■274 



400 pounds more than is necessary to balance the^-evolving weights at the 

 crank pin, that is, so far as vertical effects are concerned, the wheel is 400 

 pounds out of balance. 



Wires which have passed under the wheel at speeds below 30 miles do 

 not vary greatly in thickness. At a speed of 59 miles (333 rev.) however, 

 a very short section of the wire is left entirely round, showing clearly that 

 at this speed there is an instant in the revolution of the wheel when it 

 exerts absolutely no pressure upon the rail, and making it fair to assume 

 that there is another instant when it exerts double the pressure it trans- 

 mits when at rest. In other words, in half a revolution, occupying less 

 than a fifth of a second, the wheel pressure varies from nothing to 14 tons. 

 The increment of the pressure is really more rapid than this, for it is found 

 that the maximum lift occurs after the counterbalance has passed the 

 vertical by a considerable angle. During the upward action the wheel 

 lags and during the downward action there is a corresponding acceler- 

 ation. 



For speeds above 50 miles the undamaged portion of the wire is longer. 

 Thus for 65 miles it is about 45 inches, showing the wheel to be off the 

 rail for almost a (|uarter of a revolution, and its return to the rail is corre- 

 spondingly rapid. The destructive effect of such a blow is enormous. 



Complete wires are shown, also a diagram of a typical wire taken at 65 

 miles in which the vertical scale is greatly increased and the horizontal 

 scale is diminished as compared with the actual dimensions of the wire. 

 This diagram shows, as do all the wires, the lagging of the wheel in its 

 upward motion and the rapidity of its return to the rail. 



In addition to the immediate results yielded, this experimental investi- 

 gation may serve as a means to a more complete mathematical analysis of 

 the subject. This latter phase of the work is now being very skillfully 

 developed by Mr. Daniel Royse, M. M. E., Junior member of the A. S. of 

 M. E., to whom, also, I am indebted for numerical results derived from a 

 study of many wires. 



Tjie Colvmhian Mi'SEUM. By John- M. Coui.tkk. 

 [Abstkact.] 

 An explanation of the organization of the Columbian Museum and its 

 scientific possibilities. 



