Transit Telescope
Title
Transit Telescope
Description
A Transit Telescope is the basic instrument for determining time by stars. It is fixed such that the instrument rotates on its axis in a north-south plane.1 An observer using the transit telescope watches a chosen star pass across the cross-hairs. These time measurements probably provided time base for the Haish telescope in the Goodnow observatory and did provide time for the Rock Island railroad.
This Fauth Transit Telescope was purchased by the college in 1888 for a concessional price of $550. The transit telescope (in Noyce Hall foyer), chronograph (in display case F2), astronomical Seth Thomas clocks (in Kistle Science Library), and micrometer (in case F2) were purchases requested by Samuel J. Buck following the construction of the Goodnow observatory with its Haish telescope. “If a man makes you a present of a fine horse, immediately you begin looking about for a saddle and bridle, harness, carriage and sleigh in order to make use of the horse,”
The transit telescope is the basic instrument for determining time by stars. The axis of a transit telescope is fixed in the east west direction so that when the instrument moves, it moves only up and down in a north-south plane. This one was mounted on a Y shaped metal base and located in the brick transit house just East of Goodnow. It was reported to have an objective with aperture of 3 inches and three eye pieces, a direct, diagonal, and a nadir, with approximate powers of 50, 100, and 30, respectively. An observer would watch a chosen star pass across the cross-hairs. The time between one passage of a star and the next is one sidereal day. The interval between two successive passages of the sun past some fixed point in the sky, such as the meridian, is one solar day, and it is 3 minutes 56 seconds longer than the sidereal day. Because the observations of stars are made at night, the cross-hairs must be illuminated. The cross-hairs are in the center of the telescope tube, and a window at each end of the support admitted light from a kerosene lamp to make the cross-hairs visible. From a knowledge of the longitude of the observatory and the location in the sky of a particular star, one can calculate precisely the time at which that star passes the local meridian. If the passage is observed with the transit telescope, the derived time can be used to set a clock or, more likely, produce a correction to be applied to the clock’s reading. It is easier to use corrections than to set clocks frequently.
This Fauth Transit Telescope was purchased by the college in 1888 for a concessional price of $550. The transit telescope (in Noyce Hall foyer), chronograph (in display case F2), astronomical Seth Thomas clocks (in Kistle Science Library), and micrometer (in case F2) were purchases requested by Samuel J. Buck following the construction of the Goodnow observatory with its Haish telescope. “If a man makes you a present of a fine horse, immediately you begin looking about for a saddle and bridle, harness, carriage and sleigh in order to make use of the horse,”
The transit telescope is the basic instrument for determining time by stars. The axis of a transit telescope is fixed in the east west direction so that when the instrument moves, it moves only up and down in a north-south plane. This one was mounted on a Y shaped metal base and located in the brick transit house just East of Goodnow. It was reported to have an objective with aperture of 3 inches and three eye pieces, a direct, diagonal, and a nadir, with approximate powers of 50, 100, and 30, respectively. An observer would watch a chosen star pass across the cross-hairs. The time between one passage of a star and the next is one sidereal day. The interval between two successive passages of the sun past some fixed point in the sky, such as the meridian, is one solar day, and it is 3 minutes 56 seconds longer than the sidereal day. Because the observations of stars are made at night, the cross-hairs must be illuminated. The cross-hairs are in the center of the telescope tube, and a window at each end of the support admitted light from a kerosene lamp to make the cross-hairs visible. From a knowledge of the longitude of the observatory and the location in the sky of a particular star, one can calculate precisely the time at which that star passes the local meridian. If the passage is observed with the transit telescope, the derived time can be used to set a clock or, more likely, produce a correction to be applied to the clock’s reading. It is easier to use corrections than to set clocks frequently.
Identifier
te_291
Collection
Technology
Creator
Fauth & Co.