two-mirror heliostat
Date1923-1928
Inventory Number1997-1-1710
ClassificationHelmholtz resonator
Subject
Maker
The Gaertner Scientific Corporation
1923-present
User
Department of Chemistry, Harvard University
founded 1791
Cultural Region
Place of Origin
Dimensions45.5 × 38 × 18 cm (17 15/16 × 14 15/16 × 7 1/16 in.)
Material
Bibliography
DescriptionThis instrument consists of two silvered mirrors. The lower one rotates according to the polar axis, the higher one is fixed. The latter one is adjustable in all directions to redirects sunlight wherever desired. The polar axis, which is rotated by a clockwork mechanism encased in a drum, carries an hour circle divided to four minutes of time. The rotating mirror can be tilted in its support fork, and the tilt can be read on an arc graduated in degrees, so that adjustment can be made everyday to accommodate the changing declination of the sun. There is a bubble level on the base and a leveling screw on the long foot.
Signedon plaque: The / GAERTNER / SCIENTIFIC CORPORATION
Curatorial RemarksAn inspection tag on the instrument is dated 9/20/28. A paper tag mentions the following: "TO: PROF. GEORGE S. FORBES, MALLINCKRODT 124, CHEMISTRY, HARVARD UNIVERSITY, From: George Wald, Harvard Biological Laboratories".
FunctionThe heliostat is designed to reflect a beam of sunlight in a fixed direction, and uses a clockwork driven mirror to counteract the apparent motion of the sun through the sky. The resulting steady beam of sunlight would often be projected into a laboratory for experiments requiring intense light, physical optics studies, microscopy, analysis of the solar spectrum, etc.
According to a 1935 trade catalogue from the company: "The instrument can be adjusted for any latitude. The polar axis will be accurately set at the factory for any specified latitude and to set up, it is then only necessary to level the base and align it North and South by means of the indices on the heavy cast base".
According to a 1935 trade catalogue from the company: "The instrument can be adjusted for any latitude. The polar axis will be accurately set at the factory for any specified latitude and to set up, it is then only necessary to level the base and align it North and South by means of the indices on the heavy cast base".
ProvenanceFrom the Department of Chemistry, Harvard University.
Edward Kübel
Date: 1880-1895
Accessories: rods (3); pendulum bob; quadrant; wooden box
Object number: 1996-1-0536
Louis Jules Duboscq
Date: 1850-1880
Accessories: RAPPORT FAIT A L'ACADEMIE ROYAL SCIENCES SUR UN NOUVEL HELIOSTAT, Presente par M. SILBERMAN aine. (in instrument file folder)
Object number: 2000
John A. Brashear
Date: 1905-1915
Object number: 1997-1-0019
Gebrüder Haff
Date: 1960-1969
Accessories: plush-lined, hard green case
white card with instrument information in case
Object number: 1999-1-0005
Gebrüder Haff
Date: circa 1957
Accessories: white card with instrument information inside case
Object number: 1997-1-0447
Gebrüder Haff
Date: circa 1940
Accessories: card with instrument info and conversion table; photocopy of letter from Dr. Joachim Fischer to William J.H. Andrewes, dated 12 May 1997; photocopy of extract from Dr. Joachim Fischer's inventory of integrating instruments included with the letter
Object number: 1997-1-0444
Gebrüder Haff
Date: circa 1940
Accessories: card with instrument information and conversion table
Object number: 1997-1-0445