Part 57
GUIGNEAU, _Fr._ This word means the same thing as _chevétre_. It is a piece of wood which joins the joists of a floor, that are cut to make room for the hearth of a chimney-piece.
GUILLAUME, _Fr._ a tool somewhat like a plane which is used by carpenters, and of which there are several sorts according to the nature of the work.
GUINDAS, _Fr._ All machines which by means of a wheel and its axis serve to raise heavy loads, are so called by the French.
GUINDER, _Fr._ to draw up any weight. Hence the term _guindage_, which is applied to the movement of loads that are raised and let down.
GUISARMIERS, _Fr._ a body of free archers, or bowmen, who took their name from an offensive weapon called _guisarme_, or _jusarme_, somewhat similar to the _voulgue_, a sort of javelin, which was used in hunting the wild boar. Its length was equal to that of the halbert, and it had a broad piece of sharp iron fixed to one end.
GULLY. Any hollow which has been made by running water. Ambuscades are frequently laid in such places.
GUN, a fire-arm, or weapon of offence, which forcibly discharges a bullet through a cylindrical barrel by means of gunpowder. The term is chiefly applied to cannon.
Somnerus derives gun from _mangon_, a warlike machine, which was used before the invention of guns. He establishes his derivation by taking away the first syllable.
_Curricle_ GUNS are small pieces of ordnance, mounted upon carriages of two wheels, and drawn by two horses. The artillery-man is seated on a box, and the whole can be moved forward into action with astonishing rapidity. The tumbrils belonging to curricle guns carry 60 rounds of ball cartridges. Great improvements are daily making in this machine on account of its acknowleged utility.
_Great_ GUN. See CANNON.
_Evening_ GUN, _Morning_ GUN is generally a 6 or 12-pounder, which is fired every night about sun-set, and every morning at sun-rise, to give notice to the drums and trumpets of the army, to beat and sound the retreat and the reveille.
Morning and evening, and other signal guns, by the United States regulations, are not to be fired from larger calibres than 6 or 12 pounders; which calibres are seldom mounted on permanent works.
GUN-_fire_. The time at which the morning or evening gun is fired.
GUN-_boat_, a boat which is generally used to form a kind of floating battery, to cover the landing of troops.
GUNNEL, _or_ GUNWALE, the lower part of any port where ordnance is planted. It likewise means that beam in a pontoon which supports the main waste.
GUNNER, in the artillery, is the title of the first and second artillerist at a gun in battery; all the rest are called aids.
GUNNERY, the art of determining the motions of bodies shot from cannon, mortars, howitzers, &c. See the article PROJECTILE.
The late ingenious Mr. Robins, having concluded from experiments, that the force of fired gunpowder, at the instant of its explosion, is the same with that of an elastic fluid of a thousand times the density of common air, and that the elasticity of this fluid, like that of the air, is proportional to its density, proposes the following problem.
The dimensions of any piece of artillery, the weight of its ball, and the quantity of its charge being given; to determine the velocity which the shot will acquire from the explosion, supposing the elasticity or force of the powder at the first instant of its firing to be given.
In the solution of this important problem, he assumes the two following principles: 1. That the action of the powder on the shot ceases as soon as it is got out of the piece. 2. That all the powder of the charge is fired, and converted into an elastic fluid, before the shot is sensibly moved from its place.
These assumptions, and the conclusions above mentioned, make the action of fired gunpowder to be entirely similar to that of air condensed a thousand times; and from thence it will not be difficult to determine the velocity of the shot arising from the explosion: for the force of the fired powder diminishing in proportion to its expansion, and ceasing when it is got out of the piece; the total action of the powder may be represented by the area of a curve, the base of which represents the space through which the ball is accelerated, while the ordinates represent the force of the powder at every point of that space; and these ordinates being in reciprocal proportion to their distance from the breech of the gun, because when the spaces occupied by the fired powder are as 1, 2, 3, 4, &c. the ordinates representing it will be as 1, 1-half, ¹⁄₃d, ¹⁄₄th, &c. It appears that the curve will be a common parabola, and that the area intercepted between is an asymptote; and that the two ordinates representing the force of the powder at the first explosion, and at the muzzle of the piece, will represent the total action of the powder on the shot; but if the shot were urged through the same space by an uniform force equal to its gravity, the total action of this force would be represented by a rectangle, the base of which would be the base of the curve or intercepted portion of the asymptote above mentioned, and the height of which would represent the uniform force of gravity. Hence the square of the velocity of the shot resulting from gravity is given, being the velocity it would acquire from a height equal to the space through which the powder accelerates it; and the proportion between the hyperbola and the rectangle is given from the analogy between the hyperbolic paces and logarithms; therefore the velocity of the ball arising from the action of the fired gunpowder will be given.
