И. А. Курбасова Е. И. Силантьева

ПРИМЕЧАНИЕ
1. air- and magnetically-suspended — на воздушной и магнитной подушке
15.Прочтите текст С без словаря (6 мин.) и переска­жите его по-английски.
TEXT С. THE EVOLUTION OF VISUAL METHODS

OF RAILWAY SIGNALLING
Railways have always attached special importance to signalling for signalling determines the safety of passengers, railwaymen and rolling stock. On the other hand, it is signalling which facilitates the flow of traffic and thereby increases the track carrying capacity.

You know that the earliest railways had no signals and there was no need for signalling. The lines were short and one locomotive made one or two trips a day on a single-track line. Then traffic grew in volume and it became nec­essary to adopt some signals to control the traffic.

The first visual signals were white and black flags. Lat­er, railroads introduced the so-called ball signals (шаро­вой сигнал). These were fixed signals which were suspend­ed from high towers. The white ball was displayed when the train left the station and the line ahead was no longer (больше не) occupied; the black ball indicated a delayed train.

It was from these primitive signals that the semaphore was devised. The semaphore conveyed its information through the position of its arms (крыло) by day and arms' and light by night. In 1912, the colour-light signals were invented thereby eliminating the need for the semaphore. To govern the train movements this signal uses red, yellow and green lights indicating "stop", "caution" and "clear".