The following article is taken from the
publication Scientific American circa 1861
Improved Surveyor's Measure and
Tackle Case
Surveying
is performed by the measuring of lines and angles, and the instruments for both
of these measures have engaged the attention of numerous and of highly
cultivated minds. In the trigonometrical survey of Massachusetts, the base
line was measured along the valley of the Connecticut by means of two rods, one
held stationary while the other was carried forward and placed against its end;
instruments being used to keep the rods level and in a straight line. The
rod used for measuring lines in the coast survey was exhibited at the Crystal
Palace in 1853. It was a long barrel with complicated arrangements, and
looked as if it would require one pair of horses to transport it and another to
operate it. There has been much discussion among engineers in regard to
the comparative merits of the rod and chain, but we believe that, on the whole,
the chain continues to be much used notwithstanding its acknowledged defects.
The most prominent of the defects are: its wearing away at the joints of
the numerous links, the difficulty or rather impossibility, on account of its
weight, of straining it so that it will not sag, and the danger of stretching
it, especially at the joints, by the strain employed to prevent the sag.
In the measure here illustrated it would seem that the advantages of the chain
are all obtained, while the most serious objections to that implement are all
obviated.
The apparatus embraces two distinct
inventions, one consisting of a light, narrow steel tape, in combination with
its removable and adjustable handles, and the other, of the case in which the
tape is wound and carried. The measuring tape is of a low spring temper,
and is covered with a coating of tin to protect it from rust; it is graded and
marked in chain and links, or otherwise, as desired. The handles are
removable, and are fastened to the ends of the chain in the manner clearly shown
in Fig. 1, in the cut. The end of the tape is slipped under the clasps of
the handle, when a small hole near its end slips over a short pin fixed rigidly
to the handle; the spring of the tape holding it down upon the pin.
As the length of the tape is varied
by the changes of temperature, an arrangement is made for adjusting the
measuring part of the tape to compensate for the expansions and contractions.
The shoulder, a, on
one of the handles is formed upon a movable piece of metal which is caused to
slide back and forth along the graduated scale,
c, by turning the tangent
screw, b. By
careful measurement of the tape at the manufactory, at different temperatures,
the point indicating the desired length of measure is ascertained and marked on
the scale, c, with
the corresponding degree of temperature. Then, at any time when it is
desired to use the measure, by observing the temperature of the atmosphere as
indicated by the thermometer, E, attached to the tape case, and adjusting the
shoulder, a, to
the corresponding figure marked upon the scale,
c, a measure of uniform
length is preserved, notwithstanding the expansions and contractions of the
metal resulting from the varying temperature of the season or the day.
The handle, Fig. 2, at the opposite
end of the tape, has its shoulder,
f, formed to come against
the same side of the pin as shoulder,
a, thus securing the
utmost accuracy in the starting points from each station.
When the work is done the handles
are removed and the tape is coiled into the case represented in Fig. 1.
This may be a thin brass box, similar to an ordinary tape box. The central
plate, G, is made to revolve about the central pivot, a knob,
k, serving as a handle to
turn it. A flange is turned up on the edge of the plate, G, for the tape
to wind around, and a simple arrangement is made for gripping and holding the
end of the tape which is first pushed in the case. A small slot is cut
through the flange, and opposite this is secured a small steel spring,
i, which, as the end of
the tape is pushed under it, presses down and holds the end secure. In
order that the tape may enter the slot in the flange, it is necessary that the
plate, G, should be turned in the proper position, which is easily indicated by
the position of the knob, h.
The case serves as a convenient
quiver for carrying the pins, j,
and each time the ten are
exhausted, the "out" is marked by turning the plate, G, so that the
knob, h, will
pass forward one figure to the next, and thus the tally is kept in the safest
manner possible. A slot is cut in the case opposite each figure for the
entrance of the bolt, k,
which holds the plate, G,
securely in position until it is desired to turn it forward.
The extreme lightness of this tape
enables it to be drawn almost perfectly straight with a very slight strain; the
compensating arrangement for variations of temperature is exceedingly simple,
convenient and accurate; the case preserves the records of the measure in a
manner well calculated to insure correctness; and the whole apparatus is
certainly the best surveyor's measure that we have ever examined. It has
met the decided approval of the most eminent engineers in the country, including
that of Professor Bache, of the Coast Survey.
The patent for this invention was
granted, through the Scientific American Patent Agency, July 10, 1860, and
communications in relation to the instruments, or rights for the manufacture or
sale of the same should be addressed to the inventor, W. H. Paine, Sheboygan,
Wisconsin.
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