GUNPOWDER 



GUNPOWDER PLOT 



473 



evolution of gas locally causing a vilirutory motion 

 <>t' (begat). This led to tin- introduction of larger- 

 .-d powdeis. -<> a- ti retard llir burning ol (In- 

 -. (nit tlii- ilnl nut entirely tin away with tin- 

 |in--siire. It was next sought to diminish 

 tin- pressure l>y giving air space to the. charge, as 

 it \\as found that the density of the charge not 

 the den.-it\ Hi tlie grain -materially affected the 

 pressure; thi-aii space w.-us given hy enlarging the 

 diamlter of the gun, and although it lieeanie neces 

 sary to increase the charge so as to maintain the 

 same mu/zle velocity, it was found that the pres- 

 sure was sensibly diniinislieil. 



Hut whilst Great Britain was still adhering 

 to pebble jMiwder, other nations had adopted a 

 prismatic powder with a hole through the centre 

 of the pellets or prisms. The idea of this 

 perforated powder is due to General Rodman, an 

 American artillery otlieer, who thought that by 

 this means a charge of powder would evolve the 

 gas at a more uniform rate. In a charge composed 

 of solid grains, the grains being lighted on the sur- 

 face and burning towards the centre, the surface 

 giving off gas rapidly decreases, and therefore the 

 volume of gas given off by the grain will be 

 greatest when the charge is first hred, and will 

 rapidly fall olf ; hence the maximum pressure on 

 the liore of the gun is set up almost before the pro- 

 jectile commences to move. To overcome this, the 

 idea occurred to General Rodman to have a hole 

 through each large grain or pellet of powder, so as 

 to give the grain an interior as well as an exterior 

 lighting surface, so that as the exterior lighting 

 surface decreased the interior lighting surface in- 

 firn.~iC(l t thus preserving the ignited surface more 

 uniform during the burning of the pellet, and 

 therefore keeping up a more constant evolution of 

 gas. This tends to distribute the pressure more 

 uniformly along the bore of the gun, and increases 

 the initial velocity of the projectile. The Russians 

 in 1S60 were the first to adopt this plan, followed 

 by the Germans, the English being the last to 

 take it up ; it is now, however, adopted for the 

 heaviest guns in the English service, the charge 

 being buflt up of the hexagonal prisms already 

 described, so arranged that the holes through 

 each column of prisms shall be continuous from 

 one end of the charge to the other. The intro- 

 duction of this powder has enabled the type of 

 gun to be entirely altered ; a description or the 

 guns now in the service will be found under the 

 head of Cannon, Rifles (q.v.). We are indebted 

 to the Germans for the invention of brown or 

 cocoa powder ; it is claimed for this powder that 

 it gives a higher initial velocity with less pressure 

 than the same charge of black powder. 



The same principles as have been enunciated here 

 with regard to guns should govern the selection 

 of powder for mining or blasting purposes. If it 

 is desired to shatter a mass of rock, a very violent 

 quick- l)ii ruing jxiwder, having a great disruptive 

 force, should be used ; but if it is only desired to 

 dislodge, say, a mass of coal without shattering it, 

 a denser, slower-burning powder should be chosen. 