Mr. Robins has also given us an ingenious way of determining, by experiments, the velocity with which any shot moves at any distance of the piece it is discharged from.
This may be effected by means of a pendulum made of iron, having a broad part at bottom, covered with a thick piece of wood, which is fastened to the iron by screws; then having a machine like a common artillery-gin, on two of its poles, towards their tops, are screwed sockets, on which the pendulum is hung by means of a cross piece, which becomes its axis of suspension, and on which it should vibrate with great freedom. Somewhat lower than the bottom of the pendulum there should be a brace, joining to which the pendulum is suspended; and to this brace there is fastened a contrivance made with two edges of steel, something in the manner of a drawing-pen; the strength with which these edges press on each other, being diminished or increased at pleasure by means of a screw. To the bottom of the pendulum should be fastened a narrow riband, which, passing between the steel edges, may hang closely down by means of an opening cut in the lower piece of steel.
The instrument being thus fitted, if the weight of the pendulum, the respective distances of its centre of gravity, and of its centre of oscillation from the axis of suspension, be known, it may from thence be found what motion will be communicated to this pendulum by the percussion of a body of a known weight, moving with a known degree of velocity, and sinking it into a given point; that is, if the pendulum be supposed to rest before the percussion, it will be known what vibration it should make in consequence of such a blow; and if the pendulum, being at rest, is struck by a body of a known weight, and the vibration which the pendulum makes after the stroke is known, the velocity of the striking body may from thence be determined.
Now the extent of the vibration made by the pendulum may be increased by the riband: for if the pressure of the steel edges on the riband be regulated by the screw, so as to be free and easy, though with some minute resistance to hinder it from slipping itself; then setting the pendulum at rest, let the part of the riband between the pendulum and the steel edges be down straight, but not strained, and fixing a pin in the part of the riband contiguous to the edges, the pendulum, swinging back by means of the impulse of the ball, will draw out the riband to the just extent of its vibration, which will be determined by the interval on the riband between the edges and the space of the pin.
The computation by which the velocity of the shot is determined from the vibration of the pendulum, after the stroke, is founded on the principle of mechanics; that if a body in motion strikes another at rest, and they are not separated after the stroke, but move on with one common motion, then that common motion is equal to the motion with which the first body moved before the stroke; whence, if that common motion and the masses of the two bodies are known, the motion of the first body before the stroke is thence determined. On this principle it follows, that the velocity of a shot may be diminished in any given ratio, by its being made to impinge on a body of weight properly proportioned to it.
It is to be observed, that the length to which the riband is drawn, is always near the chord of the arc described by the ascent; it being so placed, as to differ insensibly from those chords which must frequently occur: and these chords are known to be in the proportion of the velocities of the pendulum acquired from the stroke. Hence it follows, that the proportion between the lengths of the riband, drawn out at different times, will be the same with that of the velocities of the impinging shots.
Now from the computations delivered by Mr. Robins, it appears, that the velocity of the bullet was 1641 feet in one second of time, when the chord of the arc described by the ascent of the pendulum, in consequence of the blow, was 17¹⁄₄ inches, the proportion of the velocity with which the bullets impinge, to the known velocity of 1641 feet in one second, will be determined.
Mr. Robins was (till of late) the only author who attempted to ascertain the velocity of a military projectile by experiment; yet his conclusions seem to be unsatisfactory. Perhaps he was too much attached to the forming of a system, and warped his experiments a little in favor of it. The resisting power he assigns to the air is probably too great; and his notion of the tripling of this power when the velocity of the projectile exceeds that of sound, seems to be rather an ingenious theory than a well-grounded fact. However, experiment alone must decide these points.
The great importance of the art of gunnery is the reason that we distinguish it from the doctrine of projectiles in general; for in truth it is no more than an application of those laws which all bodies observe when cast into the air, to such as are put in motion by the explosion of guns or other engines of that sort: and it matters not whether we talk of projectiles in general, or of such only as belong to gunnery; for, from the moment the force is impressed, all distinction, with regard to the power which put the body first in motion is lost, and it can only be considered as a simple projectile.
