Mr Mitcheirs Description of an Improved Water-Meter. 49 



gulato the quantity of water discharged under different pres- 

 sures, so as to correspond exactly with the index and train of 

 wheels, which can best be ascertained by trial upon setting up 

 the meter, say by a measurement of 20 gallons, and opening 

 or closing the fly leaves, to bring the quantity measured and 

 the index to correspond. 



It will be evident that the quantities of water passing 

 through a meter, upon this principle, would be correctly indi- 

 cated down to that quantity requisite to overcome the friction 

 of the screw, below which amount, however, the water would 

 pass through the cylinder without afi*ecting the index, and con- 

 sequently without being registered. Although the quantity 

 thus passing would not be coni&iderable in a well-constructed 

 meter, Mr Mitchell has recently introduced an improvement 

 which completely obviates this objection, and renders tho 

 indications correct under any circumstances, and down to 

 the smallest quantity. 



This is accomplished by means of the conical valve cock g^ 

 which is so constructed as to act instantaneously, and so keep 

 the supply either flowing at the full bore, or suddenly shut off\, 

 when the cistern is full. The opening and shutting of this 

 valve is eff'ected in the following manner : — To the end of the 

 lever h //, which works upon a journal, and is raised or de- 

 pressed by tho ball-float % are attached the two arms pp and 

 0. As the water in the cistern rises, these arms are carried 

 forward without acting, however, upon the valve, until one of 

 the chains, connecting them with the lever and lead-weight 

 n n is upon the stretch. At this point the lever and weight 

 are upon a balance, so that the least further rise of water in 

 the cistern carries it suddenly over, and allows the valve g to 

 close. A reverse motion takes place on the fall of the cistern 

 water, the action of the other arm and chain p p opening the 

 valve, which a small catch retains in its place against tho 

 force of the supply water. To prevent any injury to the pipes 

 from the sudden action of the valve, an air-vessel m is attached 

 to the supply-pipe immediately above the position of the valve. 



The introduction of this improvement, which prevents the 

 possibility of water passing unregistered through tho cylinder, 

 renders this description of meter very perfect, and capable of 



VOL. XXXV. NO. LXIX. JULY 1843. D 



