•508 report — 1879. 



SATURDAY, AUGUST 23, 1879. 

 The Section did not meet. 



MONDAY, AUGUST 25, 1879. 



The following Reports and Papers were read : — 



1. Report of Committee on Instruments for Measuring the Speed of Ships. 



See Reports, p. 210. 



2. Report of Committee on the Ordnance Datum. — See Reports, p. 219. 



3. Report of Committee on Tidal Observations in the English Channel, Src. 



See Reports, p. 71. 



4. Report of Committee on the Patent Laws. — See Reports, p. 223. 



5. General Residts of Experiments on Friction at High Velocities made in 

 Order to Ascertain the Effect of Brakes on Railway Trains. By 

 Douglas Galton, C.B., D.C.L., F.R.S. 



The experiments were made on the Brighton Railway, with the assistance of 

 Mr. George Westinghouse, with a special four-wheeled Tan constructed for the 

 purpose _; it was attached to an engine, and was run at various speeds, during 

 which time various forces were measured by self-recording dynamometers. The 

 principle of these dynamometers is that the force to he measured acts on a piston 

 fitting in a cylinder full of water, and the pressure of the water is measured by a 

 Richards indicator connected by a pipe to the cylinder ; thus, as the drum of the 

 indicator revolves, diagrams are obtained, giving the force acting on the piston. 

 The advantages of this method are obvious, because the indicator can be placed at 

 any convenient point, and the inertia of the water tends to make the pencil keep a 

 position corresponding to the mean force. A detailed description of the construc- 

 tion of the dynamometers was given to the Section last year, and on this occasion 

 the results arrived at alone will be stated. 



In most of the experiments the tyres were of steel, and the brake-blocks of cast 

 iron. Some experiments were made with wrought iron blocks, but the results were 

 not uniform or satisfactory. 



It will suffice here to give the general results arrived at. 