Every body cast into the air moves under the influence of two distinct forces. By the one it is carried forward with an equal motion, and describes equal spaces in equal times, in the direction in which it was projected; and by the other, which we call gravity, is drawn downwards in lines perpendicular to the surface of the earth, with a motion continually accelerated, or whose velocity is always increasing. If either of these forces were destroyed, the body would move according to the direction of the other alone, so far as its motion was not hindered by the interposition of other bodies; but as both continue to act, the course of the projectile must be determined by a power compounded of those two forces.
GUNNERY is also the province of the artillerist, and comprehends, in an active sense, the perfect knowlege of the power of the machine, and the proportions of powder to be employed in order to produce any required effect. It also comprehends a knowlege of the properties and composition of gunpowder, and the various kinds of shot, which are employed in the practice of gunnery; the metal best adapted to make guns, the proper weight and corresponding proportions between the calibre of the gun and the shot fired from it, and also the dimensions fitted for the various services in which gunnery is employed: for batteries of permanent works, for ships, for field service, and the light or flying artillery. Gunnery indeed comprehends all the duties of the able artillerist and bombardier.
GUNNERY. By the assistance of good tables of practice, and the tables of amplitudes, sines, tangents, and secants, all the cases in gunnery in a nonresisting medium may be easily solved; and perhaps the solution may be sufficiently correct for practice, if the initial velocity of the projectile be not so great as to make the air’s resistance considerable.
For the tables of ranges with ordnance, see the different natures, as _Gun_, _Mortar_, &c. and for the tables of amplitudes, sines, tangents, and secants, see pages 247 and 248.
_Upon Horizontal Planes._
1. The greatest range is at 45° nearly.
2. The ranges with different elevations with the same charge, are as the double sines of the angles of elevation.
3. Any angle and its complement give the same range nearly.
4. The times of flight are as the sines of the angles of elevation.
5. The altitude of the curve, at any elevation is found by this proportion: as Radius : tangent of angle of elevation ∷
range ----- : altitude. 4
6. The time of flight at 45° is equal the square root of the range in feet, divided by 4, or more nearly = √(quotient²) of the range in feet, divided by 16.1, or the space passed through in the first second by gravity.
Having the first graze with a given elevation and charge, to determine the charge for any other first graze and elevation, multiply the known charge and elevation into the proposed first graze; also the proposed elevation into the known first graze, and divide the first product by the last, for the charge required.
_Upon inclined Planes, at 45° Elevation. Case 1st. Given the charge and inclination of the plane, to find the range._
Multiply the horizontal range with this given charge, (found in the tables of ranges) by the number found opposite the angle of inclination of the plane, in the first column of multiplyers, in the table of amplitudes, under the head _Ascents_, if it be inclined above the horizon; and _Descents_, if below the horizon, for the range required.
_Case 2d. Given the range and inclination of the plane, to find the charge._
Multiply the number found in the above mentioned table opposite the angle or inclination of the plane, in the second column of multipliers, under the head _Ascents_, or _Descents_, according as it is above or below the horizon, by the given range; for the range on a horizontal plane at 45°, the charge for which may be found from the tables of ranges.
_Upon inclined planes, at any elevation._
There are always two elevations with which any range, (less than the greatest) may be made; and these elevations are always the complements of each other. The greatest range upon a horizontal plane is at 45°; or when the direction bisects the angle formed by the horizontal and vertical plane; also the greatest change upon any plane is made with that direction which bisects the angle between the plane and the zenith; and all other directions which make equal angles with this direction, (on each side of it) will also make equal ranges on the said plane; for the direction that bisects the angle between any plane and the zenith is the same with respect to that plane as the direction at 45° is with respect to the plane of the horizon.
_Rules._--1st. The elevation which gives the greatest range on a given ascent is equal to half the sum of 90° added to the ascent.
2d. The elevation which gives equal ranges on a given ascent, are the complements of each other added to the ascent.
3d. The elevation which gives the greatest range on a descent, is equal to half the complement of the descent.
If the range and inclination be given, the least charge that will reach the object, may be found as follows: multiply the tangent of the proper elevation into the proposed range, for the horizontal range whose charge is required.
