150 On the Freezing of Water in leaden Pipts, 



A, of four inches height and two in diameter, screws 01* 

 to the funnel-shaped part B, to the extremity of which is 

 soldered the straight copper cock C, which is inserted into 

 any leaden pipe, as DE, (fig. 1.) supplied at its extremity D 

 from the original forcing-pumps of the public water-work?, 

 and emptying itself into the cistern F. ab is a circular piece 

 of cork of half an inch less diameter than the cylinder A ;. 

 its upper surface is furnished with a leathern covering, and 

 from the centre of this proceeds a small wooden stem or 

 slender wire c, of such length as that, when the cork shutter 

 rests in its proper situation upon the three projecting pieces 

 d d d, the top of the wire may just emerge through the ori- 

 fice at A. Thus, if, upon opening the stopper or turning 

 the cock C, water rise into the cylindrical, portion of the 

 valve (owing to the mechanical propulsion of the fluid from 

 D onwards), the rising of the cork shutter with the fluid 

 will be perpendicularly directed by the wire so as effectually 

 to prevent the fluid from escaping at the orifice A*: on the 

 other hand, when the water ceases to be impelled from D 

 onwards, and consequently does not rise through the stop- 

 per C into A, the cork shutter remains in its former situa- 

 tion, and a free passage is allowed for air to pass through 

 the open stopper C round the edge of the shutter, as being 

 half an inch less in diameter than the cylinder. Thus, the 

 entrance of the air from A through C into any attached 

 pipe, will allow the water therein to flow out at any lower 

 orifice in such annexed tube ; which thus emptying itself 

 remains in that state till the mechanical impulsion of the 

 fluid is again commenced, that is, till the water is again 

 turned on by the turncock on the usual day of supply. 



The connection here applies to every case wherein the 

 cistern is placed at a lower level than the supplying tube 

 DE, and proves at all times a self-acting principle, as bare 

 inspection, by any one acquainted with the properties of 

 the syphon, will convince. But the case is exactly reversed 

 in those situations where the cistern is at a higher level than 

 the supplying tube, as at II. Here it is evident that, when 

 the mechanical impulsion at D is discontinued, the pipe 

 from G to D will remain full of fluid, although an air- 

 valve were placed at D> for D is lower than G» Here then 



* It is not improbable that the lower surface of the cork shutter may be 

 so moist in cold weather as to allow it to be frozen to the resting pieces 

 dd of the cylinder, preventing its rise with the water shouFd it gain ad- 

 mittance. To be sore of its desired action, we may unscrew the cylinder 

 and inspect the condition of the apparatus, and, if the cork \j£ then frozen^ 

 easily dcuch it. 



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