In 1893, the Brown & Sharpe Mfg. Co. decided to make a new standard to
replace the one they had at that date. Mr. O. J. Beale was detailed to do
this work. He prepared steel bars about 40 inches long by 1¼ inch square,
and after planing them, they were allowed to rest for several months. At
the ends of these bars he inserted two gold plugs, the centers of which
were about 36 inches apart, and a little beyond these two others about one
meter apart. A bar was placed in position upon a heavy bed. This was so
arranged that a tool carrier could be passed over the bar. The tool carrier
consisted of a light framework, holding the marking tool. One feature of
the marking was that the point of the marking tool was curved and had an
angle, so that if dropped it made an impression in the form of an ellipse.
In graduations, ordinarily, the line, when highly magnified, is apt to
present at its ends an impression less definite than in the center, by
reason of the form of the objective. The line made with the tool mentioned
is short, and that portion of the line is read which passes, apparently,
through the straight line in the eye-glass of the microscope. In order to
make these lines as definite as possible, the point was lapped to a bright
surface. After being placed in position, the microscope, which could be
placed on the front of the tool carrier, was set to compare with the
graduation on the standard bar from which the new bar was to be prepared.
After such a setting the readings were made by three persons, and by
turning the lever the marking tool was dropped, making a very fine line, so
fine indeed, that when the authorities in Washington began the examination
of the bar later on they declared that no line had been made upon these
studs.
After making the first line, the carriage was moved along to compare with
the other line on the standard, and after the correction had been made by
the use of the micrometer in the microscope, the marking tool was again
dropped, giving the second line, which was intended to mark the limit of
one yard over-all. The same operation was repeated in the marking of the
meter. The whole of this work was done, of course, with the greatest care,
and, while the theoretical portion of it appears very simple in detail, it
required a great deal of time and patience before the last line had been
made. The bar thus marked was taken to Washington, and in Mr. Beale's
presence was compared by the attendants with Bronze No. 11 and later with
Low Moor bar, No. 57.
Public-domain text, read in full here on John Shaqi.
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