SPECIFIC GRAVITIES. Barometer 30-in., Fahrenheit's thermometer 60°, distilled water is represented by 1000. in air. X=weight in water. G-specific gravity. G weight of body W W-X If the substance be lighter than water, sink it by means of a heavier substance, and deduct additional weight. The Live Oak of America. The Morra and Greenheart of British Guiana. The Teak and Saul of India. The Iron Bark of Australia. Timber is bought and sold by solid measure according to the number of cubic feet. In measuring standing timber, the length is taken as high as the tree will measure 24 inches in circumference; less than that is not considered timber. One At half this height the measurement for mean girth is taken. quarter this girth is assumed to be the side of the equivalent square area. An allowance is deducted for bark; in oak, to of circumference; less for other woods. RULE FOR FINDING THE TONNAGE OF VESSELS. (New Measurement.) The length of the upper deck is divided into six parts, a, a” and the depth taken at the foremost, aftermost, and midship points of division. These three perpendicular measurements are each intersected at four intermediate points, be", which divides them into five equal parts. The length for tonnage, fg, is the length of the ship from after side of stem to fore side of sternpost, at a height half-way up the midship line of section a'. The depths to be employed are-twice the depth of the midship line of section at a' added to once the depth of the foremost and aftermost sections, at a and a". The breadths used are-at the foremost section a, the (internal) breadth of the ship at b, added to the breadth at e. In the midship section a', three times the breadth at c' are added to once the breadth at e'. In the after section a", once the breadth b" is added to twice the breadth at e". Then, the product of the sum of the depths into the sum of the breadths, into the length for tonnage, divided by 3500, gives the number of tons for register. If the vessel has a poop or half-deck, or a break in the upper deck, measure the inside mean length, breadth, and height of such part thereof as may be included within the bulkhead; multiply these three measurements together, and divide the product by 92-4; the quotient will be the number of tons to be added to the result as above ascertained. For open vessels.-The depths are to be taken from the upper edge of the upper strake. For steam vessels.-The tonnage due to the engine room is deducted from the total tonnage computed by the above rule. To determine this, measure the inside of the engine-room from the foremost to the aftermost bulkhead; then multiply this length by the amidship depth of the vessel, and the product by the inside amidship breadth at 4 of the depth from the deck, and divide the final product by 92.4. TONNAGE OF VESSELS. (Old Builder's Measurement). L = Length of keel between perpendiculars in feet. The fore perpendicular is taken at the fore part of the stem, at the height of the upper deck. The aft perpendicular is taken at the back of the stern posts, at the height of the upper deck. The breadth is taken as the extreme breadth at the height of the wales, subtracting the difference between the thickness of the wales and the bottom plank. To Find the Number of Square Yards in a Square Sail. Head x Depth x Depth x difference of Head and Foot. |