TONNAGE. The capacity of a ship or v essel.
2. This term is most usually applied to the capa city of a vessel in tons as determined by the legal mode of measurement ; and, as a general rule, in the United States the official tonnage of a vessel is ooneiderably below the actual oapacity of the vessel to carry freight.
For the rule for determining the tonnage of British vessels under the law of England, see Mc Culloch, Com. Diet. Tonnage ; English Morehant Shipping Act of 1854, N 20-29.
The duties paid on the tonnage of a ship or vessel.
These duties are altogether abolished in rela tion to American vessels by the act of May 31, 1830, a. 1. And, by the seoend eeotion of the same act, all tonnage-duties on foreign vessels- are abolished, provided the president of the United States shall be satisfied that the discriminating or oountervailing duties of suoli foreign nation, so far as they operate to the disadvantage of the United States, have been abolished.
The constitution of the United States provides, art. 1, e. 10, n. 2, that no state shall, without the consent of congress, lay any duty on tonnage.
3. By act of congress, approved May 6, 1864, it is provided that the registered ton nage of a vessel shall be ber entire internal cubic capacity, in tons of one hundred cubio feet each, to be ascertained as follows. Measure the length of the vessel in a straight line along.the upper eide of the tonnage deck, from the ineide of the inner plank (average thickness) at the side of the stem to the inside of the plank on the stern timbers (ave rage thickness), deducting from this length what is due to the rake of the bow in the thickness of the deck, and what is due to the rake of the stern timber in the thick ness of the deck,'end also wbat is due to the rake of the stern timber in one-third of the round of the beam ; divide the length so taken into the number of equal parts required by the following table, according to the clase in such table to which the vessel belongs.
Class L—Vessels of which the tonnage length, according to the above measurement, is fifty feet or under, into six equal parte.
Class IL—Vessels of which the tonnage length, according to the above measurement, is above fifty feet and not exceeding one hun dred feet long, into eight equal parts.
Claes III.—Vessels of which the tonnage length, according to the above measurement, is above one hundred feet long and not ex ceeding one hundred and fifty feet long, into ten equal parts.
Class IV.—Vessels of which the tonnage length, according to the above measurement, is above one hundred and fifty feet and not exceeding two hundred feet long, into twelve equal parts.
Class V.—Vessels of which the tonnage length, according to the above measurement, is above two hundred feet and not exceeding two hundred and fifty feet long, into fourteen equal parts.
Class VI.—Vessels of which the tonnage length, according to the above measurement, is above two hundred and fifty feet long, into sixteen equal parts.
4. Then, the hold being sufficiently cleared to admit of the required depths and breadths being properly taken,find the transverse area of such vessel at each point of division of the length, as follows. Measure the depth at each point of division from a point at a distance of one-third of the round of the beam below such deck, or, in case gf a break, below aline stretched in continuation thereof, to the upper side of the floor-timber, at the inside of the limber-strake, after deducting the average thickness of the ceiling which is between the bilge-planks and limber-strake ; then if the depth at the midship division of the length do not exceed sixteen feet, divide each depth into four equal parts ; then measure the inside horizontal breadth at each of the three points of division, and also at the upper and lower points of the depth, extending each measurement to the average thickness of that part of the ceiling which is between the points of measurement ; number these breadths from above (numbering the upper breadth one, and so on down to the lowest breadth); multiply the eecond and fourth by four. and the third by two; add these products toget her, and to the sum add the first breadth and the last or fifth ; multiply the quantity thus obtained by one-third the interval between the breadths, and the product shall be deemed the transverse area ; but if the rnidship depth exceed sixteen feet, divide each depth into six equal parts', instead of four, and measure as before directed the horizontal breadths at the five points of division and also at the upper and lower points of the depth; number them from above, as before, multiply the second, fourth, and sixth by four, and the third and fifth by two ; add these products together, and to the sum add the first breadth and the last or seventh ; multiply the quantity thus obtained by one third of' the common interval between the breadths, and the product shall be deemed the transverse area.