Scientific Notices. INSTITUTION OF CIVIL ENGINEERS. GEORGE P. BIDDER, Esq., PRESIDENT, IN THE CHAIR. BEFORE commencing the ordinary business, the President reminded the assembled members, that at the opening of the last session they had heard from the then President, Mr. Locke, a most feeling address announcing the decease of those two distinguished members of the profession, Mr. Brunel and Mr. Robert Stephenson. How little was it imagined, that the lips which then uttered the fervent eulogy upon the memories of his departed friends, would so soon be hushed in the silence of the grave. Another of the leaders had passed away, cut off in the prime of life, and in the full vigour of his intellect. In Mr. Locke, the profession had lost one of its most eminent members, and the Institution one of the ablest Presidents that had occupied that distinguished position. Sprung originally from that great nursery of practical engineers, the works at Newcastle-on-Tyne, Mr. Locke acquired there his mechanical knowledge and his unbounded confidence in the power of the locomotive engine. He was soon transplanted, to co-operate with the late Mr. George Stephenson in several of his early works, and nearly at the commencement of the construction of the Grand Junction Railway, the separation occurred into the causes of which it was as unnecessary as it would be invidious to enter. This separation between the master and pupil occasioned painful feelings at the time, but it must now be looked upon as an inevitable necessity, for the more rapid development of the railway system, at the period when the existing modes of transit had become totally inadequate for the requirements of commerce, and for the growing wants of civilisation. It had always been observed, that whenever the necessities of society required any peculiar development of talent, or any particular invention, by the interposition of an all-wise Providence, the man and the knowledge were forthcoming to provide for the growing wants of society. On the introduction of railways, it was requisite that a vast amount of mental energy and of physical exertion should be employed, in order to render the development as rapid as possible. Mr. Locke possessed peculiar qualities of mind, which secured for him the confidence of capitalists, by whom the construction of the Grand Junction Railway was entrusted to him. At an early period of the railway epoch he became the engineer of the South-Western Line, whence he almost naturally sought for, and ultimately accomplished, the extension of the system to France, where, in the construction of the Paris and Rouen, and Rouen and Havre lines, he introduced English capital, English workmen, and English contractors, and initiated the Continental railway system. He was thus the first who promoted the establishment of the present rapid communication between the great commercial capital of Great Britain and Paris, the fashionable metropolis of the Continent. December Returning to the field of his early labors, he undertook the extension of the lines from Preston to Carlisle, and thence to Glasgow, Edinburgh, and, ultimately, to Aberdeen, thus becoming also the pioneer of the Scotch railway system. Without entering minutely into the details of his professional life, which would be given in the official memoir, it would be admitted, from what had been stated, that Mr. Locke was entitled to be considered one of the great engineers of the period, and a distinguished pioneer in the introduction of the railway system. There was a curious coincidence in the circumstances of the decease of the three distinguished men who had been removed within little more than a year. Each one had departed on the eve of, or at the completion of, some great work. Mr. Brunel might be said to have died as the "Great Eastern" steamer commenced its trial voyage; Mr. Robert Stephenson was taken away on the eve of the completion of the great Victoria Bridge over the river St. Lawence, Canada; and Mr. Locke's decease occurred on the completion of his long-cherished project-the extension of the narrow-gauge line to Exeter, the capital of the West of England. Those who had watched the career of Mr. Locke were well aware how pertinaciously he adhered to the principle of making financial results the exponent of the success or failure of engineering projects. It was not that he feared engineering difficulties, for when they were inevitable he encountered and overcome them with skill; as, for instance, in the Works of the Manchester and Sheffield Railway. But his great anxiety-and which secured for him the confidence of a large body of capitalists-was to attain his object by avoiding difficult and expensive works, from a desire that all the works on which he engaged should be commercially successful. The abnegation of professional renown, arising from the construction of monumental works, whilst establishing his reputation as an economical engineer, induced him to turn to the locomotive engine, and to tax its powers (in which he had, from the earliest period, the greatest confidence), for overcoming steeper gradients than had hitherto been deemed compatible with economy and safety. In this he was very successful; and when viewed in conjunction with the previously-mentioned general features of his professional life, it must be conceded that the decease of Mr. Locke had caused a great gap in the profession, which would long be felt. It would be improper to close this hasty