Mr Thorn's Description of a Neio Double Valve Sluice. 289 



Art. XIX. — Description of a New Double Valve Sluice. In- 

 vented by Robert Thom, Esq. Rothesay. Communicated 

 by the Author. 



The Double Valve Sluice. Plate IV. Figure 5. 



This apparatus seems to answer the same purpose as the lever 

 sluice already described in this volume, p. 100 ; but is more 

 applicable in cases where the reservoir is deep, and the em- 

 bankment consequently large. It also acts as a waster-sluice, 

 by opening and passing the extra water whenever it rises in 

 the reservoir the least above the height assigned, and thereby 

 supersedes a bye-wash. 



. In making hydraulic experiments it will also be found of 

 considerable importance ; as, by keeping the surface of the 

 water in the cistern, from which we draw water for the expe- 

 riments, always exactly at the same height, it not only saves 

 intricate calculations, but renders the result, upon the whole, 

 more correct. 



AB, a tunnel through which the water flows from the re- 

 servoir to 



BC, the aqueduct that conveys it to the mills. 



AD, a sluice that turns upon pivots at the upper side D. 



I, a lever attached to that sluice, of the same length from I 

 to D as from D to A. 



EF, a hollow cylinder. 



GH, another cylinder, (water proof, and of rather less spe- 

 cific gravity than water,) which moves up and down freely 

 within the cylinder EF. 



IBG, a chain, one end of which is fixed to the lever I, and 

 thence passing ovor pulleys B and J, has its other end fixed 

 to the cylinder GH at G. 



KL, a cistern always full of water, being supplied by a 

 spring. 



LMF, a pipe that communicates between the cistern, KL 

 and the cylinder EF. 



NO, a spindle with two valves, O and N, fixed upon it. 



P, a float that rises and falls with the water in the aque- 

 duct BC. 



The water in the aqueduct is here represented at its great 



vol. n. no. u. APRIL 1825. u 



