PYROTECHNY 



PYRRHO 



509 



Sometimes they contain iron filings. Many com- 

 positions are, however, used for stars, their various 

 colours alone necessitating this. Sparks, or small 

 stars, are also made of different colours. Maroons 

 are small boxes, round or square, bound with a 

 cord, and containing a composition which explodes 

 with a loud report. Benijal lights consist of com- 

 positions varying according to colour, which are 

 burned in small saucers : for example, a red light 

 can be produced by a mixture of chlorate of potash, 

 nitrate of strontia, sulphur, and lampblack ; and 

 a green by chlorate of potash, nitrate of baryta, 

 chloride of lead, sulphur, and resin. Theatre- 

 fires are produced by slow-burning compositions 

 containing some colouring ingredient. They are 

 burned without cases on a fireproof slab ; and all 

 substances obnoxious when burned indoors, such 

 as sulphur, antimony, and arsenic, or their com- 

 pounds, should be omitted in preparing them. 

 Magnesium powder and the minute spores of 

 one or more species of lycopodium are used to 

 imitate lightning in theatres. 



The most complicated kind of fireworks are some 

 of the rotating wheels. These are called wheels 

 because they have a framework of nave and spokes, 

 round the rim of which cases of the nature of 

 rockets are arranged. They revolve on a pin or 

 metal spindle, and the motion is produced, as will 

 be presently explained, by the recoil as the fire 

 escapes from the cases, which are connected with 

 each other by leaders. There are a numlier of 

 different forms, but they may be classed under 

 three kinds vertical, horizontal, and spiral wheels. 

 In the case of the last, a rod ( nave ) rises vertically 

 from the centre of the horizontal wheel, forming 

 the base, and upon this rod cases are arranged so 

 as to form a spiral. Pin or Catherine wheels and 

 pastilles consist each of a long paper case coiled 

 round a rod in the form of a flat spiral, the case 

 being, of course, filled with a burning composition. 

 Suns are either fixed or revolving. Fixed suns 

 are of various designs, but a common kind has a 

 numlier of cases radiating from a centre, from 

 which jets of fire proceed outwards. By a suitable 

 arrangement the lire is communicated at the same 

 time to the mouths of each of the cases. Rei-nlrim/ 

 tuns are somewhat similar to fire-wheels with 

 spokes. Of ascending fireworks the rocket is the 

 most familiar, and it has lieen known from an 

 early period. It consists of two parts viz. a long 

 stick to guide it in its course, and a head. The 

 latter, of strong paper and cylindrical in shape, 

 has its lower portion formed into a hollow cone, 

 base downwards, and round this cone is the burn- 

 ing composition. The object of the cavity is to 

 effect a rapid combustion, which fills it with heated 

 gases, and these, issuing downwards through a 

 small hole in the base, force the rocket up through 

 the air. The upper portion of the head is separ- 

 ated from the lower by a perforated plug of plaster 

 of Paris, through which a fuse passes, so that when 

 the lower portion is burned, the upper, which has 

 a conical head, takes fire and sets off its garniture 

 of stars, snakes, and other ornaments. When fire- 

 arms HIV discharged there is a recoil, in the case of 

 a heavy gun, of a short distance ; in the case of a 

 light cannon, with a larger charge in pro|K>rtion to 

 its weight, of a much greater distance ; ami in tin- 

 case of a rocket which lias a bulky charge in a very 

 light barrel the recoil is great enough to send it 

 high in the air. The motion of a fire-wheel is ex- 

 plained in the same way, there being a recoil paused 

 by the backward pressure of the heated gases on 

 the atmosphere as each case on the ring of the 

 wheel takes fire. The tonrbillion ascends and 

 rotates at the same time. Upward motion is given 

 by the tin- escaping from holes on the under side 

 of the cylinder, and rotatory motion by its finding 



vent from holes at the ends, but on opposite 

 sides. 



