 | William Galbraith - 1842 - 216 pages
...one or two horizontal wires close to each other, between which the observations are made. The central vertical wire ought to be fixed in the optical axis of the telescope, and perpendicular to the horizontal axis. These wires are visible in the day-time by the light passing down the telescope... | |
 | Nathaniel Bowditch - 1846 - 854 pages
...eye-end, and in the principal focus of the telescope, is placed the diaphragm, or wire-plate, which has five vertical and two horizontal wires. The centre...the optical axis of the telescope, and perpendicular to a line drawn through the pivots of the axis. It will be evident, upon consideration, that these... | |
 | Benjamin Pike (Jr.) - 1848 - 482 pages
...attached in the same manner to the opposite standard. Near the eye -end, and in the principal focus of the telescope, is placed the diaphragm, or wire-plate,...passing down the telescope to the eye ; but at night, when a very luminous object, as the moon, is observed, they cannot be seen. Their illumination is therefore... | |
 | Benjamin Pike - 1848 - 356 pages
...attached in the same manner to the opposite standard. Near the eye -end, and in the principal focus of the telescope, is placed the diaphragm, or wire-plate,...consideration, that these wires are rendered visible in the duytirue by the rays of light passing down the telescope to the eye ; but at night, when a very luminous... | |
 | John Ainslie - 1849 - 586 pages
...one or two horizontal wires close to each other, between which the observations are made. The central vertical wire ought to be fixed in the optical axis of the telescope, and perpendicular to the horizontal axis. These wires are visible in the day-time by the light passing down the telescope... | |
 | Elias Loomis - 1855 - 514 pages
...five or seven vertical wires, and two horizontal ones, between which the star is observed. The central vertical wire ought to be fixed in the optical axis...perpendicular with respect to the pivots of the axis. These wires are rendered visible in the day time by the diffuse light of day, which penetrates the... | |
 | 1880 - 880 pages
...eye-end, and in the principal focus of the telescope, is placed, the diaphragm, or wire-plate, which has five vertical and two horizontal wires. The centre...the optical axis of the telescope, and perpendicular to a line drawn through the pivots of the axis. It will be evident, upon consideration, that these... | |
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... h. The whole of this apparatus is movable with the telescope, and when the axis is reversed, can be attached in the same manner to the opposite standard. Near the eye -end, and in the principal focus of the telescope, is placed the diaphragm, or wire-plate,... 