such space, and shall be added to the other tonnage of the vessel, ascertained as aforesaid.

And if the vessel has more than three decks, the tonnage of each space between decks above the tonnage deck shall be severally ascertained in manner above described, and shall be added to the tonnage of the vessel, ascertained as aforesaid.

ART. 81. In ascertaining the tonnage of open vessels, the upper edge of the upper strake is to form the boundary line of measurement, and the depth shall be taken from an athwartship line extending from upper edge of said strake at each division of the length.

The marine document of the vessel shall express the number of decks, the tonnage under the tonnage deck, that of the between decks above the tonnage deck; also that of the inclosed spaces above the tonnage deck, each separately.

The measurements should be made with a water-proof tape, graduated into feet and tenths of a foot, and as nearly inelastic as possible; Chesterman's metallic tape is recommended.

A pair of sliding rods should be provided for taking the depths, with a guide and a clamp, so that they may be secured in a perpendicular position between the keelson and deck.

A-2 foot rule, with a hinge joint, is required for taking the rake of the bow and stern, and for other purposes. A carpenter's square will be found useful for setting the sliding rod perpendicular to the keelson.

For taking the breadths in the hold, which are beyond the reach of the measuring officers, 2 rods will be needed, each about 8 feet long, one having a slot or wheel at the top, through which the tape may be passed; and the other a hook, to which the ring at the end of the tape may be attached.

ART. 82. The register length, breadth, and depth are the external dimensions of vessels, and are taken for the purpose of describing them in their marine documents. (See Diagram 1, Fig. 2, and Diagram 2, in Appendix.)

The length may be taken at such a parallel distance from the middle line of the ship as may be necessary in order to clear hatchways and other obstacles, and the ends. determined by squaring out from the proper points on the middle line.

The register breadth (Diagram 1, Fig. 2) is the outside breadth of the vessel at the broadest part, and is to be

taken by means of plumb lines let fall so as to touch the sides of the vessel.

The register depth (Diagram 1, Fig. 2) is to be taken from the under side of the tonnage deck plank, amidships, to the ceiling in the hold-average thickness-at the side of the keelson, in a direction perpendicular to the keel, by means of a square placed upon the upper side of the keelson.

ART. 83. Admeasurers of vessels will not proceed to ascertain tonnage until the vessel is sufficiently cleared to comply with R. S. 4153. The tonnage measurements are taken for the purpose of ascertaining the internal capacity of vessels in tons of 100 cubic feet each.

It may, however, sometimes be impracticable to ascertain either of the terminal points of the tonnage length on the upper side of the deck. In such cases the same result may be more conveniently reached by taking the length below the tonnage deck, from the inner planking under the deck hook, at the side of the stem, to the inner planking on the stern timbers, under the deck timbers; adding the rake of the bow in the thickness of the deck hook and the rake of the stern in the thickness of the deck timbers. (See Diagram 1, Fig. 4.)

The round or spring of the beam is the perpendicular distance from the crown of the under side of the tonnage deck plank, at the center, to a line stretched athwart the vessel from end to end of the top of the beam, and is to be ascertained at every place where it is to be used in the measurement.

If necesary, the round of the beam may also be taken above the deck by stretching a line horizontally across the top of the deck athwartships, touching the deck at the middle; the height of the line above the deck at the side of the vessel will then be the round of the beam. This method is, however, less accurate, and should be used only when the other method is impracticable.

The tonnage length having been thus determined, and the number of sections to be measured and the interval between them ascertained, a line is then to be extended down the main hatchway, at the middle line of the ship, in a direction perpendicular to the keel, by means of a square placed on the upper side of the keelson; the distance of the midship section from this line at the tonnage deck is then to be set off from the line in the same direction on the keelson, which gives the position of the midship section on the keelson; and the positions of the other

sections are obtained on the keelson by setting off afore and abaft the midship one the common interval between them as already determined.

The points so fixed should be marked with chalk and numbered consecutively from bow to stern, number one being at the bow. (See Diagram 2.)

ART. 84. So much having been accomplished, fix, by means of the clamps, the sliding rod in a direction perpendicular to the keel, at one of the points so numbered, firmly between the under side of the deck and the upper side of the floor timber at the inside of the limber strake, keeping the measuring staff square to the keel in both directions by means of a square placed on the upper side of the keelson; measure the depth from the under side of the tonnage-deck plank to the ceiling in the hold, average thickness, deducting one-third of the round of the beam. Divide the depth into four equal parts if the midship depth does not exceed 16 feet, and into six equal parts if it exceeds 16 feet. Then mark with white chalk on the rod the divisional points of the depth, number one being at the top of the tonnage depth, i. e., at a distance below the deck plank equal to one-third the round of the beam at that point. At each point so marked measure the breadth from ceiling to ceiling, square athwartships, and at right angles to the rod.

