From Johann Wilhelm Abraham Jaeger
ALS: American Philosophical Society
<Frankfurt-on-Main, December 20, 1777, in French: I have a
powder mill with twenty-six mixers, and am planning a new
one on the model of an oil mill with perpendicular stone mixers,
as in the enclosure. Ordinary stone may produce explosions;
I experimented with marble and found that it apparently
did not. A foreign powder-maker whom I met told me that it
is used in all American mills. I want to be certain of this, because
of the danger involved, and appeal to you as one of our
greatest physicists and mechanics. A word in reply will make
me grateful for the rest of my life. I would offer my services to
Congress were I not, at the age of sixty and after hard campaigns
in 1741-44 that ruined my constitution, precluded from
defending the liberty that I treasure.>
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