668 



REPORT — 1893. 



Another model is exhibited with a view to illustration of the nsnal 

 method of imparting reciprocating movement by means of a crank 



Fig. 4. 



and connecting rod, and of the attainment of similar and greater 

 movements by the simple rotating weight. This model is also illustrative 



Fig. 5. 



Fig. 6. 



of several interesting questions bearing upon vibration due to rotating 

 weights in machinery as set up in frames, floors, and buildings, and 

 upon elastic vibration. 



The equations on page 666 give the range of gyration when the 

 rotating weight is in the centre of the sieve. When at the end of the 

 screen, as shown, the gyratory path at that end is elliptical, with the 

 major axis transverse to the sieve. At the other end the movement is of 

 less range, the major axis of the ellipse being longitudinal. 



