Moving Bodily an Iron Roof of 98-feet Span. (La Nature, 26 November, 1898, p. 403.) In the course of the demolitions in the Champ de Mars for the Paris Exhibition of 1900, it has been necessary to pull down the former machine-gallery, which had a width of 98 feet, and which had been left standing at the close of the last Exhibition. After the masonry of the side walls was removed, it was decided to employ part of the roofing for the New Electrical Buildings, which will occupy a position at right angles to the original machine-gallery. The simplest mode of making use of the old roof-trusses was to shift them in their entirety, and although this operation is not a novel one, it entailed in the present instance some peculiar features. By reference to a plan the Author describes the three stages in the work; a forward movement for a certain distance, a rotation through an arc of 90°, and a farther movement at right angles to the former one. The gallery it was intended to remove was divided into three sections, each comprising one bay of two complete trusses, with all the intermediate purlins and transoms. Each of these divisions was dealt with independently. In order to brace together each section, and to stiffen it for the removal, the feet of the four main stanchions were united by means of temporary lattice girders 3 feet 3 inches in depth formed of tee-iron, supplemented by vertical and cross ties of steel cable, and the complete structure was lifted from its base, supported on a staging of squared timber, and finally placed on small trucks running on rails beneath each of the four upright stanchions. Each truck moved on four small rollers placed one behind the other, and the whole weight of the structure (about 140 tons) was thus distributed over the sixteen rollers. It was easy to propel the load in a straight line, but special provisions had to be made to rotate the mass so as to assume the new direction needed. The mode of doing this by constructing the platform of each truck in such a way as to allow the weight to revolve on a central pin is described by reference to illustrations. The removal was contracted for by weight; the price, at 4s. per cwt., amounting to £1,720. G. R. R. Two Coal-Storage Buildings at West Superior, Wis., U.S. (Engineering News, New York, 18 August, 1898, p. 99.) These are dome-shaped structures, 246 feet diameter, and 100 feet high. Twenty-four arched ribs, with a tubular top member and a single-webbed bottom member, spring from the ground on hinges. A group of three ribs from one side, joined together near the top, meets a similar group from the other side in one hinge, and the four hinges thus required are independent of each other at different levels in the central vertical. The covering is corrugated iron down to 20 feet above ground and a vertical corrugated iron wall extends from the ground to nearly that height. To resist the pressure of the coal the wall is tied to a steel band about 200 feet diameter, which is buried under the coal when the building is filled. The filling takes place by means of endless-chain conveyors, fitted to a straight trimmer-trough ascending from the outside ground over the corrugated iron wall and inside the building to its apex. The bottom of the trough is formed by a movable steel band, and the opening can be placed gradually higher so that the cone of coal is formed without the coal falling deep. The emptying takes place through a radial tunnel under the floor, containing an endless-chain conveyor, which is served by a reloader. This consists of a system of pockets moving on an endless chain close above the ground from the wall to the centre of the building, and, being pivoted here, can take coal from any part of the pile to the end of the tunnel in the centre. At first the reloader lies over the tunnel buried under the coal, and till it is free the tunnel must be served by shoots suitably placed on each side of it. M. A. E. Steel Dome for the Yerkes Observatory, Lake Geneva, Wis. (Engineering News, New York, 14 July, 1898, p. 18.) The building has a diameter of 90 feet and a height of 60 feet covering the Yerkes telescope, which has an object glass 40 inches in diameter. The dome is made to revolve on a circular rail by means of an endless rope driven by electricity or by hand. It consists mainly of two parallel ribs at a distance of 12 feet. The greater part of this space is not braced across, as between zenith and horizon it forms the observing opening; their horizontal thrust is taken by a heavy lattice ring to which the twenty-two wheels are fixed. Eighteen secondary ribs are placed between the ring and the main ribs, and serve to brace the structure and to form the supporting structure of the roof covering. The observing opening can be closed by two curved shutters moving on horizontal straight rails, one being fixed to the lattice ring, and the other to the main ribs 6 feet beyond the zenith. The floor round the pier of the telescope can be raised or lowered that the eye-piece of the telescope may be accessible at all positions. The article is illustrated. M. A. E. The Ports and the Maritime Canal of Bruges. GEORGES LEUGNY. (La Revue Technique, 25 September, 1898, p. 413.) During the Middle Ages Bruges possessed one of the principal ports of the North of Europe. At that time the Flemish borders were in communication with the sea by means of the Swyn estuary. Unfortunately for the prosperity of the city the bay gradually became filled up with sand, and the citizens had to remove their port, first to Damme and subsequently to L'Ecluse. In the fifteenth century they had to abandon the Gulf of Swyn altogether, and a semi-maritime canal was constructed later to Ostend; the depth, at first only 6 feet 6 inches, was subsequently increased to 14 feet 9 inches; but the town never regained its former prosperity. In 1877 it was proposed to construct a ship canal directly to the sea, but the plan was only settled on its present basis in 1879. The law passed in September, 1895, approved of the entire project, which embraces the creation of a port of call on the coast near Heyst for large vessels, placed