The needed uniformity of
the metal was obtained by using large locomotive tires of known chemical
composition, physical properties and hardness, weighing from 1,500 to
2,000 pounds.
For the greater part of the succeeding 22 years these experiments were
carried on, first at Midvale and later in several other shops, under the
general direction of the writer, by his friends and assistants, six
machines having been at various times especially fitted up for this
purpose.
The exact determination of these laws and their reduction to formulae
have proved a slow but most interesting problem; but by far the most
difficult undertaking has been the development of the methods and
finally the appliances (i.e., slide rules) for making practical use of
these laws after they were discovered.
In 1884 the writer succeeded in making a slow solution of this problem
with the help of his friend, Mr. Geo. M. Sinclair, by indicating the
values of these variables through curves and laying down one set of
curves over another. Later my friend, Mr. H. L. Gantt, after devoting
about 1 1/2 years exclusively to this work, obtained a much more rapid
and simple solution. It was not, however, until 1900, in the works of
the Bethlehem Steel Company, that Mr. Carl G. Barth, with the assistance
of Mr. Gantt and a small amount of help from the writer, succeeded in
developing a slide rule by means of which the entire problem can be
accurately and quickly solved by any mechanic.
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