The bottom widths are to be taken only so far as the apparent flat of floor extends. Where there is perceptible rise immediately from the keelson, the bottom widths should be taken equal to the width of the keelson.

This process will be repeated at every section. should be taken in all measurements to bring them to the average thickness of the ceiling to avoid any device to lessen the ad measurement by making the ceiling thicker at the point cut by the sections. Care must also be taken that the sections shall be parallel to each other and at right angles to the axis of the vessel.

The intervals and one-third intervals of the breadths are to be carried to the nearest hundredth of a foot, and the interval and one-third interval of the length to the nearest thousandth of a foot.

No part of any vessel will be admeasured or registered R. S., 4151. for tonnage that is used for cabins or staterooms, and constructed entirely above the first deck, which is not a deck to the hull.

Any deck is a deck to the hull which has a direct bearing upon the frame timbers, even though lighter than other decks in the same vessel, and though only a portion of the

R. S., 4150, 4153.

timbers extend to such deck. In iron vessels an upper deck supported by stanchions of wood or iron bolted to the angle-irons or to the iron plating of the vessel is to be taken as a deck to the hull.

In consequence of the diversity of modes of construction, much in this particular must necessarily be confided to the judgment of the measuring officer, but in case of doubt the facts should be submitted to the Commissioner of Navigation.

The law above referred to was designed merely to exclude cabins and staterooms above the "promenade” deck of the steamers of the seacoast and lakes, or above a "boiler" deck, as used on the Western rivers. It does not have the effect to exempt from admeasurement any closed-in places, even if so situated, if used for cargo or stores.

ART. 85. If the second deck from the keel consists of several partial decks extending with breaks from stem to stern, the line of that course of decks must be taken as the tonnage deck; and if the partial decks are at different heights, the line of the lowest will be taken as the tonnage deck, and the head room above such line under the higher will be measured.

By "closed-in spaces" is to be understood spaces which are sheltered from the action of the sea and weather, even though openings be left in the inclosure. Measuring officers will exercise due vigilance that the intent of the law in this respect is not evaded.

It should be borne in mind, however, that no closed-in spaces above the upper deck to the hull are to be admeasured unless available for cargo or stores or the berthing or accommodation of passengers or crew. The engine room, pilot house, galley, windlass house, and the like are, when so situated and used, exempt.

Spaces having angular recesses in their sides, as the freight room in figure 2, plate 4, are to be admeasured in parts.

On side-wheel steamers of the Western rivers the space between the "doctor" and the first stanchion aft is to be

allowed for gangway. But if the first stanchion be more than 6 feet aft of the "doctor," then an allowance of 6 feet only is to be made for gangway. Allow, also, at the sides of the engine frame the width of the footboard of the engineer. (See Diagram 5.)

On stern-wheel steamers of the Western rivers make the same allowance for gangway aft the boilers as is made

for gangway aft the "doctor" on side-wheel steamers. The freight room is to be measured from the gangway aft to the "doctor."

If any portion of the space aft the "doctor" of sternwheel steamers be available for cargo, stores, passengers, or crew, it also must be admeasured.

ART. 86. The tonnage must be marked on the face of the beam under the forward side of the main hatch of seagoing vessels and lake vessels, and in the face of the beam under the after side of the starboard forward hatch of Western river steamers. On river steamers of the coast which carry passengers both above and below main deck, where there is no hatch to the main deck, the tonnage mark should be made on one of the deck beams in a conspicuous place, and as near as possible to the middle of the vessel. It should be in plain Arabic numerals, thus: 825, and not less than 3 inches high and not less than three-eighths of an inch deep.

On vessels whose main beam is of wood, it should be deeply carved or branded, and on vessels whose main beam is of steel or iron it should be plainly cut, or marked in oil paint, white when the beam is black, and black when the beam is of any light color.

The measurement and calculations being complete, and the tonnage duly marked on the main beam, the surveyor or measuring officer will certify the result to the collector, and such certificate (Cat. No. 897) will be preserved as a permanent record in the custom-house.

Blanks of this form should be furnished to the measuring officer, and the measurements should be inserted therein as they are taken, and the computations carried out on the same sheet. Great care will be requisite to insure accuracy in measurements and calculations. They should be verified at least twice, and for those competent to construct it the line of areas shown in diagram 3 will be found of great use for that purpose.

ART. 87. The tonnage of any documented vessel of the United States expressed in her marine papers in pursuance of a measurement purporting to be in conformity to this rule can be changed or set aside only by the Commissioner of Navigation, so long as the vessel remains unchanged in form or burden. Applications from any quarter for amendment or revision in such cases must be submitted to the Commissioner of Navigation, with precise statements of the errors supposed to exist.

The tonnage of foreign vessels is to be ascertained, when