probably at the time of their construction-in accordance with the Panama rules. In order to keep an accurate account of the tonnage of ships using the Panama Canal, it will be necessary for American warships, though they may not pay tolls, to report their tonnage according to the rules; and if foreign warships are required to report net tonnage, American naval vessels would need to report the same kind of tonnage. Moreover, the trouble and expense of ascertaining gross and net tonnage of warships would be incurred to obtain figures for a tonnage that would not be a satisfactory basis upon which to lery Panama tolls.

DEFECTS OF NET TONNAGE AS THE BASIS OF TOLLS ON WARSHIPS.

All rules for the measurement and registry of vessels are formulated with reference to vessels of commerce and not with regard to warships. To apply the rules to warships is an arbitrary and cumbersome process, producing tonnage figures that have little significance. It is a misuse of terms to speak of the net tonnage of a warship, because the net tonnage of a vessel is the measure of its earning capacity, i. e., of the space within the vessel that can be used to stow cargo or accommodate passengers. Warships are not built for the transportation of cargoes and passengers. They are fighting machines, the entire capacity of the vessel being used for the purposes of the vessel as an instrument of war.

The results obtained by British admeasurers in applying the British and Suez measurement rules to five representative warships are summarized in the following table. The normal displacement of a British vessel, as is explained on page 104, is the displacement of the warships with "legend" or designated weights of stores, coal, fuel oil, and water aboard. A vessel's normal displacement is the weight of a ship when equipped for the ordinary purposes for which the vessel is intended. It is a somewhat arbitrary statement of the vessel's displacement, but is an approximate expression of the ship's displacement when at sea.

TABLE IX.-Displacement, and gross and net tonnage, British and Suez measurements, of five British warships.1

Table IX states the percentage which net tonnage, British and Suez measurements, is of the normal displacement of the two battleships and the three cruisers for which figures are given. The percentage which net tonnage is of gross tonnage is also stated. It will be observed that the Suez rules make net tonnage a lower percentage of normal displacement and also of gross tonnage than do the British rules, whereas in the case of merchant vessels the Suez rules make the net tonnage a higher percentage of the gross tonnage than do the British rules. This indicates that the application of gross and net tonnage rules to warships is artificial and arbitrary.

Some years since, it became necessary for the Bureau of Construction and Repair of the Navy Department of the United States Government to apply the Suez measurement rules to a number of ships in the American Navy. The experience of the bureau in calculating the net tonnage, Suez measurement, of our naval vessels illustrates the difficulty of making such measurements. So many questions arose as to the definition of spaces and as to the application of the rules to particular portions of warships that the bureau was obliged to compile a detailed book of instructions for the guidance of the draftsmen who were assigned the task of

calculating the net tonnage, Suez measurement, of American warships. The book of instructions that was compiled is printed as Appendix XVII of this report.

Table X compares the normal displacement of 22 American naval vessels of different types with their gross and net tonnage as determined by applying the Suez rules to their measurement. The table is especially instructive. It shows a very wide range in the ratio of net tonnage to normal displacement, the net tonnage of the gunboat Helena being over 66 per cent of its normal displacement, while for the armored cruiser Maryland the percentage is less than 29 and for the monitor Monadnock less than 25. The ratio of gross tonnage to net tonnage, as shown in Table X for warships of different types, has such a wide range as to indicate that the net tonnage of a warship is a very arbitrary expression of the size or capacity of the vessel. It will be noted, for instance, that the net tonnage of one of the cruisers of the third class is but 45 per cent of the gross tonnage, whereas for one of the other cruisers of this class the net tonnage is nearly 63 per cent of the gross. For one of the gunboats the net tonnage is 58 per cent of the gross, while for another it is more than 67 per cent. The details contained in Tables IX and X are a strong argument in favor of basing Panama tolls on warships upon their displacement tonnage.

TABLE X.-Normal displacement, and gross and net tonnage, Suez measurement, of different types of American warships.

Unless there are special reasons why the tolls upon warships should be levied upon net tonnage, it is desirable to avoid the large amount of labor required to apply gross and net tonnage rules to the measurement of warships. As a matter of fact, the calculation of gross and net tonnage of warships would require a great deal of labor to secure results that are not satisfactory.

In testifying before the Committee on Interstate and Foreign Commerce of the House of Representatives, January, 1912, Mr. R. H. M. Robinson, Naval Constructor then connected with the Bureau of Construction and Repair in the Department of the Navy, made the following statement in regard to the "instructions and regulations" prepared by the bureau for a guide in applying the Suez rules to American ships:

"I attempted to formulate a set of definite instructions that I could hand to the draftsman and tell him how to do these things, and I found that there was an enormous number of questions that might be considered a dozen different ways, so we wrote a letter, through the Secretary of the Navy, to the Suez Canal authorities, in order to get their ruling on these questions. About a year and a half later we found that we still had a lot of questions we did not understand, and we wrote again, and, as a result of that, we have gotten up a book that would be of assistance to us in calculating the registered tonnage of a warship. It was a huge job." (H. R. Doc. 680, 62d Cong., 2d sess., p. 484.)

