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

134 All About Inventions the fall of pressure in the train pipe brought about the immediate application of the brake upon the vehicle near the point of escape, it was some time before the pressure within the train pipe at the rear of the train had fallen to an equal degree, thereby bringing a corresponding braking effect to bear upon the last vehicles. The new improvement comprised a means of per- mitting the escape of air to the requisite degree from the train pipe beneath each vehicle almost at one and the same time, and this is where the sensitive valve plays its vital part. When the pressure is released in the train pipe beneath the car immediately following the locomotive, the quick-acting valve in- stantly transmits the fall in pressure to the succeeding car, causing a certain volume of air to escape from the train pipe beneath that vehicle. The effect is then handed on to the third car, when a similar result takes place, and so on until the train pipe beneath the last vehicle ejects its proportion of air. This serial trans- mission takes place so quickly that it was found possible, when another trial was made with the fifty- wagon goods train at Burlington, to bring about the full application of the brakes throughout the length of the train in one-sixth of the time previously re- quired ; while not only was the train brought to a stop within a shorter distance, but even under emer- gency or sudden braking conditions, bumping and shocks were reduced to an almost insignificant degree- These later trials with what was now described as the “ quick-acting automatic brake ” made the strongest appeal to railway officials. At last they had been brought within reach of a device for which