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M. Pattit’s Improvements. [Book I.

ing a number of them together, as appears from the fifty-third propositionin the ‘ Century of inventions,’ “ A way how to make hollow and covera water screw, as “ big and as long as one pleaseth, in an easy and cheapway.” How, and of what materials he made this, is not known, but thefifty-fifth proposition, in the following words, has been fully and practical-ly developed by a French engineer. “ A double water screw, the inner-most to mount the water, and the outermost for it to descend, more innumber of threads, and consequently in quantity of water, though muchshorter than the innermost screw by which the water ascendeth ; a mostextraordinary help for the turning the screw to make the water rise.” In1815, M. Pattu published an account of the following improvements, bywhich the id.eas of Worcester are realized.

No. 62.

No. 60.

No. 61.

No. 60. represents two separate screws formed on the same axis, oneof which, A, is long and narrow and serves for the nucleus of C, whichis much wider and shorter. This is designed to propel the former. Thethreads of both wind round the axis in opposite directions, so that when thoseon one appear to be moving upwards, those on the other seem to be goingdownwards. The water from the stream M, is directed into the top ofthe large screw, and by its weight (as on an overshot wheel) puts thewhole in motion, and consequently the water at O, in which the lower endof A revolves, is raised into the cistern at B. No. 61 ismerely the samemachine inverted. It illustrates the applications to such locations as havea short fall above the place to which the water is to be raised. In No. 62the small screw drives the large one, through which the water from thelowest level is raised sufficiently high to be discharged at an intermediateone, as at G. From these figures it will be perceived that the screw hasbeen employed like the noria and the chain of pots, to transmit power.

This machine was formerly considered as exhibiting a very singulärparadox, viz. that the water “ ascended by descending,” and the mysterywas, how both these operations could be performed at the same time, andyet produce so stränge a result. It was remarked that when those form-ed of glass, were put in motion, the water ran down the under side of eachturn of the tubes, and continued thus to descend until it was dischargedat the top ! The whole Operation and the effects being visible, there jseemed no room for dispute, however contrary to acknowledged princi- !ples the whole might appear. The case was apparently inexplicable, andseemed to present a parallel one to that of the asymtote ; the propertiesof the latter being as incapable of demonstration to the senses, as the sup-posed Operation of this machine could be reconciled to the mind. Indeedthe proposition, that two geometrical lines may continue to approach eachother forever, without the possibility of coming in contact, is apparently,quite as impossible, as that water should ascend an inclined plane, by t hemere exercise of its own gravity. But the idea of water descending n>