$ H I 



full draught of water, when laden, it will give the burden of the ship ; 

 and then the length, breadth, and depth multiplied together, and the pro- 

 duct divided by 100 for men of war (which gives an allowance for guns, 

 anchors, &c. that are all burden but no tonnage) and by 95 for merchant 

 ships, will give the tonnage. 



N.B. A hundred solid feet make a ton. 



Required the tonnage of a ship, whose length is 300 feet, breadth 50, 

 and depth 30. 16 



Ans. 4736j^tons. ' 



RULE 3. At London, shipwrights multiply the length of the keel by 

 the extreme breadth of the ship, taken from outside to outside, and that 

 product by half the breadth ; and this they divide by 9-1 for merchant 

 ships, and by 100 for men of war j the quotients are the tonnage of the 

 vessels of their respective classes. 



Required the tonnage of an eighty gun ship, the length of whose keel 

 is 149 feet 4 inches, and her extreme breadth 49 feet 8 inches. 



Ans. 184 186 + tons. 



The following ir ethod is used in the Royal Navy : 



RULE 4. Let fall a perpendicular from the foreside of the stern at the 

 height of the hawse holes, and another from the back of the main port at 

 the height of the wing transom j from the distance between these per- 



o 



pendiculars deduct of the extreme breadth, and as many times 2% 



inches as there are feet in the height of the wing transom above the up- 

 per edge of the keel, the remainder is the length of the keel for tonnage. 

 Then multiply the length of the keel by the extreme breadth, and that 

 product by half the breadth; divide this product by 94 for the tonnage. 

 Given the length of the keel 68 feet, and the extreme breadth 22; 

 required the tonnage. 6 



Ans. I^\TT tons. 



Ship-building. 



A man-of-war of 74; guns requires about 3000 loads of timber, of 50 

 cubic feet each ; worth, at f>. a load, 15,000. A tree contains about 

 two loads, and 3000 loads would cover fourteen acres. The value of ship- 

 ping in general is estimated at 8. or 10. a ton. 



It is said that 180,000 pounds of hemp are required for the rigging of 

 first-rate man-of-war./' Young's Nat. Phil.) 



Note." -The above calculation of fourteen acres to a 74 gun ship is pro- 

 bably much too low- It will be nearer the truth to suppose each tree to 

 264 



