Roberton s Patent.—In 1801 Messrs. Roberton, of Glasgow, patented some improvements upon Mr. Watt's plans, which rendered the apparatus more com plete and convenient. To these gentlemen, indeed, is usually attributed the first successful application of the principle patented by Watt, of burning the smoke owing,_ we are inclined to believe, to the indifference of the public in the early part of Mr. Watt's career to the nuisance of dense smoke ; as, from the comparatively small number of engines at that time, the adoption of means to burn the smoke was not so much sought after. Joined to this cir cumstance may be reckoned the unskilful manner in which bricklayers, pre tending to an adequate knowledge of the subject, executed the work; which caused the principle to get into disrepute, rather than the bungling attempts to carry it into (Act. It was, in consequence, given in evidence, by numerous witnesses before a committee of the House of Commons, that more coals were consumed by burning the smoke than allowing it to pass of unconsumed in other words, that inflamed gas afforded less heat than cold smoke. The probability is, that more air was admitted than was requisite to supply the necessary quantity of oxygen to the carbonaceous matter, and that in consequence of such management, the temperature of the furnace or of the boiler was reduced, requiring an additional quantity of fuel to get up the requisite heat.
Sheffield's Patent.—In the year 1812, Mr. William Evetts, of Sheffield, took out a patent for improved reverberatory furnaces for melting metals, in which he introduced what he termed an air conductor, for the purpose of conveying a stream of pure air upon the surfaces of the metallic substances under reduc tion. This air conductor consisted of a vertical passage or tube, made in the bridge or wall of brickwork at the back of the furnace, the lower end of which opened into the ash pit, where it was widened, and the size of the aperture regulated by a valve, which valve was operated upon by a long rod passing through the front enclosure of the ash pit ; the upper extremity of the air tube or passage did not pass vertically through the bridge, but had a horizontal turn given to it, by which the jet was thrown upon the substances under operation, or against the current of heated vapours, before they passed over the bridge ; and this minor stream of fresh air was found to impart sufficient oxygen to the carbonaceous matter of the smoke, and burn it.
Legislative Enactment.—The annoyance and pernicious effects experienced by the public from a sooty atmosphere, drew the attention of the legislature to the subject, and a Select Committee of the House of Commons was appointed, in 1819, "to inquire how far it might be practicable to compel persons using steam engines and furnaces in their different works, to erect them in a manner less prejudicial to public health and comfort ; and to report their observations thereon to the House." The committee having ascertained and reported to the House that the reduction of smoke from furnaces might be practically accom plished, a bill to embrace that object was brought into the House and passed ; it was entitled—" An Act for giving greater facility in the prosecution and abatement of nuisances arising from furnaces used in the working of steam engines :" to commence Sept. 1, 1821. Among its enactions are the follow
ing ;—" That it shall and may be lawful for the court before whom any such indictment shall be tried, in addition to the judgment pronounced by the said court, in case of conviction, to award such costs as may be deemed proper and reasonable to the prosecutor or prosecutors, to be paid by the party or parties so convicted." It was also enacted—" That if it shall appear to the court 'before which any such indictment shall be tried, that the grievance may be remedied by altering the construction of the furnace, or any other part of the premises of the party or parties so indicted, it shall be lawful to the court, without the consent of the prosecutor, to make such order touching the premises as shall be, by the said court, thought expedient for preventing the nuisance in future, before passing final sentence upon the defendant, or defendants, so convicted." Gregson's Patent.—Mr. Joseph Gregson, who was one of the gentlemen examined before the Committee of the House, gave it as his opinion, that the principal causes of the nuisance were, the putting on the fire too much crude fuel at a time, and the chimney being in general too low. Mr. Gregson had a patent for a plan of a furnace for consuming the smoke, the principle of which, he stated, consisted, " first, in causing all the smoke, after it has arisen from the fire, to return into the heat of the fire before it enters the flue or chimney, and so be consumed ; secondly, in putting on no more fuel at any one time, than the smoke of which can be consumed, and that without opening the door for the purpose ; thirdly, in supplying the fire with a current of air to coun teract the effect of those winds that operate against the draft. The engraving in the next page represents a vertical section of the apparatus. The fire-place G and the feeding-door F are made as usual ; the smoke passes over the bridge D, under which is an aperture, where an intense heat is produced, which inflames the smoke in the descending flue by means of a supply of air through the aperture C ; it then passes into the flue and the chimney, A, formed in the usual manner. Z Z is an air shaft and drain to supply the fire with air through a valve situated under the fire-place. It may be deserving of remark, that the objects aimed at by Mr. Gregson in this arrangement would be considerably promoted, by making the partition between the ascending and descending flues, A and Z, of iron or copper, instead of brick ; and that an economy of fuel would result from the partial exchange of temperatures between the opposite currents. But in thus abstracting the waste heat through the medium of good conducting substances, a sufficient temperature must be left in the ascending column to maintain the draft.