Part 8

IX. The following simple micrometer may be so usefully applied to military purposes, that I shall extract it verbatim from the Philosophical Transactions for 1791, where it is described by Cavallo. This micrometer consists of a thin and narrow slip of mother of pearl, finely divided, and placed in the _focus_ of the eye glass of a telescope, just where the image is formed.—It is immaterial whether the telescope be a reflector, or a refractor, provided the eye glass be a _convex_ lens and not a _concave_ one, as in the Galilean construction.—The simplest way to fix it, is to stick it on the diaphragm, which generally stands within the tube, and in the focus of the eye glass.—When thus fixed, if you look through the eye glass, the divisions on the scale will appear very distinct, unless the diaphragm is not exactly in the focus; in which case the scale must be placed exactly in the focus, by pushing the diaphragm, backwards or forwards, when this is practicable; or else the scale may be easily removed from one surface of the diaphragm to the other, by the interposition of a circular bit of paper or card, or a piece of sealing wax.—This construction is fully sufficient when the telescope is always to be used by the same person; but when different persons are to use it, then the diaphragm, which supports the micrometer, must be so constructed as to be easily moved backwards or forwards, though that motion need not be greater than about the tenth or eighth of an inch. This is necessary, because the distance of the focus of the same lens appears different to the eyes of different persons; and therefore whoever is going to use the telescope for the mensuration of an angle, must first unscrew the tube which contains the eye glass and micrometer, from the rest of the telescope, and, looking through the eye glass, place the micrometer where the divisions of it may appear most distinct to his eye. The mother of pearl scale may be about the 24th part of an inch broad; its length is determined by the aperture of the diaphragm; its thickness that of writing paper. The divisions on it may be the 200th of an inch, which may reach from one edge of the scale to about the middle; and every fifth and tenth division may be a little longer, the tenths going quite across. When the telescope does not magnify above 30 times, the divisions need not be so minute. For the sake of those not conversant in trigonometry, the following is an easy method of determining the value of the divisions on the scale. Mark upon a wall or other place, the length of 6 inches; then place the telescope before it so that the 6 inches be at right angles to it, and exactly 57 feet 3½ inches distant from the object glass of the telescope. This done, look through the telescope, and observe how many divisions of the micrometer are equal to it, and that same number of divisions will be equal to half a degree, or 30´; and this is all that need be done to ascertain the value of the scale. The reason on which it is founded is, that an extension of six inches at the distance of 57 feet, 3½ inches, subtends an angle of 30´, as is easily calculated by trigonometry. To save the trouble of calculation, a scale may be made requiring only inspection. Thus, draw a line equal to the diameter of the field of the telescope, and divide its under side into the same number of parts as are on your micrometric scale, and, by the above operation on the wall, having determined the value of 30´, which we will suppose to correspond with 16 divisions on the scale, mark 30´ on the opposite side of the line, opposite 16 on the lower; 15 opposite 8, and so on.

By the following table the results may be ascertained by inspection only: thus, suppose an extension of 1 foot is found by the table to subtend an angle of 22′, the distance will be 156.2: and suppose at the distance of 171.8 an object subtends an angle of 20′, its height will be found to be 1 foot; or, suppose an object of 6 feet high to subtend an angle of 20′, the distance is 1030.8, by multiplying 171.8 by 6.

