124 



GAS-METER. 

 Fig. 26. 



and having 100 teeth (c has likewise the same number of teeth) ; e is the pinion 

 on the wheel d, having ten teeth ; / is the wheel driving the hand which marks 

 thousands on the index, having 100 teeth, and driven by the pinion e ; g is 

 the pinion of the wheel / driving h, which marks tens of thousands on the 

 index : in this manner any quantity may be registered. If it be required to 

 register units (and in smaller meters it is useful), the first wheel d is made to 

 drive a pinion, p, having ten teeth, to the spindle of which the hand marking 

 units is attached. 



The old contrivance of the " Tell-tale," when attached to the station-meter, 

 becomes a valuable instrument, as it serves the purpose of effectually point- 

 ing out every irregularity that occurs in the production of the gas during any 

 hour of the twenty-four. Suppose, for example, the superintendent desires 

 to know whether his workmen have at any time during the day or night made 

 the proper quantity of gas from the given quantity of coal : he may upon 

 examination find all the retorts in an excellent working state ; but whether 

 they have been so at all hours, or whether the requisite quantity of gas has 

 been really produced during the time that the pipes which convey it into the 

 mains have been open, is to him a matter of uncertainty : the " tell-tale" will 

 show him by inspection if any irregularities have occurred, and, if any, at 

 what hour : this appendage may, then, be considered as a check on the con- 

 duct of the workmen. It may also be known what man or set of men have 

 been negligent; for the retorts having their proper hours of work, will, if 



