GUNNERY. 



GUNNERY. 



666 



nary education to enable him to pass the rigid examination expected 

 of him. Not only is a regular course of instruction undergone on 

 board the " Excellent " gunnery training ship, at Portsmouth, but on 

 returning from foreign stations, and before .being permitted to enter 

 upon another ship, he is to present himself at the " Excellent," and be 

 made proficient in any improvements in gunnery which may have 

 been introduced during his absence. The discipline of a ship is much 

 dependent on his judgment, forbearance andj tact, and the con- 

 tentment of the crew is seriously influenced more or less by the 

 manner in which he conducts his duties, for he is the drill-master of 

 the ship (subject in .very large ships to the inspection of a gunnery- 

 lieutenant). Assisted by his one to four or five mates, he has to 

 instruct from 50 to 1000 men (according to the size of the ship), in- 

 cluding the junior officers, usually styled " young gentlemen," in the 

 great gun exercise, also with rifles, swords, pikes, and pistols ; has 

 charge of all the extensive and costly armaments and military stores, 

 such as guns, small arms, powder, shot, shells, rockets, &c. ; he is 

 responsible for the various batteries, and that their requisites are kept 

 at hand in convenient places, and in serviceable condition, ready for 

 action at a moment's notice. A gunner, moreover, has charge of the 

 magazine, and is required to be capable of working it in total darkness ; 

 and to be able to send up in the heat and excitement of action proper 

 charges for certain guns, &c. He must be ready at calculation, at taking 

 angles for ascertaining the distances of objects, and cutting his fuses 

 accordingly with the nicest accuracy. He must have a considerable 

 knowledge of practical geometry, to enable him to readily lay off lines 

 for concentrating his fire, tc. He must have correct notions of labora- 

 tory work in the manufacture of the various compounds for fuses, blue 

 lights, &c. He must keep particular accounts of his service expenditure 

 of stores, only receiving his pay when these are approved by his 

 commanding officers. In small vessels he keeps (with other warrant 

 officers) a lieutenant's watch on deck, and therefore must be a 

 thoroughly practical seaman, able to tack ship, rig and work a ship in 

 general, for which he must have passed a severe examination by naval 

 officers. He has constant charge of the main yard and main rigging 

 of his ship, and also the fitting of boats for armed service. His sea- 

 pay varies (according as he is a first, second, or third class gunner) from 

 1202. to 861. per annum. He is obliged to dress (in uniform) with 

 respectability and neatness for the sake of example. If married, the 

 impossibility of saving money from his pay, renders his position one of 

 some dissatisfaction in the service, and especially as the warrant officer 

 ii the only rank in the navy, from the admiral to the second class boy, 

 which does not receive the same pay in harbour service as at sea, 

 although his duties there are very often more harassing, and with more 

 risk from boating, &c. ; his harbour pay being, instead of 1201. reduced 

 to 101/., and 861. reduced to 631. per annum. He cannot leave the 

 service until entirely icorn out in it, without forfeiting all his servitude ; 

 and when pronounced by a medical survey to be unfit for further work, 

 he can expect only a retirement of about 451. per year upon the average ; 

 while if he die on service, not in action, nor suffering a violent death 

 on active duty, there was during thirty years no provision for his 

 widow. The widow's pension was withdrawn in 1830. The effect has, 

 however, operated injuriously to the naval service of the country, as 

 the emolument of gunners is considered to be so disproportionate to 

 their responsibilities, as to have kept many good men from seeking the 

 warrant. This is now happily under consideration ; already has the 

 Admiralty not only restored to warrant officers their rank as next to 

 second masters, of which they were deprived in 1844 ; but in February, 

 1860, the pension to the widows of warrant officers was very con- 

 siderately restored also. [BOATSWAIN.] The chief gunner's mate is 

 a chief petty officer, and all the mates pass examination in the 

 " Excellent." 



GUNNERY is that branch of the art of war which comprehends the 

 theory of military projectiles, and the manner of employing ordnance 

 in the attack and defence of fortresses or positions. 



