DIRECTIONS IN CASE OF FIRE.
370. In the following directions, no other object is proposed than to notice some of the more prominent and common preparations which may be generally made, and the measures to be adopted in vessels on the alarm of fire. The variety of circumstances under which that danger may be presented can only be successfully met by properly stationed, well-trained and disciplined men, judiciously directed by the Captain, and superintended by officers whose coolness and presence of mind are proof against every form and degree of danger, which alone will enable them to adopt and execute the best plans the emergency may require.
To this end the Captain will, as soon as the crew is organized, cause a Fire-Bill to be prepared, adapted to the particular arrangements of his ship, and in accordance with these Directions, by which the crew is to be drilled once a week till expert, and after that occasionally. This fire-bill should, as far as possible, conform to the arrangement for extinguishing fire during exercise at General Quarters. Much confusion has been known to arise from requiring different duties from the same person at Fire Quarters, and in case of fire when at General Quarters.
371. Should the alarm of fire be given when the men are not at Quarters, that alarm of itself is to be considered as a call to Quarters, and the men must repair to their stations at once. This must be impressed upon the men by the Division Officers. But the ordinary call for inspection is to be given as soon as practicable, by way of enforcing the order.
The alarm will be given by the sentinel near the bell, by ringing quickly and loudly successive peals for ten or fifteen seconds, with short intervals between.
The bell is to cease, however, as soon as the drum begins to sound the call to Quarters.
Should it be deemed necessary to water and provision the boats, preparatory to lowering them, the drum will beat the usual call for provisions, when the men stationed for these purposes will promptly proceed with their duties. In this case the shot shall be drawn or discharged from the guns, to guard against accidents in leaving the vessel, should it be impossible to save her.
372. The Captain will direct the Executive Officer, and such others as he may deem proper, to visit the place of the fire, and to transmit reports to him, by officers, of its character and extent, and to suggest the measures which will most speedily and certainly subdue it, or prevent its extension.
373. He will, if at sea, cause the ship to be hove-to, or steered in such direction as will be least likely to increase the activity of the fire, or will best enable the men to use the means in their power for controlling and extinguishing it.
374. If fire should take place in a ship at anchor in port or harbor, his attention must be given to prevent the communication of the fire to other vessels or combustible objects, and to have the cables ready for slipping, boats ready, and, if advisable, springs prepared to change the position of the ship, in order to prevent danger to other vessels.
375. He will decide whether the magazines and shell-rooms shall be flooded, and give orders accordingly; whether the hammocks shall be brought up and stowed; where sentinels shall be placed, and what disposition shall be made of the sick and prisoners.
If hammocks are to be brought up, each man not a Fireman, Pumpman, Hoseman, Axeman, or Smotherer, or belonging to the Carpenter's gang, or detailed as a Sentinel over boats' falls or spirit-room, will lash and carry up two hammocks and stow them in the nettings on his way to Quarters. Blankets, or other woollen materials, when wet, afford an excellent means of smothering fire, and should be left out by the party lashing up the hammocks and collected by the Smothering party, in charge of an officer, whose duty it will be to see them properly used.
376. The Officers of the respective divisions will enforce the strictest observance of orders from those under their command, and allow no one to leave his station, unless by express orders or permission. At the same time they will direct the most trustworthy of their men to perform any particular duty within their divisions which may tend to check the spreading of the fire, or furnish the means of extinguishing it.
377. Officers of gun-deck divisions will be prompt to detach, under proper officers, men who may be directed for any particular service, or who may be called from the guns by the calls for Firemen, Sail-Trimmers, or Boarders. Should the call for Boarders be made in case of fire, the men will answer it without any other arms than their swords or battle-axes. Divisional Officers near the main or other pumps, will cause the men of their divisions to aid in rigging and working them. The ship's buckets are to be passed up to the pumps, as soon as possible, by the persons who may be stationed near them, and these and the fire-buckets and division-tubs filled. The swabs are also to be got up and thoroughly wetted.
Division-boxes, and all powder or explosive materials not in the magazines, must be taken in charge by the Quarter-Gunners and placed in the safest positions, ready to be thrown overboard if ordered.
378. The Officer commanding the Powder division will himself deliver the keys of the magazines, shell-rooms, and water-cocks to the Gunner, his Mate, and the men stationed at the water-cocks, and see that they are prepared to flood the magazines, if orders should be given to that effect; but he must take especial care that the magazines, passages, and shell-rooms are kept closed until orders to open them are received from the Captain.
