SECT, x.] OF STEAM NAVIGATION. 321 



Example. If the breadth be 32 feet, the length 162 feet, and the length of the 

 engine-room 47 feet, 



(102 - 47 - 19-2 )g. = 520 tons. 



The register tonnage is the same whether the draught of water be 7 feet or 14 

 feet ; and it is the same whatever may be the form of the vessel : it is an 

 unpleasant task for an Englishman to mark as fallacious the modes of measuring 

 the capacity of vessels adopted by his government ; it is necessary however for 

 the purposes of science not only that it should be pointed out, but that the 

 error should be corrected. 1 



1 Since the publication of the first edition, the Law of Tonnage has been altered and established 

 by Act of Parliament, William IV., Sept. 9, 1835, of which the following is a summary: 



Divide the length of the upper deck between the after-part of the stem and the fore-part of the 

 stern-post into six EQUAL PARTS, and note the foremost, middle, and aftermost points of division. 

 DEPTHS. At these three points measure in feet and decimal parts of a foot, the depths from the 

 underside of the upper deck to the ceiling at the limber strake, or, in case of a break in the upper 

 deck, from a line stretched in a continuation of the deck. BREADTHS. Divide each depth into five 

 equal parts, and measure the inside breadths ^at the following points, viz., at one-fifth and at 

 four-fifths from the upper deck of the foremost and aftermost depths, and at two-fifths and 

 four-fifths from the upper deck of the midship depth. LENGTH. At half the midship depth 

 measure the length of the vessel from the after-part of the stem to the fore-part of the 

 stern-post. 



CALCULATION. To twice the midship depth add the foremost and aftermost depths for the 

 sum of the depths ; and add together the foremost upper and lower breadths, three times the upper 

 breadth with the lower breadth at the midship, and the upper and twice the lower breadth at the 

 after-division, for the sum of the breadths. 



Then multiply together the sum of the depths, the sum of the breadths, and the length, and divide 

 the product by 3500, which will give the number of tons or register. 



If the vessel have 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 bulk-head; and 

 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 found. 



To ascertain the tonnage of 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 shall be deducted from the total 

 tonnage calculated from the above Rule. To determine this, measure the inside length of the 

 engine-room from the foremost to the aftermost bulk-head; then multiply this length by the 

 midship depth of the vessel, and the product by the inside midship breadth at two-fifths of the 

 depth from the deck, and divide the final product by 92'4. 



2 s 



