge in the mid-ships the upper edge of the Gun-deck will lie one foot aboye the water line abaft and halfe a foot above water on the Stem so then letting the lower sell of the Ports be two foot from the Gun-decks the lower edge of the Ports wil be three foot from the water abaft and two foot and an halfe afore in the middle of the Gun-deck 2 foot 9 inches sufficient for so small a Vessel a greater Vessel would require to have the Guns something farther from the water then if another Waale be required first set off the Ports in their places that the Waale may ly above the Ports or else he would be cut with the ports in pieces the upper Deck with height respecting the bignesse of the Ship having respect to not over building small Ships to damage their bearing of Sail. Then for the Head the length of the Knee would be two thirds of the breadth so then the Knee of the Head in this Draught will be 12 foot 8 inches long and for his place as low as conveniently he can provided that the Rails of the Head fall not fowl of the haâ—shols because that in placing of the Knee low giveth room to round the Head and steeve it to content The place of the Knee will be at or very neer the upper Waal the upper edge of the Knee against the upper edge of the uper harping which will be very well for the lower Cheeks of the head to be faced against for by that means they wil be clear of any Seame to avoid Leakings and will very well bolt the end of the harping if a Brest-hook be fastned also within board against them will very well fasten all together Then for the steeving of him and rounding the Knee a regard must be had to the lying of the Boltspreet leaving room enough for the Lyon and Scrowl under the Boltsprit Then for the rounding of the Rails round them most at the after ends For the heights between Decks and Steeridge Cabine Fore-Castle those heights are commonly mentioned in contract by the Master or Owners building Place this Draught at Page 8 CHAP. IV. Shewing how to sweepe out the Bend of Moulds upon a Flat FIrst draw a line as the line AB then in the middle thereof as at the point C raise a perpendicular as is the line CM perpendicular to the line AB then set off the halfe breadth on either side at the Points AB and draw the two lines IA and KB parallels to CD signifying the breadth of the Vessell 20 foot then draw the two lines EF and HG signifying the breadth of the Floare thwart Ships 8 Foot more then one third part of the breadth which was formerly an old Proportion so that according to that it should have been but 6 Foot 8 Inches Herein any may do as they please give more or less my judgment is rather more then less for that it maketh a Vessell to carry more in Burden and I conceive it may if it be well ended forward it will not damage the Sayling I also think it doth stiffen a Vessell on this account Our English
Vessells have been used to have their breadth lying at the height of the Halfe Breadth then observing 1 3 breadth for the length of the Floare Thwart Ships it maketh the Vessells Body to be very neare a Circle as is a Cask which causeth such Vessells to be easie to slew in the Water yet I would not exceed neither or run into extreams herein but if I were to make a Vessell stiff I would that the Halfe Breadth be more then the draught of Water which causeth that the Body be stronger in the Water and will not Slew so easily Now to sweep out the Sides under Water I draw the Diagonall lines DA and DB then I divide the Diagonall lines into 9 parts and set off 2 of them from the Corners A and B to the points e then I set off the Dead Rising which is 4 Inches one Inch to a Foot for halfe the breadth represented in the Figure above by the little line parallel to FG from which Dead Rising take with the Compasses the Distance that will draw a piece of an Arch from ◠to ◠and so as one foot of the Compasses stand in the line EF and exactly touch the points at the Dead-Rising at f or g and touch also the points e over which point falls at ⊙ in EF or ⊙ in HG wherewith I describe the Arch e F or e G which is by the Scale in the Draught 4 Foot 8 Inches then for the other part of the Side upwards seek for a Point in the breadth line IK at which if one foot of the Compasses be set and the other foot opened to the Extreame Breadth will also draw or signifie an Arch to meet with the other Lower Arch on the Diagonall line at e which is at the points ⊙ and ⊙ thus the point ⊙ between D and K neere H Sweepeth the contrary Side I e and so the point ⊙ between DI neere E Sweepeth the contrary side at K extend the same Sweepe also above the Breadth line above Water 3 or 4 Foot the length of this Sweepe is 12 Foot 9 Inches then set off the Tumbling Home at the Height of the two first Haanses at the Maine Mast