These Articles have not been read before the Institute, but are inserted by direction of the Executive Committee.
To Determine by the Aid of Azimuth Tables the Effect Upon the Longitude of a Change in the Latitude Used in Working a Time Sight.
Proposition. The departure due to a change of one minute in the latitude used in working a time sight is the tangent of the difference between 90° and the azimuth of the body observed.
Let P be the position whose longitude has been computed with the assumed latitude. N S is the meridian through P. M is the body observed, and N P M is its azimuth. P P’ P” is the line of position perpendicular to P M. The angle NPP" is the difference between 90o and the azimuth. Let P' be a point on the line of position whose latitude is one minute greater than that of P. The departure due to this change of latitude is P'Q. The tangent of NPP” is QP’/QP=QP’, since QP is, by hypothesis, equal to one. Therefore QP', or the departure due to a change of one minute in the latitude, is the tangent of the difference between 90° and the azimuth.
Suppose P" to be a point on the line whose latitude is a minutes greater than that of P. Then RP" = QP' X a, or the departure for any change of latitude is equal to the departure for one minute multiplied by the number of minutes.
The error due to the assumption that RPP" is a plane triangle is not appreciable for ordinary purposes.
The annexed table is formed by changing the natural tangents from decimals of a minute into seconds.
To Make Use of the Method
Azimuth – 90o | Departure | Azimuth – 90o | Departure |
1o | 1” | 31o | 36” |
2 | 2 | 32 | 37 |
3 | 3 | 333 | 39 |
4 | 4 | 34 | 40 |
5 | 5 | 35 | 42 |
6 | 6 | 36 | 43 |
7 | 7 | 37 | 45 |
8 | 8 | 38 | 47 |
9 | 10 | 39 | 49 |
10 | 11 | 40 | 51 |
11 | 12 | 41 | 53 |
12 | 13 | 42 | 54 |
13 | 14 | 43 | 56 |
14 | 15 | 44 | 58 |
15 | 16 | 45 | 60 |
16 | 17 | 46 | 62 |
17 | 18 | 47 | 64 |
18 | 19 | 48 | 67 |
19 | 21 | 49 | 69 |
20 | 22 | 50 | 71 |
21 | 23 | 51 | 74 |
22 | 24 | 52 | 77 |
23 | 25 | 53 | 80 |
24 | 27 | 54 | 83 |
25 | 28 | 55 | 86 |
26 | 29 | 56 | 89 |
27 | 31 | 57 | 92 |
28 | 32 | 58 | 96 |
29 | 33 | 59 | 100 |
30 | 35 | 60 | 104 |
The time sight being worked out, enter the azimuth table with the latitude and declination used and the apparent time, or hour angle, computed, and take out the azimuth corresponding. With the difference between this and 90° enter the table given and take out the departure for one minute in seconds of arc. With this departure and the latitude enter the traverse table and take out the corresponding difference of longitude. Multiply this by the number of minutes of change in latitude, and the result is the required difference of longitude. The sign of application of this correction to the longitude computed, may be readily determined by a consideration of the direction of the line of position.
Example.
At Sea, 8.30 A. M., Sunday, 21st Dec., 1879,
Latitude 15° 47' N. I. C. 0
| h. | m. | s. |
C. | 12 | 25 | 04 |
W. | 8 | 20 | 00 |
C.-W. | 4 | 05 | 04 |
W. | 8 | 27 | 28 |
C. | 12 | 32 | 32 |
C. C. |
| 2 | 27 |
G.M.T. | 12 | 34 | 59 |
| -11h | 4 |
|
Entering the azimuth table with Lat. 16° N., Dec. 23°, 27' S. App. T. 8.h 33m, we find the azimuth to be N. 127° E. Entering the given table with 37° the departure corresponding, for one minute of latitude, is 45.”
From traverse table, with Lat. 16°, the corresponding D Long. is 47." The sign of application is evident from sketch of line of position.
The position at 8.30 A. M., carried forward to noon, gave 15° 35' N. 119° 09' 45"E, but observation at noon determined latitude to be 15° 45' N; therefore true longitude at noon was 119° 09', 45" E + 47" X 10 = 119° 17' 35" E.