_Table of Amplitudes._
+--------+----------------++----------------+ |Degrees.| Ascents. || Descents. | | | Multip’rs. || Multip’rs. | +--------+--------+-------++--------+-------+ | |1st. cl.|2d. cl.||1st. cl.|2d. cl.| | 1 | .983 | 1.02 || 1.02 | .983 | | 2 | .966 | 1.03 || 1.04 | .966 | | 3 | .949 | 1.06 || 1.05 | .950 | | 4 | .932 | 1.07 || 1.07 | .932 | | 5 | .916 | 1.09 || 1.09 | .916 | | 6 | .900 | 1.11 || 1.11 | .900 | | 7 | .884 | 1.13 || 1.13 | .884 | | 8 | .868 | 1.15 || 1.15 | .868 | | 9 | .852 | 1.18 || 1.17 | .853 | | 10 | .836 | 1.20 || 1.19 | .836 | | 11 | .821 | 1.22 || 1.22 | .821 | | 12 | .805 | 1.24 || 1.24 | .805 | | 13 | .789 | 1.27 || 1.27 | .789 | | 14 | .774 | 1.29 || 1.29 | .774 | | 15 | .758 | 1.32 || 1.31 | .763 | | 16 | .742 | 1.35 || 1.34 | .745 | | 17 | .726 | 1.38 || 1.37 | .730 | | 18 | .711 | 1.40 || 1.39 | .720 | | 19 | .693 | 1.45 || 1.42 | .704 | | 20 | .677 | 1.48 || 1.45 | .690 | | 21 | .660 | 1.52 || 1.48 | .675 | | 22 | .643 | 1.56 || 1.52 | .662 | | 23 | .625 | 1.60 || 1.55 | .645 | | 24 | .607 | 1.64 || 1.58 | .633 | | 25 | .589 | 1.70 || 1.62 | .617 | | 26 | .570 | 1.76 || 1.66 | .603 | | 27 | .550 | 1.82 || 1.69 | .592 | | 28 | .530 | 1.86 || 1.73 | .578 | | 29 | .510 | 1.96 || 1.78 | .562 | | 30 | .488 | 2.05 || 1.82 | .549 | | 31 | .466 | 2.14 || 1.87 | .534 | | 32 | .442 | 2.26 || 1.92 | .526 | | 33 | .418 | 2.41 || 1.97 | .508 | | 34 | .393 | 2.55 || 2.02 | .495 | | 35 | .366 | 2.73 || 2.08 | .488 | | 36 | .338 | 2.96 || 2.13 | .470 | | 37 | .309 | 3.24 || 2.20 | .455 | | 38 | .278 | 3.60 || 2.26 | .443 | | 39 | .245 | 4.09 || 2.33 | .430 | | 40 | .210 | 4.80 || 2.40 | .417 | | 41 | .173 | 5.78 || 2.48 | .404 | | 42 | .134 | 7.46 || 2.56 | .390 | | 43 | .092 | 10.90 || 2.64 | .380 | | 44 | .045 | 22.22 || 2.73 | .370 | | 45 | .000 | infi- || 2.88 | .360 | | | | nite. || | | +--------+--------+-------++--------+-------+
_Table of Natural Sines, Tangents, and Secants._
+------+---------+-------- Degrees.|Sines.|Tangents.|Secants. --------+------+---------+-------- 1 | .018 | .018 | 1.000 2 | .035 | .035 | 1.000 3 | .052 | .052 | 1.001 4 | .070 | .070 | 1.002 5 | .087 | .087 | 1.004 6 | .105 | .105 | 1.006 7 | .122 | .123 | 1.008 8 | .139 | .141 | 1.010 9 | .156 | .158 | 1.012 10 | .174 | .176 | 1.015 11 | .191 | .194 | 1.019 12 | .208 | .213 | 1.022 13 | .225 | .231 | 1.026 14 | .242 | .249 | 1.031 15 | .259 | .268 | 1.035 16 | .276 | .287 | 1.040 17 | .292 | .306 | 1.046 18 | .309 | .325 | 1.051 19 | .326 | .344 | 1.058 20 | .342 | .364 | 1.064 21 | .358 | .384 | 1.071 22 | .375 | .404 | 1.079 23 | .391 | .424 | 1.086 24 | .407 | .445 | 1.095 25 | .423 | .466 | 1.103 26 | .438 | .488 | 