be covered up with ballast, leaving only the rail head exposed; small limestone ballast is best suited for this purpose.

3. In very wet tunnels provision must be made for drainage, so as to keep the bed as dry as possible.

4. When the rock is poor in carbonate of lime, the ground should be completely covered with small limestone fragments, or when that is not sufficient, the roof and walls should be lime-washed from time to time. Simply sprinkling the ground with milk of lime the Author does not consider to be desirable, as in dry places it is likely to produce dust prejudicial alike to passengers and officials.

5. The engines should make as little exhaust steam as possible in tunnels, and dispense with its use wherever it can be done.

In conclusion the Author hopes that the unexpected results that he has obtained in this investigation may lead to a possible study of the subject by others.

H. B.

Increasing the Weight of Rails in Long Tunnels on the
St. Gothard Railway.

(Glaser's Annalen für Gewerbe und Bauwesen, 1889, p. 120.)

In the seventeenth Report of the Directors of the above railway it is stated that the life of the rails in long and ill-ventilated tunnels is scarcely one-third of their duration in the open air. It has, therefore, been decided in lieu of the normal rails 130 millimetres high, weighing 37 kilograms per metre (74.6 lbs. per yard), to substitute for them in tunnels heavier rails 142 millimetres high and weighing 44 kilograms per metre (88.7 lbs. per yard). That there is a practical economy in this step is shown by the following calculation, from which also it is evident that the saving effected by increasing the weight of the rails is all the greater in proportion to the assumed rate of wear, and, therefore, in proportion to the density of traffic.

Railway Workshops: their Design and Construction.
By J. DAVIS BARNETT, M. Can. Soc. C.E.

(Transactions of the Canadian Society of Civil Engineers, 1889, p. 151, 2 plates.) Beginning with "location," the Author strongly recommends that more than enough land should be purchased in the first instance, even if it afterwards has to be sold for building lots.

Foundations. For northern climates it is better that the sides of foundation-walls should be sloped rather than stepped, so as to prevent the earth from gripping the wall, which is injurious in case of frost. Pillar-footings and column-bases, when above floor-level, are usually based on sheet-lead; the Author is of opinion that the running in, between base and cope-stone, of a fine cement grout would be quite as effective and certainly cheaper. An instance of the use of iron to reduce the first cost of foundation is to be seen in the new erecting-shop of the Grand Trunk Railway at Stratford, where, instead of making continuous walls to carry the rails supporting the traverser-table, it was found less costly and quite as efficient to build disconnected piers and span them with wrought-iron beams of I section. These beams carry the rails laid upon them longitudinally, and support the flooring laid transversely.

Walls. It is best to use bold pilasters or large piers to receive all roof- and floor-beams; setting them so that they stand out prominently, and spanning the panels between them with comparatively thin bonded walls, free from bats if of brick. This method of straight lines and prominent offsets would be of pronounced value in localizing and absorbing the vibrations received from the roof or the machinery, and would result in shops having a less ugly appearance and a longer safe life.

Engine-houses or Locomotive-sheds.-In America the ordinary arrangement is an annulus, or segment of an annulus, whose centre is that of the unroofed turn-table. With this construction is combined a narrow trussed ridge-roof or a so-called flat-roof (angle 5) offering little obstruction to the wind, and permitting the use of an inexpensive roof-covering. A flat roof supported by pillars gives a very stiff building for the limited amount of material used, if sloped inwards the roof-drainage is a simple matter. The stack of the locomotive naturally going to the higher part of the building brings its front end close to the outer wall containing the windows, so that most light is received where it is needed on the moving parts of the machine. In the sparselysettled districts of America, segmental engine-houses of wood with flat gravel-covered roofs are common. They can be built for £170 per stall, the foundation consisting of cedar posts 6 or 8 feet apart, with a mud sill on which rests a pine frame of 6- to 8-inch square scantlings, the roof being single sheeted with 1- or 14-inch tongued boards and coated with paper-felt, tar and gravel; the ashpit,

25 feet long, being of brick or stone, and one iron smoke-jack being provided. The shell of a similarly roofed building with brick walls and stone foundation costs about £200 per stall. In Canada, slate is rarely used for shop roof-coverings, although the native slates are well adapted for the purpose, being very compact and non-absorbent of water. The fire risk from a roof covered with shingles-set in cement and occasionally lime-washed-is very slight; in fact, it is probable that shingles so treated are safer than slate. Referring to the longitudinal saw-tooth roofed enginehouses of the English type, it is stated that the use of this form of roof is not possible in Canada, on account of snow and frost, the Author only knowing of one single instance of its occurrence on the American Continent north of New Jersey. Where longitudinal houses are used, the Canadian substitute for the saw-tooth roof is the single slope ("flat"), or single ridge of quick pitch. An example of this type of engine-house is that built by the Grand Trunk Railway Company at Montreal. This is 76 feet wide by 282 feet long, with five parallel tracks, accommodating twentyfive long tender-engines. The Author devotes considerable space to a comparison of the relative advantages of round and longitudinal engine-houses, citing instances of each kind. On the whole, American opinion seems to favour the round house, but the Author strongly endorses the longitudinal type as eminently serviceable where a large number of engines have to be turned out, almost together, during the busy portion of the day. Many enginehouses are now equipped with a continuous 14- or 2-inch pipe, having branches to each stall and flexible couplings to each engine. Its uses are various. The steam and water from a boiler to be "blown off" and washed out are sometimes used to heat the water with which the washing out is done. The pipe may be passed into a boiler of cold water, so as to shorten the time required for raising steam. Sometimes the pipe is connected with the jetblower at the base of a locomotive chimney, and the steam used in creating a draught to quicken the newly-lit fire.

