872 
STATE AGRICULTURAL SOCIETY. 
notice of these stones is derived from the same source to which 
we are indebted for the foregoing description: 
“The success which has attended the application of Mr. Ransome’s beau¬ 
tiful process to the manufacture of artificial grindstones has been so marked 
that there seems to be little doubt that the use of natural stones for grinding 
purposes will eventually become the exception instead of the rule. Amongst 
other firms, Messrs. Bryan Donkin & Co., the well-known engineers of Ber¬ 
mondsey, have tried experiments which very decisively prove the advan¬ 
tages of the artificial over the natural stones. Messrs. Donkin were first sup¬ 
plied with a pair of Mr. Ransome’s artificial grindstones in December last> 
and early in the present year they carefully tested these stones and compared 
their efficiency with some Newcastle stones at their works. Both the nat¬ 
ural and artificial stones \<ere mounted in pairs on Muir’s plan—a system in 
which the peripheries of the two stones of each pair rub slightly against 
each other, with a view of causing them to maintain an even surface—and 
the two sets of stones were tried under precisely the same circumstances, ex¬ 
cept that the Newcastle stones had a surface speed more than twenty per cent, 
greater than that of the others. 
“The trials were made as follows: A bar of steel, three-fourths of an 
inch in diameter, was placed in an iron tube containing a spiral spring, and 
the combination was Uen arranged so that the end of the bar project from 
the one end of the tube barely touched one of the artificial stones, while the 
• other end of the tube rested against a block of wood fixed to the grindstone 
frame. A piece of wood of known thickness was then introduced between 
the end of the tube and the fixed block, and the spiral spring, being thus 
compressed, forced the piece of steel against the grindstone. The same bar 
of steel was afterwards applied in the same way, and under presicely the same 
pressure, to the Newcastle stone, and the times occupied in both cases 
in grinding away a certain weight of steel from the bar were accurately 
noted. 
“The results were that a quarter of an ounce of steel was ground from the 
bar by the artificial grindstone in sixteen minutes^ while to remove the same 
quantity by the Newcastle stone occupied eleven hours; and this notwithstand¬ 
ing that the surface speed of the latter was, as we have stated, more than 
twenty per cent greater. Taking the twenty per cent, greater speed of the 
Newcastle stone into account, it will be seen that the eleven hours run by it 
were equal to thirteen and three-quarters hours at the same speed as the ar¬ 
tificial stone, and the proportional times occupied by the two stones were 
thus as sixteen minutes to thirteen and three-quarters hours, or as one to fifty- 
two, nearly ! 
“ Such a result as this is something more than remarkable, and it is one 
which would scarcely have been credited, even by those who made the ex¬ 
periments, if it had not been fully corroberated by subsequent experience in 
the working of the artificial grindstones. Since the experiments above des- 