_Table of Angles subtended by 1 Foot, at different Distances._

+--------+------------++--------+------------+ |Minutes.| Distances ||Minutes.| Distances | | | in feet. || | in feet. | +--------+------------++--------+------------+ | 1 | 3437.7 || 31 | 110.9 | | 2 | 1718.9 || 32 | 107.4 | | 3 | 1145.9 || 33 | 104.2 | | 4 | 859.4 || 34 | 101.1 | | 5 | 687.5 || 35 | 98.2 | | 6 | 572.9 || 36 | 95.5 | | 7 | 491.1 || 37 | 92.9 | | 8 | 429.7 || 38 | 90.4 | | 9 | 382.0 || 39 | 88.1 | | 10 | 343.7 || 40 | 85.9 | | 11 | 312.5 || 41 | 83.8 | | 12 | 286.5 || 42 | 81.8 | | 13 | 264.4 || 43 | 79.9 | | 14 | 245.5 || 44 | 78.1 | | 15 | 229.2 || 45 | 76.4 | | 16 | 214.8 || 46 | 74.7 | | 17 | 202.2 || 47 | 73.1 | | 18 | 191.0 || 48 | 71.6 | | 19 | 180.9 || 49 | 70.1 | | 20 | 171.8 || 50 | 68.7 | | 21 | 162.7 || 51 | 67.4 | | 22 | 156.2 || 52 | 66.1 | | 23 | 149.4 || 53 | 64.8 | | 24 | 143.2 || 54 | 63.6 | | 25 | 137.5 || 55 | 62.5 | | 26 | 132.2 || 56 | 61.4 | | 27 | 127.3 || 57 | 60.3 | | 28 | 122.7 || 58 | 59.2 | | 29 | 118.5 || 59 | 58.2 | | 30 | 114.6 || 60 | 57.3 | +--------+------------++--------+------------+

_DRAG ROPES_—

weight length 5 pins 6 lbs. 8 oz. 21 feet. With 4 ” 5 6 13 3 ” 5 0 12

_EMBARKATION._

1. _Of Ordnance and Stores._—The first thing necessary is to prepare a list of all the articles to be embarked, with the weight of each. This list must have a large column for remarks. The tonnage required for bulky articles will be generally ⅓ more than their actual weight; but the tonnage of ordnance, shells, shot, _&c._ will be equal to their weight. If vessels be paid according to the tonnage they carry, the masters will of course stow away as much as the ships will hold; but if, by the voyage, they will be averse to loading their ships too much; a naval officer should therefore always attend to see that the ships are properly stowed.

Ordnance and stores may be embarked either for the purpose of merely transporting them to another situation, or for a military expedition. In the first case, each ship must be stowed with as much as it will carry, and every article that relates to one particular species of service or ordnance, must be put on board the same ship; that in case one ship be lost, the others may remain in themselves complete. This principle must of course be likewise attended to in an embarkation for an expedition; but a more particular distribution must take place of the stores when on board. With each piece of ordnance must be placed every thing necessary for its service; its side arms, carriage, limber, ammunition, _&c._ so as to be readily come at, when required to be disembarked. If it be an embarkation of ordnance, _&c._ for a siege, not only every thing necessary for the service of the pieces of ordnance should be arranged with them; but also every thing necessary for the construction of the battery on which they are mounted. It will be adviseable in this case, to put different natures of ordnance in the same ship, in proportions according to the service required of them. In general it will be best to put the heavy articles in first, and every thing that is light, easy to be removed, or likely to be first wanted, on the top. Previous to embarkation, the guns, carriages, waggons, _&c._ must be dismounted, but first numbered as follows: and the number of each article marked in the list, in the column of remarks. Give each piece of ordnance and its carriage the same number. Give the ammunition and other carriages, different numbers from the ordnance carriages. Then give every limber, whether of ordnance carriage, ammunition carriage, or waggon, the number of its respective carriage. If for a simple transport, arrange the small stores, side arms, _&c._ according to their several natures; but if for an expedition, every thing belonging to each particular piece of ordnance must be collected together, and the cases or chests in which they are put, marked with the number of the piece of ordnance to which they belong, their natures and description. If there be any doubt of the different parts of the carriages, being made with that uniformity, so essentially necessary, every part which is separated, must bear the number of its carriage. This precaution at any rate may be a good one, if the same vessel contain different natures of ordnance or carriages.

The axletrees need not be taken off the carriages, if the vessel be of a sufficient size to admit them when fixed, as they are not easily replaced without workmen and a tedious operation. When a carriage is dismounted, all the small articles, such as elevating screws, linch pins, drag washers, cap squares, _&c._ must be carefully collected, and secured in a box, marked with the description of stores, and number of the carriage to which they belong. All carriages or waggons embarked with their axletrees fixed, must be arranged in the ship, side by side, and alternately front and rear, that their axletrees may not interfere with each other, and take too much room. Every transport or other vessel employed in carrying troops or stores for an expedition, should be numbered on the quarters and on the bows, with figures as large as 2 or 3 feet, and on the sails, that they may be known at a distance. The number of the ship, her name and tonnage, and the master’s name must be entered in the list of the stores which she carries.

