A treatise on surveying ; in which the theory and practice are fully explained (1860)
Alsop, Samuel · Philadelphia, E. C. & J. Biddle & co. · leaf 102
The arc in this figure is divided into degrees, and elevenspaces on the arc are equal to twelve on the vernier: thereading is therefore to 5 minutes. When the figures on thearc increase to the right, the right-hand vernier is used, andvice versa. The reading on the figure is 2° 45 to the left. 181.… … In the figure, the vernier reads to minutes. When thezero of the vernier is to the left of that on the limb, thefigures begin at the zero and increase towards the left to15; they then pass to the right-hand extremity, and againproceed to the left ; that is, they stop at A and commenceagain at B.…
Surveying
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