379. He will also take care that the air-ports are immediately closed, and all other means adopted for diminishing currents of air, especially if there should be a hope of confining the fire to the lower parts of the vessel.
He will at once have the hose led from the bilge-cock, the cock turned, and, if the forcing-pump or engine is worked below the gun-deck, will see it manned and worked by some of the men of his division.
380. The Master will cause windsails to be taken down; and, if set, courses, spanker, and all lower sails hauled close up; head, channel, and all other pumps which work on upper deck, and fire-engine, if on deck, to be rigged and worked by the men of his division stationed nearest to each of them. If practicable, sails, rigging, boats, spars, and the sides of ship must be kept wet, and every exertion made to furnish a full supply of water for extinguishing the fire. Rigging-axes and battle-axes must be ready for use, in case they should be wanted for any purpose.
381. The Chief Engineer will detail such Assistant Engineers and men as may be needed to take charge of steam-pumps, to lead out hose, and to use such other means of extinguishing the fire as may be ordered or deemed advisable. If under steam, the main engine will be slowed on the first alarm of fire, unless otherwise expressly ordered, and the steam-pumps started.
382. The Surgeon and his assistants will be in readiness to destroy, if required, all inflammable fluids, or other medical stores which would increase the fire; and to superintend the removal, if necessary, of patients who may be lame or confined to hammocks or cots.
383. Exercises, by order of the Captain, following false alarms of fire, known only to him and the Executive Officer to be false at the time of giving the alarm, may, it is believed, be resorted to with advantage, especially at night.
Such alarms furnish the best means of ascertaining practically whether the necessary preparations for extinguishing fire have been duly attended to; and what degree of silence, calmness, and promptitude may be expected from officers and men in repairing to their stations, as well as in the performance of their duties in a real case of fire.
False alarms, frequently repeated, may perhaps lead some of the men to move slowly, under the impression that every alarm given is false, and merely intended for exercise; and this impression may be entertained even when a fire has actually taken place. This evil would, however, be comparatively small, since it will be readily admitted by any one who has witnessed the effect of a fire upon a crew at sea, that the great difficulty in such cases is to obtain that necessary quiet and orderly attendance at Quarters which is essential to the success of all subsequent measures.
FOOTNOTES:
[4] Note:—In order not to incumber the text with details, they are transferred to the "Notes on the Manual Exercise" (Art. 288 to 357), which are to be carefully studied. Also the notes to Pivot-Gun Exercise.
[5] See notes on this command and the succeeding one, "Load," for further important details.
[6] With the nib-blocks the train-tackle cannot be used to assist in securing the gun, unless a special eye-bolt is placed for this purpose.
[7] When the trucks are to be brought into play, the levers should be shipped on their axle-squares so as to heave upwards, past the centre, and rest against the wood of the Carriage or Slide; otherwise they must be kept in place by hand or by a pin, neither of which entirely secures the Levers from flying back and doing mischief. If hove down, they are apt to interfere with the Tackles.
In order to ship the Levers expeditiously on the proper square, both are to be marked with a cold chisel.
The Fore Carriage-Levers require the efforts of two men at each, as the weight of the gun has most bearing there; each of the other levers is readily worked by one man.
[8] Principally to moisten the Sponge, which ought never to be omitted, as there is nothing so effectual in extinguishing any fragments that might remain burning in the Bore, and cause accidental explosion in loading, particularly in blank firing. It is a mistake to suppose that this practice increases the foulness of the Bore; on the contrary, it prevents it from hardening and accumulating, as long experience has shown. Sometimes it is convenient for the Spongers to dip the Sponge alongside, and they soon acquire the habit. Superfluous moisture is easily gotten rid of by twirling the Sponge at the handle.
[9] Were it practicable to hook a tackle so that it would move the gun, even from amidships to the port, without being shifted, or were it prudent to leave the gun free while shifting the tackle, there would be no need of a second tackle. But it is not possible, in pivoting, to exert direct action for more than the eighth of a circle by one position of a tackle, and it is absolutely dangerous at sea to leave the Slide unconfined for an instant. When, therefore, the Outer-Tackle is a-block, the second tackle must be hooked and set taut.