In disembarking ordnance and stores, they must be landed exactly in order, the reverse of what they were shipped. The carriages and waggons must be mounted as soon as possible, and every nature must be arranged as far from the shore as possible to prevent confusion. If the disembarkation take place in the presence of an enemy, the vessels of course must be loaded accordingly; and the field ordnance, with their carriages, ammunition, _&c._ must be so arranged as to be first landed, and with the greatest ease possible. In this case, the entrenching tools must also be kept in the greatest readiness.—_Aide Memoire._

2. _Of Troops._—All transports taken into His Majesty’s service, are under the direction of the Transport Board, and of their agents at the different ports at home and abroad. No troops or other persons can be put on board them, or victualled, but by an order from this Board, or one of its agents. Troops embarked on board transports or ships of war (except as marines) are only allowed ⅔ of a seaman’s allowance of provisions. (See the word _Ration_.) It is therefore necessary to divide the men into messes of 6 each. Six women to 100 men embarked on foreign service, are allowed provisions; and 10 women to 100 men on home service. The births on board transports, are usually made 6 feet square, and each admits 4 men at a time; but agreeable to the regulations for the army for 1799, one third of the men are always to be on deck; therefore 6 men (or one mess) are told off to each birth, ⅓ of whom are always on watch. The commanding officer of the troops on board a transport, has a right to peruse the charter party of the ship, which points out every different article, as firing, candles, boats, utensils, _&c._ which the ship is engaged to find for the use of the troops on board. It likewise expresses the part of the ship allotted to the officers, to the master, the mate, and the agent, should there be one on board.

_EXERCISE of Artillery._—_With 9 men to a field gun._

When 15 men are attached for the service of a gun in the field, they are numbered from 1 to 15; but when the gun is not to be advanced by men, the first six numbers are left out, and the remaining nine men are numbered from 7 to 15. The exercise of field guns of a heavy nature varies but little from the light ones. Though different duties done by the men attached to the one, should, as nearly as possible, be kept up at the other; as thereby is prevented that confusion which must arise when men removed from a light gun to a heavy one, change their numbers, though their duties at each be the same. The following will be the position of 9 men, for field ordnance of all natures, in the

1. _Line of March._

Numbers 7, 9, 12, and 15, on the left of the gun; 8, 10, 13, 14, and 11, on the right; numbers 7 and 8 opposite the muzzle of the gun; 9 and 10 opposite the breech; 12 and 13 opposite the trail; 14 opposite the axletree of the limber; 11 opposite the shafts; 15 leads the limber horse; the driver leads the front.

2. _Position and Duties of 9 men when prepared for Action._

_Light Guns._—7 spunges, 8 loads, 9 serves the vent, 10 fires, 11 commands, 12 carries the match and water bucket, 13 serves 8 with ammunition from 14, who carries a cartouch and a pair of drag ropes; 15 holds the limber horse, and carries a cartouch.

_Positions._—7 between the right wheel and the muzzle; 8 between the left wheel and the muzzle; 9 clear of the rear of the right wheel; 10 clear of the left wheel, both in a line with the vent; 11 on the left of the handspike; 12 on his right, clear of 9; 13 covers the left wheel, 5 yards in the rear; 14 covers the right wheel, 10 yards in the rear. The limber is 25 yards directly in the rear of the gun.

_Heavy Guns._—This is the same as with the light guns, except that 7 and 8 stand outside the wheels, and 8 assists 7 to ram home, if necessary.

_Howitzers._—Positions are the same as the heavy guns, but the duties different. 7 spunges, uncaps the fuze, and puts in the shell; 8 takes the sheepskin out of the piece, lays it on the ground, with the woolen side up, loads with cartridge, wipes the bottom of the shell, (when 7 holds it up) puts in the sheep skin again, and pulls it out with his left hand on the word _Ready_: He stops the muzzle with it immediately that the piece is fired; 9 serves the vent; 10 fires; 11 commands; 12 carries the match and bucket; 13 serves 8 with cartridges from a cartouch; 14 serves 7 with shells from the limber, which he lays on the sheep skin; 15 attends the limber. As from unavoidable accidents the number of men attached to a gun, may be reduced, it will be necessary if the vacancies happen amongst those doing the most essential duties, to immediately replace them by those doing the most subordinate duties.

