Intelligence and Miscellaneous Articles. 395 



larger portion (viz. six-sevenths) of the gas flows down the lower 

 part, J, of the above vertical passage at the back, and along the ho- 

 rizontal tube, N, at the bottom of the meter, and through the regu- 

 lating disc or opening, Z, fixed therein, and thence passes direct 

 towards the burners, through the main exit K. The area of this 

 disc, Z, is exactly six times that of the opening, I, into the heater 

 and working parts of the apparatus. This larger portion of the gas 

 flows through these lower passages of the meter without influencing 

 any of the working parts, and for that reason is called the " Neutral 

 Gas," and the direction of its flow or current is marked by long 

 dark arrows. The smaller portion of the whole supply may be called 

 the " Working Gas." A minute quantity of this gas flows from 

 the body of the meter through the small openings, b b, perforated 

 in a solid brass cylinder, G, entering at the bottom, where this cy- 

 linder is screwed on to the top part of the heater F, and issuing out 

 in the front of the cylinder near its top, in a jet at c ; this is called 

 the " meter jet," and forms an important part of the arrangement; 

 it may, indeed, be designated as the originator of the moving power ; 

 in fact, the prime mover of the meter. The orifice, whence issues 

 the meter jet at c, is plugged with platina to prevent corrosion, or 

 any other wear and tear. This meter jet, immediately after opening 

 the main stop-cock, should be lighted, that it may at once impart a 

 corresponding amount of caloric to the heater, and thereby raise the 

 " working gas," flowing through that receptacle, to the same tem- 

 perature. This receptacle, with the connecting pipes and the brass 

 cylinder, may be considered as forming one apparatus, under the ge- 

 neral designation of the " heater ;" m, m is a pasteboard covering 

 for the heater, and all the parts connected therewith, except the solid 

 brass cylinder, pasteboard being selected as the slowest conducting 

 substance wherewith to surround them. 



The working gas, raised to a high temperature, flows down from 

 the heater through the vertical pipes L L L, and impinges on the 

 top surface of the lowest one of two hollow glass cylinders B B. 

 These cylinders are connected together in the centre of their lengths 

 by the bent hollow glass tube C, the whole being exhausted of air, and 

 partially filled with alcohol, as described in the commencement of this 

 paper. A tin collar, S, is attached to the bent tube C, and to a 

 large tin plate S, passing between the two glass cylinders ; this plate 

 unites to brass arms or bars, R R, on each side, and by these the whole 

 glass instrument vibrates on pivots, or points of suspension, at the 

 extremities, D D, of two screws, one passed through the side of the 

 cast iron case of the meter, and the other sustained from the bent 

 iron bracket or arm, T, attached to one of the hoods. E is the weight, 

 or bob, fixed to the upper end of the two brass bars, R, to act as a 

 counterbalance in the vacuum, and for the purposes previously de- 

 scribed, the pendulous motion thus obtained acting on the train of 

 wheelwork of the registering dials. The use of the tin plate, S', 

 passing between the two glass cylinders, is to prevent any of the 

 heated gas flowing down upon the lower cylinder from affecting the 

 upper one, and thereby altering the proportionate difference of tern- 