[10, 11, & 12] These orders are to be executed in quick succession, so as to be nearly simultaneous; that is, the compression is first relieved by backing its lever, upon which the Front-Levermen instantly bring the carriage on its trucks, and the gun is run back by the In-Tackles, the Out-Tackles being eased gradually, so as to check any violent movement; for the trucks, being fitted with friction rollers, allow the heavy piece to move suddenly and rapidly.
[ [13] The pivoting of so heavy a Gun is the most complicated of all the operations with it, and demands special drill. When done to windward, the hearty effort of the whole Gun's crew is required, particularly if there be much crown to the deck and no deck circles; to leeward there is no difficulty, and the time at sea to pivot from side to side may vary from four to seven minutes. The advantage of the Pivot-Boss will now appear, as it secures the coincidence of the hole in Slide with that of the Socket, and permits the Bolt to be removed out or in easily. Hitherto the difficulty of doing so without a Boss has caused delay, and contributed more than any thing else to the objections entertained against such heavy Ordnance, which have been in nowise obviated by either the Pivot Shifting-Screws of our own Navy, or the Pivot-Flap of the English Navy.
[14] Some difference of opinion may arise in regard to the shipping of these levers before the gun is run out, and they are required for pointing. To ship them now amounts to having them on the whole time—to which the only objection is, that if on, before wanted in pointing they may be in the way of the men; and, on the other hand, if not on, more attention may be demanded from 15, 16.
The question will not be material when the men are well drilled.
[ [15] The gun being now pivoted to the Port, the Breechings should be shackled and the rear Pivot-Bolt drawn, in regular order. But neither of these can be done without running out the gun a few feet. For in order to pivot with the greatest ease, the carriage had been previously run back on the Slide to the rear Hurter, so as to bring the weight of the gun as near as possible to the Rear pivot, the very best position being with the Trunnions of the Gun just forward of the Rear pivot. The shackling of the Breeching and the removal of the Bolt are, therefore, deferred until the Gun has been run out in the subsequent proceedings.
The Breeching is always to be shackled to the Ship's side—not to the Slide, which needlessly strains the pivoting, and also causes the shackle with its appliances to interfere with the working parts at the forward end of the Slide.
[16] It is generally expected that the Compressors are to supersede the necessity for a Breeching. But experience shows that in firing it is better to rely habitually on the Breeching, and use the Compressors to assist. Thus, in firing to windward at Sea, the Compressors are always to be set, but only so hard as may be required to ease the shock on the Breeching. In firing to leeward, the Compressors are not wanted, except to secure the gun in its place when in. When the Ship is not steady, but rolling, the discretion is to be exercised.
The Preventer, or Inner Breeching, will be found indispensable to avoid accident when running out to leeward in a sea-way. For with a trained crew, and all precaution in handling the levers and In-Tackles, there is a liability to the gun getting away, in which case it moves out with great violence, and may do serious damage. On one such occasion an XI-in. gun cracked the stout iron straps of the Compressors, and seemed but just prevented from freeing itself entirely and going overboard over the Port-sill. Not being able to replace the Straps, the Compressors were useless till late in the cruise. Preventer Breechings were then fitted, and answered so well that the practice was continued at sea as usual. They now form part of the equipment of all XI-in. guns, and should be just taut when the gun is out, and the Trucks of the Carriage reach but do not ascend the curve of the forward Hurter.
[17] This is to detach from the bottom of the Chamber the fragments of burnt Flannel that are apt to adhere and solidify.
[ [18] This practice encumbers the deck, and interferes materially at times with the management of the gun. Trial was therefore made on board the Plymouth, where the gun was on a covered deck, of hooks attached to the beams above, near each piece, in which the Sponges and Rammers were placed after having been used. The only objection was, that too much time might be lost in so doing; but after continued trials this was found not to be the case, when the men had been properly trained.
[ [19] Stopping the Vent is omitted by many practised artillerists, as unnecessary in extinguishing fragments of the cartridges. But as so much importance has been and still is attached to its performance, and it costs so little trouble, it seems better to continue the practice, particularly when so many accidents occur from premature explosion, not only to untaught and careless people, in saluting on holidays, but also on shipboard, where they ought not to happen.
[ [20] Sometimes the box has been fitted too tightly to the Shell, or has contracted on it, and delay is caused in loading. This should be attended to in season.
[ [21] Otherwise the stout stuff and seams found necessary with heavy charges might resist the primer, and cause a failure to explode the powder.