The method has the advantage of enabling the Navigator to correct his position at noon instantly for any difference between the latitude by observation and dead reckoning, the error for one minute having been determined at the time of working the morning sight. It also enables the second point of the Summer line to be readily determined for the sun or any other body whose declination falls within the limits for which the azimuth tables have been computed.
The use of the method gives the Navigator a clear idea of the value of a sight without the necessity of plotting the line of position, and suggests the ease with which he may, when uncertain of his latitude, find from the tables the time of crossing the prime vertical, and take his sight at, or near, that time.
C. S. Sperry, Lieut. U. S. N.
Devices for Lessening the Dangers of the Sea.
To The Cor. Secretary Of The Boston Branch Of The U. S. Naval Institute.
I beg leave to call your attention to certain devices for lessening the dangers of the sea, which, though not new, it may be well to discuss in these times when collisions at sea and along shore follow in quick succession. I have deposited at the Naval Lyceum a rough model made by my unskilled hands of a .boat and davit, such as I put upon the Meteor in 1865, and which worked satisfactorily; it will be seen that it consists of two solid stanchions bolted to the side of a ship, to which are attached two fiat iron davits or "dericks," connected by a spar to which the boat is hung by tackles as usual; these davits are steadied by permanent guys leading fore and set up in line with the foot of the davits, so that there is no necessity for coming up the guys in swinging the boat in and out.
The Boat can be secured in three positions; first, ready to lower clear of the side; secondly, stowed over the gunwale or hammock netting, and last, inboard, ready to be stowed in chocks as in a vessel with a hurricane deck, or kept suspended inboard in a. vessel with an open deck. It will be observed that the tackle falls by which the boat is hoisted and lowered, pass through a leader near the foot of the davit, so that, when made fast, there will be no movement of the boat in a vertical line by the slacking or tautening of the tackles when she is swung out or in; it will also be noticed that there are two tackles attached to a short chain passing through a fixed leader on the head of the stanchions; the object of these tackles is not to pull in the davit and boat when suspended outboard, but merely to take in the slack of the chain as the davit comes in, and, on the other hand, to ease her down to the stowing point in suspension—or into chocks.
In an arrangement for a large boat these pennants may be of chain, or of supple wire rope; the davit is to be kept from going too far out or too far inboard, by a toggle or other device near the upper end of the tackle block. The intention is to swing the boat in by a pennant or tackle at the end of each davit leading across the deck; the amount of purchase necessary to accomplish this, must of course depend on the weight of the boat and the number of hands available for the work; for the boat of a small yacht, it will only be necessary to pull her in and ease her out by hand; but for a heavy boat a tackle or at least a whip will be necessary. When the boat is to be stowed in the upright position over the gunwale, a pin passing through the stanchion and the bar davit secures her there; for a large boat chocks on the rail or gunwale to land her in will be useful if not necessary. If, as in some vessels of war, a light boat is to be hung on the same davit as a cutter, it will be necessary to elongate the bar davit, curve it outward a little, and place a light spar fore and aft, as in the case of the other boat; but, for steamers carrying passengers, and for merchant vessels, two boats hung to one davit will not be proper. This arrangement, while well adapted to war ships, is more specially devised and recommended for passenger vessels and most especially for such steamers as navigate our sounds and rivers, where in general there are few expert, well drilled seamen to manage. It is an excellent plan for the smallest yacht. In examining my rough model on so small a scale it will be necessary for you to make some allowances for my imperfect mechanism. The common crooked davit is open to several objections, one of which is often mitigated by causing the davit to swing in and out through a projecting clamp with pins and holes to confine the davit in the position to lower the boat, and also to keep it upright near the side of the ship, still the fore and aft guys and the Toppinglifts must be tended.