Oil-house.-A special feature of American engine-houses is a detached oil-house; a fire-proof brick structure with iron roof, roof-covering, and shutters, and floor of concrete or asphalt. Underneath it are iron storage reservoirs, with inlet pipes so arranged that oil received in bulk can gravitate from the tank-car into any of them. Thence it is lifted by hand- or steam-pump into small tanks on the upper floor, and is drawn thence by tap for engine or train use. The cellarage is warmed by steam-pipe from outside, and gas or electric light is used, no lamp or torch being admitted.

Sand-house. From 8 to 10 tons of sand for increasing adhesion of driving-wheels are issued daily at central stations, and large quantities have consequently to be stored, the Columbus (Ohio) sand-store having a capacity of 1,000 tons. The building is of wood, with hinged shutters at top to permit the air to assist in sand-drying. The floor is of dry brick, set on edge with a tile

The

drain below. When required for use, the top layer of sand is shovelled into hoppers containing 1-inch pipes circulating live steam and spaced 21 inches apart. When dry the sand falls through an opening in the bottom on to a concrete floor. Grank Trunk Railway Company has recently employed belt and bucket elevators worked by hand-power for delivering the sand to the box on top of the locomotive.

Coal-shoots are mentioned, but the Author considers that the varying local necessities do not permit any uniformity in this

matter.

General repairing- or erecting-shops.-The consideration which governs the amount of floor-space is the time required to repair an engine. In America a common average is: For heavy repairs, equivalent to a wear of 100,000 miles, 90 days; for medium repairs (70,000 miles), 60 days; for light or specific repairs (30,000 miles), 30 days; general average, 60 days for a wear of 67,000 miles. On this basis, the Author is of opinion that there should be stall-room in the repair-shop for 10 or 11 per cent. of the total engine stock. It may be expected that 4 or 5 per cent. will be in the paint-shop going out, and that 5 per cent. are having their boilers washed out, or undergoing trifling repairs, not requiring them to enter the shop. This leaves 80 per cent. of the motive power effective and at work daily.

The Author next deals with, in succession, traversers, overhead travelling-cranes, the transmission of power, machine-grouping, foundry, brass foundry, smiths' shop and boiler-shop, the particulars given referring for the most part to ordinary practice. He then describes various constructions of floors for workshops. A continuous concrete floor used at Columbus (Ohio) has for its foundations 6 inches of broken stone, then 8 inches of finely-broken stone mixed with cement, and for the surface, a compound 4 inches deep of Portland cement, asphalt and sand, which, being slightly elastic, is not readily cracked. South and West of Philadelphia, a solid floor is made by rolling the earth and then bedding half round locust stringers, spaced 30 inches apart, in 4 inches of concrete. The stringers are floored with 2-inch pine plank. Oak flooring is often used in that neighbourhood, being cheaper than white pine in the local market. The Georgia Central Railway insulates the floors of its shops from the damp earth by running in rosin. In Canada a cheap floor for light weights is made by bedding halfround cedar in a foot of engine-cinders, and nailing 2-inch pine plank on top.

Turntables.-The American pattern of turntable is a "top-deck" structure of cast-iron up to the common diameter of 60 feet. The weight of table and load is carried on a single fixed central pyramid, with an anti-friction cap on the top. No gearing is used; a short lever or hand-spike stands out from one end, and two men are usually sufficient to walk the table and its load around. Turntables of 100 feet in diameter are invariably of wrought-iron with deep side girders, the load being carried on the bottom deck. The

motive-power is usually an independent boiler and engine, running on the ring-rail and coupled to one end of the table by drag-links or other special form of adjusting connection. Particulars are given of the mode adopted by the Author for putting in the foundations of a 50-foot turntable in running sand.

Car-shops. The roofed space required for repairs of freight-cars is severally limited, as 25 per cent. of the work can be done in the open air. The annular form of car-shop, with radial tracks, is occasionally used in America, requiring a turn-table of exceptional dimensions, usually 100 feet in diameter, to permit, not only of a coach or two freight-cars, but also of the small tank-locomotive doing the shunting to turn upon it. There are certain points in favour of the annular form of car-shop if it is intended exclusively for new construction, but the Author prefers the longitudinal freight-car shop, which is of the simplest construction, often wide enough for six or seven parallel tracks and from 200 to 500 feet long.

Warming and Ventilation. - Certain workshops, as paint-shops, need special provision for warming and ventilation. A successful arrangement is the use of a fan to draw air through a nest of small steam-pipes, and then to force the warm air into a light galvanized iron tube, from which it is passed into overhead branch pipes, and delivered through slide gratings below controlled by the workmen. Particulars are given of the application of this system at the Columbus paint-shops; also of a similar method adopted for widely scattered shops at Cleveland (Ohio), by Mr. J. Walker.

The Paper concludes with some considerations on the general disposition of railway workshops, many examples of European and American practice being cited. There are two Appendixes giving the relative area of railway shops for the locomotive and car departments respectively, on the lines mentioned in the text.

A discussion followed the reading of the Paper, chiefly directed to the relative advantages of the round and longitudinal types of engine- and car-house, the prevailing opinion appearing to favour the longitudinal form.

F. G. D.

The Nogent Tramways worked with Compressed Air.
By MAURICE DEMOULIN.

(Revue Générale des Chemins de fer, Sept. 1889, p. 264.)

This is a system of tramways, comprising a length of 7.44 miles now open, commencing at Vincennes, following the road from Vincennes to Nogent and Ville-Evrard, and comprising numerous inclines up to gradients of 1 in 19. The rails are laid to the ordinary gauge, sometimes on the footpaths or the side-slopes, sometimes on the pavement. For side-slopes a flat foot-rail is employed, weighing 40 lbs. per yard, laid on transverse oak