ADVANTAGES OF DISPLACEMENT TONNAGE AS A BASIS OF TOLLS UPON WARSHIPS.

The first reason why Panama tolls on warships should be based upon displacement tonnage is that the size of warships is everywhere officially stated in units of displacement tonnage. This practice has prevailed since 1872, when displacement became the legal tonnage of British warships. In all countries the tonnage of naval vessels is their displacement.

Originally the British Navy measured warships by the rules that were employed in measuring merchant vessels, but the purpose of the early laws was to ascertain the dead-weight tonnage which vessels were able to carry. When the more primitive measurement rules were supplanted in Great Britain by the "builders' old measurement" rules, which were applied to British vessels from 1713 to 1835, the purpose of measurement was still to determine the dead-weight tonnage of vessels, and the same rules were applied to merchantmen and to warships. The British measurement acts of 1836 and 1854 substituted for the rules that had been used to determine the dead-weight tonnage other rules formulated with a view to ascertaining the cubical capacity of vessels. The capacity ton instead of the dead-weight ton came to be the unit for merchant vessels. The acts of 1836 and 1854, however, were not applied to the measurement of warships for the purpose of giving them their official tonnage rating in the Royal Navy List, but inasmuch as warships were not constructed to carry dead-weights, it was recognized that the b. o. m. tonnage was an inaccurate unit for the rating of warships. It was the custom of British marine architects in designing warships to indicate the size of the ships by their displacement tonnage. This was also the practice of the continental European countries. The practice that had thus for some time prevailed caused the British Government in 1872 to make displacement the legal tonnage of British warships, although for a few years thereafter the Royal Navy List gave for each vessel both its b. o. m. and its displacement tonnage. This practice, however, was soon abandoned, and for many years the official tonnage of the naval fleets of Great Britain and all other nations has been the displacement tonnage of the vessels.

British warships, it is true, carry certificates stating their gross and net tonnage, according to the British measurement rules, and warships, when commissioned, are provided with a Suez Canal tonnage certificate, but these certificates are furnished the warships solely as a basis of tonnage payments at foreign ports and at the Suez Canal. The warship's displacement scale and curves are its real tonnage certificate, and the tonnage as read from the displacement scale and curves carried by every warship may readily be taken as the basis upon which Panama Canal tolls shall be paid.

A second advantage that will result from making displacement tonnage the basis for Panama Canal charges is the approximate fairness of that tonnage as between different classes of war vessels. Vessels of war as well as those of commerce are of many different classes; some are of high and others of low speed; some are heavily armored to resist attack and others are of light construction to give them great mobility. No single tonnage unit can be adopted that will enable warships to be closely compared on a basis of tonnage. In the case of naval vessels, as well as in the case of merchant ships, the most that can be done is to adopt a tonnage unit that will treat different classes of vessels as fairly as it is possible to treat them.

The main types of warships to which the Panama rules must apply are indicated by the following descriptive classification: 1

(1) First-class battleships, which are characterized by heavy armor, complete armament, moderate speed as compared with fast cruisers, and maximum size. Until recently their normal or official displacement tonnage ranged from 10,288 to 26,000 tons, but battleships are now being built in Great Britain with a tonnage of 30,000. The American battleship Pennsylvania is to have a displacement of 31,000 tons.

(2) Armored cruisers, which are generally of somewhat greater speed and less armor and armament than battleships. Their displacement tonnage is about the same as that of battleships, ranging, until recently, from 9,000 to 19,000. Recent development has so reduced the distinction that it is difficult, in some cases, to distinguish between armored cruisers and battle

1R. H. M. Robinson, Naval Construction, chs. 9 and 11.

ships. Several British and German armored cruisers have recently been constructed with displacements about as great as those of the largest battleships-28,000 and 28,800 tons. The terms "battle cruiser" and "cruiser of the line" are, moreover, being applied to some warships, and in some cases it is largely arbitrary whether the vessels are classed as cruisers or as battleships. (3) Monitors, which are used especially for harbor and coast defense. They are armored vessels which have from 3,000 to 6,000 tons normal displacement.

(4) Unarmored cruisers, including protected cruisers, which are used chiefly for scouting purposes. They have medium offensive qualities and small defensive ability, but are of maximum speed. They are generally smaller than armored cruisers and battleships, and have a normal displacement of 3,000 to 10,000 tons.

(5) Gunboats, which are used for patrol and police duty and are small vessels of 100 to 1,700 tons normal displacement.

(6) Torpedo boats, which have a normal displacement of 30 to 340 tons.

(7) Torpedo-boat destroyers, which are built for maximum speed. Their weight is reduced to the minimum consistent with strength, their normal displacement ranging from 200 to 1,073 tons.

(8) Submarines, which are small vessels of from 40 to 400 tons normal displacement. The speed qualities and, to some extent, the other characteristics, both of merchant vessels and of warships, are indicated by their coefficients of fineness or block coefficients. Vessels are often compared with reference to their coefficients of fineness. The coefficients of merchant vessels range from 0.4 for fine-lined yachts to 0.8 for freight steamers. The main classes of vessels in the British Navy have coefficients ranging from 0.4 to 0.65, as is well shown by the following statement of the "average values of the coefficient of fineness," contained in Attwood's "Warships":

Battleships....
Cruisers....