My opinion (perhaps worth very little for a man-o-war) is that no boat davit should depend much on any attachments by lifts to the vibrating masts; but that each davit should depend for its integrity on the fixtures to the hull of the ship instead of placing boats abreast of the rigging in order to avail ourselves of lifts leading to the masts. I prefer to place my boats whore there is nothing to prevent swinging them directly in board, and if necessary lowering them into chocks. It may seem out of place to you, gentlemen, all of whom are supposed to be experts in devices for the management of' boats and ships, for me to say so much on so small a thing; but in these days of collisions and maritime suicides it may not be in vain for me to go into these minute details, in the hope that some precious lives may be saved by adopting a simple boat davit. It may be a small thing to allude to the usual manner of arranging the tackles of' boats; it is usual and I may say customary in the boats of merchant ships, and invariable in coasting steamers to place a ring in the stem of the boat somewhat fir down out of' the way and a swivel hook in the lower tackle block; now, in lowering a boat not provided with a patent detaching apparatus which no stranger knows how to operate, when she strikes the water down falls the heavy block, and so jambs the hook and ring that it is not very easy to unhook it, especially if as usual the boat is bobbing up and down, and instances are not rare of jammed fingers, and of the bow being first unhooked, when the painter not being led along forward, round swings the boat and she swamps or is so entangled that she must be cut adrift. In my arrangement, as illustrated in the model before you, the ring is placed in the block, and the hook is a permanent fixture in the boat. Every seaman can easily appreciate the simplicity and usefulness of this plan as a life-saving and finger-saving device as compared to the other. I trust you will pardon me for saying so much on so small a matter. I beg leave to present to you a small pamphlet just printed and for sale by Messrs. A. Williams & Co. entitled "The life-boat and other life saving inventions." It is mainly copied from the "Journal of the National life-boat Institution for Aug. 2, 1880" by permission of the authorities thereof and contains very little original matter. My intention was to circulate freely a large number of this brochure on the occasion of the celebration of the 250th anniversary of the settlement of Boston, on the 17 instant, but, owing to circumstances beyond my control, it could not be done, and so I conclude to make the most of them by distributing them among personal friends and selling to those who choose to pay a small sum.
Regretting that my health prevents my reading this paper myself,
I am, very respectfully, your servant,
R. B. Forbes.
Sept. 30, 1880.
Breaking Up Old Guns by Dynamite.
Two old guns, captured from the Turks, were destroyed, in Dec. 1879 by Capt. Elsner, in the following manner. The guns, one 9.5 cm calibre, 1.52 m. long, the other 10 cm. calibre, 65 cm. long, with flaring mouth 17 cm. in diameter were fastened upright by burying their cascables in the earth; the vents were then plugged and the bores filled with water. The first gun was charged with 0.96 kg. of dynamite, held in two cylindrical zinc boxes, 15 cm. long and 5 cm. in diameter, which were lashed butt to butt with projecting strips of wood lashed to the sides. By this means the charge of dynamite was brought in line with the trunnions, 23 cm. above the breech. Au ordinary priming cartridge with a Bickford fuze was attached to the upper charge and ignited. After the explosion, the cascable remained in the ground while the end of the chase, 30 cm. long, with a strip 6 cm. broad, blown from its side was found about twenty paces off, the remaining pieces, averaging from 15-20 cm. in length and from 6-10 cm. in width being scattered about within a radius of one hundred paces.
The second gun was charged with 0.72 kg. divided into one charge of 0.48 kg. with two of 0.12 kg. tied beside it. It was fired in the same manner as the first but the bottom of the bore was filled with stones to bring the dynamite in line with the trunnions. In this experiment, the cascable was split, and fragments of the gun, averaging from 10-15 cm. in length and from 6-10 cm. in width were scattered about within a radius of one hundred and fifty paces.
In examining the charges of dynamite hitherto employed for breaking up cast-iron guns, no agreement as to the necessary quantity can be found. Part 1, for 1875, of this Journal records the results of some experiments made in France, shortly before. The guns broken up with dynamite (No. 1) were one each of the following calibres, 16.4 cm. (30 pdr.), 15.3 cm. (24 pdr.), 13.4 cm. (16 pdr.), and a 32 cm. mortar. The charge of dynamite was divided into three parts, one being placed in the base of bore, one in the axis of the trunnions, and one in the muzzle; all three filling the bore completely, the spaces between being filled with water. The estimation of the distributed charge necessary was arrived at by the following formula:—
L=(77.4)[(R2-r2)/(r2)]
in which r is the diameter of the bore in mm., R is the distance from the axis of' the bore to the outside of gun in mm., and 1 the amount of dynamite necessary, in grammes.
