278 THE SCIENTIFIC PAPERS Of. 



Barr and Macnal, of Paisley, are examples of single cylinder 

 meters, with tumbler arrangements to reverse the valves suddenly, 

 in order not to check sensibly the column of water moving through 

 the pipes. Captain Ericsson, of America, and Mr. Chrimes, of 

 Rotherham, simultaneously proposed a meter consisting of two 

 cylinders working on cranks at right angles to one another, in 

 order to equalise the flow through the pipes, and to be able to 

 apply slide valves, worked by eccentrics, in place of the more 

 complicated tumbler arrangements. Mr. Eoberts, of Manchester, 

 constructed, in 1851, a cylinder meter, made to tumble or oscillate 

 by the weight of the piston. Messrs. Bryan, Donkin & Co., of 

 London, invented, in 1850, a disc meter ; Mr. Parkeusou, of 

 Bury, and Messrs. Chadwick and Hanson, of Salford, have 

 substituted india-rubber diaphragms for the piston and the disc 

 respectively. Mr. Adamson, of Leeds, made a meter resembling 

 the rotary engine, in which direction he has been followed by 

 several others. 



The last named meter is the only one of this class that has been 

 practically used for several years (at Leeds), but was finally super- 

 seded, on account of excessive wear and tear, and frequent 

 stoppages. 



A meter " by area of flow " pre-supposes a constancy of pres- 

 sure, and knowledge of the time of continuation of flow. It is 

 practically resorted to for measuring approximately large volumes 

 of water, by passing it over an overflow, and taking into account 

 the depth of water column, its breadth, and the time of flowing. 



In Paris, Genoa, and other cities on the continent, the water 

 has for many years been supplied to each individual consumer, 

 through very contracted jets at the extremities of the pipes, 

 through which the water continually issues with supposed uni- 

 formity of speed into receiving cisterns. It is evident that this 

 mode of supply is fraught with all the inconvenience of the inter- 

 mittent system, without possessing the advantage of relieving 

 occasionally the supply pipes from pressure, for the purpose of 

 repairs, &c. 



The great inconvenience of this system is illustrated by the 

 fact, that many houses in Paris require upwards of ten cisterns for 

 the supply of the different inmates. It is unjust, for it obliges 

 every consumer to pay at a maximum rate. . 