sketch without alluding to the extent to which both Mr. Locke and Mr. Robert Stephenson had acquired the confidence and esteem of a large circle of friends in the House of Commons. They had ably maintained the dignity and the independence of an important profession, which should always be adequately represented in Parliament. They went there without any personal objects beyond that of fair ambition to attain an honorable position; whilst there, they were eminently useful, and it might be hoped that before long other active useful members of the profession would assume their places in the House. , December 1st, 1860, The discussion upon Mr. ScoTT's Paper, On breakwaters, Part II., which was commenced at the closing meeting of the last session, but but was not then concluded, was continued throughout the evening. It was remarked, that in shallow surface waves, the action of the oscillating water might be successfully resisted by pitched stone walls, concave and cycloidal outwardly. But a true breakwater must produce tolerably smooth water, not in the case of oscillating waves in shallow foreshores, but in heavy waves and deep water. A ground swell consisted of waves of translation, occompanied by oscillating surface waves. These two classes must co-exist in deep water, after a heavy storm. Heavy rollers" like those off the Cape of Good Hope were waves of translation, consisting of vast masses of solid water moving in one direction with great velocity. Their action was nearly as powerful at a great depth as at the surface. They were like the tidal "bore" of the Hooghly, or the Severn, or the Dee. They could not be diverted, but must be stopped or broken. This could only be done by a mass heavy enough to be undisturbed by the momentum. A wall of vertical masonry was considered to be the best reflector-cost and durability apart; but a wall inclined at an angle of 45° would also reflect a wave of translation, and at this inclination large blocks judiciously placed would not be disturbed, even although a considerable breach was made in the wall near them. When any approximation to reflection of the wave, by walls not too remote from the vertical face, was abandoned, then reliance must be placed on breaking the wave. For breaking the heavy ground swell, a long sea-slope, with the convex section rounded off at the forefoot, was thought to be the most suitable. The intention in this case was to cause the great wave to begin breaking as early as practicable, to make the breaking last some time, and thus insure the diminution of its momentum being as complete as possible-the wave breaking on itself, and not upon the stones. In practice, both the ground swell and the surface wave-or both waves of translation and of oscillation-had to be contended with. An upright wall, also a convex sea-slope and a vertical pier above, dealt with both. But it was contended, that an outer convex sea-slope of rubble, with a retired vertical wall, and a retiring slope on the top of it, was a better arrangement. Floating breakwaters did not destroy waves of translation; nor did open piles and gridirons stop waves of oscillation; but a number of parallel rows of piles would diminish waves of translation. It was remarked that Kingstown Harbour had been constructed on the long-slope principle-the slope being 5 to 1-at a total cost of only eighteenpence per ton, an amount which had been exceeded by the cost of the scaffolding alone of some modern public harbours. The great breakwater at Portland was also constructed on the same system, and the present engineer had stated, in evidence, that vertical walls would only be necessary for quays or wharves on the inside. In deep water piers the long slope appeared, therefore, to be preferred to the upright face. It was contended that the pier at Blyth could not, with propriety, be adduced as an example of the success of a work with vertical walls when exposed to a heavy sea. It was constructed on a ledge of rock, the surface of which was from 6 feet to 10 feet above the level of low2 z VOL, XII. water of spring tides, having a breadth of about 400 feet seaward of the pier. The seaward margin of the rock bore the name of the "Sow and Pigs," and was situated at a distance of 1100 feet from the foot of the pier, thus protecting it from heavy seas, which were broken half a nautical mile from the line of the pier. In addition to this great natural protection, there also existed, at 60 feet seaward of this work, an old long slope pier, which extended for à length of about 700 feet from the shore. The pier at Blyth was, however, a cheap and proper one for the situation. In reference to Table Bay, it was stated, that the chief danger to shipping and to any breakwater in course of and after erection, arose from the gales from the north and north-westward. These were always accompanied by a heavy swell, the waves of which, from the configura tion of the botton over which they passed, assumed the character of mountainous "shoal water waves." The greater portion of the breakwater would have to be constructed in water six or seven fathoms deep, or a short distance outside of the breaking point of the crest of the waves in the north-westerly gales. Looking at the model of the breakwater proposed by the author, and recalling to memory the volume and the peculiar character of the waves, the condition in which they would arrive at the proposed structure, the momentum and velocity with which they would be