winch is also fitted with an electro-magnetic brake and hand brake. The turning motor (3 HP. at 1,440 revolutions per minute) actuates a steel worm, the axial pressure of which is taken up by double ball-bearings. A clutch coupling enables the electric drivinggear to be disconnected and hand mechanism to be substituted, whilst the momentum of the swinging jib is absorbed by a frictioncoupling. The current from the overhead wires is transmitted through a triple trolley connected with a reversing-switch, which is turned over when the trolley-poles are reversed for changing the direction of motion. The accumulator-battery consists of sixty cells, and weighs about 46 cwt. The crane has a lifting capacity of 25 cwt., the pitch of the jib is 20 feet, and the weight of the crane, accumulators, etc., on the main pillar is 9 tons.

C. S.

Common Standard Locomotives (Harriman Lines) in America. (American Engineer and Railroad Journal, New York, 1905, May, pp. 154-59, June, pp. 200-206, July, p. 250.)

In July, 1902, a policy of standardization of the entire locomotive equipment of the railroads known as the Harriman lines was inaugurated. The railways concerned are the Union Pacific, Oregon Short Line, Oregon Railroad and Navigation Company, Southern Pacific, Chicago and Alton, and the Kansas City Southern, comprising about 18,000 miles and now operating more than 3,000 locomotives and 90,000 goods-wagons. The policy is part of a plan which has been applied by Mr. Harriman in unifying practice as far as practicable throughout these lines.

The director of maintenance and the director of purchases, in conjunction with the general manager and the superintendents of motive power of these lines, have standardized all classes of locomotives, goods-wagons, and passenger-coaches, including every detail. Complete specifications are made standard for locomotives and wagons, reducing the purchasing to the simplest possible terms. This is the opening article of a series on the complete locomotive standards. At the present time 366 of the standard locomotives are in service. That these standards are likely to influence the practice of other railways is indicated by the fact that 37 locomotives of one of the types are now being built for the Erie Railroad. Four types are adopted for future construction as follows:

Atlantic type passenger, Pacific type passenger, consolidation goods, and heavy shunting engines. It is intended to provide for all the demands of the immediate future from these four designs. The existing equipment provides a sufficient number of light locomotives for many years.

Side elevations and sections of the four standard types, together with a list of comparative dimensions and ratios, and a number of details, are given in these articles. J. M. M.

Standard Bridge Plans and Specifications of the Harriman Lines, U.S.A.

(Railway and Engineering Review, Chicago, 6 May, 1905, pp. 316-22.)

The so-called Harriman lines include the Southern Pacific, Union Pacific, and Oregon Short Line roads, and the Oregon Railway and Navigation.

The maintenance and operation departments of all these lines. are centred under one management in Chicago. One of the objects of centralizing the supervision of so many large systems of railways was to adopt standard plans and specifications for the most important portions of work in maintenance and operation, and this has been done extensively.

This article deals with the standard plans and specifications adopted in May, 1904. These standards were adopted after a convention of the Engineering and Maintenance Departments of the roads named, and the plans were prepared by the Maintenanceof-Way Department of the Southern Pacific Company.

The standard plans comprise plate-girder deck spans, 20 to 100 feet in length over all, varying by differences of 10 feet; riveted through trusses for 100, 110, 125, 140, and 150 feet spans between centres of bearings; and pin-connected through trusses for spans of 150, 160, 180, and 200 feet.

Brief particulars are given of all these spans, and also the weight of steel in each span. Illustrations reproduced from the working-drawings of five of the standard plate-girder spans, one through riveted span of 100 feet between centres of bearings, and one through pin-connected span of 200 feet between centres of bearings, are given in the text. The standard specifications under which these designs have been prepared are given in full, and cover material, workmanship, loads to be carried, stresses, and general details. The article is accompanied by eight figures in the text showing numerous details.

J. M. M.

Reconstruction of the Baltimore and Ohio Railroad Bridge over the Ohio River, at Benwood, West Virginia.

J. E. GREINER, M. Am. Soc. C.E.

(Proceedings of the American Society of Civil Engineers, New York, March, 1905, pp. 194-203.)

An Act of Congress provides that bridges built over the Ohio River below the mouth of the Big Sandy River should have an elevation of not less than 90 feet above low-water mark, and a span of not less than 300 feet over the main channel.

The original bridge was composed of nine deck spans of the

Bollman type, four deck spans and two through spans of the Linville type, with approaches. The length of the iron bridge between centres of abutments is 1,435 feet. This bridge was opened for traffic in 1871.

The rebuilding of this bridge was not a continuous operation, but was effected in sections, those spans which were most expensive to maintain being replaced first. Each section was designed in accordance with the specification in use on the Baltimore and Ohio Railway at the time the design was made; the result being that the new structure is not of uniform strength.

The Bollman spans have been replaced by braced deck girders and the Linville spans by through curved girders. All the spans except the one over the main channel were erected on staging. The span over the main channel was erected on the cantilever principle; the adjoining span on the west side was designed to act as one shorearm of the cantilever during erection, by temporarily connecting their top and bottom booms; the existing span to the east did not require replacing, and as it could not be used as a shore-arm, temporary shore-arms were placed on either side of it during the erection of the main span. The old span over the main channel carried the traffic, and supported the traveller during the erection of the new span. This span was designed so that the trusses and upper bracing cleared the old span, the cross-girders and railbearers were fixed temporarily at a lower level than their permanent position.

To facilitate the connecting up of the cantilever at the centre, jacks for lowering or raising were arranged at the east end of the channel span and at the west end of the adjoining span on the

other side.