[ [22] It was the habit at the Experimental Battery, and in the experimental cruise of the Plymouth, to mark the handle of the Rammer, so that there should be no doubt as to the charge being home. This is always useful, but particularly so in case of the gun bursting, as it makes sure of an important fact.
[ [23] It is a common practice in loading, to expend much zeal in striking the cartridge one or two blows to insure its being home, which is quite unnecessary when the mark on the handle affords so much better evidence thereof.
[ [24] The XI-in. Shell weighs, when loaded, 135 lbs.; the lifting and entering it into the muzzle was one of the objections of those who were opposed to the use of heavy calibres. There was not one of the crew of the Plymouths XI-in. gun who was not found able, on trial, to take up the Shell and unassisted to put it in the Bore, when the ship was still. At sea a very simple implement was used—an iron segment with a bent handle on opposite sides. The Shellmen, 7, 8, turned the shell out of the box into this ladle, placed on the deck near No. 3, the Loader, who, when ready, took the left handle, and No. 5 (the 2d Loader) the right. These two lifted the Shell towards the muzzle, and No. 4 (Sponger), standing on the Slide, received the right hand from No. 5 as soon as within reach. No. 3, stepping on the Slide, and No. 4 continued to raise the Shell to the muzzle, which was not difficult, because of the Bore being conveniently high above the Slide on which they were standing; the Sabot projecting beyond the Ladle was entered into the muzzle, and the Shell pushed in, No. 5 taking the ladle back and laying it on the deck.
[ [25] As this is very firmly fixed in the recess of the metal stock, it is to be removed by pulling directly on the tail, which, if twisted, will be likely to break, and thus cause a loss of time. The patch is passed to the Gun Captain, who puts it in his belt-box, and is afterwards handed to the Quarter deck by the Lieut. of Division, in order to verify the number of shells fired. When the Fuze has been uncovered, care must be taken not to let it be touched by the moisture of the hand, or by the sea-water.
[ [26] As the blow might dislodge the priming of the Fuze and prevent its ignition. It is well to dispense with any wad, even a grommet, if possible.
[ [27] A good exemplification of the principle assumed for this exercise, that when any one of the men has executed an order, he shall not remain in position until the order is given which requires him elsewhere; for he may not have any part in the next order, or even in that second next, as occurs after pivoting, when only a few numbers participate in the following orders: Sponge—Load, the remainder only doing so at the third following, viz.: Run Out.
[ [28] No operation with this gun requires more care. There is a weight of 20,000 lbs. moving on friction Rollers along a metal plate, down an inclined plane—if once permitted to get loose and to be propelled by the motion of the ship, the momentum is immense, and must disable some of the apparatus, perhaps the Gun-Carriage itself. On such an occasion the preventer breeching is invaluable, and will be the best safeguard, if fitted so that when well stretched it will not permit the fore trucks to ascend on the curve of the Fore-hurter, for it is this which strains the strap of the Compressor.
Permitting the gun to go out with much force also displaces the shell, whether a grommet-wad be used or not.
[ [29] To windward, with a steady inclination, the precautions used to leeward are unnecessary. On the contrary, the difficulty is to move so great a weight up the inclined plane. Therefore, the carriage is released from all restraint, and all the available force put at the Out-Tackles, taking advantage also of whatever roll there may be to windward.
[ [30] This must, of course, be regulated by circumstances, as already mentioned in Note 10; as to windward, set the compressors moderately; to leeward, not at all; off the wind, according to the roll. Let the compression be so adjusted as to allow the muzzle just to come in.
[31] It is an old custom for the Gun Captain to keep the Priming-Wire in the vent while the loading is going on, feeling from time to time if the charge is home. It is a bad practice, because there is a liability of being caught by the charge as it comes along the Bore, and having the wire bent, thus spiking the vent, for a while at least. The mark on the Rammer handle is the best evidence that the charge is in place. The object now is only to clear the vent of pieces of cartridge stuff, which not unfrequently get into the vent, and choke it so as to prevent the primer from exploding the powder.
[ [32] Though the primers seldom fail to penetrate the flannel stuff of the cartridge, it is well to pierce the latter with the wire, so as not to omit any means that may insure the instant discharge of the gun.
[ [33] The Sight-Bar of the XI-in. Gun is graduated to its own charge only; if reduced charges are ever used, it will only be at short distances, when the gun needs no elevation. The Bar will then be down entirely, its head resting on the Box.
