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LIX. Description of Mr. Malam's Gas-Me(gi*. 



JlLS soon as coal-gas came to be extensively applied to the pur- 

 poses of street illumination and to domestic use as a substitute 

 for lamps and candles, it b?canie an object of great importance 

 to the proprietors and managers of the different gas-works to 

 ascertain with accuracy the quantity of gas expended in propor- 

 tion to the number of jets or bnrm^rs made use of. 



The essential conditions of any apparatus for this purpose are, 

 that the pressure on the gas while passing through the measurer 

 shall at all times be uniform ; and that it shall register truly 

 when that pressure is very small, and when the current of gas is 

 very feeble. 



The first gas-meter was constructed by Mr. Clegg, and is se- 

 cured to the inventor by a patent. It consists essentially of a 

 cylinder, divided into cells, inclosed and revolving in an outer 

 cylinder, which is less than half filled with water. The gas en- 

 ters laterally through the perforated axle, into that cell of the 

 inner cylinder which happens to be nearest the surface of the, 

 water. It displaces the fluid from this cell, consequently de- 

 stroys the equilibrium of the cylinder, and communicates to it a 

 rotatory motion. When the cell, so filled with gas, has made 

 nearly half a revolution, it conies again in contact with the wa- 

 ter, which forces the gas out of the cell into the exterior cylinder, 

 from which it passes into the conducting pipes, A train of 

 clock-work is placed so as to register each revolution of the in- 

 terior cylinder; and the cubic contents of this being known, of 

 course the whole quantity of gas pu'ssing through the machine in 

 a given time is ascertained. 



Mr. Malam's gas-meter is constructed on the same gctieral 

 principles, but with such improvements as induced the Society to 

 confer on him a high honorary reward ; but whether the machine, 

 in their opinion so improved, is completely open to public use 

 before the expiry of Mr. Clegg's patent, the Society does not 

 presume to determine. Secretary. 



No. 10, Roinney-Tcrrace, WestiuiHster, 

 March 10, 181'). 

 Sir, — IIerrwitm I have forwarded to you a gas-meter of my 

 invention, capable of supplying four Argand burners, eaih con- 

 huming about four cubic feet of gas per hour. In doing so, I am 

 to inform vou, tiiat it is now nearly two years since I first put 

 my invention into practice, during which time the action of the 



• from the Trnniiurlhins of the Sucieltj for the EufOurugemtriU of Arts, 

 Manufactures, and (Commerce, vol. xxxvii. The gold Isis medul of the So- 

 ciety was voted to Mr. .John Malain, of Westminster, for this communication, 

 and a model of the machine is placed in the Society's Repository. 



Z z '^ meter 



