The vertical mirror, its potential applications to theodolites and two star image stopping micrometers |
| |
| Authors: | L A Kivioja |
| |
| Institution: | (1) School of Civil Engineering, Purdue University, Lafayette, Indiana |
| |
| Abstract: | A small area of a mirror can be made vertical with a high degree of accuracy by using a free mercury surface and an autocollimation
target made of a mirror. The direction of the horizontal axis of a theodolite can be established, made and kept perpendicular
to the vertical mirror for all telescope altitudes and the direction of the line of sight can be made, perpendicular to the
horizontal axis with the same high degree of accuracy. Observations can thus be made on any part of a chosen celestial vertical
circle much more accurately than by using the best striding levels. This application is potentially useful in determination
of: astronomical longitude; changes in longitude differences with time, or the possible East-West component of continental
drift; right ascension differences between stars; and the rotation rate of the Earth. Other applications include a leveling
instrument of a new type, checking of tubular spirit levels, monitoring tidal variations in the direction of the plumb line,
establishing an accurate 90° angle, and checking the graduations of the horizontal and vertical circles of theodolites. The
impersonal micrometer for special astronomical observations stops the star image. Only parallel rays will enter the telescope
when the observer is tracking the star keeping the star image stationary at the center of cross hairs. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