During the same year, two cast-iron guns of 12 cm. and 13 cm. calibre, were broken up by dynamite (No. 1), in Ingolstadt. One charge only was used—placed probably in the bore, opposite the thickest part of the gun, the remaining space being filled with water. Before explosion the gun was lowered into a pit, where it lay at an inclination of 450 to the horizon, against the side. of the pit. The estimation of the amount necessary to destroy the gun by means of a single charge was obtained from the following formula:—
L=0.0001 Q. Kg.
where Q is the weight of the gun in kilogrammes. This gives one gramme of dynamite for ten kilogrammes of iron. The charge taken for the 12 cm. gun weighing 1650 kg. was 0.165 kg., and for the 13cm. gun, weighing 2360 kg. was 0.236 kg., and by them the guns were blown into twelve or fourteen pieces.
Let us compare the results obtained with the German 13 cm. gun with those given by the French 13.4.cm. gun, weighing 2220 kg. According to formula (1), there was needed for the French gun 1.47 kg. in the base of bore, 0.747 kg. in the axis of the trunnion, and 0.658 kg. in the muzzle; a total charge of 2.447 kg., ten times the amount placed in the German gun. The latter was blown into twelve or fourteen pieces and the former into one hundred and thirty pieces, the largest weighing 158 kg.
The heavier Turkish gun, weighing between 450 and 500 kg. was broken into about fifty pieces; the lighter, weighing between 370 and 400 kg. into about forty pieces. Applying formula (1), we have for the heavier gun r=47.5 mm., R1 for base of bore=200 mm., R2 for the trunnion axis=140 mm., and R3 for muzzle=130 mm. These values substituted give l1=1295. grm., l2=594. grm., l3=502. grm., a total charge of l=2.3911 kg, more than two and a half times greater than the charge used. But by formula (2) we find the charge required for this gun, L=50 grm. to be only one nineteenth of the amount actually used. For the lighter gun we have R1=200 mm., R2=160mm., R3=110 mm., and r=50 mm.; and by substitution in formula (1) we have l1=1161 grm., l2=715 grin., l3=297 grm., a total charge of 2.173 kg. But from formula (2), we have L=40 grm., and we again find a large discrepancy in the size of the charge required. From formula (2) there can be found the minimum charge of dynamite which will break a gun into large fragments. In formula (1), it is obvious that the ratio of the charge increases as the calibre decreases.
In Part 17, "des Technischen Unterrichtes fur die K. K. Genie Truppe, we are directed in estimating the explosive charge for cast iron guns to reckon 0.1 kg. of dynamite for each centimetre of the calibre of the bore. From this we would have for the larger Turkish gun of 9.5 cm. calibre, 0.9 kg. of dynamite which was the amount used in the experiment.
Translated from the Mitteilungen uber Gegenstande des Artillerie und Genie-Wessens. 1880, 5th Part by Prof. C. E. Munroe.
On Torpedo Boat Tactics.
Translated from the Mittheilungen aus dem Gibiete des See-wesens. (Vol. VII, No. 4.)
By Thomas Brassy Esq., M. P.
We are informed that the Russian Navy was supplied with no less than one hundred and twenty torpedo boats in the course of last year. To train the crews, and establish a definite system of torpedo tactics, twelve of these boats were kept in commission last summer; and thus the commanders who had completed the greater portion of the torpedo course, as well as the crews, had an opportunity of making themselves familiar with the method of handling these boats, and with the system of torpedo maneuvers generally. The experiences acquired in the course of the commission have been brought together by Lieut. Witheft. They were discussed at a conference of officers belonging to the Torpedo School and the Navy generally, and they are epitomized in the following paper.