Destroyers..

0.6 to 0.65 .5 to .55 .4 to .45

The range of the coefficient of fineness or the block coefficients of selected representatives of different types of vessels in the United States Navy is stated in Table XI. The vessels in the American Navy have practically the same block coefficients as do vessels of corresponding types in the British Navy.

TABLE XI.-Range of block coefficients of selected representatives of different types of American naval vessels.

The coefficient of fineness, as is shown by the facts regarding British and American warships, is less for battleships than for ordinary freight vessels. Moreover, the difference between the coefficient of cruisers and the coefficient of battleships is less than the difference between the coefficients of fast passenger steamers and heavy freight ships. The range in the coefficients of fineness is somewhat narrower for naval vessels than for merchant ships.

Absolute equality of treatment of all ships can not be attained by any single basis of tolls, but approximate fairness can be secured for warships by basing the charges upon displacement tonnage. This is the opinion of such naval experts as Mr. R. H. M. Robinson, who has already been quoted in this chapter. In his testimony before the House Committee on Interstate and Foreign Commerce he stated that

The displacement of a warship is the most accurate means of estimating the value of that warship or the power of that warship. It is not an absolutely accurate measurement, but it is the most accurate measure you could name. If a ship has 20,000 tons displacement, it is reasonable to presume that it is twice as valuable from the military standpoint as a 10,000-ton ship or a ship of 10,000 tons displacement.1

1 Hearings on the Panama Canal, Committee on Interstate and Foreign Commerce, H. R. Doc. No. 680, 62d Cong., 2d sess.

In reply to the question whether tolls charged upon displacement tonnage will be fair as between different types of warships, the Chief of the Bureau of Construction and Repair of the Navy Department stated (in a letter dated Mar. 24, 1913) that

In view of the services performed and the general status of ownership, etc., of war vessels, the bureau believes that there should be no question that tolls based upon displacement will be fair and equitable, both from the point of view of the canal authorities and the owner of the vessel.

A third advantage which displacement tonnage has as the basis of tolls on warships is the ease and certainty with which the tonnage may be determined. Displacement tonnage can be ascertained for any vessel at any given draft by reading the tonnage from the document showing the displacement scale and curves, which is carried by every warship as one of its necessary papers. Figure 28 reproduces the displacement curves and scale of a representative battleship.

To ascertain the displacement tonnage of a warship the draft of the vessel forward and aft is read and the mean draft is found. The displacement curve and the corresponding scale of tons show what the ship's displacement tonnage is at the vessel's mean draft. In case there is a difference between the draft forward and aft a slight correction must be made, and for that purpose curves of "addition to displacement for 1 foot change of trim" by head or stern are given on each scale. Ordinarily, a warship rides on even keel and the correction, if any, amounts to but a few tons. In any event, the determination of a warship's displacement tonnage from its displacement curves and scale is a simple problem whose solution depends neither upon detailed measurements nor upon arbitrary definitions and rules, as does the problem of ascertaining the gross or net tonnage of a warship.

THE FOUR MEANINGS GIVEN DISPLACEMENT TONNAGE OF WARSHIPS.

The draft of any particular warship, and hence its displacement, depends upon its lading, whether it is light or is partially or fully loaded with supplies, fuel, water, and other weights. Displacement as applied to warships may have the four following meanings:

1. Normal displacement, which is the tonnage officially assigned to a warship as its permanent tonnage rating. In the United States Navy normal displacement means the weight of a ship completely equipped with a full complement of officers and men and their belongings, and with all general equipment, armament and machinery, and having on board two-thirds of its full allowance of stores, coal, fuel oil, and water. When each warship is designed it is given an official load line or normal displacement draft. The normal displacement is intended to represent the usual or normal weight of the ship, and, if the same rules and practice prevailed in all countries and at all times, normal displacement might be made the basis of canal tolls. Normal displacement, however, does not have the same meaning everywhere. It depends upon the rules prevailing in different countries with respect to the amount of stores, coal, fuel oil, and water which a ship shall have on board when its displacement is "normal." The rules may also be changed from time to time by any given country, and new rules may be adopted to apply only to new vessels. A warship always retains the normal displacement originally assigned to it, and thus inequalities between old and new vessels are certain to result from alterations in the regulations.

The British practice in determining normal displacement differs from the American. In the United States the general rule is that the normal displacement of a warship is its displacement when the vessel has on board two-thirds of its fuel, stores, and supplies, whereas in Great Britain certain legend weights of stores, coal, fuel oil, and water are assigned to each warship. The weights thus assigned vary according to the special purposes and services of the vessel. Ordinarily these "legend" weights are considerably less than two-thirds of the maximum amounts that may be put aboard vessels. In most British battleships the maximum coal capacity is over 2,000 tons, but the legend weight of coal in many cases is as low as 1,000 tons or 900 tons, and is sometimes even less. Ordinarily the normal weight of coal on a British warship is less than one-half the maximum coal stowage capacity. Similar variations prevail in