588 



BOILER KOIS-LE-DUC. 



the productions of poetical genius to a fixed standard. 

 U.'s censures of Tasso aiuKjuinault, with some other 

 equally unfounded opiniuns, display a narrowness of 

 spirit. He had many opponents, who accused him <>l 

 want of fertility, invention, and variety. To refute 

 them, he wrote his Lutrin, a mock-heroic poem, 

 which is still unrivalled in the eyes of the French. 

 A music-stand, which had been removed from its 

 place, had occasioned dissensions in a chapter: this 

 is the suliject of 11. 's poem, in which his art of making 

 petty details interesting, <l<MTves :is much praise as 

 the other excellences ot' his poetry already enumer- 

 ated. In his life, 15. was amiable and generous. 

 Louis XIV. gave him the place of historiographer, 

 in connexion with Racine. As he had attacked the 

 academician- in sc\i r.il of hi- \\ritings, he was not 

 received into their society until lb'S4, and then only 

 by the interference of the king. He died in 1711, 

 t>t' the dro^rf. M. de St Surin has publislied (Euvres 

 de lioilrau, witJi a commentary, Paris, 18^4, four 

 vols. The first volume of Daunou's (member of the 

 institute) (Euvres completes de Boiieatt, with a lite- 

 rary and historical commentary, appeared iu Paris, 



BOILER ; the name applied to the vessel in which 

 vapour is generated for the steam engine. These 

 vessels are of various forms ; that most commonly in 

 use being rectangular, and formed of plates either of 

 copper or malleable iron. There is a certain deter- 

 minate size which a boiler ought to have, in order to 

 supply an engine of a given power. The general rule 

 for the boilers of low pressure engines, stationed on 

 land, being five feet surface of water for each horse 

 power, while marine engines are allowed only three. 

 To prevent accidents from explosion, the metal of the 

 boiler should have a sufficient thickness, and ought 

 also to be furnished with a safety-valve which shall 

 open outwards, and allow the steam to escape when its 

 pressure becomes greater than is necessary. This, 

 and the various otner contrivances connected with 

 the boiler, will be best understood from the following 

 figures and description, extracted from an extensive 

 article on this subject in Grier't Mcch. Diet. 



Fig. 1. 



Fig. I, is a longitudinal, and Fig. 2, a cross section, 

 and the same letters are used for the same parts in 

 both, aa is the boiler, surrounded by the flues bb, 

 c is the chimney, d is the ash-pit, and e is a space for 

 holding any ashes that may be carried over the divi- 

 sion behind the furnace bars, this space being cleaned 

 out through the opening /, which is built up when 

 the boiler is in action, so that no air can be admitted 

 into the flues, g is a space in the top of the division 



I f, I 



behind the furnace, to 

 iillow the flame and 

 smoke to pass over; 

 h is the mouth of the 

 furnace, and i the 

 )rs, A- is a plate l>c- 

 hind the Iwrs, furnish- 

 ed v.-iih a handle /, 

 with which, when it 

 is drawn out, the dan- 

 ders may be forced 

 into the ash-pit. On 

 the top of the man- 

 hole /i, a valve is 

 shown, wfiich opens 

 inwards, in order to 

 prevent the sides of 

 the boiler from being 

 crushed in when tin- 

 steam in the interior 

 happens to be con- 

 densed; n is the steam 

 pipe and safety valve (see Safety f'alve) ; o shows tin- 

 gauge cocks for ascertaining the height of the water 

 in the boiler, (the surface of the water is shown by 

 the dotted line.) The stone float p is partly balanced 

 by the weight q, which is hollow, in order, if required, 

 to hold additional weights for regulating the float ; 

 r is the fulcrum on which the lever ss turns, and t is 

 the centre of the lever which works the small valve 

 fixed in the bottom of the top part of the feed-pipe, 

 which admits the water into the boiler. This water 

 flows into the top of the feed-pipe from the hot water 

 pump. When the water in the boiler becomes less 

 by evaporation, the level of the surface will be lower- 

 ed, and consequently the stone float will descend, and 

 the other end of the lever which works the valve in 

 the feed-pipe will be raised, and the valve opened, 

 and water admitted until the fluid rises to the proper 

 level. The feed-pipe u ought to be so high, tliat 

 there cannot be a possibility of the water in the boiler 

 being forced out through it by the pressure of the 

 steam. When the steam gets very strong, the water 

 in the boiler is, by the increased pressure, forced 

 through the pipe w up into the feed-pipe, and acts 

 upon a float which is connected by a chain passing 

 over the pulleys ww, to the damper ;r, which damper 

 passes into the flue and damps the fire. In the bot- 

 tom of the top part of the feed-pipe there is fixed a 

 small pipe to allow the chain of the damper to work 

 through the bottom, and not allow any water to pass 

 into the boiler which does not pass by the feed-valve. 

 There is attached to the top of the feed-pipe, a .small 

 pipe for the purpose of carrying off the surplus water 

 which is supplied by the hot water pump, but is not 

 required for the boiler. 



Bois-LE-Duc (the French name for the Dutch Her- 

 topenbosh, also Jtn BosK) ; a fortified city in the pro- 

 vince of North Brabant, in Belgium, with 3770 houses 

 and 13,300 inhabitants, at the confluence of the 

 Dommel and the Aa, which form, by their junction, 

 the Diest. Lon. 5 9' E. ; lat. 51 40' N. It has 

 many manufactories, and much trade in corn, some 

 saltworks, a lyceum, ten Catholic churches, four Cal- 

 vinistic,and one Lutheran. Godfrey, duke of Brabant, 

 founded this important military post in 1184. The 

 fortifications now consist of strong walls and seven 

 bastions, but it owes its security, chiefly, to the faci- 

 lity with which the whole country around can be laid 

 under water (the new canal to Maestricht has sixteen 

 sluices). B. is defended by several forts and a cita- 

 del. The city has four gates, and three entrances 

 from the water. The cathedral is one of the finest 

 in the Netherlands. The city suffered much in the 

 religious wars of the 16th century, and fell'into the 



