All About Inventions and Discoveries
The Romance of modern scientific and mechanical Achievements

98 All About Inventions back is not so pronounced in Britain as in other countries. But while the overhead and underground conduit practices prevail, they do not monopolise the methods of tramway operation. In some instances, instead of the collector of the car being in constant contact with the conductor, current is picked up at intervals. Plates or studs are set in the roadway at certain intervals and over the underground conductor. Norm- ally, these contacts are free from the conductor. When the car reaches a stud a magnet on the car repels the plate, driving it towards the cable beneath, until a contact with the latter is established. The current now flows up through the stud, to be collected by a skate carried beneath the car. When the skate has passed, the plate returns to its normal position flush with the road surface, and free of the conductor below. Consequently, it is “ dead,” and one may tread on it with safety. In this system of operation it will be seen that the car is really driven forward by a continuous succession of intermittent boosts, the current derived from one stud being suffi- cient to propel the vehicle to the succeeding stud. The benefits accruing from a well-laid-out system of tramways may be appreciated even in Britain. Circular routes provide attractive pleasure trips through interesting or entrancing country, enabling one to stretch the lungs with pure air with the minimum of physical effort. But it is in the United States where the greatest advantages of electric traction are revealed. Higher speeds are permitted there than here, with the result that in the rural districts, where the highways are practically free from other