Modern Chain of Pots.

127

Chap. 15.]

and the imperfect Substitutes for cog wheels, identieal withthose of Egypt and Asia , and may be considered a fair representative of this machine asused in the agricultural districts of the ancient world.

No. 55, represents a section of a mod-ern machine. The wheel is placed in orover a cistern designed to receive the wa-ter. Buckets are secured to the chain be-tween the joints of the latter, and thewheel as it revolves, receives the cen-tre of these joints on the ends of itsarms, which are suitably shaped for thepurpose. The buckets therefore fall inbetween the arms of the wheel and be-come inverted in passing over it as inthe figure.

No. 55. Modern Chain of Pots.

The chain of pots has been appliedto a great variety of purposes. It hasbeen employed for ages, in cleansingdochs, deepening harbors, &c. Thevessels being made of iron and formedlike wide scoops, are made to pass un-der pulleys attached to the bottom of amoveable frame, which is raised andlowered, to suit the varying depth ofthe channel. Besson also proposed itto raise mortar, &c. to the top of citywalls, fortifications, &c. and whereverlarge quantities were required ; an ap-plication of it that is worthy of the notice of extensive builders, for thetime consumed and exertion expended by a laborer, in ascending a long lad-der or flight of stairs to deposit a modern hodful of mortar, and returningthrough the same space, is hardly consistent with the spirit of economyand useful research that characterizes the age. The amount of force con-sumed in bearing his own body twice over the space, independently of theload, would in a well regulated device of this kind produce an equal re-sult. Oliver Evans introduced the chain of pots into his milis, for the pur-pose of transmitting flour and grain to the different floors.

It has been adopted as a Substitute for water wheels. As the noria,whenits motion is reversed by the admission of water into its buckets atthe upper part of the periphery, is converted into an overshot wheel—sothe chain of pots, has in a similar manner, been made to transmit powerand communicate motion to other machines. In locations where there isa small supply of water, but which falls from a considerable height, it be-comes a valuable Substitute for the overshot wheel, as a first mover. Itis remarkable that this obvious application of it should not have occurredto European mechanicians previous to the 17th Century. It was designedby M. Francini, and by the direction of Colbert, the illustrious and pa-triotic minister of Louis XIV , one was erected in 1668, in one of the pub-lic gardens at Paris. A natural spring in this garden supplied water forthe plants. It was received into a large basin, and to prevent its over-flowing, the surplus or waste water was discharged by a gutter into a well,at the bottom of which it disappeared in the soil. M. Francini took ad-vantage of this fall of waste water in the well, and made it the means ofraising a portion of the spring water sufficiently high to form a jet d’eau.