154

Chain Pumps m Ships.

[Book I.

hale up like buckets.”* How such intelligent men as the Jesuits undoubt-edly were, could use such language, if an effective chain pump was thenknown in Europe , it is difficult to conceive.

Although the Chinese pump has been mentioned by all travelers, noone has entered sufficientiy into details, to enable a mechanic to realize theconstruction of the chain—mode of fixing the pallets—where they areattached to it, (at the centre, or on one side,)—nor how they are car-ried over the wheels or rollers. One cause of the superiority of tbeseoriental machines over those of Europe , was the small degree of fric-tion from the rubbing of the pallets, when passing through the trunk; woodsliding readily over wood, when both are wet: another was the accuracywith which the working parts were made. The experience of ages, and theimmense number of workmen constantly employed in fabricating them,through every part of the empire,had brought them to great perfection: butthe position in which they are worked, also contributed to increase the quan-tity of water raised by them, for except in particular locations, they are al-ways inclined to the horizon, as shownin No. 64. Nowit has been ascer-tained that to construct and use a chain pump to the best advantage, the dis-tance between the pallets should be equal to theirbreadth, and the inclinationof the trunk about 24°, 21'. When thus arranged, according to Belidor , itproduces a maximum effeet. b The author just named speaks of one atStrasburgh, the chain of which was made of wood, which being lightand flexible, was very efßcient, requiring much less labor to Work it thanthose in which the chains were iron. This leads us to a remark whichwe do not recollect to have seen in any English work, viz. that in mostif not,in all the Chinese smaller pumps, the chains are of that material.One of them is thus described by the Jesuits : “ Une machlne hydraulique,dont le jeu est aussi simple que la composition. Elle est composee d’wmchatne de hois, ou d’une Sorte de chapelet de petites planches quarrees desix ou sept pouces, qui sont comme enfilee parallelement ä d’egales dis-tances. Cette chaine passe dans un tube quarre,” &c. c

In the latter part of the 17th Century, chain pumps were used inBritish men-of-war. In Dampier’s Voyage toNew Holland in the ‘Roe-buck,’ a national vessel, he mentions one. This ship on returning homeSprung a leak near the Island of Ascension, and the water poured in sofast, he relates, that “ the chain pump could not keep her free—I set thehand pump to work also, and by ten o’clock, sucked her—I wore the shipand put her head to the southward, to try if that would ease her, and onthat tack the chain pump just kept her free.” English ships of war nowcarry four of those pumps, and three common ones, all fixed in the samewell; whereas it would appear from Dampier, that they had formerly butone of each. “ In the afternoon, (he observes,) my men were all employedpumping with hoth pumps.” Shortly afterwards the ship foundered. d Thevessels of Columbus were furnished with pumps; and so were those ofMagalhanes ; but these were probably the common instruments referred toabove as ‘ hand pumps.’ e

In Dampier’s time chain pumps were very imperfect. The chain, andthe wheel, which carried it, were inaccurately and badly made; hencewhen the machine was worked, the former was constantly liable to sbpover the latter; and the consequent violent jerks, from the great weightof the water on the pallets, often burst the chain asunder, and under cir-

* Atlas Chinensis, translated by Ogilvy. Lon, 1671, page 675.

b Arch. Hydraulique , Tom. i, 363. c Histoire Generale, Tom. viii, 82, and Duhalde,Tom. ii, 66. d Dampier’s Voyages, Vol. iii, 191, 193.

'Irving’s Columbus Vol ii, 127, and Burney's Voyages, Vol. i, 112.