STANDARD - Survey Instrument Antique Center!

Graduation Reading to 2O".
A
Fig. 6.
Folding Vernier. Made to order only.
Fig. O. Circle divided into 20' spaces same as Nos. 4 and 5.
Single Opposite Verniers having one zero point in center with two rows of figures.
Note. With this style of single vernier angles may be read to left or right. If angles are being
read clockwise start with the zero point under A and continue to the left until the 10' mark is
reached, then if no coincidence is found, continue by taking the 1(X mark at the opposite end of the
vernier (right end) and reading toward the 2(X mark. In reading angles in the opposite direction use
the figures which slope toward the right.
Graduation Reading* to 1C" (on a 7 or 8-inch Circle).
Fig. 7.
Usual Style of Verniers for Triangulation.
Fig. 7. Circle divided into 10' spaces.
Single Opposite Verniers reading to 10" (59 spaces into 60).
Whenever desired double opposite verniers can be furnished, with two rows of
figures on limb from to 360 in opposite directions.
Note. In cases where less weight and greater compactness and portability of instrument are
desirable, as in instruments often furnished to the Government for use in mountains and in the
tropics, a 10" graduation can be placed upon a 6# inch circle. The spacing however is very close,
and while this size of circle will give almost equally as accurate results, its reading must necessarily
prove more fatiguing to the eye.
Graduation Reading to 5" on 8-inch Circle.
Sometimes it is requested to graduate an 8-inch circle to read to 6" direct, when the
circle will be divided into 5' spaces and the vernier 59 spaces divided into 60 parts. As a
rule this r^aduation is not desirable for vernier instruments on account of the close
spacing on circle and verniers which of necessity must prove inconvenient in usual engineering
practice because of its greater liability to error in reading.