A. W. B.

Bonhomme Suspension Bridge over the Blavet.

G. LEINEKUGEL LE COCQ.

(Le Génie Civil, Paris, vol. xlvi. pp. 217-20.)

The development of the town of Lorient, situated on the right bank of the River Blavet, has been greatly retarded by the want of ready means of communication with the smaller towns on the opposite bank of the river, all road-traffic having to be carried over the bridge at Hennebont, about 4 miles inland. The narrow portion of the estuary about midway between Lorient and Hennebont has long been thought to be an ideal site for a suspension bridge, but the towns most interested were quite unable to defray the cost of erecting such a bridge. The Government, although conceding that a bridge would be of great service in developing the district, and, further, that it might prove of considerable value in the event of war, did not incline to carry out the work, but proferred to have it done by private enterprise; and with this

object a concession to construct the bridge and to take tolls was granted in 1900 to Mr. Arnodin, who commenced the work forthwith, and completed it in November, 1904.

The total length of the bridge is 237 metres (778 feet), with one central span of 163 metres (535 feet) and two short spans of 37 metres (121 feet) each, between the main piers and the anchorages. The minimum height of the underside of the structure is 26.95 metres (88 feet) above high water of equinoctial spring tides. The main span may be considered as divided into three parts, the central portion being hung from five continuous cables on each side, and the two end portions, each 36 metres (118 feet), from six diagonal cables on each side. A diagram showing this arrangement is given. The height of the masonry piers is 45.10 metres (148 feet) above H.W.E.S.T., and upon these are placed expansion-blocks. The five main cables on each side pass directly over these blocks, and are made fast to a suitable anchorage on shore, but the diagonal cables for both main and the side spans are made fast to the expansion-blocks, pulleys being used to equalize the load. Auxiliary anchor-cables are attached to each expansionblock to balance the horizontal component of the stresses due to the main cables, which would tend to move the blocks towards the centre of the span. A novel feature in the bridge is that a portion of the roadway is made with reinforced concrete. This roadway was subjected to a most complete series of tests, heavy weights being applied locally by means of levers. The deflection throughout the tests was singularly small.

I. C. B.

Suppression of Timber in the Decking of Modern Suspension Bridges. G. LEINEKUGEL LE Cocq.

(Le Génie Civil, Paris, vol. xlvi. pp. 253–56.)

Timber has long been felt to be anything but a perfect material for the decking of bridges owing, particularly, to its uncertain durability, and to its property of swelling when exposed to damp, and of contracting when dried. It has, however, three important advantages: (1) lightness, (2) elasticity, and (3) the facility with which it can be procured. As regards the first, it is not an unmixed advantage to have a light deck, for the greater the dead load as compared with the live load, the greater will be the rigidity of the structure. As regards the second, the improvement in design of the more modern suspension bridges has resulted in a much higher degree of stability, thus rendering the property of elasticity by no means so important: and as regards the third advantage, the supply of large balks of timber is becoming more restricted year by year. Many arrangements of iron plates supporting woodenblock flooring have been tried, but, although they are uniformly

1

satisfactory in use, their initial cost is very high, and their weight somewhat excessive. A Table, showing the cost and weight of the various forms of decking, is given. Before the construction of the Bonhomme suspension bridge, Mr. Arnodin, the contractor, had a series of experiments made on flags of reinforced concrete, which material he eventually used for the decking of the side spans and for that portion of the main span which is carried by the diagonal cables, i.e., for the whole deck with the exception of the middle length of the main span. The experiments were conducted on flags, 5 metres by 0.67 metre by 110 millimetres thick (16·40 feet by 2.20 feet by 4.33 inches), the centre of gravity of the reinforcing bars being 20 millimetres (inch) from the under face of the flag. Forty-two days were allowed for the flag to set, at the expiration of which time it was placed on supports 4.80 metres (15.75 feet) apart, and a central load of 180 kilograms (396 lbs.), increasing by equal increments of 80 kilograms (176 lbs.), was applied, the deflection for each load being noted. When the central load was just over 900 kilograms (1,980 lbs.), a point where equal increments of load ceased to produce the same deflection, small cracks were noticed on the under side of the flag, denoting that the iron ties had so far stretched as to separate themselves in places from the less elastic matrix. The stress on the iron was then 42 kilograms per square millimetre (27 tons per square inch). The flag was also subjected to a vibratory motion caused by two men marking time" at the centre. The amplitude of the deflection thus produced was 40 to 45 millimetres (1 to 13 inch), and although this was repeated time after time no cracks resulted. The Author considers that reinforced concrete in this form might well replace wood in the decking of suspension bridges.2

66

I. C. B.

New Road-Bridge over the River Thur in Switzerland.

BERSINGER.

(Schweizerische Bauzeitung, Zürich, vol. xliv. p. 157. 6 Figs.)

A new secondary road is being made between Oberbüren and Niederhelfensivel, and a bridge of novel construction has been built over the River Thur at Bilivel-Oberbüren in Canton St. Gallen. This bridge was constructed of reinforced concrete by Messrs. Maillart and Co., of Zürich, and the site is favourable as the banks are rocky. The bridge consists of two arches of 115 feet (35 metres) span and 13 feet (4 metres) high; the breadth between the balustrades is 12.5 feet; and the method of construction is new. There are three principal parts:—(1) the arch, which is 6.24

1 See preceding Abstract.

2 See also Minutes of Proceedings Inst. C. E., vol. clxi. p. 374.