Aquatic fireworks, in which the devices which 

 come in contact with the water require to be pro- 

 tected with grease or oil, consist of skimmers or 

 water-devils, floating Chinese trees, gerbs, and 

 Roman candles, water-mines, water fire-fountains, 

 &c. Among recent novelties in pyroteclmy are 

 firework-pictures of battles, reviews, and other 

 scenes. Of these perhaps the most popular is the 

 enlargement, in lines of fire, of the portrait of an 

 eminent person in whose honour some public 

 gathering has taken place. The displays of fire- 

 works on some occasions of national rejoicings in 

 Great Britain have cost sums approaching or ex- 

 ceeding 30,000. The greatest displays of com- 

 paratively recent date have taken place during the 

 visits of foreign sovereigns to the country. See 

 also LIFE-SAVING APPARATUS, ROCKET, SIGNALS ; 

 and T. Kentish, The Pyrotechnist's Treasury : Art 

 of making Fireworks (2<l ed. 1887). 



Pyroxenes, a group of minerals, comprising 

 both monoclinic and rhombic forms. The mono- 

 clinic pyroxenes are silicates of lime, magnesia, 

 anil iron alumina being absent or sparingly 

 present in some, while others contain a larger 

 percentage. The more important monoclinic forms 

 are Augite (q.v.) and Diallage (q.v.), both being 

 constituents of igneous rocks. The rhombic 

 pyroxenes are silicates of iron and magnesia. 

 There are three: Enstatite (q.v.), which contains 

 less than 5 per cent, of ferrous oxide ; Bronzite 

 (q.v.), in which the percentage is from 5 to 15; 

 and Hypersthene (q.v.), containing 15 per cent, 

 and upwards. All these are important constituents 

 of igneous rocks. 



Pyroxylic Spirit, also called WOOD-SPIRIT 

 and WOOD-NAPHTHA, is a mixture of acetone, 

 methyl-alcohol, acetate of methyl, &c., obtained 

 by the destructive distillation of wood in the manu- 

 facture of Pyroligneous Acid (q.v.). Many of its 

 properties are the same as those of common alcohol ; 

 and now, notwithstanding a long opposition from 

 the Revenue Board, its manufacture and importa- 

 tion are regularly allowed. It is of nearly equal 

 value to alcohol in making varnishes, as it dissolves 

 the resins, oils, and other similar substances. It 

 has a peculiar naphtha-like odour, which is in- 

 separable from it, and prevents its use as a potable 

 spirit at present ; but it is asserted that some 

 makers produce it almost odourless, and that it 

 sometimes takes the place of common alcohol in 

 the manufacture of cheap perfumes. It is used in 

 making Methylated Spirit (q.v.). 



Pyroxylin, a name for Gun-cotton (q.v.). 



Pyrrhic Dance, the most famous war-dance 

 of the ancient Greeks, especially the Spartans. 

 The name was said to be derived from Pyrrichos, 

 the inventor of the dance. The Pyrrhic measure 

 in prosody consisted of two short syllables. See 

 DANCING. 



PyrrllO (Gr. Pyrrhon), the founder of a school 

 of Greek scepticism, named after him, was a native 

 of Elis, Ixmi in the third quarter of the 4th century 

 B.C. A pupil of Anaxarchus, he followed him 

 when he went in the train of Alexander to Asia 

 and India. He lived to be ninety years old. Our 

 knowledge of his teaching is derived principally 

 from his pupil, Timon 'the Sillograph ' (i.e. 

 writer of silloi, ' satiric poems'); he himself left 

 no writings. Pyrrho taught that we can know 

 nothing of the nature of things, but that the best 

 mental attitude is suspense of judgment, which 

 brings with it calmness of mind. Pyrrhonism is 

 often regarded as the ne plus ultra of ( philo- 

 sophical) scepticism : consistent Pyrrhonists were 

 said even to doubt that they doubted. 