1.112 27 | .454 | .510 | 1.122 28 | .469 | .532 | 1.133 29 | .485 | .554 | 1.143 30 | .500 | .577 | 1.155 31 | .515 | .601 | 1.167 32 | .530 | .625 | 1.179 33 | .545 | .649 | 1.192 34 | .559 | .675 | 1.206 35 | .574 | .700 | 1.221 36 | .588 | .727 | 1.236 37 | .602 | .754 | 1.252 38 | .616 | .781 | 1.269 39 | .629 | .810 | 1.287 40 | .643 | .839 | 1.305 41 | .656 | .869 | 1.325 42 | .669 | .900 | 1.346 43 | .682 | .933 | 1.367 44 | .695 | .966 | 1.390 45 | .707 | 1.000 | 1.414 46 | .719 | 1.036 | 1.440 47 | .731 | 1.072 | 1.466 48 | .743 | 1.111 | 1.494 49 | .755 | 1.150 | 1.524 50 | .766 | 1.192 | 1.556 51 | .777 | 1.235 | 1.589 52 | .788 | 1.280 | 1.624 53 | .799 | 1.327 | 1.662 54 | .809 | 1.376 | 1.701 55 | .819 | 1.428 | 1.743 56 | .829 | 1.483 | 1.788 57 | .839 | 1.540 | 1.836 58 | .848 | 1.600 | 1.887 59 | .857 | 1.664 | 1.942 60 | .866 | 1.732 | 2.000 61 | .875 | 1.80 | 2.063 62 | .883 | 1.881 | 2.130 63 | .891 | 1.963 | 2.203 64 | .899 | 2.050 | 2.281 65 | .906 | 2.145 | 2.366 66 | .914 | 2.246 | 2.459 67 | .921 | 2.356 | 2.559 68 | .927 | 2.475 | 2.669 69 | .934 | 2.605 | 2.790 70 | .940 | 2.747 | 2.924 71 | .946 | 2.904 | 3.072 72 | .951 | 3.078 | 3.236 73 | .956 | 3.271 | 3.420 74 | .961 | 3.487 | 3.628 75 | .966 | 3.732 | 3.864 76 | .970 | 4.011 | 4.134 77 | .974 | 4.331 | 4.445 78 | .978 | 4.705 | 4.810 79 | .982 | 5.145 | 5.241 80 | .985 | 5.671 | 5.759 81 | .988 | 6.314 | 6.392 82 | .990 | 7.115 | 7.185 83 | .993 | 8.144 | 8.206 84 | .995 | 9.514 | 9.567 85 | .996 | 11.430 |11.474 86 | .998 | 14.301 |14.336 87 | .999 | 19.081 |19.107 88 | .999 | 28.636 |28.654 89 | .999 | 57.290 |57.299 90 |1.000 |infinite.| ---- --------+------+---------+-------
GUNS.--_Calibres of European Guns, expressed in inches._
+---------+---------+---------+---------+---------+---------+ | English.| French. | Spanish.| Dutch. | Russian.| Portug. | +---+-----+---+-----+---+-----+---+-----+---+-----+---+-----+ |pr.|inch.|pr.|inch.|pr.|inch.|pr.|inch.|pr.|inch.|pr.|inch.| | 42|7.018| --| -- | --| -- | --| -- | 36| 6.86| 48| 7.49| | 32|6.41 | 36|6.9 | 36| 6.84| 32| 6.4 | 30| 6.47| 36| 6.8 | | 24|5.823| 24|6.03 | 24| 6.03| 24| 5.92| 24| 6. | 24| 5.93| | 18|5.292| 16|5.26 | 18| 5.52| 18| 5.45| 18| 5.45| 18| 5.4 | | 12|4.623| 12|4.78 | 12| 4.8 | 12| 4.76| 12| 4.76| 12| 4.7 | | 9|4.200| 8|4.18 | 9| 4.2 | 8| 4.13| 8| 4.17| 9| 4.3 | | 6|3.668| --| -- | --| -- | 6| 3.78| 6| 3.78| 6| 3.75| | 4|3.204| 4|3.315| --| -- | --| -- | --| -- | --| -- | | 3|3.913| --| -- | --| -- | --| -- | --| -- | --| -- | | 1|2.019| --| -- | --| -- | --| -- | --| -- | --| -- | +---+-----+---+-----+---+-----+---+-----+---+-----+---+-----+
_Length and weight of English Brass guns._