_The following method of distributing the duties amongst a smaller number of men, will be equally applicable to all natures of field ordnance._

+-------+-------+---------------------------+----------------------+ | Nᵒ. |Nature.| Numbers retained. | The vacancies, | |of men.| | | how supplied. | +-------+-------+---+---+---+---+---+---+---+---+---+--------------+ | 9 |Gun | 7 | 8 | 9 | 10| 11| 12| 13| 14| 15| complete. | | |Howr | 7 | 8 | 9 | 10| 11| 12| 13| 14| 15| | +-------+-------+---+---+---+---+---+---+---+---+---+--------------+ | |Gun | 7 | 8 | 9 | 10| 11| 13| 14| 15| Nᵒ. 12 being | | 8 | | | | | | | | | | dropt, Nᵒ. 11 | | |Howr | 7 | 8 | 9 | 10| 11| 13| 14| 15| does his duties. | +-------+-------+---+---+---+---+---+---+---+---+------------------+ | | | | | | | | | | Nᵒ. 14’s pouch is | | |Gun | 7 | 8 | 9 | 10| 11| 13| 15| laid on the ground; | | | | | | | | | | | 13 carries it when | | | | | | | | | | | moving. | | 7 +-------+---+---+---+---+---+---+---+----------------------+ | |Howr | 7 | 8 | 9 | 10| 11| 14| 15| Nᵒ. 8 serves himself | | | | | | | | | | | with cartridges | +-------+-------+---+---+---+---+---+---+---+----------------------+ | |Gun | 7 | 8 | 9 | 11| 13| 15| Nᵒ. 9 serves the vent | | 6 | | | | | | | | with his left hand, | | |Howr | 7 | 8 | 9 | 11| 14| 15| faces about and fires. | | | | | | | | | | Tube box on left side. | +-------+-------+---+---+---+---+---+---+--------------------------+ | |Gun | 7 | 8 | 11| 13| 15| Nᵒ. 11 does all the duties | | 5 | | | | | | | of 9, as in the last | | |Howr | 7 | 8 | 11| 14| 15| change, his own duties, | | | | | | | | | and those of 12. | +-------+-------+---+---+---+---+---+------------------------------+ | 4 |Gun | 7 | 8 | 11| 15| Nᵒ. 8 fetches his own ammunition;| | |Howr | 7 | 8 | 11| 15| 7 serves his own shells. | +-------+-------+---+---+---+---+----------------------------------+ | |Gun | 7 | 11| 15| Nᵒ. 7 serves and loads all the | | 3 | | | | | ammunition.—Nᵒ. 7 & 15 must | | |Howr | 7 | 11| 15| change duties occasionally. | +-------+-------+---+---+---+--------------------------------------+

3. _To Limber up._—_Light Guns and Howitzers._

The whole of the men face towards the gun; 11 unships his traversing handspike; the limber is brought up by 15, rather to the right of the gun, and then turned to the left about; 12 and 13 raise the trail, and place it on the limber, in which they are assisted by 7 and 8 bearing down on the muzzle, and 9 and 10 at the wheels; 11 chains the limber.

_Heavy Field Guns, or Howitzers._—The only difference from the above is, that 9 and 10 assist 12 and 13 to raise the trail, and 14 and 15 stand to the gun wheels.

4. _To unlimber._—_Light Guns and Howitzers._

The whole face towards the gun; 11 unchains the limber; 12 and 13 lift the trail off the pin tail, and set it on the ground, in which they are assisted, as in limbering up, by 7, 8, 9, and 10; 11 ships the traversing handspike, and the whole assume the position for action. The limber is led by 15, and the driver, 25 yards to the rear, and there turned to the left about. The leading horse is unhooked by the driver, and tied to the rear of the limber.

_Heavy Field Guns, and Howitzers._—The same as the light ones, except that 9 and 10 assist 12 and 13 to raise the trail, and 14 and 15 stand to the gun wheels. The heavy guns have generally mounted riders, in which case the leading horses are not unhooked.

