act passed for completely lighting the cities of London and Westminster.

"In 1553, at the Hague, lights were ordered to be placed before the doors, on dark nights; and in 1678 lamps were placed in all the streets. In 1669 Amsterdam was lighted with horn lanterns. Hamburgh was lighted in 1674. In 1679 every third house in Berlin was to show a light; and in 1682 it was lighted, but very badly, as it still is, at the public expense. Hanover was lighted in 1696; but Dresden, Leipzig, Cassel, Halle, Gottingen, Brunswick, Zurich, and some other German towns, not till the eighteenth century. Venice, Messina and Palermo are all lighted; so are Madrid, Valencia and Barcelona; but Lisbon is still in the dark, as is Rome. Sextus V. made an attempt to have the streets lighted; but the most he could accomplish was to increase the number of lamps placed before the images of the saints.'

"Mr. Murdoch (says the Ecclectic Review of Accum's Treatise on Gas Lights) seems entitled to the credit of being the first to bring the new mode of applying coal gas to the purpose of illumination into practice, and Mr. Samuel Clegg, of Manchester, has the principal merit, as it regards the construction and application of the requisite machinery." Mr. Ackerman has calculated that, while the old method of illuminating his printing office cost him no less than 1607. per annum, the expense by the new system is only 401. per annum, or only about one fourth as great as the former.

"Such (adds Mr. Ackerman) is the simple statement of my present system of lighting, the brilliancy of which, when contrasted with our former lights, bears the same comparison to them as a bright summer sunshine does to a murky November day: nor are we, as formerly, suffocated with the effluvia of charcoal, nor the fumes of candles and lamps In addition to this, the damage sustained by the spilling of oil and tallow upon prints, drawing books and papers, &c. amounted annually to upwards of 50%. All the workmen employed in my establishment consider the gas lights as the greatest blessing, and I have only to add that the light we now enjoy, were it to be produced by means of Argand's lamps, or candles, would cost at least 3507. per annum.

"With regard to the apparatus and machinery employed for the production and use of the gas, we cannot of course be expected to give in this place any description: indeed such description would be altogether unintelligible without the assistance of plates. Suffice it to say that the coal is introduced into iron cylinders, callcd retorts, which being made air-tight, and placed upon the fire, the gaseous products are made to ascend, together with other productions, in the form of liquid. These last are conveyed into proper receptacles, while the gaseous matter is conducted by pipes into places for purification; and then, thus purified, made to pass into the several conduits for use. The products of coal, treat

ed in this manner, are, beside the gas in question, coke, coal tar, and an ammoniacal fluid, all of which are materials of much value and use, and, as we have seen by Mr. Ackerman's statement, cause a very considerable deduction of the required expenditure in the production of the gas."

Mr. Accum thus answers the arguments against gas lights which is drawn from the danger of using them.

"In fact (he says) no danger can arise from the application of gas lights, in any way, but what is common to candle-light and lamps of all kinds, and is the fault of none of them. Even in this case the gas lights are less hazardous. There is no risk of those accidents which often happen from the guttering or burning down of candles, or from carelessly snuffing them. The gas-light lamps and burners must necessarily be fixed to one place; anb therefore cannot fall, or otherwise become deranged, without being immediately extinguished. Besides, the gas-light flames emit no sparks, nor are any embers detached from them. As a proof of the comparative safety of the gas lights, it need only be stated that the fire offices engage themselves to insure cotton mills, and other public works, at a less premium, where gas lights are used, than in the case of any other lights,"

Some account of Mr. Samuel Clegg's improvements of the Appa. ratus employed in Gas Illumination. By William Thomas Brande, esq. F. R. S. and E. Prof. Chem. R. I.

(From the Quarterly Journal of Sciences and the Arts.)

In the last number of this journal I have detailed such facts as I conceived might be generally useful, respecting the application of coal gas to the purposes of illumination. On the present occasion I am enabled, by the kindness of Mr. Clegg, to describe some new apparatus, and several important improvements which he has successfully adopted at the large establishment at Westminster, belonging to the Gas Light Company.

Since I wrote my former paper upon this subject I have had the superintendance of the construction of a gas apparatus, which the Apothecaries' Company have erected at their hall, near Blackfriars bridge, and by which their different laboratories and warehouses, as well as the exterior of the building, are now exclusively lighted. I have here learned several facts connected with the production and management of the gas, which are new to me and which, if verified by future experiments, will be detailed in this journal.

One of the most important parts of the gas apparatus, and at the same time most difficult of construction, are the gasometers and reservoirs. As these are commonly made they require a cis

tern or vessel of water, of very large dimensions, in which they are suspended, and rise and fall perpendicularly, as the gas enters and escapes; and it is extremely difficult to prevent leakage, and other accidents, unless very great expense be incurred in their construction, by nicety and solidity of the workmanship. Upon the perfect regularity of their action, too, the steadiness and perfection of the flames will materially depend; and, owing to the mode of suspension generally employed, this is scarcely attainable where the instrument is of very large dimensions.

The following is a description of a rotary gasometer, erected by Mr. Clegg at the Westminster works, and in which, while the above objections are in a great measure obviated, several other advantages are incurred. Its action is so steady and regular that it has been found advantageous to suffer the gas to pass through it from the vertical gasometers, previous to entering the main pipes for the consumption in the streets and houses; and the cistern which it requires is comparatively small. [It is represented in our plate.]

Fig. I. A. A. B. B. C. D. E. represents about two thirds of a hollow rim of a wheel into which the gas is received. The end A. A. is closed; the end C. D. E. is open from D. to E; the pipe F. G. H. connects the two ends of the segment or hollow rim, and is made of sufficient weight to counterpoise the whole. This pipe is inserted air-tight into the rim at F., and contains a stop betwixt G. and H. At G. is joined a pipe, forming a communication with the hollow axis O., upon which the rim turns, and which supports it by arms and braces, after the manner of other wheels, and revolves upon a friction sector. I. K. L. M. represents the cistern of water, in which the rim is immersed sufficiently deep to counteract the pressure of the gas.

It is evident that the gas, being conveyed into the open end of the hollow axis O., which is closed at the opposite end, will proceed by the pipe G. F. into the closed end of the gasometer at F. The operation will be as follows:-Supposing the closed end A. A. at the surface of the water in the cistern, and the gas flowing in as just described, the end of the gasometer A. A. will begin to fill, and consequently to ascend, and the wheel will continue to move upon its axis, until the open end D. E. comes nearly to the surface of the water; and, when the gas is required to be discharged, it will return through the same channels by which it entered.

A sufficient power or pressure is given to the wheel for discharging the gas at the velocity required, by means of an adequate weight, suspended by a chain over a pully; which chain is fixed to the wheel, upon a small circle, made fast to the arms, near to and round the end of the axis. Thus the wheel will retrograde as the gas is discharged, until the end A. A. again arrives at the surface of the water, when the whole of the gas will be discharged.