piece of machinery, working with a degree of precision at once the admiration of the employer and the pride of the engineer.

I would have all engines and machines kept clean and in good order; and hence the advantage of our polished surfaces, and the mathematical exactitude with which the steam-engines of the present day are executed.

But in these constructions, we have other advantages besides those of appearance, or a desire to please the eye. A well-constructed machine, neatly executed, has a wonderful effect upon the mind of its keeper. It only requires a few months to accustom him to habits of cleanliness and order, and the time is probably not far distant when we may look forward to that important class of men being better instructed and better calculated for the discharge of their various duties than we can hope for in the present state of our educational resources. In conclusion, permit me to avail myself of the words of a distinguished writer, who, speaking of the steam-engine, says that— It is a thing stupendous alike for its force and flexibility; for the prodigious power which it can exert, and the ease, and precision, and ductility with which it can be varied, distributed, and applied. The trunk of an elephant, that can pick up a pin or rend an oak, is nothing to it. It can engrave a seal, and crush masses of obdurate metal like wax before it; draw out, without breaking, a thread as fine as gossamer, and lift a ship of war like a bauble in the air. It can embroider,

and forge anchors, cut steel into ribands, and impel loaded vessels against the fury of the winds and waves.' It can do all this and more since the eulogium here quoted was pronounced; and I look forward to the time when still greater improvements will be effected in the action of the steam-engine and the use of steam.

171

LECTURE VIII.

ON THE CONSUMPTION OF FUEL AND THE PREVENTION OF SMOKE.

THERE is, perhaps, no subject so difficult, and none so full of perplexities, as that of the management of a furnace and the prevention of smoke. I have approached this enquiry with considerable diffidence, and after repeated attempts to derive some definite conclusions, I have more than once been forced to abandon the investigation as inconclusive and unsatisfactory. The difficulties of the question do not arise from any defect in our acquaintance with the laws which govern perfect combustion, the economy of fuel, or the consumption of smoke. They chiefly arise from the constant change of temperature, the variable nature of the volatile products, the want of system, and the irregularity which attends the management of the furnace, and above all, from the want of some acknowledged system for bringing a due proportion of air in contact with the combustible gases in the proper manner. Habits of economy and attention, with regard to a few simple and effective rules, are either entirely neglected or not sufficiently enforced, and it appears obvious to every observer that much has yet to be done, and much may yet be accomplished, provided the necessary precautions are taken, first to establish, and next to carry out, a comprehensive and well-organised system of operations. If this were accomplished, and the management of the furnace consigned to men of more intelligence, properly trained in relation to their respective duties, all

these difficulties would vanish, and the public might not only look forward with confidence to the working of our engines in the manufacturing towns, but the proprietors of steam-engines would be more than compensated for their additional expenditure by the saving of fuel which the improved system of management would insure. Under the hope of attaining these objects, I shall endeavour to show, from a series of accurately conducted experiments, that the prevention of smoke and the perfect combustion of fuel are synonymous, and completely within the reach of all those who choose to adopt measures calculated for the suppression of the one and the improvement of the other.

On a former occasion I had the honour of presenting to the British Association an enquiry into the merits of Mr. C. W. Williams's Argand furnace as compared with those of the usual construction. On that occasion it was found, from an average of a series of experiments, that the saving of fuel (inclusive of the absence of smoke) was in the ratio of 292 to 300, or as 1 : 1·039; being at the rate of 4 per cent. in favour of Mr. Williams's plan. Since then a considerable number of experiments have been made by Mr. Houldsworth, Mr. Williams, and others; and having occasion in the course of this enquiry to refer to these researches, it will be unnecessary for the present to notice them further than to observe, that they have been made with great care, and that they present some curious and interesting phenomena in connection with the further development of this subject.

The complex nature of the investigation has rendered it necessary to divide the subject into sections, for the purpose of observing, not only the relative tendencies and connection of each, but to determine, by a series of comparative results, the law on which perfect combustion is founded, and its practical application insured.