Steam Navigation Company, and many others who have either introduced the use of auxiliary steam power, or are about to do so, into their magnificent vessels now employed on the great routes to our Eastern possessions and our Australian Colonies. The advantages to be obtained by the application of this power are, however, so ably set forth by Mr. Bourne, that we cannot do better than by giving his views upon the subject. He says:

"The application of the screw as a propelling instrument to aid the progress of sailing ships is, in my judgment, its most valuable application; and if it be the fact, that vessels of this class are capable of carrying more cheaply, as well as more rapidly, than the ordinary class of sailing ships which are unprovided with auxiliary power, then the inference is inevitable, that the commerce of the world must henceforth be carried on by vessels of this description. It is certainly conceivable that, by the application of a certain proportion of steam power to accelerate the progress of sailing ships, so many more voyages may be performed in a given time as to increase the returns in a larger proportion than the use of steam power increases the expenses; and if it can be shown that this result is practically attained, then it follows that the vessels offering these advantages must supersede all others. It is not in calms alone that an auxiliary screw may be usefully employed; but, in light beam winds, it will enable the sails to intercept a new current of wind by the advance it gives to the vessel; and in strong winds it will, by its operation in virtually reducing the resistance of the hull, enable the vessel to use up the power of the wind more effectually, by preventing the rebound of the wind from the sails. An auxiliary screw, therefore, will not only operate in aiding the progress of the vessel to the extent of the velocity which it directly imparts, but it will further aid the progress of the vessel by enabling the sails to act with greater efficiency. A strong wind blowing against the side of a house gives no motive power to that house; and a strong wind blowing against the sails of a very slow sailing ship will impart very little motive power to the ship, but the wind will rebound from the surface of the sails with nearly its original velocity. The power imparted to a ship by the sails depends conjointly upon the amount of the pressure and the space through which the pressure acts in a given time; and if the motion of the vessel be very slow, the power communicated will be very small, whatever the pressure of the wind may be. If, however, the vessel has been already put in motion by the action of a screw, the pressure of the wind must act through a considerable space in any interval of

time; and by the application of a screw, therefore, the efficacy of the sails will be increased in the proportion of the increased speed. It will follow, moreover, that the action of the sails will increase the efficacy of the screw; for, as the speed of the vessel will be increased by the sails, the screw will act upon a larger volume of water per revolution, and the slip of the screw will be thereby reduced. If a screw vessel be set to encounter a head wind, it follows that, as the diminished advance compels the screw to act for a longer time upon the same water, the inertia of the water is inadequate to prevent the rotation of the blades in the manner of a centrifugal fan; and the thread which should be traced in the water being broken or stripped, there is necessarily a large amount of slip. When the progress of the vessel, however, is aided by sails, this action is reversed, and the screw operates, under such circumstances, in a more efficient manner than if the assistance of sails were not employed. In most vessels, therefore, which are fitted with an auxiliary screw, the engines are kept constantly at work, whether there is an absence of wind or whether the wind is favourable or adverse; for in strong favourable winds the screw enables the sails to extract more power from the wind, and in adverse winds the screw will enable the vessel to sail closer to the wind. Both of these effects, however, are equally producable by increasing the size of the hull; for an increase of the size of the hull has precisely the same operation as applying an auxiliary screw, so long as the vessel is under sail. The combination of the two expedients, however, will have the best effect; and very large sailing vessels of a very sharp build, and provided with a moderate amount of auxiliary power, will achieve as high a measure of speed as common paddle steamers of smaller dimensions, but of a far larger proportion of power to tonnage, under all circumstances, except when set to encounter head winds. It is quite possible, however, I consider, to construct sailing vessels which shall sail directly against the wind, and in time, no doubt, this improvement will be accomplished. Sailing vessels will then be able to perform their voyages without tacking, as is now done by paddle vessels of large power; and, if furnished with a screw, the screw will then be able to work with much the same efficiency whatever be the direction of the wind relatively with the vessel's course.

"At the time of the first introduction of screw vessels, I drew up an estimate of the comparative expenses of conveying a given quantity of merchandise in paddle vessels of full power, and in screw vessels of auxiliary power, and I deduced from thence the conclusion, that

paddle vessels with a large proportion of power to tonnage must be abandoned in the coasting trade. The formation of coast lines of railways having had the effect of withdrawing from those vessels many of the first-class passengers, and also those finer articles of merchandise for the conveyance of which high rates of speed are alone of importance, it became clear that screw vessels maintaining a somewhat inferior speed, but apable of earning a profit at such low rates of freight as would not enable paddle vessels of full power to run at all, must be the only species of vessel that would be successful, and therefore the only species of vessel which could remain in use under the circumstances recited. The large increase of screw vessels since that time, and their gradual supercession of paddle vessels in the coasting trade, and in all other trades of a similar character, has confirmed the accuracy of these views; and paddle vessels, except for river navigation or the conveyance of important mails, appear likely, before long, to become only matters of history."

