414 SEVENTH REPORT—1837. 
ratio of the forces to resist impact. Before closing the expe- — 
riments, it may, however, be proper to state that, in additionto — 
the methods described in the preceding inquiry, that of grinding 
was adopted. For this purpose, an apparatus was made to 
grind each iron under an equal pressure, in order to ascertain 
the comparative resistances of different specimens of the same 
size, as compared with the results from chipping and filing 
given before. This was done with equal weights, upon equal 
sections, and during equal periods of time; and each piece was 
carefully weighed, in order to determine which of the irons was 
most easily reduced. Notwithstanding the care taken to en- 
sure correct results, I was unable to procure data from which 
any thing satisfactory could be obtained. For instance, in the 
Coed-Talon, Elsicar, and Milton irons, each specimen (nearly 
cubical) was reduced, as in the Table below, where W is a 
constant weight. 
Weight before Weight after Loss. 
grinding. gricding. 
Grains. Grains.| Grains. 
Coed-Talon No. 2 cold blast iron ...... W-+ 356 Ww — i161 217 
Coed-Talon No. 2 hot blast do.......... W + 264 WwW + 128 136 
Hlsicar’ *.6.<cesnesee cold blast do.......... W + 155 w-+ i4 141 
Miltonie?.: axauseace hot blast do.......... W + 211 w-+ 78 133 
The above results, selected from upwards of fifty experi- 
ments, are given, not for the purpose of comparison, but in 
order to enable others to follow up the experiments with 
greater success. I am of opinion that something may be done 
in this way, providing cast-steel cutters are used instead of a 
grindstone, the interstices of which become filled with metal- 
lic particles during the process, as the specimens are reduced ; 
consequently the surface of the stone becomes smoother, and 
the angular points blunted. 