[ [34] One turn of which is equal to one degree of the quadrant, and may be of service when the Sight-Bars are not.
The carriages of Gun Sloops and other vessels carrying XI-in. guns allow of an elevation of 20°.
[ [35] When the vessels are moving, it is best to train the gun a little ahead, watching when the object draws in line; then, as the roll brings the piece right in elevation, it is fired.
[ [36] Many officers are of the opinion that this order should be divided—"Load with Cartridge," and "Load with Shell." But those guns would be very badly served which should wait until this time to give the order for the species of projectile or class of fuze required. After "Load," is the proper time to give subsidiary order to Shellmen what projectile and length of fuze to bring for next fire.
[ [37] "In 10,000 fires, when testing guns of different calibres, with the regulation locks, less than fifty primers failed from all causes."
CHAPTER V.
RIFLED CANNON.
384. The rifled cannon at present in service are—
Parrott.
| Denomination. | Weight. | Charge. | Weight of Shell. | Weight of Shot. |
| lbs. | ||||
| 6.4-inch, or 100-pounder | 9,700 | 8 lbs. rifle. | 80 lbs. | 70 lbs. |
| 5.3-inch, or 60-pounder | 5,400 | 6 lbs. rifle. | 50 lbs. | 60 lbs. |
| 4.2-inch, or 30-pounder | 3,550 | 3¼ lbs. cannon. | 29 lbs. | 30 lbs. |
| 3.67-inch, or 20-pounder | 1,750 | 2 lbs. cannon. | 18 lbs. | 20 lbs. |
Dahlgren.
| Denomination. | Weight. | Charge. | Weight of Shell. | Charge. |
| lbs. | ||||
| 4-inch, or 20-pounder, bronze howitzer | 1,340 | 2 lbs. cannon. | 18 lbs. | 0.86 lb. |
| 3.4-inch, or 12-pounder, bronze howitzer | 880 | 1 lb. cannon. | 11 lbs. | 0.50 lb. |
Charges for Parrott's Shell.
| 8-INCH. | 100-PDR. | 60-PDR. | 30-PDR. | 20-PDR. | ||
| lbs. oz. | lbs. oz. | lbs. oz. | lbs. oz. | lbs. oz. | ||
| Long | — | — | 3.4 | 1.8 | 1. | |
| Short | — | 3.11 | 2.2 | — | — |
Shell and Shot Gauges.
| 100-PDR. | 60-PDR. | 30-PDR. | 20-PDR. | ||
| Greatest | 6.36 | 5.27 | 4.17 | 3.64 | |
| True diameter | 6.35 | 5.26 | 4.15 | 3.63 | |
| Least | 6.33 | 5.24 | 4.14 | 3.61 |
387. In the rifle-guns of Mr. Parrott, provisionally adopted, it is intended to retain the full charge of powder which a smooth-bore gun of the same calibre would have with a round shot. The projectile for the rifled gun is to be usually ten times the weight of this charge.[38]
388. To obtain greater initial velocity, projectiles of less than the full weight have been provided—solid shot of 70 pounds for the 100-pounder, with the front end "chilled." Such projectiles, though not suited for long ranges, will be effective at 1,000 yards or less, and are well calculated to act against oblique surfaces of iron.
389. The powder for the 100-pounder and 60-pounder should be of Rifle (or, as formerly called, No. 7):—for the smaller calibres, 30-pounder and 20-pounder, of Navy cannon powder. The cartridge-bags are the same as those prescribed for similar calibres of smooth-bore guns.
390. The Parrott guns have been arranged for the use of a certain kind of projectile, supplied by the inventor. These have reference not only to the calibre and mode of rifling, but to the design of the gun itself. For these reasons, the inventor objects to the use of any other than his own form of projectile in the guns of his invention. This request has been acceded to in the heavier calibres. The shells of Schenkl and Hotchkiss have also been used, however, in the smaller calibres.
It is not considered expedient to describe these projectiles, and it is therefore directed that the Commander, Executive Officer, and Gunner shall make themselves thoroughly acquainted with their construction, and the percussion and time fuzes issued with them, before sailing. The Ordnance Officer will furnish them with any information on these subjects in his possession.
