Hopkins' experience working with stone leads him to believe
that one more ingredient, even more basic than sand, will
improve the efficiency of the granite cutting: water. Water,
Hopkins argues, will wash away dust that acts as a buffer to
the sand, slowing the progress.
Adding water, though, makes it harder to pull the copper saw
back and forth. While Hopkins is convinced water improves the
speed of work, Stocks' measurements show that the rate of
cutting is the same whether water is used or not.