Torpedoes were employed most extensively in the American war, and no less than forty ships were destroyed. The greater number of these ships were blown up by defensive torpedoes, and only a small portion by the offensive torpedo. The conditions of torpedo warfare remained unchanged until the successful results of offensive operations in the Russo-Turkish war encouraged the Russian Government to order the large flotilla of torpedo boats already referred to. It was in that war that the aggressive torpedo, in the hands of adventurous and daring men, was shown to be a weapon capable of being used with the most deadly and decisive effect, and, after a certain amount of successful practice in the management of these small crafts, it clearly appeared that they could be employed as aggressive weapons, with much less risk than might be inferred from the results of the earlier attempts, which had been made in America. To insure success, you require a good materiel, and the boats must be managed by men trained to the peculiar and hazardous service which they will be called upon to undertake. Every division of torpedo boats should be instructed how to conduct an attack with every prospect of success, without the support or cooperation of any other naval arm. In the recent Russo-Turkish war, nine attacks in all were made with torpedo boats; viz., 1, by Dubasoff and Schestakoff, on the Danube; 2, in the roadstead of Batoum; 3, by Skridloff, on the Danube; 4, by Niloff, on the Danybe; 5, by Puschtschni, Zatzarennyi, and Roschdestrocuski, at the Suliva mouth; 6, in the roadstead of Soukourn-Kale by Zatzarennyi, Pisarewskyi, and Wischnewetski; 7, in the roadstead of Batoum, by Zatzarennyi and Schtschetinski. The remaining attack was conducted by submarine mines in the Sulina mouth of the Danube.
When we come to examine the incidents of each of these attempts which were attended with a greater or lesser measure of success, without entering upon a general criticism of the campaign, it will be remarked that every attack was successful when undertaken according to a well matured plan by a group of torpedo boats; and that no attack succeeded that was made by a single boat. As an illustration, we may point to the attack made by Dubasoff and Schestakoff on the Turkish monitor, to the attack made by the boats of the Constantine in the roadstead of Soukoum, and to the attack on the guard ship at Batoum, by the boats of the Constantine, with the Whitehead torpedo. All the other attacks were unsuccessful, including the solitary attacks by Skridloff and Niloff, as well as the attacks, which were undertaken indeed by a group, but in which one of the boats, owing to undue precipitation, made an attack unsupported. Thus it happened in the first expedition against Batoum, and in the attacks at the Sulina mouth.
When we turn to the equipment of the torpedo boat, the first and most essential point is, that the torpedo and the torpedo boat should, so to speak, form one single weapon, so that the attention of the commander may never be divided between the conduct of the boat and the handling of the torpedo. A second essential is, that the arrangements should be such as to secure the instantaneous explosion of the torpedo, without the chance of a miss-fire. These two conditions apply more to the case of the torpedoes which are fired automatically, or by electricity. There must be a double set of conductors for the electric fluid, and the igniting apparatus must act upon receiving a slight blow. The equipment of the spar torpedo requires that all the gear should be exposed. This is not the case with the Whitehead. To hit a target of the size of a ship with a spar torpedo demands no peculiar dexterity, although the attack often fails from the colliding of the boats engaged. On the other hand, the success of the attack is certain, if the blow has been dealt home. The assailant know precisely what is taking place and the fate of his adversary is decided before his eyes.
There are not many advocates for the towing torpedo. As a means of attacking ships, which are protected by barricades or other obstructions, (and we must expect hereafter to deal with obstructions of that nature) this torpedo may be reckoned as altogether ineffective. Again there is great risk that the tow line will foul the propeller, as happened in the case of the boats of the Constantine on two occasions. Opinions are generally in favor of fitting boats with spars carried on the side. Although this method has been definitively adopted, it may not be superfluous to state the reasons why torpedoes so fitted have been found useless on certain occasions. The advocates of the towing torpedo insist on the facility with which the enemy may be attacked on the broadside, without slackening speed on the part of the assailant. Such an attack is almost free from danger to the assailant; but it does no injury to an enemy protected by obstructions. The harmless explosions will only steel his courage and accustom him to await calmly all future attacks. The attack with the spar torpedo presents some points of difficulty. The boat may be too far from, or perhaps some feet too near the enemy's ship. In the former case, the automatic explosion inflicts little damage: while in the second case, that, namely, when the boat is too near, and the spars cannot be extended to their full length, it may happen that the explosion may cause damage to the boat itself. These are the grounds on which the use of the spar torpedo on the broadside does not altogether commend itself.