391. The projectiles consist of shells, shrapnel, and solid shot. All rifled projectiles used in the Navy are of the expanding class; that is, forced into the grooves by the action of the charge of powder, and require no other precautions in loading than common spherical shells.
392. It is, however, essential—
1st. That the base of every rifle-projectile, especially the Parrott, shall be thickly greased before entering it into the gun. [39] For this purpose common pork slush, prepared by several washings in hot fresh water, may be used.
2d. That the bores of all guns shall be frequently washed, the grooves of rifled guns cleaned of all residuum and dirt, and a moist sponge invariably used. After firing, the bore should be oiled with a sponge.
The attention of Commanding Officers is especially called to this requirement; and the Bureau desires that the action of Parrott's and other rifle-projectiles fired under the above conditions, may be carefully observed and reported; for it is believed that nearly all the failures of projectiles in actual service result from the grooves being filled, after a few rounds, with a hardened residuum of powder.
393. It is also necessary that the shell shall be close home on the powder, otherwise the necessary expansion will not take place, and the shell will tumble immediately after leaving the gun, utterly destroying its range and accuracy.
394. In order to be certain that the projectile is properly home, the rammer-handle must be marked to indicate it.
395. It is very important that dirt, sand, or other foreign substances should not be carried into the gun on the sponge or the projectile, or by the wind in batteries on shore.
In using guns on shore, a canvas muzzle-bag, a soft wad, or a light stopper of wood, suggest themselves as means of security during the interval between loading and firing the gun. The cover or stopper might be removed, or left to be blown away at each discharge.
The longer the interval above alluded to, and the higher the elevation at which the gun is kept, the more important and necessary are these precautions.
396. Much care is taken to give the projectiles uniformity of size; and if the powder is of suitable quality, those now supplied will almost invariably take the grooves. Should difficulty in this respect, however, be experienced, it may be remedied by separating the brass ring from the iron at three or four points of the circumference. This should be done with a cold chisel, very slightly, and so as not to interfere with the loading. It is only necessary to sever the contact of the two metals.
397. As the projectile slides in the gun with very little friction, particularly when greased, the gun should therefore be elevated and eased out when firing to leeward, that the shot may not be started from its seat. An experiment to test this, showed that running a 100-pounder out with the force of its crew against the forward hurter, the gun being level, started the shot forward nearly two feet.
Placing a grommet or other wad over elongated projectiles is positively prohibited.
398. The 100-pounder and 60-pounder guns being, respectively, of the calibres of the 32-pounder and 18-pounder spherical shot, and fired with the same charges, these shot may be fired from them with excellent effect, particularly on ricochet. The round shot should be sewed up in canvas or felt, strapped to a sabot, or snaked between two grommet-wads.
399. Both percussion and time fuzes are supplied for these rifle-guns. When the object to be fired at presents a sufficient resistance, such as masses of timber or earth, ships, or solidly-built houses, the percussion-fuzes alone should be used from rifled cannon. They will, however, frequently fail to explode the shell at long ranges, owing to the shell not striking on its apex; or, if fired into loose earth, which checks its momentum too slowly to make the plunger strike with sufficient force.
400. It has been observed that time-fuzes burn with greater rapidity in shell thrown from rifled cannon. Being in front, they are subjected to greater pressure from the air. A similar effect is produced when the fuze is confined under a water-cap, as in the naval time-fuze.
401. The fuze-holes of the heavy shells are cast larger than the diameter of the regular fuze-stocks of the navy, which can, however, be used with the aid of a bouching or an adapting ring, always sent with the shells.
This bouching has heretofore been made of cast zinc. Others with a flange and washer and the thread cut are now supplied, and the use of the old rings is prohibited.
402. If it be desired to explode the shell in front of or in the midst of a body of troops, or after having penetrated some resisting obstacle, the time-fuze should be used. This is the only fuze to be used with shrapnel.
403. The Vent is made in a bouching of pure copper screwed into the gun. In the largest calibres the interior orifice is lined with platinum.
The upper portion of the copper in naval guns is replaced by steel, to obtain a harder surface for receiving the blow of the hammer. The steel is three-fourths (3/4) of an inch thick.
A new vent can be readily put in, after getting out the old one, without injury to the screw-thread. This can be done by boring out the bouching with a drill, which leaves a thin shell containing the thread. Into the hole thus made insert a square mandrel about four inches, driving it lightly; by wrenching it, a portion of the shell of the bouching can be detached and removed by unscrewing. This may be repeated, and the whole of the old copper removed. The screw-thread is then to be cleaned out, and the new vent-plug screwed in.
