Collimator lens and meridian mark

Title

Collimator lens and meridian mark

Subject

Astronomy
Optical instrument

Description

Metal, glass

Measures 8 ¼ x 6 x 11 ½ inches, lens is 1.7” in diameter.
Director G.W. Myers articulated the need for a Meridian or mire Mark in a March 6, 1897 letter to university President Draper. “Mire mark and Collimator for 3-inch Combined and Transit and Zenith Telescope.” The collimator was mounted in the north window of the east-central transit room on a brick pier, cased in wood above the level of the floor, with a wooden box as a cover. The wood reduces the impact of the brick’s radiant heating. The meridian mark was located on a distant pier north of the building at the focal point of the collimator lens. The Meridian mark was removed with the construction of Smith Hall (1917), the pier for the collimator was removed during the 1956 expansion of the Observatory. At the Elgin Watch Company Observatory (Illinois), there was also a 3-inch Warner & Swasey transit with a meridian mark 100 feet to the north consisting of a metal plate with a hole three thousandth of an inch in diameter serving as an artificial star.

Creator

Warner & Swasey Company

Source

Payne, W.W. (1927 January) Elgin Observatory. Popular Astronomy. 35 (1) 1-9.

Publisher

Astronomy Department, University of Illinois, Urbana, Illinois

Date

1897

Contributor

Michael Svec

Rights

Copyright by Michael Svec

Format

image/jpg

Language

English

Type

physical object

Identifier

University of Illinois Observatory Collection A136

Coverage

University of Illinois Observatory, Urbana, Illinois

Files

DSCN0208.JPG

Collection

Tags

Citation

Warner & Swasey Company, “Collimator lens and meridian mark,” University of Illinois Observatory Collection, accessed December 16, 2017, http://uiobservatory.omeka.net/items/show/18.