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unless the bars are covered, it is sure to cool down the temperature and occasion great waste of fuel.

In a private communication with one of the reporters, Mr. Williams contends for the use of his air-diffusion plates behind the bridge on the principle of the Argand burner; but there is this difficulty, that the very evil we are anxious to avoid, is to some degree aggravated by an excess of air, or, as he himself calls it, an overflooding,' which should be carefully avoided if we are to economise fuel by the same process that we get rid of the smoke. Mr. Williams very properly observes, that we must keep in view that the gas of a ton of coal requires,

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cubic feet of hydrogen and oxygen for the combustion of one ton of coal. These are facts which have been determined by Mr. Williams experimentally, and the public are greatly indebted to that gentleman for the able manner in which he treats his subject, and the great amount of intelligence which he has brought to bear upon the principle as well as practice of obtaining a better system of management, and in following up a more correct principle of combustion.

From Mr. Williams' statement given above, and from the various projects adopted by others for the attainment of the same objects, it appears to be the general opinion that the admission and diffusion of air behind, or through the bridge (marine boilers only excepted), is the only feasible means of preventing the generation or emission of smoke. This is certainly an effectual remedy as far as it goes, but injurious as regards the economy of fuel, and that for the following reasons—namely, that an aperture for the admission of an increased quantity of oxygen required to assist combustion after the furnace is charged is not wanted, when the coal has been deprived of its bitumen; after that period, when the furnace becomes bright, a smaller quantity is required, and any excess beyond what is necessary to combine with the gases accelerates combustion, cools down the furnace, and increases

the quantity of fuel consumed. Now, in situations where the boilers are in excess of the power, these apertures are not required, as the Cornish system of slow combustion clearly demonstrates, whilst, at the same time, it teaches how that process may be adopted, and that with the same success as exists in that district. At other times where the boiler space is limited, the introduction of the fair diffusion principle will greatly mitigate the evil, but it will not, in our opinion, effect the same satisfactory remedy as may be obtained by enlarging the power of the boiler.

In cases where the owners of furnaces have to force the fires, and are limited beyond the power of enlarging their boilers, we should then recommend for adoption the multitubular system, which effects in a small space what would otherwise be required by increasing the number of, or dimensions of, those of the common construction. This tubular system is always effective, provided sufficient surface is given to absorb the heat as it passes from the furnace. In marine and stationary boilers 16 to 18 square feet have been considered sufficient for every nominal horse-power of the engine, but it is safer and better to take 24 square feet, provided a saving of fuel, accompanied by the absence of smoke, is to be effected. With that measure of heating surface much may be done; but it will be found still far from perfect, unless care and constant attention be paid to the management of the furnace.

In this respect a good system of management becomes indispensable, and although firing machines have been adopted, with numerous ingenious devices for regulating the time of firing, and other projects for accomplishing the same object by the diminution and pressure of the steam, yet we have never found these self-acting machines answer the purpose so well as the human hand. The management of the furnace appears to be a separate system, which may be learned by attention to a few simple rules, so as to give perfect satisfaction.

In these statements we have endeavoured to lay before the authorities such information as appears to us calculated to abate the nuisance of smoke, and purify the black dense atmosphere which hangs over the city of Glasgow. That these dark and gloomy vapours can be prevented from ascending, we entertain

no doubts; and after the observations we have considered it our duty to make, and which apply with equal force to other manufacturing towns, it rests with the public authorities of the city to enforce, mitigate, or improve these practical recommendations.

W. FAIRBAIRN.

JAMES LESLIE.

ROBERT JOHNSTON.

In the Dean of Guild Court of Glasgow.

Further Report by WILLIAM FAIRBAIRN, JAMES LESLIE, and ROBERT JOHNSTON, in the Case at the instance of the Procurator Fiscal of Court against Messrs. CHARLES TODD and HIGGINBOTHAM.