Mr. Bourne then produces some very important facts as to the economy obtained by the conveyance of freight in screw propelled vessels, as compared with sailing vessels and paddle-wheel steamers, all of which are so plain and convincing that we cannot be surprised at the rapid progress which has been made by the principle of screw propulsion during the last two years, and in fact, since its first introduction, which is hardly more than ten years since. It need hardly be remarked that the principle has been extensively introduced into Her Majesty's navy, as also into that of France and other maritime powers, and has been, as before stated, adopted in the fleets of our great commercial steam companies, and in the United States, the scientific detail of which will be found set forth in the work before us. We cannot, however, close the notice of this treatise without referring to a very novel and important proposition of the author, namely, the introduction of a system by which the conjoint action of paddles and screw may be applied to propelling steam vessels, thereby obtaining a much greater amount of speed than is now accomplished by ordinary paddle-wheel boats, and that with no additional expense as regards fuel. One great result to be obtained from this plan would be to enable the companies who are now running paddle-wheel vessels, the want of power and speed in which is now a subject of great and general dissatisfaction, to maintain a higher rate of speed than they now accomplish, at a very small expense, and thereby save a great sacrifice of property, which is now inevitable. We may remark, that the Royal West India Mail Company, and in some cases the Penin

sular and Oriental Company, and others of lesser note, would do well to consider this subject. A still greater end may, however, be accomplished by this plan, namely, its introduction into vessels of a larger class than any now employed, in which all the great improvements of the day may be introduced, both as regards construction and carrying capacity, and by the aid of the conjoint propelling powers now suggested, a greater amount of speed obtained than anything now existing in ocean steam navigation. This very desirable object is now likely to be attained through the enterprise of the Eastern Steam Navigation Company, who at their last meeting resolved, under the advice of Mr. Brunel and several eminent engineers and shipbuilders, to build vessels upon these principles, which should accomplish the voyage to Calcutta from this country in from twenty-five to thirty days, at the same time affording a more superior class of accommodation to passengers than has hitherto been offered by any other route, and with every capacity of conveying merchandise at the same rates as by sailing vessels. It appears, therefore, that Mr. Bourne's plan, which he states was offered to and declined by the Directors of the Peninsular and Oriental Company, is now likely to be carried out by a company who will probably, at no very distant day, rank as their most formidable rivals in the passenger traffic to the East.

In closing our notice of Mr. Bourne's book, we cannot but express our satisfaction at the manner in which the work is placed before the public, both as regards subject-matter and the diagrams by which it is illustrated. The work is dedicated to the memory of the author's father, Captain Bourne, R.N., the founder, and for many years a highly esteemed Director of the Peninsular and Oriental Company.

The Colonial Church Chronicle and Missionary Journal, for July. Francis and John Rivington, London.

THE last number of the Colonial Church Chronicle and Missionary Journal contains a great deal of interesting matter regarding the celebration of the third jubilee of the Society for the Propagation of the Gospel. We transcribe from its pages the following particulars :

"At nine o'clock on Tuesday, June 15th, Westminster Abbey was opened for the celebration of the Jubilee, and every available place was soon filled. At ten o'clock, the following prelates entered the choir, viz., His Grace the Archbishop of Canterbury; attended by his trainbearer and two chaplains, in their surplices; His Grace the Archbishop of York, the Bishops of Salisbury, St. Asaph, Chichester, Oxford, Argyle and the Isles, Ripon, Fredericton, Michigan, Western New York, Edinburgh, Glasgow, Moray and Ross, Bishops Carr and Spencer. The prayers were offered by the minor canons. The first lesson was read by the Bishop of Argyle and the Isles; the second by the Bishop of Western New York. "Comfort ye my people" was the anthem appointed for the day. The Communion Service was read by the Archbishop of Canterbury; the Epistle, by the Bishop of Michigan; the Gospel, by the Bishop of Edinburgh; the Offertory Sentences, by the Bishop of Ripon; the Exhortation, by the Bishop of Moray; the Invitation, by the Bishop of Glasgow. The Holy Communion was then administered to more than 850 communicants, clergy and laity, in perhaps about equal proportions; and the alms offered by the congregation amounted to the sum of £440. An admirable sermon was preached by the Bishop of Oxford, from Ezra iii. 12, 13, which, we believe, is in the course of publication. In the evening of the same day, St. James's Church, Piccadilly was opened for Divine service, which was celebrated by the rector, the Rev. John Jackson, M.A., the sermon being preached by the Bishop of Western New York, who took his text from Malachi i. 11. It was such as to produce a deep interest amongst a numerous and most attentive congregation. A collection was made at the conclusion of the service, which amounted to £35. The ordinary anniversary of the Society was commemorated at St. Paul's Cathedral, at half-past three o'clock, P.M., of this day, when the sermon was preached by the Bishop