Fig. 



332 Mr. A. Trevelyan on the Vibration of heated Metals. 



Description of the Figures. 

 Fig. I. Is the lead block on the rounded surface of which the 

 bar rests, by that means the vibrations being more 

 distinctly seen : this block is screwed to a flat brass 

 plate, having three small flat knobs to rest on. 

 2. Shows the ring on which the bar is to be placed to 

 produce the tone: it is better to have an unequal notch 

 for the bar to rest on, thus 



Fig. 3. Is the back part of the bar, showing the ridge on which 

 it ought to rest when placed on the lead. 



Fig. 4. Is the upper side of the bar, hollowed out in the centre 

 so as to bring the gravity more to each side. 



Fig. 5. Is the bar with a ball at each end, to be laid across 

 the vibrating bar, so as to cause it to move through a 

 larger arc. 



Fig. 6. Shows how the bars ought to be arranged for exhibit- 

 ing both the vertical and lateral motion. 



Fig. 7. Shows the bar as placed for producing the tone. 

 Figs. 3. 4. 5. 



Fig. 1, 



Fig. 7. 



Fig. 2. 



