Marine auxiliary turbines were first undertaken in 1911, when four 400-kW 1500-r.p.m. d.c. turbo-generator sets were ordered for the famous Cunarder Aquitania. Later on, propulsion turbines and reduction gears began to be made and in 1917 two 2500-s.hp geared sets were built for the Assiout and Amarna owned by the Moss Steamship Company. These were very successful: subsequent orders covered nine more sets, a further fourteen were built under licence, and ten 1000-s.hp units were supplied for ships built in Canada.

ELECTRICAL EQUIPMENT
For large generators the cylindrical rotors, which had superseded the salient-pole engine types, were at first of laminated construction, and it was not until 1911 or thereabouts that solid rotor forgings began to be used. Another development of the period was multiple-inlet ventilation, and from about 1918, as sizes increased the stator end windings were insulated with mica tape to enable them to be run at higher temperatures.

At this time a 25,000-kVA 25-c/s generator for the Dalmarnock turbine mentioned on page 60 was under construction, the biggest two-pole machine that had been made in this country. As the Glasgow authorities feared loss by submarine, the stator weighing about 30 tons travelled by road with frequent stops for traction engine maintenance. The journey took nearly three months, and the stator arrived covered with names written in chalk. It transpired that the truck and its retinue had created great interest, and, watchful of war security and other considerations, the crew had told inquirers that it was part of a German submarine and that names could be chalked on it at a shilling a time. Shortly afterwards another stator almost as large was sent to the Clyde area by sea—the normal method—and arrived safely in about five days.

Hydroelectric equipment also had been made in large sizes. Three 12,000-kVA waterwheel generators were supplied to Tyssefaldene in Norway in 1913, and they are still running. Towards the end of the war several generators were made for stations in the Pyrenees, for instance one of 2000 kVA at 1000 r.p.m. and one of 5000 kVA at 1500 r.p.m.; the latter was fitted with a cylindrical rotor designed to allow it to run at 85 per cent overspeed.

Transformers progressed chiefly in the direction of higher voltages The first British transformers for 22-kV service were made at Trafford Park in 1909, and for 55-kV service (3000-kVA units) in 1912. These were for the export market, but by 1912 some 22-kV units were also being built for use at home.

In 1918 the first 33-kV and 66-kV transformers were made. The 33-kV units were used for interlinking the supply systems of Manchester and Salford. The 66-kV units, for the