470 



GUNNY-BAGS 



GUNPOWDER 



commentaries on Robins's work to the general 

 knowledge of the subject which existed up to the 

 end of the 18th century. In 1840 Professor Wheat- 

 stone invented an electric chronoscope for measuring 

 velocities, which was followed by those of Navez- 

 Leurs, Bashforth, Noble, and De Boulenge. In 

 1878-80 the Rev. F. Bashforth produced his chrono- 

 graph for measuring the resistance of the air to 

 the motion of elongated projectiles. By means of 

 his tables and the various instruments now placed 

 at their disposal, mathematicians are able to calcu- 

 late the proper length, thickness of metal, size of 

 chamber, charge, form of projectile and method 

 of rotating it for a gun of given calibre, and also 

 to determine the time of flight, penetration, height 

 and velocity at any point, and elevation required 

 for any range, &c. The latter are most necessary 

 in order that the gun may be skilfully handled, 

 and each weapon has its ' range table ' made out, 

 giving these particulars. 



The official Text-book of Gunnery (1887), by 

 Major Mackinlay, R.A., is one of the best modern 

 treatises on this subject, and has been largely 

 quoted in foreign works, notably in the External 

 Ballistics of Captain Ingalls, U.S. Artillery. 



In 1880 Major F. Siacci, of the Italian Artillery, 

 put forward a method of solving trajectories and 

 problems in ballistics, and his formulae have been 

 used by artillerists of all nations with very satis- 

 factory results. 



Without explaining the intricate calculations and 

 delicate instruments used, it may be interesting to 

 give a few examples of gunnery problems. A shot 

 was fired at Shoeburyness in 1887, and called the 

 Jubilee shot, from a 9 '2-inch wire-gun at an angle 

 of 40 elevation, by which it was thought an 

 extreme range would be obtained. The calculated 

 range was 20, 765 '3 yards (say 12 miles) ; maximum 

 height, 17,110-6 feet ; time of flight, 63'787 seconds ; 

 angle of descent, 53 50'. The actual range was 

 20,236 yards. 



The necessary elevation for a 12-inch 45-ton gun, 

 firing with a charge of 295 Ib. and a muzzle velocity 

 of 1910 feet per second at a point 3000 yards distant 

 and 1270 feet above it, is found to be 2 25'. An 

 8-inch howitzer of 70 cwt. is to breach the escarp of 

 a ditch 50 feet wide, with common shell and delay- 

 action fuze the angle of descent must be 14 and 

 the striking velocity not less than 600 feet per 

 second ; required the least necessary distance of the 

 howitzer from the escarp, the requisite charge of 

 powder, and angle of elevation. Answer, 1936 

 yards, 6 Ib. R.L.G. 2 powder, and 13 23'. 



In designing a rifle of which the velocity is to be 

 800 feet per second at 1000 yards, and trajectory in 

 no place higher than 32 feet, it is necessary to know 

 the proportions of weight of bullet to calibre, which 

 are found by Siacci's formulse to be 358 grains for 

 a calibre of '38 inch, or 254 grains for '32-inch 

 calibre. 



From these and similar examples it will be under- 

 stood that gunnery has become one of the exact 

 sciences. The excellence of modern machinery 

 enables the manufacture of weapon, projectile, 

 powder, and fuze to satisfy the demands of the theo- 

 rists, while such inventions as Watkin's position 

 and range finders and Scott's telescopic sights put 

 it in the power of the trained artilleryman to show 

 equally good results in practice. See BREECH- 

 LOADING, CANNON, RIFLES ; for the School of 

 Gunnery at Shoeburyness, see ARTILLERY. 



Gunny-bagS are made of a coarse jute fabric 

 (see JUTE), and are very largely exported from 

 India to various parts of the world. American 

 cotton is largely packed in these. They can be 

 manufactured at a low price, hence the great 

 demand for them. The name gunny is applied 

 to the cloth as well as to the made-up bags. About 



1850 the peasant hand-looms of Lower Bengal met 

 both the nome and the foreign demand for Indian- 

 made gunny-bags indeed the making of these 

 was then the great domestic industry of that portion 

 of India, giving occupation to men, women, and 

 children of nearly every class. Even boatmen and 

 domestic servants employed their spare moments 

 at them. At the present time the number made at 

 the great steam-factories, of which there are now 

 twenty-three in India, far exceeds what is pro- 

 duced by hand -looms. For example, in the year 

 1885, 82,779,207 gunny-bags were exported from 

 India, of which only five millions were woven by 

 hand. In the same year forty millions of these 

 bags were sent from Bengal to other parts of India, 

 and it was estimated that nearly as many were 

 used in Bengal itself. The total value of the 

 Bengal trade in jute manufactures (mainly gunny- 

 bags or cloth) in 1885 was believed to be not far 

 short of 3,000,000. In India gunny-bags are em- 

 ployed for agricultural and internal trade purposes, 

 but many are also sent out of the country filled 

 with grain and other produce. Cloth and bags of 

 the same kind are made in Dundee. 



Gunpowder is a well-known explosive mixture 

 composed of saltpetre, charcoal, and sulphur mixed 

 together in certain proportions, somewhat varying 

 in different countries and in different descriptions 

 of powder. 



The early history of gunpowder is very obscure ; 

 but there appears to be little doubt that the ex- 

 plosive nature of saltpetre (the great bulk of which 

 comes either from India or China) when mixed with 

 charcoal or carbon was known to the Chinese for 

 many centuries before the Christian era. It may 

 be assumed that the discovery of this property of 

 saltpetre was accidental : a wood-fire lighted on the 

 earth where saltpetre was mixed with the soil 

 would bring the two ingredients together, and the 

 action of the heat would be sufficient to show the 

 nature or property of the mixture so brought about 

 when raised to a certain temperature. It is certain 

 that fireworks were known in China from very' early 

 periods ; but in a pamphlet written by Colonel 

 Omodei (Turin, 1834), and later in an article in the 

 Athenaeum of December 26, 1868, by Captain (now 

 Lieut. -General ) Henry Brackenbury, R.A., the 

 question as to the first invention of gunpowder was 

 fully discussed, and the conclusion arrived at was. 

 that there is great reason to doubt whether either 

 the Chinese or any other Asiatic people invented 

 gunpowder in its true sense, or were the first to 

 use it as a propelling agent. It was left for more 

 western nations to develop the discovery of the 

 Chinese, and our first knowledge of the use of gun- 

 powder as a military agent dates from the 7th 

 century, when it was used by the Byzantine em- 

 perors, under the name of Greek Fire (q.v.), in the 

 defence of Constantinople against the Saracens, 

 who, discovering the secret of its manufacture, used 

 it against the Crusaders, not however as a propelling 

 agent, but in the form of rockets or liquid fire. Its 

 first use in Europe as a propelling agent was in 

 Spain, where both the Moors and Christians used 

 some description of artillery as early as the 12th 

 century. Roger Bacon first introduced it into Eng- 

 land. Whether he discovered it independently 

 of foreign aid, or whether he conceived the idea 

 from ancient manuscripts, is uncertain; but the 

 latter is the more probable, as the name first given 

 to it was crake, presumably a corruption of the 

 word grec. Bacon's discovery dates from a period 

 early in the 13th century, but, owing to the crude 

 and uncertain means adopted for mixing the 

 ingredients, it was of no practical value till the 

 German monk, Berthold Schwarz, introduced, 

 somewhere about the year 1320, a method of manu- 

 facture by which the ingredients were thoroughly 



