 | Andrew Mackay - Latitude - 1809 - 412 pages
...the screws of the telescope, till the mark is apparently in the middle between the wires; then .is the axis of the telescope parallel to the plane of the instrument, and the difference, if any, between the divisions pointed out by the indices of the screws, will be... | |
 | Nautical astronomy - 1821 - 708 pages
...this purpose. If the sun is used, one of the coloured glasses must be placed at C and another at D. To make the axis of the telescope parallel to the plane of the instrument. The telescope may be raised or depressed by means of two screws attached to the standards i, k, (fig.... | |
 | Edward Riddle - Nautical astronomy - 1824 - 572 pages
...greater exactness. The adjustments of the instruments are, to make all the mirrors perpendicular, and the axis of the telescope parallel to the plane of the instrument ; the fore horizon glass parallel, and the back one perpendicular to the index glass, when О on the... | |
 | Nathaniel Bowditch - Nautical astronomy - 1826 - 764 pages
...this purpose. If the sun is used, one of the coloured glasses must be placed at G snd another at D. Te make the axis of the telescope parallel to the plane of the instrument. The telescope may he raised or depressed by means of two screws attached to the standards i, k, (fig.... | |
 | Thomas Curtis (of Grove house sch, Islington) - 438 pages
...x the stem of the collar passing by means of a screw by which it can be raised or depressed through the plane of the instrument. Turn the eye-piece of the telescope till two of the wires in its focus, as ab, cd, appear parallel to DE, when the other two ef, gh, will of course be... | |
 | George Clinton Whitlock - Mathematics - 1848 - 338 pages
...passing each other, should exactly coincide. Third Adjustment. To make the line of collimation, or the axis of the telescope, parallel to the plane of the instrument. Turn the eye-piece till the two wires stretched parallel to each other in the common focus of the lenses for the purpose... | |
 | Charles William Hackley - Trigonometry - 1851 - 524 pages
...the other, the horizon glass must be adjusted by a screw or screws attached to it for the purpose. 3. To make the axis of the telescope parallel to the plane of the limb. — Bring the images of two objects which are more than 90° apart, to coincide upon one of the... | |
 | John William Norie - Nautical astronomy - 1852 - 844 pages
...and their planes parallel to each other when the index-division is at 0 on the arch ; also, to set the axis of the telescope parallel to the plane of the instrument: each of these particulars must be examined before an observation is taken, and the adjustments, if... | |
 | Thomas Liddell Ainsley - 1864 - 360 pages
...will the horizon-glass be truly parallel to the index-glass. 4¿A. The axis of the telescope must be parallel to the plane of the instrument. Turn the...focus appear parallel to the plane of the instrument ; then select two objects, as the sun and moon, whose angular distance must not be less than from 1... | |
 | William Thomas Read - Nautical astronomy - 1869 - 176 pages
...adjustment ; if not, turn the lower screw at the back of the glass until the adjustment is complete. IV. — To make the axis of the telescope parallel to the plane of the instrument. Make one of the wires in the focus of the telescope parallel to the plane of the instrument. Select... | |
| |
... instrument is out of adjustment in this respect, the direct and reflected images will not coincide, but the reflected image, as the arm moves, will be slightly above or below the direct image. Adjust the horizon-glass so that the two images coincide... 
