amined and proved before they are filled with gas for use. To obviate, as far as possible, the probability of accident, no one is permitted to be employed unless it has been found to resist a pressure of more than two hundred pounds on the square inch, above that degree to which it may be exposed when filled with the gas in its compressed state.

This most important and original contrivance is owing to the genius of Mr. Samuel Clegg; and perhaps it is the most useful and beneficial of any of the inventions which have been introduced into the operations of Gas-lighting.

The Gas Meter has undergone the practical test of several years, and experience has proved its advantages both to consumers and proprietors. It is now very extensively used at most of the Gas-light establishments in the United Kingdom, and the regularity and accuracy with which it effects its purposes, at once demonstrate its utility and excite admiration. It obviously tends to render Gas-lighting more general, because it enables the consumer to light up his house, in

any way, as occasion may require, without being subject to the inconvenience of burning the gas only at fixed periods; while the Gas Companies have the satisfaction of knowing that the gas consumed is registered by the meter.

Though the first contrivance of measuring the gases by means of a machine is due to Mr. Clegg, yet the original invention has been matured and very materially improved by Mr. Samuel Crosley, of the City Road, London, the present proprietor of the patent. The construction of the Gas Meter is rather complicated even in its most improved state, and would require several figures to represent its various parts; but it is presumed that the subsequent description, with the aid of the figure, which is a section of it through the middle of the drum, will render its principle and operations easily understood. The interior consists of a hollow wheel, or drum, which is divided by the plates (c, c, c), into the several compartments (2, 3, 4), and it revolves on its axis in an air-tight case (1, 1), which is rather larger than itself, and both the case and the lower compartments of the wheel are filled with water to a little above the axis (5, 5). Each compartment has two apertures, (z, a,) one for admitting the gas, and the other for discharging it; and these openings are placed in such situations, that at the time the gas is entering into any one compartment, its outlet is beneath the surface of the

water; 6 is the pipe by which the gas passes to the burners; and 7 shews the space between the outer case and the drum. Thus the gas being conducted into the meter at the ordinary pressure given it by the gas-holders, the wheel is made to revolve by the filling of the compartments in succession; and by this operation the compartment which is previously filled discharges its contents into the outer case, whence it passes off to the burners to be consumed. As the entering in and escape of the gas occasion the hollow wheel to revolve, its axis at the same time communicates motion to a series of wheel-work, which registers, by its revolutions, the exact quantity of gas that passes through the meter. In fact, the operation of the meter is so efficient for all its purposes, that by inspecting the index the precise number of cubic feet expended may at any time be known either by the consumer, or by the companies. This imperfect description will, it is hoped, clearly evince the ingenuity exercised in the contrivance of the Gas Meter, and elucidate both its principle and action: its superior merit has been proved by the accuracy of its results in extensive practice; and in proportion as it is nicely examined will its great utility be duly appreciated.*

Is it not probable that the number of gas-lights would be greatly increased if the use of gas meters was generally

THE LARGE GAS METER AND TELL-TALE.

The Gas Meter which is used for measuring the gas as it is produced at large works, is of course made on a scale proportioned to their magnitude. Mr. Crosley has constructed them large enough for measuring thirty or forty thousand cubic feet per hour, with an ingenious contrivance adapted to them called a Tell-Tale, which shews the quantity of gas generated in every hour, and therefore operates as a constant check upon the workmen both day and night.* The important advantages attending it have occa

adopted? For it must be obvious that it would enable every consumer of gas to burn as many lights at the time, as his occasions might require, and in the same way as he would be able to do by using any other kind of light. The companies might charge any price, which they deemed a fair and satisfactory remuneration; and if any inconvenience attended the practice, a remedy would soon be found.

* The "Tell-Tale," which is so important and useful a contrivance, was first employed by Mr. Lowe, at the Char tered Gas Works, in the year 1823; and the accuracy of its indications has demonstrated its great utility. As its obvious purpose is to measure the whole quantity of gas produced,