348 



Mr Vincent, Experiments on Impact. 



the bottom of the mould. On planing up, the surface showed 

 a fine grained crystalline structure. In Fig. 11 the ordinates give 

 the diameter of the dents in cms. but the abscissas give the 

 diameter of the balls in inches. 



The points thus determined come very nearly on a straight 

 line and this is true for a range of diameters from a quarter of an 

 inch up to two inches. The small discrepancies would have 

 probably disappeared if it had been practicable to have used the 

 average of several results for each ball. This was not done, as it 

 was desired to use the same surface throughout, and not to use it 

 all up on one or two points, as was done in the experiments in 

 which three balls were dropped from the same height. The 

 points plotted are the results of one experiment for each ball. 



The constant p computed from Fig. 11 is 7*3 x 10 8 . 



Using the block of lead which gave the result p = 12 x 10 8 , 

 some experiments were made to test the validity of the formula 



or 



P 



pV=Mgh, 

 _ S2g MDk 



when the material of the impinging sphere was varied, 

 results are set out in the table below : — 



The 



If the formula had been obeyed the last two columns should 

 each contain equal numbers. The numbers are not very different 

 and the formula is obeyed approximately. 



