Page:Royal Naval Biography Marshall v4p2.djvu/489

 “To prepare for action, the mortar being fixed in the box, unscrew the pressure bolt and adjust the re-action bolt. the upper part of the mortar port should be made to sway up, and the lower part to fall outward on hinges. Then, suppose a mortar weighs four tons, and that the recoil force pressing downwards was equal to one ton. To the counterpoise beam fix the weight equal to five tons, the spindle pressure would raise the mortar box to the height of the pressure bolt; it is then ready for action, and would continue so during any length of firing upon unerring principles. The counterpoise lever projecting over either gunwale, with a concave weight lowered by a chain under water, would regulate the concussion; and the pressure on the air-vessel would negative the shock on board. The strain on the pivot bridge, which may be altered at pleasure, according to the charge of powder, from the pivot socket on the cross beam to the pivot socket upon either gunwale, would be equal and regular, consequently no concussion more than a common discharge from the broadside of lower-deck guns would be felt.

“It is presumed by this plan shells may be thrown with more precision, and the powder reduced according to its resistance, shewn by the counterpoise beam on firing the mortar. If a pound of powder will at an angle of 45° throw a shell a given distance, it will raise the lever bar (say) one inch, and every range in like manner will be shewn by an index wire fixed to the beam, and a useful correction obtained. Should the powder on board be damp, or of less strength than range powder, the distance cannot be accurately obtained, as now practised, consequently this advantage would be highly important in night bombardment. The quantity of powder for each range will not be correct if damp or deficient in strength; but the recoil force is shown at every discharge, and the range by the index always visible to the eye. I have tried this plan, and found it to answer upon a small scale, and hope the utility of the invention will attract the attention of your Lordships to so important an object. I have the honor to be, &c.

(Signed)“.”

“To the Right Hon. Lords Commissioners of the Admiralty.”

“Devizes, 24th Sept. 1829.

“My Lords,– Having observed in the public papers that some improvements are about to take place at Portsmouth, in reference to the naval ordnance, I beg to call your Lordships’ attention to the inventions I have at various periods brought forward for the benefit of H.M. service; and although I have not been so fortunate as to see the whole of them adopted, yet I flatter myself, in respect to my improvement in ship guns, the following observations will be found deserving of your Lord, ships’ attention.

“It is stated, that a method has been discovered by which guns in ships or batteries may be pointed in any direction, with much greater