 | Frederick Walter Simms - 1834 - 124 pages
...sliding-vane, with a wire placed across a square hole in the centre, as shown in the annexed figure : this vane being raised or lowered by the assistant, until...be the apparent difference of level, which, if the distance between the staff and instrument is great, requires to be corrected for the curvature of the... | |
 | Frederick Walter Simms - 1834 - 134 pages
...the vane, noted on the staff, is the height of the apparent level above the ground at that place. 1 When both the staves are used, they should be set...be the apparent difference of level, which, if the distance between the staff and instrument is great, requires to be corrected for the curvature of the... | |
 | Frederick Walter Simms - 1836 - 160 pages
...GRAVATT'S construction, will scarcely ever need being repeated. OF THE LEVELLING STAVES. LEVELLING-STAVES. the telescope, the height of the wire in the vane,...be the apparent difference of level, which, if the distance between the staff and instrument is great, requires to be corrected for the curvature of the... | |
 | Frederick Walter Simms - 1850 - 184 pages
...apparent level above the ground at that place. j=, 1 When both the staves are used, they should be MJ set up at equal distances on each side of the spiritlevel...be the apparent difference of level, which, if the distance between the staff and instruI ment be great, requires to be corrected for the curvature of... | |
 | Robert Hirsch - 2008 - 416 pages
...pictures outside, on a clear day, in direct 282 ' ' i, I ' / f f - - r 9.8 When copying work, two lights should be set up at equal distances on each side of the camera at 45-degree angles to the work being copied. Meter from a gray card, not off the surface of... | |
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... vane being raised or lowered by the assistant, until the cross wire corresponds .with the horizontal wire of the telescope, the height of the wire in the vane, noted on the staff, is the height of the apparent level above the ground at that place.... 