The gauge throughout to be 24 inches, and the lines to be provided with a turnout alongside of each holding of a certain size, and at each place where an agricultural industry such as dairying is established. Stations, means of warehousing, and workshops to be provided only in the proportion of one to each line, all stopping places to require but trifling expenditure. The rolling stock in proportion to each line to be 2 steam locomotives; 2 composite carriages; 2 timber waggons; 5 covered waggons; 20 goods waggons, of sorts. The total capital cost, if undertaken on such a moderate scale, would be 287,1057., or 1,4367. per mile. The estimate of total takings, allowing one mixed train ench With 247,200 train lines per annum this gives 1s. 6d. a mile. The nett receipts for mails, parcel, excursions, and advertising Total nett revenue or about 21. 188. per cent. £10,300 8,214 £18,514 £6,180 1,782 £7,962 Extra nett revenue would be derived with extra mileage run, and it might be expected that two all-round journeys would before long be necessary on several lines. The author omits the question of the purchase of land. Parliament proposes that the public inquiries preliminary to these light railways shall be essentially local. The views as regards compensation and the necessity of buying land will be governed by considerations which will be local in every respect; and if it is in the interests of the locality generally that their expenditure be kept at a minimum, they need not at most exceed 1007. a mile, or 20,000l. altogether. The burthen of the guarantee of this fund I propose shall be the only one to be taken by the County Council, and when that is realised, I think individual interests will receive no unfair share of consideration. At 4 per cent., including a sinking fund, this may at first throw 8007. a year on the rates, but it will soon be earned. In return, the local authority to have a deferred charge on the earnings, and powers to become sole proprietors at the end of a term of years, and in the meantime to be represented on the board of direction. 2. The Gobert Freezing Process for Shaft-sinking and Tunnelling under Rivers. By A. GOBERT, Ingénieur Civil of Brussels. The process consists in freezing water-bearing strata and running sands by means of liquid ammonia poured straight into the freezing-pipes, which are sunk vertically into the ground which is to be frozen. The liquid ammonia, in passing into gas in the freezing-pipes, produces a more intense cold than that obtained by unfreezable liquids, which are themselves rendered cold by the evaporation of ammonia. By adopting direct evaporation, the danger is avoided of rendering the ground unfreezable in the event of the escape of the unfreezable liquid; the cost of the installation is reduced by dispensing with the unfreezable liquid, and with the apparatus used for rendering it cold; and the power of the refrigerating machine is much better utilised. The process possesses the advantage of being able to freeze the bottom without freezing the upper layers. Thus, when it is necessary to deepen the lined shaft of a mine which has been flooded, the freezing-pipes can be placed inside the lining, without any risk of bursting the lining by the freezing of the water which is inside it. In the case of tunnelling under a river, as the evaporation of the ammonia takes place below the water-level, hardly any of the cold is lost in the contact of the pipes with the water; whereas a great quantity would be lost in employing an unfreezable liquid. 3. East Anglian Coal Exploration, Description of Machinery Employed. By J. VIVIAN. 4. The Effect of Wind, and Atmospheric Pressure on the Tides. In this paper it is shown that while a general rule, founded on observations made by Sir J. W. Lubbock, as to the effect of atmospheric pressure in raising or depressing the height of the tides has been formulated, no attempt has yet been made to deduce any law as to the more important effect of gales of wind; and shows that the subject is one of considerable importance to navigation, especially to pilots and captains of coasting vessels, who frequently have to cross over bars and shoals in navigable channels with a very narrow margin of water under the keel, while tides are frequently raised or depressed to the extent of several feet by gales. In the author's opinion the use of the barometer cannot be made of service in predicting the condition of the tide, as the pressure varies on different parts of the coast, and in order to calculate its effect on the tide the direction of the gradient of pressure and the locality of high and low pressure must first be known. This can only be ascertained by consulting the weather charts issued from the meteorological office. This source of information is not available on board ship or at many of the smaller ports. A rapid alteration in the pressure of the atmosphere is almost always accompanied by wind, which affords a more ready and reliable guide for the immediate purposes of navigation. From an analysis of two years' tides at the Port of Boston, and excluding occasions when the element of wind would affect the case, the author found that out of 152 observations, 61 gave an opposite result to that which would have been expected; a high barometer frequently being accompanied by a high tide, and a low barometer by a low tide. On the other hand, with few exceptions, it is found by experience that when the wind blows with any force along a coast in the same direction as the main stream of the flood tide, the tides at all the ports along that coast will be higher than the calculated height given in the tide tables; and when the wind blows against the flood tide, high water will be lower than calculated. The author gives numerous instances of the effect of gales in raising and lowering the