Under the head of ARTILLERY will be found an account of the intro- 

 duction of gunpowder for the purpose of discharging ball from cannon, 

 and a description of the earlier forms in which they were made. Under 

 the head of ORDNANCE it described the present construction of cannon 

 and their weights and sizes. Representations of the forms of many 

 ancient pieces of ordnance may be seen in the ' Treatise on Artillery,' 

 by Diego Ufano, 1614, as well as in the ' Prattica Manuale di Artiglieria,' 

 by Luigi Colliado, 1606. Generally the ancient fire-arms were so con- 

 structed as to discharge masses of enormous weight ; and it is said, that 

 when Mohammed II. besieged Constantinople, he employed pieces whose 

 calibre (diameter of bore) was equal to 12 palms, and which projected 

 against the walls of the city stones weighing 1200 Ibs. At present a 

 rapid succession of discharges from a comparatively small kind of 

 ice is considered more efficacious, when directed against the 

 walls of a fortress, than the few shots which can be fired from such 

 unwieldy machines. The 13-inch shell which is now employed weighs, 

 when loaded, about 200 Ibs. ; but when the French besieged the citadel 

 of Antwerp in 1832, the Belgians brought up a mortar whose calibre 

 was 24 ( inches, and whose shell when loaded weighed 1015 Ibs. The 

 I >y it was not, however, so great as had been antici- 

 pated. 



Tartalea appears to have been the first mathematician who wrote on 

 the motion of balls when projected from fire-arms, and in his ' Quesiti 



et Inventione Diversi,' which was printed at Venice in 1546, he inves- 

 tigates a few particulars concerning that kind of motion ; but the low 

 state of the theory of such motions at that time may be imagined, 

 when we consider that he thought it necessary to disprove the opinion, 

 which then prevailed, that one part of the trajectory, or path, of a 

 cannon-ball was rectilinear. 



In 1638 Galileo published the ' Dialoghi delle Scienze Nuove,' in 

 which, together with his investigations concerning the composition of 

 motions in general, he shows that a shot projected from a gun describes 

 a parabolic curve. He states that the shot is urged by the impulsive 

 force of the powder in a rectilinear direction, coinciding with the axis 

 of the bore, and that it would move with a uniform velocity if it were 

 not continually deflected by the attraction of gravity from that direc- 

 tion ; he shows also that this deflecting force, exerted in lines perpen- 

 dicular to the horizon, would cause the shot to descend in such lines 

 with a variable velocity. Now, the spaces which would be described 

 in consequence of the projectile force, being proportional to the times 

 of describing them, and the spaces described in consequence of the 

 earth's attraction being proportional to the squares of the times, it 

 followed, from the relation between the spaces so described, that the 

 shot, which, according to the laws of the composition of motions, would 

 always be at the intersection of the lines representing the spaces, must 

 describe a curve with respect to which the corresponding lines would 

 have the same relation ; that is, a parabola. 



Galileo expressly says that this curve would be described by the 

 shot, if it were not resisted by the air ; he was aware of that resistance, 

 and he proposes a method of finding its effects. It is now well known 

 that the resistance of the air, when the motion of the projectile is rapid, 

 is such as to cause the latter to describe a curve-line very different 

 from a parabola ; and, consequently, that the parabolic theory, as it is 

 called, is of small importance as a guide to the practical artillerist ; 

 yet, as it possesses a certain interest on account of its connection with 

 the general subject of projectiles, and is a step to the investigation of 

 the real trajectory, we will proceed, before entering upon that investi- 

 gation, to give a demonstration of the fundamental proposition, and 

 exhibit a few of the principal deductions which are usually made 

 from it. 



The following investigation of the curve described by the centre of 

 gravity of a shot projected obliquely in a vacuum is extracted from 

 Captain Boxer's ' Treatise on Artillery :' 



Fig. 1. 



Let v = the initial velocity in the direction A o. 



a = the angle o A x made by the direction of projection with 



horizontal plane. 

 X and y = the horizontal and vertical co-ordinates at any point 



p in the curve, from the point of departure A as the origin. 

 ( = the time of flight to the point P. 

 f. X = the whole horizontal range. 

 L K = the greatest height of ascent. 

 T = the time of flight to the point X. 



Now, if no force were acting on the projectile it would, by the first 

 law of motion, move on for ever in the line A G with the velocity v. 

 This motion is, however, in fact modified by the action of two forces- 

 the resistance of the atmosphere and gravity ; and as it is proposed to 

 leave the former out of consideration for the present, it only remains 

 to compound the motion produced by gravity, which, by the second 

 law of motion, is the same as it would produce upon a body at rest, 

 with the uniform motion in the line A a, in order to obtain the actual 

 motion of the shot upon the hypothesis assumed. 



We have then &p = distance described with the velocity v in the 

 time = t = v t. 



x=AM = Ap cospA M = V< cos a, (1) 



M/> = A p sin p A M = v < sin a, 



p t = distance described from rest by the action of gravity during 



the time t=^yfl, 

 y =MP=MP jpr = V(sino 4jr< (2) 