404. Sights.—These consist of a fixed sight upon the right rimbase, and a brass movable sight placed in a socket which is screwed into the rear of the reinforce at the breech of the gun. The movable sight is furnished with a sliding eye-piece, and is graduated up to 10°. The eye-piece is also capable of lateral adjustment to allow for the drift as far as 10°, and for the effect of the wind. It is desirable that the sights should be placed on both sides of the breech; otherwise, in firing from a port at extreme train, there is a considerable loss of lateral aim. Furthermore, with the sight on the right rimbase, it is not convenient for the 2d Captain to attend the screw without interfering with the aim.
405. These guns are all rifled to the right, by which it is understood that the upper surface of the projectile is made to turn from left to right, the observer looking from the breech towards the muzzle of the gun.
406. Drift.—This is a deviation caused by the direction of the rifling, is always to the right when uninfluenced by the wind, and is to be allowed for.
407. The drift is in practice confounded with the deviation produced by the direction and force of the wind, which may either annul or increase it, according to whether it blows from right or left across the line of fire. At long range it is also necessary to consider the motion of the vessel across the line of fire. Suppose this to be at the rate of six knots, and the gun is elevated 15°, the time of flight would be by the Tables, 18 sec., while the deviation arising from this cause would be upwards of 60 yards. It is therefore of great importance that the Captain of the gun shall be carefully instructed in making this adjustment of the eye-piece.
408. Elevating Screw.—To obtain readily the changes of elevation necessary in the use of rifled cannon, the heavier calibres are made with very small preponderance, and are supplied with an elevating screw which is attached to the carriage at the lower end, while the nut is connected with the cascabel of the gun. Both screw and nut admit of movements by which the screw can take any position required in the various degrees of elevation. The parts should be allowed a certain amount of play; if binding is prevented, it is believed that the evident advantages of the screw may always be obtained.
409. Ranges and Time of Flight.—So far as ascertained, are contained in Table VII., Appendix B.
410. Precautions to be Observed.—In the use of these rifled cannon, it is of the utmost importance that all the directions relative to the lubrication of the shell, its being close home, charge and kind of powder used, and lining of the shells, shall be carefully observed.
Many premature explosions of shells having taken place in these guns, which are attributed to various causes, such as,—defects of metal, porosity, faulty fuzes, concussion and friction of the powder within the shell,—it is ordered that, on the occurrence of a premature explosion or rupture of a shell within the gun, it shall be immediately washed out and a careful examination made of the interior of the bore, by the mirror and by taking impressions in wax (see [Mode of Taking Impressions, p. 16, Part III.]), and all the circumstances of the case reported to the Bureau, specifying the kind and calibre of the shells, kind of fuzes, the charge and kind of powder, with its manufacturer's name: and,
Were the shells filled completely, and with what kind of powder?
Were the shells coated inside with any kind of composition?
Are any cracks or marks of scoring visible in the bores?
In rifled cannon, cracks or injuries produced by firing, or the rupture of shells, are to be sought for—thus,
1. Around and in rear of the vent-bouching.
2. On the top of the bore, between the trunnions and reinforce-band.
3. On the lower side of the bore, near the seat of the shot, at the junction of the lands and grooves.
4. Near the inside of the muzzle, caused by explosion of shells.
Although shells have been frequently ruptured in the guns without leaving any visible traces of injury, yet they may be developed after a certain number of rounds. Thus, in proving a gun at West Point, a shell exploded in the gun at the second fire: on examination, no traces of injury could be perceived; but, on a re-examination of the gun after the tenth fire, a fine transverse crack was discovered in the rear of the vent, extending two-thirds round the bore. It is therefore important that frequent examinations shall be made, even if no apparent injuries exist, as it is the opinion of the inventor of the guns that the principal, if not the only cause of failure of these guns in service, is due to the rupture of shells within the bore.
Experiments have been made, and are still in progress, which appear to show that these premature explosions may be to a great extent obviated, if not altogether prevented, by lining or coating the rough surface of the interior of the shell with a smooth and elastic coating.
All rifle-shells, except those for howitzers, before being issued for service, shall therefore be lined or coated on the interior with a mixture composed of—
16 ounces of soap—common yellow, not salt-water soap.
