148
Chain Pump.
[Book I.
CHAPTER XVII.
The Chain Pümp —Not mentioned by Vitruvius —Its supposed origin—Resemblance between it andthe common pump—Not used by the Hindoos, Egyptians, Greeks or Romans—Derived from China —Description of the Chinese Pump and the various modes of propelling it—Chain Pump from Agricola—Paternoster Pumps—Chain Pump of Besson—Old French Pump from Belidor—Superiority of the Chi nese Pump—Carried by the Spaniards and Dutch to their Asiatic possessions—Best mode of makingand using it—WoodeD Chains—Chain Pump in British ships of war—Dampier—Modern improvements_Dutch Pump—Cole’s Pump and experiments—Notice of Chain Pumps in the American Navy —De-scription of those in the United States Ship Independence—Chinese Pump introduced into America byVan Braam—Employed in South America —Recently introduced into Egypt —Used as a substitute forWater Wheels—Peculiar feature in Chinese ship building—Its advantages.
The chain pump, although not described bf Vitruvius , is introduced atthis place, because it seems to be the connecting link between the chain ofpots and the machine of Ctesibius . Some writers suppose it to be derivedfrom the former ; nor is the supposition improbable. Numerous local cir-cumstances would frequently prevent the chain of pots from being usedin a vertical position, and when its direction deviated considerably fromthe perpendicular, some mode of protecting the loaded vessels while as-cending rugged banks, &c. became necessary. An open trough or wood-en gutter through which tbey might glide, was a simple and obvious de-vice, and one that would occur to most people ; bnt such a contrivancecould not have been long in use before the idea musthave been suggested,that pieces of plank or any solid substance which would occupy the entirewidth of the gutter, might be substituted for the pots, since they wouldobviously answer the same purpose by pushing the water before themwhen drawn up by the chain. If this was the process by which the transi-tion of the chain of pots into the chain pump was effected, there can belittle doubt, that old engineers soon perceived the advantages of coveringthe top of the gutter, and Converting it into a tube ; as the machine couldthen be used with equal facility, in a perpendicular, as in any otherposition.
It may be deemed of little consequence to ascertain the circumstanceswhich led to the invention of the chain pump ; yet a knowledge of theperiod when this took place would be of more than usual interest, on ac-count of the analogy between it and the ordinary pump, and of the rela-tionship that appears to exist between them. The introduction of a tubethrough which water is raised by pallets or pistons, is so obvious an ap -proach to the latter, that it becomes desirable to ascertain which of thembears the relation of parent to the other, or which of them preceded theother. But to what ancient people are we to look for its authors ? Notto the Hindoos, or the Egyptians, for it is incredible that either of thesepeople shonld have lost it, if it was ever in their possession. Its cheapand simple construction—its efficiency and extensive application, wouldcertainly have induced them to retain it in preference to others of lessvalue. Nor does it appear to have been known to the Greeks ; for theirnavigators would never have employed the screw as a ship pump, (asAtheneus says they did,) if they had been acquainted with this machine.Of all hydraulic tube machines, the screw seems the most unsuitablefor such a purpose. It requires to be inclined at an angle that is not onlyinconvenient but generally unattainable in ships. But if the Greeks had