It is usual to supply torpedo boats with drifting torpedoes. In order to use them it is necessary to place the torpedo boat in the path of the enemy's ship, the impact of which causes the torpedo to explode. The chief defect of this description of torpedoes consists in this, that they explode not under the ship, but at the water line. Hence if the ship be protected by nets or other obstructions, the torpedo can inflict no injury. The ship can be struck only when several torpedoes are fired in succession, and an opening is thus made in the obstructions. Even in this case, however, success is far from certain. In addition to this, where there is an ebb and flow of the tide, the drifting torpedo is as dangerous to your own ships as to those of the enemy: and at night, more particularly, it is impossible to get out of its way. Drifting torpedoes are therefore to be used by the torpedo flotilla, only in cases where the attack is being undertaken according to a plan laid down beforehand, with sufficient accuracy, and it can be known to every man taking part in the expedition, where and when the torpedo is to be used. Having recognized these two important defects, it may be inferred that these torpedoes are chiefly valuable as a means of destroying the morale of the enemy, and fettering his movements by the apprehension that he may possibly encounter one of these weapons every time his ship is brought to a stand-still. As an engine of destruction, these torpedoes cannot yet be accepted as practically effective.
From this general view of the materiel of torpedo warfare we turn to the tactics to be employed in the use of these weapons. It has already been observed that an isolated attack with torpedo boats must only be attempted in exceptional circumstances. It must be assumed that the vessel which it is proposed to attack is protected with nets or floating obstruction. If a division of torpedo boats is available for the proposed attack, it will be desirable to break up the division into three groups, to each of which a special duty will be assigned. Further, each boat in the several groups must confine itself to the special task which has been assigned to it. Assuming that the enemy is effectually protected by obstructions, nets, or other barriers, the first group is required to remove them. The second group makes the attack. The third group is held in reserve. Their task consists in rendering help and filling up any losses caused in the two leading groups by the defense of the enemy. As soon as each group has been completed, and their precise duties have been assigned to them, the operations must be carried out according to a well-considered and well-defined plan.
The pioneer group after their task has been completed will fall back into the reserve. The attack must be made simultaneously by the boats of the attacking group. The speed of all the boats must be regulated by the speed of the slowest boat. The commandant of the division, who must take his place in one of' the boats of the reserve division, gives the signal for the attack. The highest speed of the slowest boat should be made the maximum speed as long as possible, so as to ensure that each boat shall come up to the attack at the right time. The farthest stations will be assigned to the slowest boats, so that all may come up with the enemy simultaneously. The engines should be slowed at some fathoms distance, and should be reduced to half speed when about twelve fathoms from the object. By adopting these dispositions it is possible for the commandant of the boats to satisfy himself that his own spar, with the torpedo attached to it, remains uninjured up to the last moment before the blow is delivered, that it is clear of the spars rigged out from the other boats in the group, and that the electrical firing gear is in order. It is to be observed that the risk of injury to the electrical explosive apparatus is not so great as when submerged spars are used. The electrical firing gear should be used only when the automatic gear fails; otherwise it may happen if the distance has been misjudged, that the torpedo will be fired too far from the object. The torpedo should be brought under the ship's bet tom. If the Whitehead torpedo is used, care should be taken not to aim at a vessel amidships, for there the armor is carried down to a considerable depth under water. A spar torpedo will in case of necessity be used against a perpendicular broadside. The effect of the explosion, the torpedo striking at an acute angle, will in most cases be greater in proportion as the centre of the charge is brought closer to the ship's side.
From what has been said it will be obvious that, in order to ensure a successful result, the attack should be made from at least four points before or abaft the beam, whether on the port or starboard side. For such an attack there will be required four pioneer boats, to clear away the obstructions round the ship, four boats to make the attack, two boats in reserve, and one for the commander of the division—in all eleven boats.