The instrument generally used for taking velo- 

 eities is a chronograph, the invention of Major De 

 Boulengd of the Belgian Artillery. It consists 

 of a brass column supporting two electro-mag- 

 nets. No. 1 electro-magnet supports a long cylin- 

 drical rod, called the chronometer, covered by 

 a zinc tube ; No. 2 electro-magnet supports a 

 shorter rod. Two screens of copper wire are 

 placed at certain fixed distances in front of the 

 mu/.zle of the gun. No. 1 electro-magnet is mag- 

 netised by the current passing through the first 

 screen, and No. 2 by the current passing through 

 the second screen. As the shot passes through the 

 first screen the current is broken, and the rod or 



chronometer -u-pi-nded by No. 1 electro- magnet 

 falls by gravity. Similarly, when the shot pMMft 

 through the second screen, the shorter weight HIU- 

 pi-nded by No. 2 electro-magnet falls on to a dbc, 

 which, pressing a spring, causes a knife to be re- 

 leased, and tlii-, darling forward, strike* the 

 chronometer in it- fall, making an indent in the 

 zinc i n 1 . The distance of t hi- indent from the zero 

 point lii-ing measured oil on a scale specially gradu- 

 ated for the instrument gives the velocity of the 

 shot between the two screens, from which can lie 

 calculated the muzzle velocity. Another scale gives 

 the time of flight. 



The pressures in the bore of the gun are calcu- 

 lated by means of a crusher gauge. A small 

 copper cylinder is inserted in the gauge, which is 

 screwed into the gun at that part where it may 

 be desired to measure the pressure. The copper 

 cylinder is measured before and after the discharge 

 of the gun, the amount by which it is shortened by 

 the force of the explosion being the measure of the 

 force, or pressure, exerted. The actual pressure 

 in tons to the square inch is calculated by means 

 of a mathematical table prepared for different 

 coppers. 



See Wardell, Gunpowder and Gun-cotton ( 1889 ) ; 

 Cundill, Dictionary of Explosives ( 1895 ) ; Eissler, Modern 

 Explosive* ( 1889 ) ; Guttmann, Manufacture of Explosives 

 (1895); Sanford, Nitro- Explosives (1896). For Smoke- 

 less Gunpowder, see GUN-COTTON, RIFLES ; and for laws 

 relating to gunpowder, see EXPLOSIVES. 



Gunpowder Plot. This plot was an attempt 

 on the part of a small number of Roman Catholic 

 gentlemen to destroy by gunpowder King James I. 

 and the Houses of Lonls and Commons on the day 

 of the opening of parliament, November 5, 1605. 

 The design originated in the busy brain of Robert 

 Catesby (q.v.), who had already suffered for the part 

 taken by him in Essex's plot. He and his fellow- 

 conspirators were driven to desperation by the 

 faithlessness of James, who before his accession had 

 led the Catholics to expect some measure of tolera- 

 tion, but soon afterwards put in full force the penal 

 laws against popery, and showed a disposition to 

 increase rather than to mitigate their rigour. Early 

 in 1604 Catesby communicated his plan to "John 

 Wright and Thonias Winter. Guy Fawkes (q.v.), 

 a brave soldier serving in the Spanish army, was 

 brought over from Flanders, and together with 

 Percy was admitted to the plot after taking an 

 oath of secrecy. All five then received communion 

 from the hands of the Jesuit Gerard, who, how- 

 ever, was not informed of the conspiracy. On 

 24th May Percy hired a room adjoining the 

 Parliament House which they intended to under- 

 mine. The adjournment of parliament from time 

 to time caused sundry postponements of the work. 

 In December the digging was begun. The diffi- 

 culties were greater than was expected, and it 

 became expedient to call in the assistance of fresh 

 associates John Grant, Robert Winter ( brother of 

 Thomas), and Bates, a servant of Catesby. In the 

 following March the conspirators were able to hire 

 a convenient cellar immediately below the House 

 of Lords. The mine was now abandoned, and the 

 cellar was stored with casks of powder, covered 

 with faggots. 



All was ready by May. Money was now wanted 

 to provide men, horses, and arms for the insur- 

 rection, which it was intended should break out in 

 the midland counties, where the chief conspirators 

 had congregated. So about Michaelmas some rich 

 Catholics, Sir Everard Digby, Ambrose Rpok- 

 wood, and Francis Tresham were induced to join. 

 Tresham lacked the courage and fanaticism of his 

 fellows. Wishing to save his friend Lord Mont- 

 eagle, he wrote to him on Saturday, October 26, a 

 mysterious letter, which was shown to Lord Salis- 



