in order to procure the money necessary to enable them to keep pace with their requirements. When dealing separately with the several Colonies, the proportionate area of territory to each mile of railway has been stated; but this ratio is such an important gauge of their respective capabilities for future developments, that the facts as regards the larger of the Colonies mentioned may with advantage be again quoted for comparison with Great Britain and with each other. It is noteworthy that whilst our own country has for the last three hundred years been steadily building up a great empire, by the acquisition of colonial possessions in various parts of the globe, it is only within the last decade that any other European State has taken any action of importance in the matter of colonization. It is also worthy of remark that, within those portions of the world possessing such a climate as to admit of the employment of white labour upon out-door operations, there is not now a single region of any magnitude available for colonization. It is an indisputable fact that no inconsiderable part of the area of the globe is under the imperial ægis of Britain; can this be held to be accidental in the ordinary sense of the word? I trow not. For myself, I can only see in it the working of an overruling Providence. Permit me, before concluding, to say a word as regards the capabilities and possibilities yet to be developed by the Civil Engineer-whether in the Colonies or in the Mother Country. The field is indeed a vast one; great advances have been recently made, and are still being made, in every branch of engineering, among which the foremost place must, at present, and most appropriately, be assigned to that great structure, the Forth Bridge; of the principles and of many of the details involved in which we may, it is to be hoped, confidently look forward to a technical description being presented to our Institution by the Engineers of the work. Notwithstanding these great advances, he would be rash indeed who would venture to prescribe a limit to engineering achievements. I do not pretend to dogmatize, but venture to express my conviction that so long as the present dispensation may last, so long will there be a continuous progress in the science and practice of every branch of labour in the field appertaining to the Civil Engineer. Neither to the Engineer, nor indeed to any other disciple of natural science, would it seem to have been announced -I say it with all reverence- "Thus far shalt thou go, but no farther." I have submitted in detail the sizes of the most important of our Colonial Dependencies; it is only, however, by summing up their areas that anything like a correct idea of the magnitude of the British Empire can be arrived at. Consider the British Colonies in groups, corresponding with the several quarters of the world :— 770,000 Africa North and South America, including the West) 3,650,000 Indies and other islands As a matter of fact, our Colonies proper, exclusive of British India, are equal in extent to one-sixth, or, including India, to nearly one-fifth of the entire land area of the globe. Bearing in mind how small-indeed how comparatively insignificant in point of size is this little island of ours, "this precious stone set in a silver sea," now become a Mother of nations, we cannot fail to realize that, as members of this mighty Empire we are partakers in a great and goodly heritage. That the benefits of civilization have gone forth with our fellow-countrymen to the most distant parts of the earth cannot for a moment be doubted; nor will it, I trust, be questioned by any whom I address, that the greatest of all has been the Gospel of the Grace of God. Granting this, it may with con fidence be affirmed that, among the material benefits which sur round our fellow-countrymen (our "kith and kin") in their new homes across the sea, by no means the least will be those which can fairly be claimed as having been attained through the instrumentality, the skill, and the labours of the British Civil Engineer. On the motion of Sir John Fowler, K.C.M.G., Past President, seconded by Sir Charles Hutton Gregory, K.C.M.G., Past President, it was resolved by acclamation : : "That a cordial vote of thanks be passed to the President for his interesting address, and that he be asked to permit it to appear in the Minutes of Proceedings." The President, after acknowledging the resolution and consenting to the publication of his address, proceeded to distribute the Medals, Premiums, Miller Scholarship, and Miller Prizes awarded by the Council for the Session 1888-89 (vol. xcviii. pp. 224 and 225). 19 November, 1889. Sir JOHN COODE, K.C.M.G., President, in the Chair. (Paper No. 2404.) "Water-Tube Steam-Boilers for Marine Engines." WATER-TUBE boilers are those in which the water to be evaporated is contained within the tubes which form the heating-surface. In the year 1878, Mr. Flannery contributed a Paper to the Institution,' showing what progress had been made up to that date with this kind of boiler at sea. This communication and the discussion which followed clearly proved that, although considerable saving of fuel might be obtained with water-tube boilers, as then made they were unsuitable, because the tubes forming the heating-surface were burnt, owing to insufficient circulation. The subject to which the Author desires to direct particular attention is therefore circulation; and by this term to convey the idea of motion of the water contained in a steam-generator from the upper surface of the liquid, down to the lower parts of the generator, and returning again to the upper surface. Motion of water, simply from the point where the feed-water is admitted to a point in the boiler where it becomes steam, he would wish to hold distinct from the idea of circulation. Having so defined the term, he would divide all boilers into classes depending on the manner in which circulation takes place. The motion may depend on difference of density in the ascending and in the descending columns of water, or mechanical means may be provided to induce or compel the necessary motion of the water in the generator. In order to give more definite meaning to the classification of boilers by these peculiarities of circulation, the Author would direct attention to Plate 1, Figs. 1 to 8. If an open vessel containing water, such as shown in Plate 1, 1 Minutes of Proceedings Inst. C.E., vol. liv. p. 123. Fig. 1, should have its lower surface uniformly heated, circulation will immediately commence. Before the water begins to boil this circulation will be feeble, owing to the small difference of density in its different parts. When, however, boiling takes place, the action will become energetic, but will be wanting in order; it is struggling and confused, and nowhere acquires any high velocity. This may be taken as a model of probably the oldest and simplest form of boiler, and the circulation has the same character as that of by far the greatest number made, including modern marine boilers, and, as Mr. Flannery showed, the first water-tube marine boilers also. Plate 1, Fig. 2, represents Mr. Loftus Perkins' water-tube boiler. This belongs to the class in which there is no circulation, and consequently pure water must be used to avoid the deposit of sediment at and about the water surface, or that part furthest from where the feed-water enters. Plate 1, Figs. 3 and 3a, represent a large class, in which straight tubes are placed over the fire, and, by being divided into numerous sections, avoid the difficulties to some extent caused by unequal expansion; but the circulation is not sufficient to allow the boilers to be forced to the degree necessary to make a light steam-generator, although it is assisted by a pump returning water from a separate vessel used to divide the water from the steam. In this particular it is similar to Plate 1, Fig. 4, Mr. Herreshoff's boiler, which, however, seems to gain by having only one passage, so that any water in going through the boiler must traverse the entire heating-surface. This boiler has been made to stand forcing much better than the Belleville. The circulation, when the rate of working is changed, is difficult to manage. In proper working water comes over with the steam; with a reduction in the flow of steam this is liable to cease; superheating then commences, and if more feed-water be suddenly pumped in, the effect is. at first to suspend boiling in some of the coils, with the result of reducing the volume of the water contained, and thus failing to arrest the superheating as quickly as might be wished. The Field tube, Plate 1, Fig. 5, is the first example given of circulation depending on difference of density, in which circulation is for the most part systematic. The Field tube consists mainly of two concentric cylinders; the outer surface of the larger one is heated, the intermediate space between them forms a channel for the ascending current, and the denser water descends |