Chapter XIX: Part XI: Platforms

1. What is a _platform_?

A strong flooring upon which a piece of ordnance, mounted on its carriage, is manœuvred when in battery.

2. What is the object of a platform?

To facilitate the service of heavy guns and mortars, and to insure accuracy of fire.

3. Mention the kinds of platforms in general use in the service.

Fixed platforms for casemate and barbette batteries in fortifications, which are constructed with the works; the siege-platform for guns and howitzers; and the siege-platform for mortars; the rail-platform; and the ricochet-platform.

4. What properties should wooden platforms possess?

Strength and portability.

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5. Are the pieces composing siege-platforms of the same or different dimensions?

All of the same dimensions, viz: 9 feet long, 5 inches wide, and 3½ inches thick; except the sleepers, which in the mortar-platform are one foot less in length.

6. What is the weight of each piece?

About fifty pounds.

7. What is the number of pieces in the siege-platform for guns and howitzers?

Forty-nine in all, one being used as a _hurter_ on the front part of the platform to prevent the carriage from running too far forward; and twelve for sleepers.

8. Describe the method of laying a platform for a siege-gun or howitzer.

First establish the centre line of the embrasure, and stretch a cord on this line from the middle of the embrasure to the rear. This is the _directrix_ of the platform.

Lay the two outside sleepers parallel to this _directrix_, their outside edges being fifty-four inches distant from it. The four other sleepers are laid parallel to these, the edge of each fifteen and a half inches from the edge of the next. The upper surface of the front ends of these sleepers to be fifty inches on a vertical line below the sole of the embrasure.

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They are laid with an elevation to the rear, of one and a half inches to the yard, or four and a half inches in their whole length. This elevation may be determined by placing a block four and a half inches high on the front end of the sleeper, and laying a straight-edge, with a gunner’s level on it from this block to the rear end, then so arrange the earth as to bring the level true in this position. The next set of sleepers are laid against and inside of the first, overlapping them three feet, having the rear ends inclined outwards, so that the outer edges of the exterior ones shall be each fifty-four inches from the directrix, and the spaces between the edges of the others the same as in the first set, viz: fifteen and a half inches from the edge of one to the edge of the next, all having the elevation to the rear of one and a half inches to the yard, and perfectly level across. The earth is then rammed firmly around these sleepers, and made even with their upper surface. The first deck-plank, with a hole through each end for the eye-bolts, is laid in place perpendicular to the directrix, its holes corresponding with those in the sleepers. The hurter is placed on it, and the bolts driven through the corresponding holes in these pieces. The hurter should be so placed as to prevent the wheels from striking against the epaulment when the piece is in battery. If the interior slope has a base of two-sevenths of its height, the inner edge of the hurter should be two and a half inches from the foot of the slope. The other planks are then laid, each one forced against the preceding, the last plank having holes for the rear eye-bolts. By drawing out or driving in the outside sleepers, the holes through their rear ends are made to correspond with those in the last deck-plank, and the bolts are put in.

Drive stakes in the rear of each sleeper, leaving their tops level with the upper surface of the platform. Raise, ram, and level the earth in rear of the platform, so as to have a plain, hard surface to support the trail when the recoil is great. The earth at the sides should be raised nearly as high as the platform, and well rammed, giving it a slight inclination outwards to allow the water to run off.

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9. What are the dimensions of this platform?

Fifteen feet by nine feet.

10. Why is the elevation to the rear given to this platform?

To diminish the recoil and to permit the water to run off.

11. Describe the platform for a mortar.

The mortar-platform is composed of only half the number of sleepers and deck-planks required for the gun or howitzer platform. It is laid level, and the front and rear deck-planks are connected by eye-bolts to every sleeper. Its depth is one-half that of the previous platform.

12. Describe the method of laying the rail-platform.

The rail-platform for siege-mortars consists of three sleepers and two rails for the cheeks of the mortar-bed to slide on, instead of the deck-plank, and is very strong, and easily constructed and laid.

The pieces being notched to fit, are driven together at the battery, the distance between the centre lines of the rails being equal to that between the centre lines of the cheeks. The earth is excavated eight and a half inches, the depth of the sleepers, and the bottom made perfectly level. The directrix being exactly marked by stakes, the platform is placed in position, its centre line coinciding with a cord stretched between the stakes marking the line of fire. The earth is filled in as high as the upper surface of the sleepers, and firmly rammed; and stakes are driven in the rear angles formed by the sleepers and rails, and one at the rear end of each rail.

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13. Mention the parts of the _ricochet-platform_.

1 Hurter, 8 ft. long, 8 in. wide, and 8 in. thick.
3 Sleepers, 9 ft. “ 5½ “ “ “ 5½ “
2 planks, 10 ft. 8 in. l’g, 13 “ “ “ 2¼ “
1 plank, 7 ft. long, 13 “ “ “ 2¼ “
1 piece plank, 2½ ft. long, 13 “ “ “ 2¼ “
And some stakes.

14. Describe the method of laying this platform.

To lay this platform, place the hurter perpendicular to the line of fire, and secure it by four stakes, one at each end and two in front, 31½ inches from the middle towards each end: lay the three sleepers parallel to the hurter, the first 16 inches from the rear edge of the hurter, the second 43½ inches from the rear edge of the first, and the third 43½ inches from the rear edge of the second. Lay the plank 31½ inches from the directrix of the platform to the centre of the plank. Place the piece of plank 60 inches from the rear edge of the last sleeper, and bed it in the ground. Place on the last sleeper and this piece of plank, _the_ plank (7 feet long), its front edge 106 inches from the rear edge of the hurter.

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