]04 Mr. Thorn on New Self-acting Sluices. 



cylinders may be placed, the pipe that communicates between 

 the cylinders and the water within the embankment must al- 

 ways have its opening there exactly at the level of high-wa- 

 ter mark, or at the greatest height to which the water therein 

 is to be permitted to rise. 



On this principle a self-acting dam may be raised in any 

 river or stream, up to high-water mark, by which means a 

 considerable reservoir will be obtained, whilst, during floods, 

 the dam will fold down, and no new ground be overflowed. 



In lawns or pleasure grounds, through which streams or 

 rivulets flow, these sluices might be applied to advantage ; 

 for by placing one on the bank of each pond, the water with- 

 in would always be kept at the same height, whether the 

 weather were wet or dry ; and hence flowers or shrubs might 

 be planted close to the water's edge, or in it, (as best suits 

 their respective habits,) and their position with regard to wa- 

 ter would always be the same. 



Plate II. Figure 7. A. 

 This is merely a different construction of the waster sluice 

 figure 7. 



AB is the sluice which turns on pivots at the upper edge A. 

 CD, a lever attached to that sluice. 



E, a hollow can of cast iron attached to the extremity of 

 that lever at D, and into which small stones are put until it 

 becomes heavy enough to shut the sluice against the pres- 

 sure of the water in front. 



F, a pulley. 



G, a hollow cylinder of copper (or tin-plate painted,) with 

 a small aperture in its bottom. 



DFG, a chain, one end of which is fixed to the lever at 

 D, then, passing over the pulley F, has its other end fixed to 

 the cylinder G. 



AH, a tube which communicates between the water in 

 front of the sluice AB and cylinder G. 



When, therefore, the water in front of the sluice is not so 

 high as to flow along the tube AH, the sluice AB remains shut, 

 but when the water rises so as to flow along that tube, it fills 

 the cylinder G, which then descending, raises the lever CD and 

 can E, and opens the sluice. Again, when the water falls so as 



