220 The Rev. Samuel Haughton's Account of Experiments made 



is ready to perform its office of stopping a train moving with any moderate 

 degree of velocity. The engine or foremost carriage of the train runs forward 

 upon the sledge, and, striking against its curved front, receives a shock, which, 

 if the sledge were immoveable, would be as fatal as the shock caused by im- 

 pinging upon a stone wall ; but the sledge, having sustained a portion of the 

 shock, slides forward, and the remainder of the momentum is gradually de- 

 stroyed by its friction against the rails. 



The first time I had an opportunity of seeing the Friction Sledge in action 

 was upon the 20th of April, 1849, on which occasion no accurate record was 

 kept of its performance ; it appeared, however, so completely successful in a 

 practical point of view, that I was induced to attempt a few experiments, with 

 a view of obtaining a correct knowledge, theoretical and practical, of its mode 

 of action. I take this opportunity of acknowledging the kindness of the Board 

 of Directors of the Dublin and Kingstown Railway, in allowing the use of wag- 

 gons and a portion of the rails suited to the experiments ; and of stating the 

 obligations I am under to Mr. Wilfred Haughton and the Rev. Joseph A. 

 Galbraitii, without whose assistance in conducting the experiments, and after- 

 wards in calculating their results, I should have been unable to complete this 

 account. 



Our first experiments were performed on the 27th of April, 1849, with an 

 engine and train of five empty passenger carriages,* in the presence of the Rev. 

 T. RoMNEY Robinson, D.D., of Armagh Observatory, and Mr. Bergin, Secretary 

 to the Dublin and Kingstown Railway. On this occasion our mode of measuring 



* The velocity of tlie train on this occasion was determined by counting with a chronograph 

 the time occupied in performing the last four or five revolutions of the driving wheels of the 

 engine; this determination, however, was rendered uncertain by the occasional slipping of the 

 wheels on the damp rails. 



