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September, 1920 also to ships measured for registry, but to which it is impossible to apply rule I. Rule II is as follows for wooden ships: G+BN, Tons under deck=( 5 XL X.0017, where L is length on upper deck from out- side of outer plank on stem to perpendicular line from aft of rabbet in sternpost, just below where the counter plank crosses B = outside breadth of ship. G is outside girth of ship from height of upper deck at one side to height of upper deck on oppo- site side. The gitth is taken by means ots chain passed under keel of the ship. For an iron ship the same rule is used, but the final multiplier is 0.0018. To the result found as above has to be added the tonnage of poops or other spaces above the upper deck, which is simply found by dividing the product of the mean length, breadth and depth by 100. In the act of 1854 the multipliers for wooden and iron ships were, respectively, 0.0018 and 0.0021, but as these were found to give results largely in excess of rule I, the factors were altered in 1858 to those given above. The principal use of rule II was to find the tonnage of foreign vessels for payment of dues previous to the adop- tion of the Moorsom system by other nations. Net Register Tonnage From the gross tonnage found, as al- ready indicated, there are certain deduc- tions to be made in order to obtain the net register tonnage. The allowances on account of pro- pélling space are briefly as follows: Paddle vessel, in which the tonnage of the space solely occupied by and necessary for the boilers and machinery is above 20 per cent and under 30 per cent of the gross tonnage; in screw steamers, in which the tonnage of such Space is above 13 per cent and under 20 per cent of the gross tonnage, a deduction of 32 per cent of the gross tonnage is allowed. As regards all other ships that are under or over above percentages, the actual space occupied by boilers and machinery may be measured, and in Paddle vessels the allowance is 1% times the actual space, and in screw Steamers 134 times the actual space. i Screw steamers the contents of the shaft trunk are deemed to form part of the engine and boiler space. Oey merchant shipping (tonnage) oe the allowances for propelling a € will in the future be limited for vessels (except those used exclu- 'act of 1889, which. provides THE MARINE REVIEW sively as tugs) to 55 per cent of the tonnage remaining after deducting from the gross tonnage any deductions allowed under Section 79 of the prin- cipal att top master's and crew's ac- commodations, navigation spaces, boat- swain's stores, donkey engine and boiler, peak tanks, etc. Allowance for Crew Space The rule for measuring engine and boiler. space provided for the inclusion of light and air spaces above the crown of the engine room and the intention of the act was clearly to provide for such spaces, as indicated in Bigg. .2. Spaces were, however, framed in above the upper deck, as shown, but by the act of 1854 could not be measured in the gross tonnage. In 1879 the owners of the steamer Bo/slom of Kee/ FIG. 38--CURVE OF DISPLACEMENT IsABELLA contended that this upper space should be included in the engine room space, and their claim was al- lowed as being justified by the terms of the act. A 'reduction. in tonnage was consequently obtained on _ this ground, but this was corrected in the that in the future such spaces as those indi- cated must be included in the gross tonnage. Besides the allowance for propelling power in steamers, all vessels may have a deduction made on account of crew space. To obtain the allowances under this heading the crew space must be in- spected and approved by a surveyor appointed by the board of trade, and provided not less than 72 cubic feet of space or 12 feet of deck area are set apart for each seaman or apprentice. An act passed in 1867 allows the actual cubic. content of all spaces occupied by the crew except the master to be deducted from the gross tonnage. In the act of 1854 all spaces above the upper deck for the sole accommo- dation of the crew were exempted from measuiement; but the act of 1867 pro- vided for the exemption of crew spaces below thé upper deck, and omitted to repeal the exemption under the act of 1854. a The effect of this was that if the crew were berthed above the deck the space occupied was exempted from measurement by the act of 1854, and then by the act of 1867 allowed to be Sag deducted from the gross tonnage: or, in other words, allowed for twice. The Owners of the steamer IsABELLA, already referred to, raised this point in 1879, and obtained judgment in their favor and since then-a number of other ves- sels have obtained similar reductions in the net register tonnage. The act of 1889 repealed the clauses of the act of 1854 dealing with "crew spaces," so that in future no reduction will be made for such spaces, unless they first have been included "in the measurement of gross tonnage. This act also provides for the fol- lowing deductions: _l. Sailing ships: Any space exclu- sively used for storage of sails, not exceeding 21%4 per cent of the gross tonnage of the ship. 2... Any. ship: (a) Any space used exclusively for the master, (b) Any space used exclusively for the working of the helm, capstan and anchor gear, or for keeping charts, signals, and other instruments of navigation and _ boatswain's' stores, Cc) The space occupied by the don- key engine and boiler, if ¢on- nected with the main pumps of the ship. (d) Any other space (other than double bottom) adapted only for water ballast. These deductions are allowed pro- vided the spaces referred to are certi- fied by a board of trade surveyor as reasonable in extent and efficiently con- structed, and they must be permane.tly marked so as to show the purpose for which they are intended. Measuring Deck Cargo ~By the merchant shipping act of 1876, provision is, made for the measurement of space occupied by deck cargo as follows: If any ship engaged in the oversea trade carries cargo in any space on the upper deck which has not been measured under the act of 1854, the tonnage of the. space occupied by the cargo is to be measured and added to the taxable tonnage. This regulation gives a variation in the taxable ton- nage from one voyage to another. The usual definition of home trade taken in this act, is the coasts of the United Kingdom and those of the continent from the Elbe to Brest. The Danube international commis- sion adopted in 1860 the Moorsom sys- tem of measurement, and subsequently accepted a method of allowance for propelling space as follows: The actual machinery space was meas- ured exclusively of bunkers, and 1% times that space allowed for paddle steamers and 134 times for screw steamers, subject to the total allowance not exceeding 50 per cent of the gross tonnage, except in tugs. This is usual-