24 32 36 42 4ft. Oin. 4ft. lin. lbs. 7.7356207-896334| 8'057048 Abs. 5 6:116756 8-217762 9.346604 | 9-541325 | 9736046 | 9·930767 | 12·246524 | 12.501660 | 12-756796 | 13:011932 Explanation of the table, 16-400370 | 16-683135 | 16·965900 In this table the first column contains the nature of the ordnance, and the numbers in the other columns are their respective charges of gunpowder in pounds, when the thickness of the object to be destroyed is as specified at the top of the columns. If the thickness be given in inches and parts of inches take such parts of the difference between the charge for the given number of inches and the next greater, and add them to the charge first found for the given number of inches for the charge required. The value of the decimal part of each will be had by multiplying it by 16, the number of ounces in a pound, and pointing off in the product from the right hand towards the left as many places for decimals as are contained in the given decimal, and retaining the number on the left of the point for the ounces, increasing it by,,, or 1, when the first figure of the decimal is 2, 5, 7, or 8, respectively, This hint is merely given for those practitioners into whose hands this table may fall, who are not very conversant in decimal arithmetic. SCHOLIUM. SCHOLIUM. charge in a This problem is not only of the utmost importance, and The problem practically useful in naval engagements, but in several in- applicable to military as well stances also of military operations; as the bursting open as naval operagates of besieged cities with promptitude and effect, and tions. breaking up all fortifications composed of wooden materials, especially those of a splintering nature, to which the foregoing charges apply most correctly. In the case of a naval Advantage of action, where the object to be penetrated is of oak sub- a proper stance, the ball, by having a small motion when it quits the seafight, ship's side, tears and splinters it excessively, breaking away large pieces before it, which are not so easily supplied in the reparation, whereas, on the other hand, if the shot had any considerable velocity when it quitted the side, the effect and disadvanit produced would be merely a hole, which would be stop- tage of too much powder. ped instantly by the mechanic employed for that purpose; and indeed in a great measure by the springiness of the wood itself; for I have seen in his Majesty's dock-yard at Woolwich, captured men of war having a number of shot holes in them almost wholly closed by the wood's own efforts; and that required nothing more than a small wooden peg or a piece of cork to stop them up perfectly. All the mischief therefore the balls can do under such circumstances of extreme celerity is, merely killing those men who may chance to stand in the way of their motion. stances, or If any object to be destroyed be so thick, that it cannot Cases of be completely pierced by any common engine; or if it be thicker subof a very brittle nature, such as stone or brick; then that stone or brick charge is to be used, which will give the greatest velocity to walls. the shot, to produce the greatest effect. But in many cases of bombardment this charge is by no means to be preferred; for though the effect produced each individual time be greater, yet in any considerable time the whole effect would be less than that from a smaller charge oftener fired, on account of the extreme heat it would give to the engine after a few discharges; and in consequence of which greater time would be required for cooling the gun, and preparing it for farther service, EXAMPLE Case of burst. ing open a gate with a 24 pounder. Acate may be Burst by the recoil of a EXAMPLE II. Required the charge for a 24 pounder shot to burst open the gates of a city with the greatest ease possible, the substance of them being elm 1 foot thick.ta: to pla Here the object to be penetrated being elm, the small letters in the general formula for the charge "S dow 2 Ds X 1600* must be made to express the several numbers of some ex- 1 S drzw 2DS X 16002 45 X 9 2 × ·46 × ¦¦ × 10002 = 104 X 111 3.50831 lbs. or 3 lbs. 8 ozs. for the weight of the charge required in this case. Retaining the experiment of Dr. Hutton as a standard for all cases where the object to be penetrated is of elm, we shall get by reduction Sd v2 w 2 Ds × 16002 = *0676% Sw the charge for any piece of artillery the diameter of the shot of which is D, and weight w; S being the thickness of the object as before. It is not unworthy of remark, that the gate of a besieged place, or any like things, might be effectually broken open by the gun itself charged only with powder, by placing it close to the gates with its muzzle from them; the momentum of recoil being generally sufficient to force such ob jects completely. From the circumstance, that no English admiral or comwander ever commences firing till his ships are about to be grappled grappled with those of the enemy, or until they have approached them so nearly as to affect in no sensible degree the first force of the shot; the above paper has, it is presumed, as much claim to utility as any that has ever yet been offered to the navy in the science of gunnery: and even if the vessels be not so closely in action, but are fighting at the distance of about 30 or 40 feet from each other, no danger would result from the above charges, provided that the shot impinged perpendicularly on the side of the vessel; on account of the splitting of the timber in some degree, which would make ample compensation for the defect of velocity occasioned by the resistance of the medium... It is impossible to deduce charges, that shall produce Distant firing. with certainty the effect above stated when fired at any considerable distance from the ship. The uncertainty of the impact being perpendicular from the unsteadiness of the vessels renders the thing at once nugatory, without any consideration of the real resistance of the medium, to the ball, and the deflection of the latter from a right lined direction. If the obliquity of the impact be given, or can be determined, then, the problem being otherwise rightly solved, a charge can be found, which shall answer the same purpose as those above given; but, if this be impossible (which it most decidedly is), then will the problem be at best but spéculative upon certain hypotheses. I shall however give an investigation of the problem” on the principles of resistance generally allowed, and then conclude the subject by a few observations. PROBLEM II. charge, that To determine the same as in the last Problem, when the Engine To find the is at any considerable Distance from the Object, and the Resistance of the Air taken into the account. Here, as in the former proposition, the Velocity V = Sdr2 Ds the principle of resistance just adverted to, which considers the fluid as infinitely compressed, and the particles thereof perfectly is to be esteemed the velocity of impact. Now on shall do most execution at distance. |