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"TAE Marine REVIEW 43 EXPERIMENTAL TANKS IN BRITAIN. We are indebted to Messrs. John Brown & Co., of Clydebank ship building yard, Scotland, for the five photographs which here illustrate the ship model experimental tank erected in their works, and which proved of such value to them in investigating and obtaining the necessary informa- tion for designing the mammoth Cun- ard vessel, Lusitania, which they have recently launched. The acquisition of this tank has been a decided advantage to them in solving the best form and to this subject were recently compiled by Engineering, London, in which it is pointed out that the only two prop- erly equipped experimental tanks in the world belonging to private ship building firms are situated on 'the Clyde.' Of these the first is that put down by Messrs. Denny Bros., at Dum- barton, while the second is that now under notice. The other tank is owned by the Norddeutscher Lloyd, and is situated. at Bremerhaven; of the re- maining nine existing tanks, six are storing models, and the other, placed between the dry docks, is used for loading and trimming purposes. The towing-truck can be run over the cen- tral dry dock, and the dynamometer and propeller gears examined from it; the latter must be raised to clear the dock sill. At the south end there is a sloping beach, 25 ft. long, to assist in breaking up the waves formed by the passage of a model through the water. A recess, however, is left up the mid- dle to prevent screws or models being FIG. I.--CLYDEBANK. EXPERIMENTAL TANK. LOOKING SOUTHWARDS SHOWING DRY AND WET DOCKS. x proportions for any required vessel, and has also aided them much in guid- ing the choice of the most suitable propellers for each ship. At the pres- ent time when the steam turbine is re- placing the reciprocating engine, it is especially useful in finding the effec- tive horsepower from model experi? ments, rather than to have to work en- tirely from former experiences of in- dicated horsepower in reciprocating engines. The high number of revolu- tions necessary for turbine efficiency causes modificdtions in the design of suitable propellers, so that previous - practice has to be departed from. Tank experiments can however, be relied on to supply the necessary informa- tion to go upon. ; Some interesting particulars relating government basins, the property re--- spectively of Britain, the. Netherlands, Italy, France, Russia and the United States of America. Cornell and Michi- gan universities and the technical high school at Charlottenburg are each - equipped with.one. At Paris a tank is being constructed for the use of the admiralty and the students of the uni- versity, and several others have "been proposed in Britain and Japan. _ The waterway of the Clydebank tank extends for 445 ft., of which 400 ft. is deep, varying from 9 ft. at the north end to Io ft. at the south end. This fall of one foot is gradual, and is for the purpose of drainage when emp- tying. The breadth is uniformly 20 ft. "At the north end there are wet and dry docks; of the wet docks, one is for run aground. The basin, which is rectangular in cross-section, is formed of concrete, with expanded metal and puddled'> clay backing. The building is of brick, and, besides the tank. proper provides accommodation for a large drawing office, a tracer's room, and superintendent's office, with the necessary fireproof record-rooms, etc. Adjoining the tank and in communica- tion with it is a complete new depart- ment for model makers. These assist in the work of the tank by making cores for the casting of paraffin wax models, and in fairing down the latter when they come from the shaping ma- chine. As it is necessary to keep the temperature of the tank at or about .a uniform degree, winter and summer, a complete system of hot water piping