TRANSACTIONS OF THE SECTIONS. 189 



c. To determine how far the sudden application of a very large amount of 

 brake-power can he resorted to with safety in heavy trains running- 

 at high speed. 



A special Committee of the Railway Companies' Association, on which Mr. 

 Oakley, the General Manager of the Great Northern Railway Company, sat as 

 Chairman, was appointed to confer with us as to the course the experiments should 

 take, the trains that should he furnished for the purpose, and the ground on which 

 the trials should he conducted. 



We selected for this latter purpose the portion of the Nottingham and Lincoln 

 branch of the Midland Railway which extends from Newark to Thurgaton, as 

 offering a piece of line comparatively level and free from any sharp curves ; and 

 through the admirable arrangements made by the Midland Company, we were 

 enabled to carry on the experiments without interruption for the period of a whole 

 week, having free use of the down line of railway, the traffic both ways being 

 worked for the time over the up line. 



Six railway companies furnished for the trials eight complete trains with 

 engines and tenders complete. These trains represented as many systems of con- 

 tinuous brakes, comprising four classes, viz. — 



1 Clarke and Webb's brake. 

 Fay's brake. 

 Applied by ordinary mechanical gear. 

 {Smith's Vacuum brake. 

 Westinghouse's Vacuum brake. 

 Actuated by atmospheric pressure produced by exhaustion of 

 air. 

 I Westinghouse's Air brake. 

 Class 3. < Steel-M c Innes's Air brake. 

 ( By air pressure. 



{Clarke's Hydraulic brake. 

 Barker's Hydraulic brake. 

 By hydraulic pressure. 



The ground chosen for the trial was measured and staked out with a view to 

 obtaining accurate records of the speed of the trains before and after the applica- 

 tion of the brakes. 



It was also levelled, and the gradients thereby carefully determined and laid 

 down in section. The part on which the brakes were generally applied was a dead 

 level. The War Office placed at our disposal the valuable services of Captain 

 (then Lieutenant) R. G. Scott and Lieutenant M. H. P. R. Sankey, of the Royal 

 Engineers, aided by twelve non-commissioned officers and men of that corps. With 

 their aid we were enabled to record in full detail, and with great accuracy, the 

 particulars of each train and of each experiment. 



The speed of the trains was ascertained by means of stop-watches, and to ensure 

 further correctness independent results were recorded by an electric instrument. 

 This was arranged to record in half seconds the time the trains should take to pass 

 over a definite number of the spaces. By clockwork arrangement a long slip of 

 paper was unwound from a drum and passed between rollers. The time corre- 

 sponding with half-second beats of the pendulum was marked upon the paper by 

 a pecker in red ink, and when the flange of the leading wheel of a train passed 

 one of the posts the instant was denoted by a mark in black ink made on the 

 paper slip by another pecker actuated hj a magnet. Opposite each post a circuit closer 

 was fixed to the inside edge of the rail, and when the flange of the wheel pressed 

 down the lever, the circuit was closed and the magnetic action induced. 



The time was measured by noting the positions on the tape of the black or space 

 dots with reference to the red or time dots, which denoted the half-second intervals. 



It was arranged that each train should correspond with that of an ordinary 

 fast passenger train, with average load consisting of engine, tender, thirteen 

 passenger carriages, and two brake-vans, and that each carriage should be loaded 

 with a weight corresponding with three quarters of a cwt. per seat, to represent an 

 average load of passengers with luggage, and that each van should be loaded with 



