can well be added, is itself susceptible, popularly speaking, of a further development, and what is known amongst engineers as superheating, is now daily acquiring a greater amount of favour. The process and its effect are simple and easily understood.

In its passage from the boiler to the cylinder, where its work has to be performed, the steam loses a certain amount of heat; in other words, a portion of it becomes condensed into water; and in addition to this, a certain proportion of partially vaporized water passes from the body of that liquid in the boiler along with the current of steam into the cylinder. The steam thus deteriorated is, according to the more recent plan, "superheated" in its passage, the result being an improvement in its quality: for owing to its more perfect vaporization and its increased temperature on its arrival in the cylinder, it possesses more elasticity, and necessarily a greater impelling power. The superheating process is performed by allowing the steam to pass through an apparatus of tubes, around which the flame or heated gases and atmospheric air circulate in their passage from the boiler to the chimney, thus converting the water-charged steam into elastic vapour, or what is technically called dry steam; and utilizing an amount of heat which would otherwise have been wasted.

Another equally simple, useful, and interesting improvement in engineering science, is "surface condensing." The ultimate effect is the same as that of the foregoing process, namely, an acquisition of power without any additional expenditure of fuel. No doubt our readers will have frequently observed a jet of steam passing into the sea from the hulls of steam-vessels. This is the partially condensed steam, after it has done its work in the cylinder; and in order to supply its place, a fresh stream of cold sea-water is admitted into the boiler. The object of surface-condensing is to save the steam by converting it into warm water and returning it to the boiler. The apparatus somewhat resembles the last-named; but cold water for condensing takes the place of steam for superheating. Instead of the cold seawater passing into the condenser, there to be mixed with the steam and pumped off again along with it, the steam alone passes through tubes in the condenser, and around these, there flows a current of cold seawater, which is subsequently pumped out, without having come in direct contact with the steam. The latter is returned into the boiler, and thus, instead of cold water charged with saline matter, that vessel is supplied with distilled water at a temperature of 100° to 120°. The foregoing observations apply to the condensation of waste steam from the ordinary low-pressure engine, but a still further improvement has been added, inasmuch as the steam usually ejected into the atmosphere from the high-pressure engine is now conducted into the vacuum in the

cylinder of a low-pressure engine, working in conjunction with the former, and thence through the surface-condensing apparatus back into the boiler in the form of heated distilled water, thus practically working two distinct engines.*

These are but two of the improvements which have been introduced into a single branch of mechanical science, and if our space allowed it, we might touch upon many others in its various sections. We could speak of the advances in railway travelling, especially over short distances, and underground, instancing the Metropolitan Railway, with its convenient carriages, excellent system of lighting and signalling, and consequently the comparative safety with which the trains pass to and fro. We might refer to the introduction of coal-cutting machinery,† which will, we trust, one of these days, put an end to the destruction of human beings under the most terrible circumstances that can be conceived; to the improvements in machinery for the utilization of hitherto waste products, and new substances, and which along with others already named, could not in their turn be accomplished but for the employment of improved forms of iron, such as the cheaper steels and semi-steels, homogeneous metal, malleable cast-iron, &c.; but our readers must be content with these passing remarks on the progress of Mechanical Science, and pass on with us to the last subject which demands our notice, and without which our work would be far from complete.

We now refer, not to any special branch of science or human industry, but to the progress of scientific education, and that chiefly in our own country.

Whether this be effected by means of Philosophical Institutions for the middle and higher classes; in the University Lecture Hall for students, or through the machinery of the Science and Art Department of the State; it is entitled to, and will receive, our earnest consideration; and as far as the nature of our work admits, a warm support will be accorded to Science instructors of every rank and station; indeed it will be our earnest desire, however limited may be our influence, to promote the welfare of all scientific men, from the most illustrious observer, to the humblest labourer in the fields of Science.

And now, conscious that in this extended but hasty survey, we must have said much that is open to doubt and criticism, and left unsaid

* Of the two steamers Hibernian' and 'Bohemian,' both of which are about the same tonnage, plying between Liverpool and Canada, the former is fitted with a surface-condenser, but not the latter. The former consumes 44 tons of coals per day, and makes 12 knots per hour; the latter requires 55 tons per day, and steams only 11 knots per hour.

† Concerning which, some valuable information will be found in the present number of our Journal.

many things which readier pens or abler minds would have treated with accuracy and clearness, we have a few parting words to add to our readers, and more especially to a large class to whom we look for considerable support, and who may do much to facilitate our labours; we mean ministers of religion.

