392 Intelligence and Miscellaneous Articles. 



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motion with a power equal to the weight and height of the fluid 

 raised. To ensure, however, the proper pendulous motion, it is 

 necessary to attach a counterbalance to the weight of the glass cy- 

 linders and their connecting tube ; this is further required, for the 

 purpose of regulating the quantity of alcohol to be driven into the 

 upper cylinder. The descent of this cylinder constitutes one vibration, 

 the counter weight giving it such sufficient preponderance or mo- 

 mentum in its descent, as to cause it to impart motion, with cer- 

 tainty, to a train of wheel-work, revolving in the way usual in gas- 

 meters ; and the vibration, and consequently the corresponding con- 

 sumption of gas (or light), thereby becomes registered. The manner 

 of suspending the glass cylinders, and fixing the counterbalance 

 weight, is hereafter described. 



The next considerations are — 1st, how is the tube or receptacle 

 before mentioned (and which will be called the " heater ") to be 

 placed over the lower cylinder, so that, in discharging thereupon the 

 hot gas, it may not communicate any of its heat to the upper one ? 

 and, 2nd, how to place the upper cylinder in a medium always at 

 the same temperature as that of the room in which the meter is to 

 work ? it being absolutely necessary to keep the two cylinders at 

 two greatly opposite temperatures, that shall always bear the same 

 relative degree or difference to each other. 



The first of these objects is arrived at easily by placing a tin plate 

 between the two cylinders, as is clearly shown in the figures, and 

 pointed out in the mechanical description following. The second 

 necessary effect is attained by inclosing the whole meter in a thick 

 cast-iron case ; in the interior of which, and forming parts of the 

 same casting, two semi- cylindrical projections* or hoods are so placed 

 as nearly to surround that glass cylinder which alternately becomes 

 the uppermost one. The conducting power of this mass of iron is 

 amply sufficient to carry off all the heat radiating from the case of 

 the heater (this heater being, as before stated, enveloped in a case 

 or clothing of the best non-conducting material) ; and not only so 

 to radiate this heat, but to be always of the same temperature as the 

 room in which the meter is placed. These hoods, therefore, consti- 

 tute a very essential part of the apparatus ; for if the temperature 

 of the upper glass cylinder were to vary materially, so would that of 

 the lower one, and consequently the rate of the meter would also 

 vary ; but, by this very simple contrivance, the temperature of the 

 heater, and that of the lower glass cylinder, will be always of the 

 same relative temperature to that of the upper cylinder. 



Take an example : — Let the " heater " be at 150° of Fahrenheit, 

 and the room — and therefore the cast-iron parts of the meter — at 

 60°, then the gas which flows from the heater on to the lower glass 

 cylinder will be at the same temperature, viz. at 150°, and thus the 

 moving power (originating from the meter jet) will be equal to 90°, 

 which represents the heat imparted by the meter jet, such being a 

 constant and uniform quantity. If the temperature of the apartment, 

 and consequently that of the iron case, hoods, &c, be raised to 80°, 

 the temperature of the heater will be increased 20°, becoming 1 70°, 

 the moving power being constantly 90°. It has been deemed neces- 



