 | Frederick Walter Simms - Astronomical instruments - 1834 - 134 pages
...estimating exactly half the quantity of deviation. To set the Telescope perpendicular to the vertical Axis. Place the telescope over two of the parallel...over each pair alternately, and moving them until the air-bubble settles in the middle. This must be repeated till the telescope can be moved quite round... | |
 | Frederick Walter Simms - Astronomical instruments - 1834 - 124 pages
...the adjustment will be complete. Before making observations with this instrument, the adjust* ments should be carefully examined and rectified, after...over each pair alternately, and moving them until the air-bubble settles in the middle. This must be repeated till the telescope can be moved quite round... | |
 | Frederick Walter Simms - Architecture - 1836 - 160 pages
...Telescope perpendicular to the vertical Axis. Place the telescope over two of the parallel plate- screws, and move them (unscrewing one while screwing up the...over each pair alternately, and moving them until the air-bubble settles in the middle. This must be repeated till the telescope can be moved quite round... | |
 | Benjamin Pike - Science - 1848 - 356 pages
...in contact ; but if the wires have any parallax, the object will appear flitting to and from them. error must be corrected by turning the screw, B, and...over each pair alternately, and moving them until the air-bubble settles in the middle. This must be repeated till the telescope can be moved quite round... | |
 | Benjamin Pike (Jr.) - Scientific apparatus and instruments - 1848 - 482 pages
...steadily in contact; but if the wires have any parallax, the object will appear flitting to and from them. error must be corrected by turning the screw, B, and...over each pair alternately, and moving them until the air-bubble settles in the middle. This must be repeated till the telescope can be moved quite round... | |
 | John F. Heather - Scientific apparatus and instruments - 1849 - 208 pages
...refraction, for any distance not exceeding ten chains, the maximum error being only yjj^gth of a foot." Before making observations with this instrument, the...rectified, after which the screw B should never be touched ; but at each station the parallel plate screws alone should be used for setting the axis round which... | |
 | Frederick Walter Simms - Astronomical instruments - 1850 - 184 pages
...in contact ; but if the wires have any parallax, the object will appear flitting to and from them. the air-bubble of the level settles in the middle...over each pair alternately, and moving them until the air-bubble settles in the middle. This must be repeated till the telescope can be moved quite round... | |
 | Sir Henry Edward Landor Thuillier - Surveying - 1851 - 826 pages
...refraction, for any distance not exceeding ten Chains, the maximum error being only Tgo(jth of a foot." Before making observations with this instrument, the...should be carefully examined and rectified, after * Whatever be the distances between the stakes a, b, and c, the following proportions ought to hold,... | |
 | Benjamin Pike - Medical instruments and apparatus - 1856 - 412 pages
...other two screws, and make it level by moving them, and the adjustment will be complete. Before makmg observations with this instrument, the adjustments...over each pair alternately, and moving them until the air-bubble settles in the middle. This must be repeated till the telescope can be moved quite round... | |
 | John Fry Heather - Angles (Geometry) - 1859 - 198 pages
...refraction, for any distance not exceeding ten chains, the maximum error being only i^th of a foot." Before making observations with this instrument, the...rectified, after which the screw B should never be touched ; but at each station the parallel plate screws alone should be used for setting the axis round which... | |
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... error must be corrected by turning the screw, B, and the other half by the two parallel plate-screws over which the telescope is placed. Next turn the telescope a quarter round, that it may lie over the other two screws, and make it level by moving... 