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It would avail us little, if, after intimating, as we have done in the preceding pages, that the social, and even the political bearings of Science will not be overlooked, we were to remain silent on the great question of Theology. To do this, would be simply to arouse suspicion, and lead to misconstructions which a frank exposition of our views may obviate and we have less hesitation in approaching so delicate a question, from the conviction that however adverse may be the views of individuals, or even, here and there, of some body of narrowminded theologians, a vast majority of our religious teachers look with anxiety, and without apprehension, upon each new revelation of the laws of nature, and watch with interest its bearings upon theological inquiry. Scientific knowledge will never lower man's religious nature, nor render it any less devotional, unless it be employed for worldly purposes, or perverted to private ends by the promptings of passion. Sound Science must make some enemies, for, as we have already said, it drives superstition before it, as chaff is driven before the wind, and it may answer this or that prophet of our day to sneer at its propounders as self-righteous, or to hold them up to scorn as infidels; but every sincere and devoted preacher of the Truth, knows it to be not only to his interest, but that it is indispensable that he should be acquainted with other branches of knowledge than those immediately connected with his vocation, and that he should at least march abreast with, if not precede, the foremost rank of lay intelligence. That many such inquiring men will be amongst our readers, as they may already be found amongst our contributors, we have no doubt whatever, and the question arises, how shall we deal with such subjects as are supposed to have a more or less direct bearing upon Theology?

There need be no hesitation in furnishing the reply.

It would ill serve the ends of truth in any form, if we were to interfere with the free discussion of scientific topics on the ground that the views enunciated might give offence to the believers in some particular theological doctrine. Such a course would defeat rather than promote the ends of true religion, and it may even be necessary that we should now and then be tolerant of the expressions of what may appear erroneous or extreme views, for the purpose of ultimately eliminating the truth. Whilst, however, we have too much faith in the good taste and right feeling of our collaborateurs to suppose that freedom of discussion would ever be employed as a cloak for irreverence, we

are bound to state that it will not be with our cognizance or sanction, if any expression in the slightest degree savouring of this quality finds its way into our Journal; and we add this, not to curry favour with those to whom these remarks are more particularly addressed, but in order that persons who are anxious to consult these pages with a view to the acquisition of sound science for the purposes of religious teaching, may not be driven away, to make place for others of a less friendly disposition, whose aim will be to detect heresy, or to turn the revelations of nature into a means of upholding superstition.

The cause of science may be advocated on the ground that it tends to the comfort and material prosperity of the human race; or because it serves to elevate man's intellect, and to enable him better to fulfil his brief mission on Earth; but its highest title to a foremost place in the literature and teachings of the day is found, not in either of these advantages, but in the fact that by disciplining the minds of men it imparts to them a purer and more elevated conception of the Creator, and prepares them for the comprehension of the highest truths, thus helping to fit them for a purely spiritual existence.

ORIGINAL ARTICLES.

THE COAL RESOURCES OF GREAT BRITAIN.

By EDWARD HULL, B.A, F.G.S., of the Geological Survey of

Great Britain.

Or all sciences, none, perhaps, is so generally regarded as devoid of practical application as Geology. The employment of Astronomy in Navigation is known to all; the numberless uses of Chemistry in the Arts are self-evident; Mineralogy is, of course, of value in detecting minerals; Physics, in laying down the principles of the electric telegraph, and Mechanics, in the construction of machinery. But Geology! "what can be the use of Geology?" asks the world. If you answer that it has served to throw a flood of light on the past history of our globe, such a reply will not satisfy the utilitarian; and the "practical" miner will say (though erroneously) that he can work his way in the earth in search of the minerals as well without, as with, a knowledge of Geology. To all such inquiries, as to the practical use of this science, let me proceed to give a final answer. Premising that Geology is capable of application in the elucidation of a number of questions affecting our every-day life, which cannot be dwelt upon here, I may state that it is pre-eminently useful, and indispensable in enabling us to estimate the extent of those stores of mineral fuel which Providence has laid up in the strata of the earth for the service of man.

The coal stored up in the bowels of the earth is limited in quantity, and, like the Sibylline Books, when once burnt, is irrecoverable; every day sees this store diminished; and just as the master of a house, at the approach of winter, wishes to ascertain the quantity of fuel in his cellar, so must it be a subject of moment to us as a nation-depending as we do so largely on the supply of coal for our manufacturing, commercial, and even political, pre-eminence,-to ascertain as far as possible, to what extent we may reckon on the continuance of this great source of motive power. Without the aid of the science of Geology, such an inquiry could only have ended in disappointment; with it we have all the materials necessary for the solution of the problem, as far at least as regards the actual quantity of coal itself.

The strata, or "measures," containing the beds of coal, belong, for the most part, to the great Carboniferous System of Rocks. They occur generally under two modes of arrangement; either as "basins