and Foarcastle 2 foot of a side then draw a line from the said 2 Foot of Narrowing at the points o v till it break off on the back of the Sweep on either side This kinde of Demonstration I conceive most suitable to our following discourse of Arithmeticall Work I could have cited other wayes but I Judge this way sufficient CHAP. V. The Description of the Rising Lines aftward on and forward on with the Narrowing Lines and Lines of Breadth As also the Narrowing Lines at the top of the Timbers DRaw a Hanging line on the Draught from the Keele from the middle of the Keele to the height of the Water line on the Post which will be the Rising line as the line DE this line DE is supposed to be sweept or drawn by a Semidiameter of a Circle extended on a Perpendicular raised at the point E for if it be shorter then such a Semidiameter of the true Circle it will make a fuller line then it should be and so must not be so long or else it will make a breach at the beginning of the line this if the Centre be supposed to be Abaft such a Perpendicular that should draw a Rising line Abaft I say that it will shorten the Rising line and make it fuller then it should be or then if it be farther forward it will be straighter then a Circle and also be a breach at the beginning of the Rising line therefore it should be a Circle I say whose Semidiameter will be on the Perpendicular line at the beginning of any such Rising line on the Heele either Afoare or Abaft and the like ought to be for all other crooked lines as the narrowing lines Abaft or Afoare or at the Narrowing of the Floare or other Circular lines as Hanging of Waals and the like the way whereof I shall describe to finde the lengths of all such Sweeps by Arithmetick as also the true Rising Narrowing of any Timber according to exact peeces of Circles very usefull for the setting of Bows to trie whether they hang to a true Sweepe or no I shall demonstrate it I say in the following discourse and in this place end what I intend to say For Demonstration then At ¾ of the Keele forward I draw a Rising line forward to the height of the Water line forward on the Stemm as you see the line op and the little line between these two lines parallel to the inside of the Keele marked Eo is the dead rising 4 inches high as in the bend of Moulds it is parallel to FG the height of the breadth from the Mid-Ship forward is the lower Edge of the upper Waale but afterward on it is the pricked line between the Water line and the lower Waale on the Post which runneth forward to the edge of the Waale and hath Figures set to it to signifie the places of the Timbers marked 1 2 3 4 5 to 15 as you see answers to the Figures on the Keele and the Letters set to forward on signifie the places of the Timbers forward marked ABCD to L in the middle of the Vessel the places marked with a Cipher signifie the Flats which have onely Dead rising although they ought to have some of them something more Dead rising then each other and those that have least to be placed in the middle of the rest that so there be no Clings in the Buldge but that it have also a little Hanging in it it will seeme the fairer Then I draw a straight line parallel to the bottome of the Keele as is the line FG parallel to the line AB the Keele and distant 10 foot by the Scale which is the halfe breadth of the Vessell for this line signifieth a line stretched from the middle of the Sterne-Post to the middle of the Stem called by Ship-wrightes a Ram-line Parallel to this Middle line I draw another line straight marked nm and is 4 foot asunder from the Middle line to signifie the halfe length of the Floare thwartships as in the Bend of Moulds EF is distant from DC 4 Foote then I draw a Crooked line Abaft within this line nm to signifie the narrowing of the Floare to bring or forme the Vessels way Abast as you see the line ik Abaft and Afoare it is represented by the line lo then here in this Draught I draw a Sweepe or a piece of a Circle from the point G the marke of the Timber G on the Keele to the halfe breadth of the Stemm to the point G on the Stemm signifying the Sweep of the Harping and is Sweept by the breadth of the Vessell 20 Foot the piece of the Pricked Circle Abaft at the Starne which is drawn by a Centre on the line FG is the length of the Transom thwart the