7 ounces of tallow.
7 ounces of rosin.
The tallow should be melted first, then melt and add the rosin, and, lastly, the soap, bringing the mass to a heat that will make it very fluid.
The shells having been first thoroughly cleaned, fill them about one-third full of the composition, roll them slowly so as to spread the mixture over the whole interior surface, and then pour off the residue. This coating should be about five-hundredths (0.05) of an inch in thickness, and is expected, from a series of experiments made for the purpose, to prevent the premature explosion of shells in the bores of rifled guns.
The Bureau further directs that hereafter the charge of the 100-pounder, or 6.4 inch, Parrott rifle, shall be reduced to eight (8) pounds of rifle, or No. 7 powder, and that only the short shell or solid shot, not exceeding eighty (80) pounds weight, and spherical projectiles, prepared as directed in the Circulars of February 24th and July 6th, 1864, be used in this gun.
411. Exterior Dimensions of Boxes Containing Parrott's Projectiles.
| Long. | Wide. | High. | ||
| Inches. | Inches. | Inches. | ||
| 100-pounder, short | 1 | 18¾ | 8¾ | 8¾ |
| 60-pounder, short | ||||
| 30-pounder, containing | 10 | 25¼ | 11 | 15¾ |
| 20-pounder, containing | 10 | 25¼ | 10 1/2 | 13 |
412. Hotchkiss's Projectile for 20-pounder and 12-pounder Howitzer.
| 20-pounder, containing | 5 | 24 | 12 | 6 1/2 |
| 12-pounder, containing | 10 | 20 | 9 | 9 |
413. Schenkl's Projectile for 20-pounder and 12-pounder Howitzer.
| 20-pounder, containing | 5 | 24 | 14 | 7 |
| 12-pounder, containing | 10 | 22¼ | 9 1/2 | 11 1/2 |
414. J.A.D. Projectile for 20-pounder and 12-pounder Howitzer.
| 20-pounder, containing | 3 | 15 | 12¼ | 7 |
| 12-pounder, containing | 5 | 19 | 10¼ | 6 |
FOOTNOTES:
[ [38] Owing to the recent accidents which have taken place with these guns, the 150-pounder has been withdrawn from service, and the charge of the 100-pounder provisionally reduced to eight (8) lbs. of Rifle powder, and the short shell of eighty (80) lbs. only is to be used.
[ [39] The Schenkl, Hotchkiss, and some other projectiles, have a small quantity of grease attached.
CHAPTER VI.
MONITORS.
The diagram represents the interior arrangement of the turret of the Monitors for the long and short XV-inch guns.
NOMENCLATURE.
A. Ammunition-scuttle.
B. Starting-bar for revolving turret and training gun.
C. Shaft on which turret revolves.
D. Travelling-bar on which moves the shell-whip.
E. Position of Engineer stationed at bar to revolve turret and train guns.
F. Compressor-wheel to check recoil, hove taut before firing.
G. Crank for running gun in and out.
H. Smoke-box of XV-inch (Passaic class).
O. Officer at sight-hole.
P. Port-hole.
R. Port-stopper.
S. Sight-hole.
416. In the Passaic class the ports for the XV-in. gun are only of sufficient dimensions to allow the passage of the shot at such elevations and depressions as were judged necessary: the gun being fired entirely within the turret. In order to protect the crew of the gun from the blast of the explosion, the smoke-box was devised, which to a certain extent accomplished the desired object, but at the expense of rapidity of loading.
417. In designing the Tecumseh class it was decided to enlarge the port, so as to allow the face of the muzzle to run out flush with the exterior of the turret. The gun was therefore lengthened sixteen (16) inches, and the muzzle turned down to the minimum size.
418. The contracted space within the turret rendered it necessary to introduce additional mechanical aids in lieu of manual labor in running out, loading, and checking the recoil.
D. Van Nostrand Publisher. Julius Bien, pr.
419. The exercise therefore conforms to the established exercise for great guns only as far as circumstances will admit.
The gun is supposed to be run in, and not loaded.
WORDS OF COMMAND.
I. "Provide the Gun!"
II. "Serve Vent and Sponge!"
III. "Load!"
IV. "Prime!"
V. "Elevate!" (or Depress).
VI. "Run Out!"
VII. "Train!"
VIII. "Ready—Fire!"
IX. "Run In!"
X. "Secure!"