in communication with an inner harbour at Bruges by means of a deep and wide maritime canal. The execution of the scheme was, on the 10th January, 1896, entrusted to a company, and the contractors, Messrs. L. Coiseau and J. Cousin, have undertaken to complete the works by September, 1902, for the sum of £1,558,000. The sea-wall enclosing the outer harbour will start from the coast between Blankenberghe and Heyst; its plan is curvilinear, composed of two arcs of circles, the one having a radius of 1,311 yards and the other of 2,187 yards. The total length is 2,250 yards, but the first 335 yards of the superstructure, starting from low-water mark, will rest upon open steel piling, in order that the tidal scour may carry away the silt from the harbour. The remainder of the sea-wall will be founded upon monolithic concrete blocks weighing from 2,500 tons to 3,000 tons each. Details are given respecting the construction of the pier, the entrance channel, the locks, &c., and the inner harbour. The maritime canal, which starts immediately behind the locks, in the same line as the approach channel, is 6.21 miles in length, with a depth of 26 feet 3 inches. The interior port will comprise two basins-the east basin, 26 feet 3 inches in depth, and the western and larger basin, having a depth of only 21 feet 4 inches. Details are given of the present state of the works, and the general arrangement of the scheme is shown by sketch plans. The company has obtained the concession for a period of 75 years. 1 Minutes of Proceedings Inst. C.E., vol. cxxix. p. 414. G. R. R. Sea-Coast Protection Works in Holland. Vox HORN. (Centralblatt der Bauverwaltung, 1898, p. 339.) Cross sections are given of the works at Honds bossche-Pettem which have a length of 5,520 metres (3.4 miles). The embankment rises to a height of + 6 to 7 metres (19.7 feet to 23.0 feet) above high water, and the slopes vary from 40: 1 to 2:1; it is composed of clay partly protected by stone paving and strengthened by pilework at the foot. The works have cost about £275,000 since 1867. Owing to the absence of fore-shore, the great depth of water near the coast line and the heavy sea prevalent, the outermost point of the island of Walcheen has been difficult to protect from the sea. The embankment, as now existing, has a length of 3 kilometres (2.2 miles) and the cross section changes but slightly. Its height varies from + 4.50 to +6.50 metres (14.8 feet to 21.3 feet) above high-water level and the chief slopes from 25: 1 to 6:1. The toe of the bank is supported by sheet piling, and from low to above high-water mark the embankment is protected by stone paving resting on a layer of clay 1 metre (3.28 feet) thick. It is intended eventually to pave the whole surface. Above and below high-water mark piles driven into the bank at intervals and braced together longitudinally and transversely serve as wave-breakers. These piles indeed break the waves, but also loosen the paving, and are therefore being gradually done away with. Five cross sections are given of this embankment. W. B. The Protection of Canal-Banks. HIPPEL. (Centralblatt der Bauverwaltung, 1898, p. 294.) The following method was employed to protect a length of bank on the Wentow Canal. From the bottom of the canal to the maximum water-level the bank has a slope of 1 to 1, and is protected by a continuous sheet of concrete, 20 centimetres (7.8 inches) thick, commencing at the foot of the bank and terminating in a horizontal ledge 0.75 metre (2.46 feet) wide. The depth of water is 2.54 metres (8.33 feet). A network of round rods 6 millimetres (0.24 inch) in diameter with a mesh 0.25 metre (9.75 inches) square, is embedded in the centre of the concrete, and is secured by wire ties to two longitudinal flat bars and transverse flat bars every 3.5 metres (11.48 feet). The flat bars are laid on edge, and where they [THE INST. C.E. VOL. CXXXV.] 2 c cross are twisted so that they meet on the flat, and are riveted together. The framework of flat bars is anchored back by four short screw anchors to every length of 3.5 metres, the distance between the transverse flats. The method is not costly, and work can be done quickly; in the case described a length of 135 metres (443 feet) was built in eighteen days. The article is illustrated by six cuts. W. B. Steel Dam for a Reservoir in Arizona, U.S. (The Engineer, 12 August, 1898, p. 148.) To secure a permanent supply of water on one division of its line in Arizona, the Atchison, Topeka and Santa Fe Railway has formed a reservoir by building a dam across Johnson's Cañon, capable of containing 40 million gallons. The dam is of steel with a concrete wall along its toe and a short abutment of concrete at each end. The steel portion is 190 feet long at the crest, with a maximum height of 40 feet; it is composed of a row of steel frames 8 feet apart, having a slope of 45° on the water face. The covering plates are steel, inch thick, about 16 feet long by 8 feet broad. The plates are dished to increase their resistance to the water-pressure. A. W. B. The Basic Company's Flume, Idaho U.S. (Engineering and Mining Journal, vol. lxvi. p. 455.) The Basic Company has installed a water-power plant on Grimes Creek to furnish, electrically, the power needed to work with dredges, extensive tracts of auriferous gravel. This necessitated the construction of a canal 43,868 feet in length, 15,765 feet being ditch, and 28,102 feet being flume. Of the latter, 1,977 feet are on trestle work, and 163 feet are in a tunnel. The ditch is of uniform dimensions throughout, having a width at the bottom of 60 inches, at the top of 135 inches, and a depth of 36 inches. Its gradient is 5-28 feet to the mile. The flume is of two sections, the larger being 54 inches wide and 27 inches deep, and the smaller being 48 inches wide and 27 inches deep. The small section has a gradient of 10.56 feet to the mile, whilst the large section has the same gradient as the ditch. The tunnel is 5 feet wide at the bottom, 4 feet at the top, and 6 feet high, these dimensions being inside the timbers. The trestles are all of single-deck work, the highest support being 25 feet, and the |