AMERICAN INSTITUTE. 581 



Mr. Tillman gave his opinion with illustrations upon the black 

 board. 



The chairman also spoke, and illustrated his views upon the 

 black board. 



Mr. J. K. Fisher — Mr. Chairman : The effect of the oscilla- 

 tions of locomotive engines was not fully appreciated until within 

 a few years; nor was a remedy adopted until long after it was 

 proposed by Mr. Heaton, who was one of the steam carriage pro- 

 prietors. He explained the cause of the fore-and-aft motion, 

 and the slueing or serpentine motion which results from the fore- 

 and-aft motion taking place at different times on the two sides; 

 and he first proposed to neutralize by counter-weights, moving in 

 a direction contrary to that of the pistons. The utility of this 

 counter-weighting is shown by a statement in Clark on Railway 

 Machinery, that an engine on the Orleans railway, which never 

 could attain a speed above 25 miles per hour with a given train, 

 was counter- weigh ted, and run with the same train at 40 miles. 

 This result was supposed to be partly due to the correction of 

 some unobserved derangement, while the engine was in the repair 

 shop, and to make sure on that point, the counter- weights were 

 removed, but the speed fell to 25, and rose to 40 when the counter- 

 weights were replaced. Now by the formula of Eussell, the 

 resistance at 40 miles per hour is 25 pounds per ton, and at 25 

 miles it is 18 pounds; hence the power to overcome the resistance 

 to forward motion at the higher speed was greater than at the 

 lower in the proportion of 40 to 18; and from this it follows that 

 55 per cent of the power existing at the lower speed had been 

 expended in shaking the engine, and in the wear and tear conse- 

 quent on that shaking. 



In the best shops these irregular motions, resulting from the 

 unbalanced momentum of the reciprocating and revolving parts, 

 are now avoided by counter-weighting. But there are other 

 oscillations which still .remain uncorrected, for we cannot con- 

 sider as correction the avoiding of them by the expedient of stiff 

 springs, as is recommended by Clark, and practiced by builders 

 generally. 



If rails were perfectly straight and even there would be no 

 necessity for springs to prevent vertical oscillations, or pitching 

 and rolling; but as this condition never exists or can exist while 

 rails are flexible, or could be maintained at any cost that could 

 be afforded, there must be this dilemma : the unevenness and 

 flexure of the rails will pitch and rock the whole machine if 