foot long and 34 foot in bredth as the bredth added to the length and the half bredth added together make 165 that divided by 5 yields 33 and so many yards is the length to be of that Mast the fore-mast must be a yard shorter at the head that is to say besides the height of the step which commonly in most ships the step of the fore-mast standeth higher from the bottom of the ship than the step of the Main-mast the foremast must be shorter by that difference and one yard more or the bigness of the ship considered 4 foot shorter at the head or besides the difference below 114 34 17 165 10 165 33 55 The Top-masts two thirds of the length of the lower Masts The Main-yard to be 2 ◠and ◠22 of the Main-mast as in the Mast aforementioned of 60 foot long two thirds of 60 is 40 and the 2 12 of 60 is 5 added to 40 make 45 for the length of the main yard The foreyard to be 6 7 of the Main-Yard as the Main-yard being 45 foot divide 45 by 7 so cometh 6 in the quotient and a fraction remaining of 3 signifying 3 7 so that the 1 7 of 45 will be 6 and 3 7 you must take 6 times so much a◠6 times 6 makes 36 and if you take 6 times 3 7 make 18 7 that is two whole numbers and 4 7 remaining which added to 36 make 38 and 4 7 of a foot for the length of the fore-yard The Top-sail Yards must be half the length of the lower Yards the Mizne Yard usualy is made of equal length with the fore-yard the Crosjack yard of equal length with the Main top-sail yard and the mizen Top-sail yard to be half the length of the Crosjack yard The mizen Mast to be of the length of the Main-top mast from the upper Decks and so much longer as is the height of the ship between Deck the Boltspreete to be of length equal to the fore-mast from the upper Deck of the Fore-castle upwards For the bigness of these Masts to a yard in length ¾ of an inch or else ¼ of an inch to the foot and so of yards likewise only the Boltspreet somthing bigger would be the better if he be made as big as the fore-mast CHAP. XIV Concerning Rowing of Ships when they are becalm'd I Have here invented a meanes of Rowing of a Ship by the heaving at the Capstane where will be many benefits First of a greater purchase of strength for it is evident that 10 Men at a Capstane shall heave a Ship a Head when 30 Men shall not Haall her a Head by hand nay 50 neither shall they be so soon tired for that Owers are a great weariness to the Armes beside a double motion of the body as when the stroak is fetched to way down the Ower that the blade may be elivated out of the Water where it must be kept so untill another Let the two lines C D and C D represent the sides of the Ship 16 foot broad as is the line C C 16 foot long by the Scale of the Draught and let the two long squares d d and d d represent the two Bitt-pins with the Cross-piece of let the Black between the two Bit-pins represent a Roule or Windless with a Surdge in the middle as is the Surdge of a Crab or Capstane in the two ends of this Roule let there be placed two Winches as you may see represented by Cranks a and a let there be made a hollow place in the Head of the Bit-pins for these two Winches to rest in that they may turne round in them and bide in them then let there be two pieces of Timber equall in length to the space of the Ship you would have filled with Oares represented by the two black lists marked b b and b b then let there be fitted two small pieces made of good Ashe or some good strong Wood of equall length as is the two black Lists n L m L fastned into the pieces of the frame as at the points L and L by a Boult but so that they may play on that Boult and the other ends must be with a Hoale made in the ends put over the handles of the Cranks at n and m then in the two long pieces for the frame let the Oares be fixed as at the points 1 2 3 4 5 6 7 of each side of the Ship representing 7 Oares of a side they may be fastned in the Frame by a Mortis made therein and a Tenent on the Oar made to go slack in that the Oar may play and have liberty to fetch a Stroak in the middle whereof must be placed a Iron bolt to fasten him and keep the Oar from launching in and out and on the Roughtre or side of the Ship as in C D and C D must be placed Thoule pins to each Oare as in Boats that Row then must you have a Halser splised together in manner of a Viall that must take two or three turnes about the Roule in the Surdge as you may imagine at the middle of the Black Roule or notch therein and pass from thence to the Capstane with two or three turnes there also then this Viall also reeved thorough some other Blocks as in manner of Snach block and these blocks placed between the Capstane and the Roule you may thereby increase that purchase so as that it may heave very easie and with great strength so as to be able to Row a Ship a Head in a calme or in little winde two threee or four leagues a watch or more according as the Ingine shall be better or worse fitted for if you marke in the Figure of the Work and suppose the Viall Reeved and by heaving of the Capstane shall turne the Roule as the Crankes goeth round it shall carrie with it about and then the small pieces shall cause the frame to pass forward to and again to fetch a stroake with the Oares FINIS