N " D = 65.00 | s = 5 + 2.25 - 1.75 = - 5.50 O " E = 58.33 | t = 5 + 1.33 - 1.01 = - 5.32 P " F = 55.83 | u = 5 + .88 - .61 = - 5.27 Q " G = 54.50 | v = 5 + .59 - .41 = - 5.18 R " H = 53.67 | w = 5 + .43 - .24 = - 5.19 S " I = 53.09 | x = 5 + .28 - .16 = - 5.12 T " J = 52.67 | y = 5 + .20 - .06 = - 5.14 U " K = 52.36 | z = 5 + .11 = - 5.11 V " L = 52.22 | ____________________________________________|___________________________________ --_The Engineer._ * * * * * A SPRING MOTOR. An exhibition of a spring car motor was given at a recent date at the works of the United States Spring Motor Construction Company, Twelfth Street and Montgomery Avenue. As a practical illustration of the operation of the motor a large platform car, containing a number of invited guests and representatives of the press, was propelled on a track the length of the shop. (This was in 1883.) The engine, if such it may be called, was of the size which is intended to be used on elevated railways. As constructed, the motor combines with a stationary shaft a series of drums, carrying springs, and arranged so that they can be brought into use singly or in pairs. Each spring or section has sufficient capacity to run the car, and thus as one spring is used another is applied. There is a series of clutches by which the drums to which the springs are attached are connected, with a master wheel, which transmits through a train of wheels the power of the springs to the axles, of the truck wheels. The motor will be so constructed that it may be placed on a truck of the width of the cars at present in use, and will be nine feet long, with four traction wheels. It is proposed do away with the two front wheels and platform, so that the front of the car may rest on a spring to the truck. There will be an engine at each end of the road, which, it is calculated, will wind up the springs in at least two minutes' time.