MY LORD AND GENTLEMEN,-In obedience to the further remit of Court of date the fifth day of October last, we have again visited and carefully inspected the Defenders' premises, and have now to report, that we have seen no cause to alter in any respect our former Report, which we therefore adhere to and confirm. In that Report we described accurately the state of the Defenders' Works as we found them, showing that a great and unnecessary waste of fuel was there going on, and that a wasteful expenditure of that kind was invariably accompanied by its attendant evil-smoke. We then pointed out how this state of things might be remedied, and the consumption ofsmoke effected. This object, we stated, might be attained in one of three ways, namely :-(1) by a common circular boiler of sufficient power; (2) by the introduction of the double flue and double furnace boiler with alternate firings, which, we stated, was probably a more economical plan than the preceding; or (3), by the introduction of one of the multitubular boilers 24 feet long, 7 feet diameter, with double furnaces, mixing chamber, and about 110 to 120 three-inch tubes, as shown on a sketch which we submitted (No. 2); this we distinctly added, being

in our opinion the best and most approved plan. In addition to this, we gave rules to be observed in the management of the furnace. Remaining of the same opinion, after inspection and deliberation, we cannot suggest any other remedies.

We observed, on our second visit, that the Defenders had, to some extent, complied with the instructions in our former Report, and thereby effected a considerable improvement; but there is yet much to be done to lessen the emission of smoke from their chimney; and we do not think, therefore, that their partial compliance with our instructions ought to be accepted, as satisfying the requirements of the statute referred to in the remit to us. At any rate, we hold it not to be in our province to recommend anything short of the best and most approved plan known at the time, as we have done; and that if any other plan is to be adopted, this must be matter of arrangement betwixt the parties, with which, we presume, we have no power to interfere.

All which is respectfully reported by

W. FAIRBAIRN.

JAMES LESLIE.

ROBERT JOHNSTON.

1st March, 1855.

APPENDIX VI.

Experiments on the Iron Targets at the Arsenal, Woolwich.

The following experiments were undertaken to determine the effect of shot upon the hull of an iron vessel, and also with the view of providing means for stopping the passage of water through a shot-hole near the water-line. The latter object is sought to be effected by packings of various kinds fixed behind the sheathing plates, and which by their elasticity will close over the hole after the passage of the shot through them.

The gun used in the experiments was a 32-pounder, placed at the distance of thirty yards from the targets, and loaded both with the full charge of 10 lbs. of powder, and a charge of 2 lbs., to produce the effect of a long shot. The initial velocity of the ball with the full charge is about 1800 feet per second, and of the 2 lb. charge 1000 feet. The diameter of the shot is 6 inches.

Target No. 1 is made of three thicknesses of -inch plates, riveted together by double rows of rivets, arranged in rectangles of 24 in. x 14 in. Through this only one shot was fired with the full charge, which made a clean hole, with very little tearing or raising of the edges, and no rivet heads started near the hole. The three thicknesses cut out by the shot all flew into angular splinters of 1, 2, and 3 inches long, diverging from the hole in all directions. When the full charge is used, no disturbance in the plate or the rivets round the hole is observable. This target was not stiffened with angle-irons.

No lining was placed behind this target.

Target No. 2 is formed of single 4-inch plates, flush-jointed, single-riveted, with two frames 9 inches deep attached by double angle-irons 6 in. x 3 in. One half of this target is lined at the back with pure india-rubber, and the other half with a mixture of india-rubber and cork-dust, containing 25 per cent. of the latter by weight, 12 inches thick. These linings are held to the sheathing by 1-inch screw-bolts, with square heads outside, and nuts with washers of 5-inch plate 8 inches square inside, the plates (or washers) completely covering the elastic lining. The bolts are in the centre of each square, or 8 inches apart each way.

Through the india-rubber and cork-dust five shots were fired, all striking (as was intended) between the bolts. Two with 10 lb. charge made clean perforations through the outer shell, and passed through the lining without shattering it much, but knocking off, each, four or five of the back plates with great violence, and the splinters from the perforation in the outer shell passing through the lining also. The elastic lining closed completely over the hole, so as to exclude water thoroughly. Several proportions of india-rubber to cork-dust have been tried, but this one is found to be the best. The three other

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