EXPEBIMENTS have recently been made on the first of four six-car tube trains manufactured by the Metropolitan-Cammell Carriage and Wagon Co., Ltd. for the London Passenger Transport Board. The train is composed of three two-car units, each car having the whole of the electric equipment under the floor. This avoids the necessity of a switch compartment, and so the new six-car train has approximately the same sitting accommodation as the existing seven-car train. The acceleration has been increased to two miles per hour per second and the braking rate (deceleration) to three miles per hour per second. The increased power has been gained partly by driving directly fifty per cent of the axles and by arranging so that more of the weight of the train is available for cohesion. The total horse-power of the new trains will be 1,650, as compared with 960 for the existing six-car trains. Several firms have suggested various schemes for operating the trains, but the following features are common to them all. All the control is operated at 50 volts and each car is separate and complete. Resistance switches are never called upon to brake under load. Each of the bogies is of all-welded construction and eaeh carries one traction motor on the inside axle. This arrangement provides 58 per cent of the available weight of the car for adhesion. Three of the trains are streamlined at the driving end. The driver's seat is in the centre of the cab, with the master controller and braking controller on either side. The air-operated sliding doors are electrically controlled. Particulars with photographs are given in the Electrical Review of November 20.