travelling, as well as the possibility of gales occuring during the progress of the works-the opinion that the proposed structure was inapplicable could not but be concurred in. And even if the work could be completed, so far from the waves being broken up, or neutralized, it was believed, to use a sailor's expression, they would go "clean over it ;" and that, by the action of a succession of such waves, the entire fabric would be speedily reduced to the state of a dangerous shoal water reef in the entrance of the Bay. It was urged that no uniform rule could be laid down, as to the best form and material for maritime works. It might be safely stated, that the comparative suitability, economy, and duration of any hydraulic work would be almost, if not entirely, proportionate to the amount of knowledge and skill bestowed on the preliminary survey of the physical features and hydraulic phenomena of the locality. The misconceptions arising from the terms "wave of oscillation" and "wave of translation," as applied to the wind-waves of the ocean and sea coast, had, it was thought, contributed in no small degree to the many crude and impracticable schemes which from time to time were brought forward as universal modes of constructing breakwaters and sea defences. It was observed, that the discussion resolved itself into two separate questions-the one, as to which was the best form of wall, in a theoretical point of view, to resist a deep sea wave; the other, the cost of securing that form; and the consideration of cost might lead to the adoption of the less perfect line. It was argued that the vertical wall was preferable to either the cycloidal, or the long slope systems; and the objection to vertical walls, that they were liable to be breached, was not considered to be valid. If stone was abundant and cheap in the neighbourhood of the works, a rubble breakwater, though requiring more than ten times the amount of material which might be necessary for an equally strong vertical wall in the same situation, might yet be December 1st,' 1860. , the more economical structure; but where stone was scarce and dear, the pierre perdue system was inapplicable. In fact, each case must be separately considered. It was thought, that as the hydraulic laws which regulated the motion of waves were fixed and immutable, although the local circumstances might vary in each, yet that some definite conclusion could be arrived at, as to the best form of breakwater; first, for the deep water oscillating wave, and secondly, for the shoal water wave of translation, or wave of percussion. It was believed that the long rubble slope, say of 7 to 1, between the levels of high and low water, which converted the deep water oscillating wave into a wave of translation, was an error of construction, not only as regarded original costs, but also future maintenance of the works. The long sea slope was exposed both to the percussive action of the waves of translation, and to the recoil of the sea, or what sailors termed the under-tow of the wave. In shallow water, with insecure foundations, the cycloidal form was looked upon as the best; but in deep water, for resisting the simple oscillating wave, the vertical wall would be found to be the most economical and durable, and the proper form. It was contended, that in constructing Harbours of Refuge, the object need only be to break the great force of the waves, and not to endeavour to secure such smooth water within, as to enable trade to be carried on, which should be done in an interior harbour, alongside quays. There were several advantages in keeping the superstructure low, say not above high water of equinoctial spring tides. In a military point of view, such a breakwater would act as a glacis to vessels of war inside, over which they could deliver their fire, and be themselves protected, to a great extent, from an enemy outside. It was asserted, that the expense of building the counter-forts, shown in the design proposed by the author, would be greater than building a second longitudinal wall; and that the cost of the whole work would be much in excess of what had been estimated. Also, that a heavy wave, striking upon the gridiron surface formed by the iron girders spanning the intervals between the counter-forts, would have a greater tendency to run up and over the work in a body, than to pass between them and be divided. In reply, it was assumed, that the principle which had been contended for seemed now to be admitted—namely, that the vertical face was the best form hitherto employed. But it was thought by some that the vertical face could only be obtained at great expense. Cost, no doubt, must decide the question; but by adopting the system advocated in the former paper, of first constructing a timber breakwater, and subsequently facing it with stone, it would be found that the vertical face was the cheapest as well as the best. The gridiron breakwater, it was assumed, would be better still, where there was a heavy sea and small rise of tide, and was the form best fitted to deal with waves of great magnitude. It had been said, that rollers could only be broken by opposing mass to mass. The object of the new design was to break the wave without opposing mass to mass. It had been proposed to place an isolated mass of stonework parallel with the breakwater seaward. This would be effective, but it would constitute a second breakwater, and as the slopes must be long, it would be expensive. It |