Even supposing the newest type of torpedo boat to possess contrivances for closing all apertures simultaneously, experience proves that officers, as well as men, prefer to make the attack with open hatches, a circumstance which would probably be the cause of some loss of life. This can, however, scarcely be a point of serious importance, since a torpedo boat with a speed of ten knots would only require 4.8 minutes to pass over a distance of fifteen hundred metres exposed to the enemy's fire. The prospect of great loss of life would delay, or even entirely defer, an attack, although in former times many boat expeditions and boarding attacks, requiring much more determination, and involving the probable loss of many lives, have been carried out successfully. The attack by torpedo boats is, in fact, a kind of boarding attack under far more favorable conditions for the attacking party than in the old days, the cutlass, the boarding pike and the battle axe having been supplanted by electric and automatic firing apparatus. If only five of the eleven torpedo boats sent forth on an expedition return uninjured, they will have succeeded in their task; the other six will only have performed their duty, and their loss will be fully repaid by the destruction of the enemy's ship. The results of the attacks by torpedo boats in the course of the late war, which were carried on latterly almost without any loss on the part of the assailants, cannot be regarded as very considerable. In the future, we shall probably have to deal with enemies more determined and alert, and a more serious loss in men and materiel must be anticipated. When a boat is destroyed in the attack it does not necessarily follow that the crew should lose their lives. The attack must be made stealthily, so as not to attract the attention of the enemy. This will not be so easy in. the future as in the last Russo-Turkish war, although it is true that in that war, boats of a speed of from six to eight knots were used, while the new boats will make their attack at speed of thirteen knots.
It is difficult to give any positive opinion as to whether it is best to make an attack in broad day light. In very dark, stormy nights, the enemy will generally be more watchful. A single ship can scarcely be defended effectually, even in the day time, against a flotilla of' torpedo boats. Our present experience scarcely enables us to say whether the attacks in the day, or those in the night, have the best chance of success, even assuming there may be a greater loss of life in the former. It may happen that you find an enemy who, having observed a division of torpedo boats coining down upon him, has made every preparation to repel their attack; but it does not follow that he may be able to make an effective defense. Here it would seem that the chances of success are greater in a daylight attack. A ship attacked in the night can make use of the electric light; the assailant should endeavor as long as possible to keep out of sight, and therefore the torpedo boats should be painted of such a color as to be the least conspicuous under the electric light. The usual dark grey colors are conspicuous, inasmuch as they appear much lighter, and indeed become a pure white when seen by the electric light. Experiments in the Black Sea showed that a light brown or chocolate was the least conspicuous color.
It is to be remarked that no special code of signals has yet been devised for torpedo boats. In the absence of these two boats belonging to the same fleet may possibly attack one another. The equipment of the torpedo boats with machine guns deserves very careful consideration; it is still difficult to pronounce an opinion as to their suitability. In making an attack it will be impossible to open fire with these weapons; they can be employed with effect only against boats, or to cover a retreat. The pyroxyline rockets may be found more useful: they have been supplied to torpedo boats; they do not load them too deeply, take up little room, and can be used with equal advantage for signaling purposes both in advancing to the attack and in retiring. The explosion of these rockets on board the ship which is attacked would create no small confusion.
The general conclusions to which we have been led by the foregoing observations on attacks by torpedo boats may be summed up as follows:-
- Attacks by single boats are only to be attempted as a last resource
- The attack must be made according to a carefully considered plan.
- The torpedo boats are to be equipped with either the Whitehead or the spar torpedo.
- A squadron of torpedo boats must be divided into groups; the pioneer group, the assaulting group, and the reserve group.
- The torpedo should be fired automatically, and only when this plan fails should the electrical firing apparatus be employed.
- Thespar should be sunk as soon as the boat is reduced to half speed or stopped. At full speed the spar should be triced up clear of the water.
- The attack should be made, at a signal from the commander, simultaneously from several points.
- The speed of the torpedo boats before the attack, until they reach the positions which have been assigned to them, should be regulated according to the speed of the slowest boat.
- The commander of the division should remain in the rear, with the boats of the reserve group.
- The torpedo must be brought in contact with the bottom of the unarmored ends of the ships.
In order to be able to apply all these rules effectively in war, it is necessary in time of peace to train every torpedo division to apply them as far as possible, under the conditions which would arise in actual warfare. This would be easily effected if the maneuvers of an attack were intelligently put in practice according to a predetermined plan, against a fleet at anchor and under way, with dummy torpedoes. At the end of the course of instruction, an attack might be made as a test of the efficiency which had been attained with loaded tuxedoes against a raft or pontoon towed.
It is only after considerable practice that success can be obtained in this new method of warfare. Trials with single boats can only be regarded as a preliminary to maneuvers with a complete division of boats. They in no way ensure success when a boat is for the first time attached to a division, without having been exercised in making attacks of a similar nature in time of peace.
Journal of the Royal United Service Institution, No. CVII.