It must be understood, that simply to _limber up_, or to _unlimber_, means that the gun is to be placed upon its limber, or lifted off, without changing its direction; but guns may be limbered up to the _front_, to the _right_, or to the _left_, according as it is intended to advance in any one of those directions; and unlimbered to the _rear_ to prepare for action to the _front_, to the _left_ for action to the _right_, and to the _right_ for action to the _left_. To limber up, or to unlimber, in any of these situations, is exactly the same as those already given, except that in the first, previous to limbering up, the trail is thrown round by No. 11, assisted by 12, if necessary, into the direction specified by the word of command, and the limber is brought up to that side to meet it; and in the second, the trail, after being taken off the limber, is carried round to the _rear_, _right_, or _left_, according as the word of command expresses, before it is put to the ground, and the limber goes round to the rear of the gun.

It must be here remarked, that the _front_ of a gun, or line of guns, or column of guns, is that to which the men at the gun front, without any respect to the situation of the gun or carriage. The trail of the carriage, when moved round to the rear or the contrary, whether in limbering up or unlimbering, must always be carried round to the _right_, and the limber, or a horse, when brought up to advance or retire a gun, must always be brought up on the _right_ side, and go off on the _left_; and whenever the limber is turned about, it must be to the _left_ about. By attending to these precautions the greatest confusion is avoided.

_Other Methods of advancing Guns._

5. The gun being in the position for action, _prepares to advance slow_; 7 and 8 step outwards, 3 yards; 9 and 10 place themselves in line with the axletree, leaving room for 12 and 13, (who each bring a drag rope from 14) to pass between them and the wheels; 12 and 15 as they pass give the chain ends of the drag ropes to 9 and 10, who hook them to the washers; 12 and 13 man the Front pins, 7 and 8 the center, and 9 and 10 the rear.

This is only practised with light guns.

_Prepare for Action._—7, 8, 9, and 10 quit their pins; 12 and 13 go to the rear; 9 and 10, as soon as 12 and 13 have passed them, unhook the drag ropes; 12 and 13 carry them to 14; 13 gets his ammunition.

6. _Prepare to advance with a Horse._

_Light Pieces._—7 gives his spunge to 9; 7 and 8 unhook the chain traces from the breast of the carriage, and lay them over the spokes of the wheels; the driver brings up a horse to the front, by the right; 7 and 8 unhook the horses traces from the back band, and hook them to the short gun traces, and then take post outside the wheels; 7 takes his spunge.

_Heavy Pieces._—This is done with two horses, one before the other; 7 and 8 hook the horse, the driver rides to the rear horse, and 9 and 10 hook the rear horse to the short gun traces.

_Prepare for Action._—The different numbers exactly undo what they have just done.

7. _Prepare to advance with a Limber._

The only difference between this, and advancing with a horse, is that the limber is brought up to the front; and 15 brings up a drag rope, the center of which he lays over the pin tail, and 7 and 8 hook the ends to the short drag chains of the carriage.

_Methods of retreating Guns._

8. _Prepare to retreat slow._—7 and 8 place themselves in a line, with the axletree of the carriage on each side; 9 and 10 in a line with the trail; 12 and 13 get each a drag rope from 14, and give the chain ends to 7 and 8, who hook them to the drag washers; 7 and 8 man the rear pins: 9 and 10 the center-pins; 12 and 13 the front; 10 carries the linstock; 15 turns the limber. This is only done with light pieces.

_Prepare for Action._—7 and 8 unhook; 9 and 10 quit their pins; 12 and 13 carry back the drag ropes to 14; 14 gets his ammunition; 15 turns the limber to the front; the whole resume their places in action.

9. _Prepare to retreat with a Horse._

_Light Pieces._—7, 8, 9, and 10 place themselves as in retreating slow; 13 gets a drag rope from 14, and gives it to 9 and 10, who lay the center of it across the top of the traversing handspike, and then under the trail hooks; 12 and 13 hook the traces of the horse brought up by the driver to the ends of the drag rope; 15 turns the limber.

_Heavy Guns._—This is done in the same manner, but with two horses; 9 and 10 hook on the rear horse, and 12 and 13 the leader.

_Prepare for Action._—The same numbers undo what they have just done.

10. _Prepare to retreat with a Limber._

The limber is brought up to the trail of the carriage; 12 and 13 bring up each a drag rope, and hook the chain ends to the limber; while 9 and 10 hook the other ends to the trail hooks.