RAILWAY CONSTANTS. 



231 



is 6570 feet. If a quarter of a mile be deducted for the increase 

 of this distance produced by the effects of the wind, the reduced 

 vahie of S would be 5250 feet, which, combined with the above 

 values of the other quantities, would give p = 6*508, and the 

 corresponding value of/ would be 0'00274. 



In the last three experiments we have M' as before, and 

 M = 18'05. The mean value of V is 49*45, and the mean value 

 of S = 7520 feet, from which, if a quarter of a mile be deducted 

 as the effect of the wind, we shall have S = 6200. Hence 

 p = 6*331, and /= 0*00249. 



If a mean be taken between the two values of / thus found, 

 we shall have 



/= 0*00261 = — . 



'' 383 



This value of/ is in accordance with the approximation obtained 

 from the experiments of M. de Pambour. 



The next set of experiments which demand attention Avere 

 made upon the Grand Junction Railway. 



The section of the Grand Junction Railway from Madeley to 

 Crewe is as follows : 



This series of planes was staked out in the following manner : 

 a stake marked was placed at the foot of the plane at Charl- 

 ton, at the point where the gradients of 1 in 178 and 1 in 265 

 meet. The plane ascending towards Madeley was divided into 

 spaces of 100 yards by 57 stakes, numbered 1, 2, 3, &c., up- 

 wards from the stake ; and the plane falling 1 in 265 from 

 Charlton towards Basford was also divided into like spaces by 

 17 stakes, numbered 1, 2, 3, &c., to 17, commencing from the 

 stake 0, the remainder of the line to Crewe being divided by 

 quarter-mile-posts. 



Five merchandise wagons were loaded with iron chairs, so as 

 to weigh precisely six tons each gross. The empty wagons 

 weighed two tons each. 



These wagons were constructed with high sides and ends, 

 capable of being removed and laid flat upon the platforms of the 

 wagons, so as to expose a greater or less bulk of carriage alter*- 



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