262 



REPORT — 1841. 



The front surface of a single carriage was enlarged by two side boards, 

 each extending the whole height of the body of the carriage, and each being 

 twenty inches in width. The surface thus added was equal to about twenty- 

 two square feet ; the total surface being therefore increased from sixty-two 

 square feet to eighty-four square feet. The carriage was made to descend 

 the Sutton Incline. See Tables XVI. and XVII. The following is an 

 abstract : — 



The differences are very slightly in favour of the ordinary front, but they 

 are altogether so small as to prove that magnitude of frontage, independently 

 of the general magnitude of the train, does not affect the resistance. From 

 this point of view we shall be able to estimate in its true light the value of 

 calculations of resistance to railway trains, deduced from a priori reasonings 

 depending on such limited data as have been hitherto furnished by inquiries 

 grounded on the force exerted by the atmosphere against the surface of bo- 

 dies moving at various velocities. 



There still remained an important point to decide. In a train of vehicles 

 the front surface mainly encounters the brunt of the concussion with the air. 

 The air, being displaced, is forced outwards towards the sides of the train ; 

 but it might be presumed, that, as the separate carriages composing the train 

 are placed at an interval of perhaps three feet apart from each other, a rela- 

 tive vacuum would be produced behind the first carriage, causing a rush of 

 air between the intervals, and until the equilibrium were restored a resistance 

 over and above what would have been observed had no such interval existed. 

 The same cause would take effect in like manner upon the second, third, and 

 succeeding carriages, occasioning to each successively a slight resistance. 



An experiment with a train of eight carriages on the Madeley Plane dissi- 

 pated all doubt upon this head. 



Round the corners of the ends of those carriages tenterhooks were nailed, 

 and the intervals between the carriages were entirely closed up by closely 

 woven canvas stretched tightly from carriage to carriage, and converting the 

 whole train into one unbroken mass. 



The train was allowed to descend the series of inclined planes between 

 Madeley and Crewe. See Tables X. and XI. 



The result was in favour of the train without any canvas. The difference 

 of total distance run in an eight miles journey was 364 yards ; of time twenty- 



