638° REPORT—1883. 
action must be secured: between signals and switches, to prevent accident. Sir ° 
Sharles Hutton Gregory, in 1843, at the Bricklayers’ Arms Junction, gathered 
together chains from all the signals into a stirrup frame, and a sort of parallel » 
motion was fixed to the frame between the stirrups, in such a manner that the 
depression of any stirrup pushed the parallel motion so as to block one or more 
of the other stirrups, and thus it was impossible to give two signals which 
conflicted with one another at the same time. The switch levers were fixed on the 
same platform with the stirrup apparatus, but were not interlocked with it. The 
switchman, while working the switches with his hands, worked the signals with his 
feet. But the switches were not interlocked till 1852. At Hast Retford Junction 
a simple contrivance was used to effect this purpose, which Mr. Ransome considers. ° 
the germ of the elaborate apparatus which is now used at most of the great 
junctions throughout the country, the main principle of all the systems being that ' 
locking bars moving in horizontal planes should interlock the levers moving in 
vertical planes. 
You are acquainted with the outside at least of those long glass houses 
built high above the line, at important junctions where hundreds of trains pass 
rapidly by day and night, and you may have caught sight on your way of the long 
rows of levers with which they are filled. It is with these handles that the signal- 
man inside the glass house sets the semaphore in motion, and at the same time 
opens the points to direct the train on to a particular line, and perhaps simul- 
taneously close or lock the points of a branch line, thereby preventing the 
possibility of a second train coming on to the line previously occupied. When 
the lever is once drawn over, a mechanical contrivance called a ‘locking bar’ pre- 
vents the points being moved until the whole of the train has passed. In fact, 
with the present apparatus for signalling, the number of trains that may be worked 
on a line of railway with perfect safety is enormous, and may be said to have 
reduced the element of human fallibility to as low a point as human ingenuity is 
capable of compassing. 
Audible signals are in use only in foggy weather, and the detonating signal, 
designed by Mr. E. A. Cowper in 1841, continues to be generally employed in this 
country for that purpose. 
The subject of brake power is one to which very great attention has been given, 
both in this country and abroad ; and certainly, next to the condition of the 
permanent way and the efficiency of the signalling apparatus, perhaps nothing in 
connection with railways is of greater importance. Many lives and much property 
are hourly dependent ina greater or less degree on the power and efficient state 
and immediate action of brakes. It has been found that most of the collisions 
which have occurred might have been prevented had those in charge of trains 
possessed the power of stopping them within a few hundred yards. The higher the 
speed and thé heavier the train, the greater the necessity for a powerful and simple 
brake, capable of being applied throughout the train in the shortest possible time. 
While trains travelled at slow speeds and consisted of a small number of 
comparatively light carriages, the brake on the wheels of the guard’s van and the 
reversing power of the engine were fairly efficient means of retarding the motion, 
or completely stopping trains within a distance absolutely necessary for the com- 
paratively safe’ working of railways. But the demands of the public for increased 
speed, or the increased speed offered as one of the results of competition, and the 
growing length and weight of trains caused by the rapid augmentation of the 
number of passengers, outran the power of the brakes to control effectually the 
movements of ‘the train. Means were sought to add to the control of trains by 
brakes; first, by using the power of the steam acting directly on the brakes; 
secondly, by the connection of several of the old brakes, so as to unite them 
under the control.of a single brakesman; and thirdly, by the introduction of 
brake apparatus connected with the buffers, so as to make the momentum of the 
train itself available in generating a retarding force, a result which has not been 
realised in practice. Colonel Yolland reported to the Board of Trade, in 1858, 
the result of a series of trials with brakes designed on these principles. The 
application of the brake to the engine was an old device which had heen abandoned 