natural height of the tides, and tables showing the effect of the gales of November 1893 and 1894 on the tides at the principal ports round the coast of Great Britain. These figures show that the variation is on some occasions as much as from 5 to 6 feet, and the difference in the height between two succeeding tides as much as 8 feet. From an analysis of the register of tides at Boston Dock on the East coast over two years, the author found that 24 per cent. of the whole tides recorded were sufficiently affected by the wind as to vary 6 inches from the calculated height; thirty varied by 2 feet, seven by 3 feet, six by 34 feet, three by 4 feet, two by 4 feet, one by over 5 feet, and one by 6 feet 3 inches. From these tides, checked by comparison with those at other parts of the coast, the author has formulated a table showing the amount to be added to or deducted from the height of the tide of the day as given in the tide tables, according to the strength and direction of the wind: Approximately it may be taken that with a given force of wind of 3 on the Beaufort scale a tide will be raised or depressed by half an inch for every foot of range; with a force of from 4 to 6 the variation may be expected to be 1 inch for every foot; with a gale of from 7 to 8, 14 inch; and if the gale increases to 10, then 2 inches. For example, supposing the rise of a Spring tide at any particular port to be 16 feet above low water, and the wind to be blowing with a force of 5, then 16 multiplied by one inch would make that tide 16 inches higher, or 17 feet 4 inches. It is not intended that any absolute reliance can be placed on the formula, but that it may be taken as a sufficiently approximate guide by which pilots or captains of coasting vessels may be able to form some estimate as to the extent to which the tide will be affected, and consequently the depth of water available over bars or shoals. FRIDAY, SEPTEMBER 13. : The following Papers were read : 1. Notes on Autumn Floods of 1894. 2. On Weirs in Rivers. By R. C. NAPIER, and F. G. M. STONEY. 3. An Experiment in Organ-blowing. By W. ANDERSON, C.B., D.C.L., F.R.S. An organ of sixty-one stops and four manuals at the Goldsmiths' Technical and Recreation Institute, New Cross, London, was found defective in its blowing apparatus. Sir Frederick Bramwell, Bart., LL.D., F.R.S., and the author, governors of the Institute, were requested to look into the matter, and finding that the maximum pressure required was only 10 inches of water, determined to adopt an ordinary smiths' fan, driven by an electric motor specially wound and coupled direct to the fan spindle. Some preliminary experiments showed that a fan with a 10-inch outlet and a six bladed 25-inch impeller, driven at about 1,900 revolu tions per minute, was amply competent to give the pressure and volume of wind required. Some apprehension was felt lest the pulses due to the fan migh interfere with the lower notes of the organ, but exhaustive trials have shown tha no such interference takes place. 4. The Growth of the Port of Harwich. By W. BIRT. 5. The new Outlet of the River Maas at the Hook of Holland, and th Improvement of the Scheur Branch up to Rotterdam. By L. F. VERNO HARCOURT, M.A., M.Inst.C.E. The gradual shoaling of the mouths of the Maas, coupled with the increasi draught given to sea-going vessels, rendered the access to Rotterdam inadequate the first half of this century. An attempt was made to obtain a deeper entrar than existed at the mouth of the new Maas by the construction of the Vonne Canal in 1827-29, enabling vessels to enter by a somewhat deeper mouth to the south; but the available depth over the bar of this mouth was often only 12 feet, and under the most favourable conditions vessels drawing more than 17 feet could not go up to Rotterdam, and even then the route was very circuitous, and the journey occupied at least eighteen hours. In 1858 Mr. Caland proposed cutting a new direct outlet for the Scheur branch of the Maas across the Hook of Holland, continued across the foreshore into deep water by fascine-work jetties, and this scheme was approved and commenced in 1863. The north jetty was carried out in 1863-74 to a length of 2,187 yards, and the south jetty in 1864-76 for 2,515 yards; the channel across the Hook was excavated, 164 feet wide and 10 feet deep, in 1868-71; and the old outlet to the south of the Hook was closed by a dam in 1872. The new channel was first used by fishing vessels in 1871 and by steamers in 1872. The river was also regulated by training works, in a gradually widening channel, from Rotterdam to the Hook. The scour, which had been relied upon for widening the cut and deepening the channel across the foreshore between the jetties, proved inadequate to accomplish this, and accordingly in 1882 the widening of the narrow cut by excavation and the deepening of the jetty channel by dredging, and its narrowing 656 feet by a low training bend to the south, were commenced. The river above has also been further regulated and deepened by training and dredging, and the escape of the ebb tide into the old Maas has beer prevented by the contraction of the entrance to the junction channel. By these works the river has been made to widen out uniformly from 330 yards at Rotterdam to 765 yards at the ends of the jetties; and not only has the navigable channel been widened and deepened, but the flow has been rendered uniform and the tidal scour has been increased. The minimum depth at low tide between the jetties and in front has gradually been increased from 10 feet in 1882 up to 26 feet in 1893, and the rise of tide adds about 5 feet. The maximum draught of the vessels navigating the new channel has increased from 19 feet in 1882 up to 25 feet in 1893; and the number of vessels drawing 23 feet and over has risen from 16 in 1886 up to 150 