In addition to the ocean storages referred to, there are a very large number of subsidiary storages arranged at convenient places inland for local distribution, the oil being conveyed from the main storage by means of railway tank wagons and motor vehicles. In addition to these, however, there are a large number 01 subsidiary storages on the coast, which are fed by means of coastal boats, also from the ocean storage. In order to meet the enormous ind widespread demand for the large variety of oils consumed in this country for purposes of transport and industry, thousands of small storages and agencies exist throughout the kingdom. It is estimated that the number of tank wagons engaged in carrying oil in this country is about 3,000, and in dis tributing the various oils to agencies an extensive fleet of motor wagons and horse-drawn vehicles is provided, delivery in these cases being in the form of barrels and tins. It is estimated that there are about 300 motor wagons on the road for oil distributing purposes in this country.
The greater portion of the oil imported to Manchester and other parts is carried in bulk by tank steamers, although considerable quantities of barrelled oil are brought to the port of Manchester by the regular liners from North America. The facilities at some of the installations include special conveyors for the quick and economical handling of barrelled oil from ship into storage depot alongside. The oil is distributed from these storages by rail and by road vehicles, while there exists water Ztransit by means of tank barges over thv inland canal'systems of Lancashire, Yorkshire, and the Midlands. Hitherto the polit y of the directors of the Manchester Ship Canal Company has been to prohibit the passage ,over the waterway of petroleum spirit or other oils flashing at less than 73° Fahr., but, in order to meet the request of theeprincipal firms who desired to establish depots on the waterway for low flashing oils, the Canal Authorities decided to permit petroleum spirit, etc., to be imported into the lower section of the Canal near Eastham. The facilities to be granted for dealing with the traffic include the construction of a dock at Stanlow Quarry, with an entrance and turning basin, in which tank steamers laden with such com modities could be accommodated. The dock would be closed by means of a floating caisson to prevent, in case of accident, the escape of spirit into the Ship Canal.
The last ten years have shown remarkable growth in the number of oil-tankers in use, no fewer than over 500 vessels having been put into service during this period. The number of tankers now in use throughout the world is approximately 750, representing close on 4,000,000 tons. It is somewhat difficult to ascertain the annual carrying capacity of this fleet, but, if we allowed a round trip every two months, this would enable 24,000,000 tons of oil to be transported. There are, however, a large number of vessels, which could accom plish more journeys than this each year, and, allowing for these, it is probable that the total quantity of oil transported from the various sources of production approximates more nearly to 30.000,000 ton•.
The bulk of the...," oil carrying vetsel4 are constructed on the Ifihermood longitudinal sy?t&m, the proportion amounting to about 9G per cent. Another of oil tanker construction was introduced about a year ago, which deserve reference. In this method of construction the main transverse frames and beams include ordinary rolled sections spaced in the ordinary way, but they arc simple units not supplemented by floors, web frames, or any such additional material and obstruction in common use. Uniformity of stresses
and sufficient strength arc obtained in the frame members by the introduction of built longitudinal members running from and connected to the transverse boundary bulkheads at the ends of each compartment or hold. The longitudinal members consist of the vertical keelsons along the bottom, which are connected to the transverse frame bars and the shell plating of the ship, and of the horizontal side stringers or shelves, which are disposed along the sides of the vessel, and are similarly connected.
By virtue of this design ordinary transverse frames and beams are used, but floors are entirely dispensed with, and the usual deep vertical webs may be either dispensed with or reduced in number, the necessary strength being secured by the introduction of deep keelsons extending and connected to the bottom plating and by horizontal stringers or shelves suitably spaced and arranged and extending, like the keelsons, the full length of each hold to the boundary transverse bulkheads to which they arc securely connected. The frames may be in one length from the deck to the centre keelson of the ship, and suitably connected thereto, or cut at one or more of the other keelsons, and their ends suitably connected thereto, uniform stress on the frames being obtained by a suitable disposition and arrangement of the keelsons and the stringers. Advantage is taken of the close spacing of the transverse bulkheads in these vessels, and of the great strength provided by the continuous longitudinal centre line bulkhead to spring fore and aft girders along the bottom and under the deck, and connecting these to the transverse bulkheads ; and by fitting strong stringers or horizontal girders round the sides and bulkheads, forming the whole into a series of box-like structures, adequately strengthened by these horizontal and vertical belts of deep girders. The distinguishing characteristics of the system of construction are its extreme simplicity and the reduction of the different sizes of sections involved, the general uniformity in length and dimensions of these, the speed and facility with which the whole ship's structure can be put together, and the consequent reduction of the amount of labour and time involved. There are further advantages of openness and accessibility of all the holds and spaces, and the minimum amount of work and time involved in the event of damage repairs being required in any part of the structure.
Another aspect of tanker construction is that the piping essential to efficient work is of a most complicated character, and the difficulties of attending properly to this installation are obvious. With the object of simplifying this work, as well as of improving generally the construction of merchant vessels, a device known as the Duct Keel was introduced. This form of keel is said to provide a solution of the problems which have to be faced in arranging for the necessary suction and filling systems, and also for the heating pipes. On the vessels now under construction, in which this system is adopted, practically the whole of the oil fuel and bilge systems are accommodated in the box ketl, and the saving in the cost of the installation is very marked, while the acceid?ibility of the piping under all conditions of loading should prove of great convenience. The difficulty of attending on piping systems which run either through oil fuel tanks or through the bilges into oil fuel tanks is very considerable, and this is stated to be entirely eliminated when the piping systems arc run through a duct keel.