in 1893. Vessels can now reach Rotterdam from the sea in two hours; and the total number of vessels using this new channel has increased from 6,946 in 1879, with a capacity of 8,314,000 cubic metres, up to 9,628 in 1893, with a capacity of 20,432,000 cubic metres. Before the construction of the Moerdyk bridge, about twenty years ago, and the extension of the railway to Rotterdam, passengers from England to Rotterdam and Amsterdam had to go by Ostend and Antwerp, and by steamer from Moerdyk to Rotterdam; and even after the completion of the railway the journey was a long and circuitous one. Rotterdam also, thirty years ago, was a small town and a somewhat insignificant port. The new deepened outlet and the extension of the railway from Schiedam to the Hook, together with the improved accommodation provided at Harwich, has opened a short cheap route to North Holland, and also to the Continent beyond. The improvement, moreover, of the river has transformed Rotterdam into a large port; large basins surrounded by quays have been found opening into the river, in addition to quays along the river; and considerable extension works are in progress for providing further accommodation for vessels and the rapidly growing trade of the port. Having travelled to Rotterdam in 1865 and 1867 by the old route, by railway from Antwerp in 1880, and down the river from Rotterdam to the outlet, and last year from Harwich to the Hook, and also both up and down the river and through the port, I have myself had an opportunity of witnessing the marvellous development of Rotterdam and the changes which the works since 1882 have made in the river between Rotterdam and the sea. The total cost of the river works, up to their completion this year, has amounted to about 2,950,0007. 6. The Snowdon Mountain Tramroad. By F. OSWELL, Assoc.M.Inst.C.E. The idea of a railway up Snowdon was first suggested as long ago as 1871 when the late Sir Richard Moon, at the opening of the Llanberis-Carnarvon Railway, referred to the possibility of such an undertaking. Several attempts made since that time to set it on foot have failed, but in November last year the necessary arrangements were made with the landowner, and the works were begun in the middle of December. The line is set out with a special regard to the tenants' interests, at the same time to secure, wherever possible, the finest views for the passengers consistent with easy gradients and light earthworks. Leaving the Llanberis Station, which stands on the main road, midway between the L. & N.W. Station and the Victoria Hotel, the line follows the stream as far as Cae Esgob, where it crosses it in front of the old King's House, passes near the Methodist Chapel (Hebron) on the left, and at two miles reaches and crosses the bridle path by a bridge. The first half-way house is passed 60 feet, and the second 180 feet below, the tramroad at this point arriving on the watershed which it follows for half a mile, and crossing the bridle path again at 34 miles, 2,550 feet above the sea, remains below it (at one point as much as 200 feet below) until 44 miles, when path and tramroad run nearly side by side to the summit, terminating at the site of the hotel that is to be built here, 3,500 feet above the sea, and 50 feet below the plateau where the present huts stand. Here a fine view is obtained over the Bwlch Main Watershed towards Beddgelert, as well as in other directions. The length of the line is 43 miles, the total rise 3,140 feet, the steepest gradient 1:55; the average gradient 1: 7.83. Two miles of the entire length are in curves, of which there are thirty-four in all, with radii of 4, 5, 10, 12, and 20 chains. There are to be terminal stations at the top and bottom, three intermediate equidistant passing places, and an additional station at the waterfall (Cenwant Mawr). The works consist chiefly of a viaduct 500 feet long, near the beginning of the line, composed of fourteen brick arches 30 feet span carried on masonry pier a second viaduct of four similar arches crossing the side of the waterfall ravine, an arched bridge of 50 feet span over the stream, and five smaller bridges. The permanent way is all of steel, the rails being of the Indian State Railways pattern, 41 lb. to the yard, 9 metres long, carried on rolled steel sleepers, to which they are attached by clips and bolts. The sleepers are spaced throughout 0.90 metre apart, and the fish plates are 3 ft. 6 in. long, with slots in the ends to admit the clip of adjacent sleepers, each pair carrying six fish bolts. The rack is of the Abt pattern and laid double throughout, the bars being 1.80 metre long, spanning two sleepers and breaking joint with each other. They are inch thick on grades of 1 10 or flatter, and 1 inch thick on all steeper grades. They are carried on rolled and milled steel chairs, which are attached by heavy bolts to the sleepers. The locomotives have been built at Winterthur in Switzerland with the object of saving delay, and they contain all the latest improvements known for this class of engine. They carry two double differentiating pinion wheels on the axles of the driving' wheels, which latter run free on the axles, so that the engine cannot travel on adhesion rails alone. 6 There are two cylinders 12 in. diameter by 24 in. stroke; the rigid wheel base is 4 ft. 5 in. There is a third axle carrying trailing wheels under the cab. There are eight break blocks, four to each pinion. These breaks may be worked by hand, but are applied automatically by steam power if a certain fixed rate of speed is exceeded. There is also an air-break, worked in conjunction with the hand-break in descending, which retards or arrests the motion by forcing air into the backs of the cylinders after steam has been cut off. All the permanent way material has been made by English firms. The |