Willis Pendulum Astrolabe
Astronomy
Navigation
Surveying
Optical instrument
Measuring instrument
The Willis Pendulum Astrolabe was used primarily by the armed forces to determine latitudes and longitudes. The astrolabe is stored in a large green wooden box. It is marked “PENDULUM ASTROLABE David White Co. Milwaukee Wisc USA, No. 65649, M-5107, 1952, U.S.” The instrument was invented by John Willis> The advantage of the Willis pendulum was that it used a mirror instead of mercury as a reflecting surface. It was able to measure position on earth to within 20 feet. The David White Company was founded in 1895 and continues to provide precision optical tools used in surveying.
David White Company
University of Illinois, Astronomy Department, Urbana
Circa 1952
Michael Svec
Copyright Michael Svec
image/jpg
English
physical object
University of Illinois Observatory, Urbana, Illinois
4-inch reflector Celestar
Astronomy
Optical instrument
Telescope
Metal, glass, wood
Celestar telescope with fork-type mounting and electric drive. Includes wood tripod, slow motion adjustment both axes, right ascension and declination setting circles and achromatic 30 mm finder scope. A chain links the three legs. White and blue color metal tube houses a 4-inch f/8.75 mirror, Newtonian design. A few hundred of this model were made. It cost approximately $200 in 1954. Came with two 1 inch focal length eyepieces, a 1/3 inch focal length eyepiece and a achromatic Barlow lens. Serial number 456.
J.W. Fecker, Pittsburgh
Astronomy Department, University of Illinois, Urbana
circa 1956
Michael Svec
Copyright Michael Svec
image/jpg
English
physical object
University of Illinois Observatory
Conical log-spiral antenna
Astronomy
Electric apparatus
Radio telescope
Measuring instrument
Wood, metal
Base is 8-inch in diameter and it is 19 ½ inches long.
Design of the array element was done by Professor John D. Dyson. Installed on the Vermilion River Radio Observatory's 400 x 600 foot cylindrical radio observatory, in operation between 1960 and 1970.
University of Illinois
Swenson, George. “The Illinois 400-foot radio telescope.” IEEE Antennas and Propagation Society Newsletter, vol. 28, no. 6, pp.13-16, December 1986.
Sky and Telescope, December 1962, page 322
Astronomy Department, University of Illinois, Urbana, Illinois
1960
Michael Svec
Copyright, Michael Svec
still image of physical artifact
English
physical object
University of Illinois Observatory, Urbana, Illinois
Self winding clock
Astronomy
Clocks
Measuring instruments
Wood, metal, glass
Purchased by the Astronomy Club in 1985 at an estate sale, the clock was missing the dial and door but still retained the wooden case, paper instructions, wires, hands, pendulum, and clock mechanism. In 2011, Dr. Bruce Hannon restored the clock adding a replacement door and dial, and updating the battery connections. During the restoration he discovered the pendulum regulating solenoid was missing. Serial number engraved on the clock mechanism is 112040. Dates to 1917.
Self Winding Company clocks were accurate spring-driven, pendulum regulated, clock. Batteries powered an electromagnetic winding mechanism. In addition, a signal from an external source, usually Western Union telegraphic signals, helped regulate the pendulum keeping the time in synchronization with a standard clock. Western Union received the time signal from the US Naval Observatory. The pendulum movement is accurate to an error less than 1 minute per week, so the Western Union telegraphic signal could correct and eliminate the error.
Self Winding Clock Company, New York
Astronomy Department, University of Illinois, Urbana, Illinois
circa 1917
Michael Svec
Copyright Michael Svec
still image of artifact
English
physical object
University of Illinois Observatory, Urbana, Illinois
Post card 'Radio telescope at the Vermilion River Observatory'
Astronomy
Photography
Post text: "Radio telescope at the Vermilion River Observatory, University of Illinois. Giant radio telescope 600 feet long, 400 feet wide. A wire mesh on the surface reflects cosmic signals to 274 antennas on the wooden truss, 153 feet high. It is used to catalog discrete radio sources at a frequency of 611 megahertz. Sponsored by Office of Naval Research."
Champaign-Urbana News Agency
Personal collection of Michael Svec
circa 1962
Michael Svec
image/jpg
English
document
Vermilion River Radio Observatory, Danville, Illinois
Hough observing chair
Astronomy
Furniture
Wood, metal
Wooden frame with moveable seat and eight steps on four castors. Measures 45” x 48” x 103” tall. Moving adjustable chair with foot-rest connected to counter weights slides up and down in the middle of the stairs with in a wooden track. Seat held in place by friction. A small table that attaches to the chair is missing. Two drawers added later under the steps. Follows the design of Professor George Hough of Dearborn Observatory as published in the March 1881 Monthly Notices of the Royal Astronomical Society, volume 41 pages 309-312.
Bevis and Company built the ladder for $25 based on design provided by Warner & Swasey.
Bevis & Company, Urbana Illinois
Astronomy Department, University of Illinois, Urbana, Illinois
1896
Michael Svec
Copyright Michael Svec
image/jpg
English
physical object
University of Illinois Observatory, Urbana, Illinois
30-inch mirror
Astronomy
Optical instrument
Telescope
Wood, metal, glass
Frustrated by the selenium cell photometer's lack of sensivity, Joel Stebbins purchased a large 30-inch reflector in 1912. The original telescope was purchased from C.W. Draper, $1500, #573, July 26 1912. It has previously been owned by Elmer Gates who used the telescope as a burning glass. According to Robert Baker: “The original telescope was made by the Brashear Company after the specifications of an individual whose plan was apparently not astronomical. According to one account he purposed using it as a burning glass for manufacturing diamonds. Another story is that he expected to observe the flight of souls. However this may be, the instrument was finally on the market at a very small price and my predecessor, Professor Joel Stebbins, recommended its purchase by the University. The telescope was quite unusual as its original purpose appears to have been. The 30-inch mirror had a focal length of only 20 inches and such necessarily imperfect definition that it was not the easiest matter to distinguish between a star and the moon.” A 1914 article in the Urbana Daily Courier states that the original mirror was by Brashear and was used in Washington DC as a huge burning glass, used to melt platinum.
Once in place, Stebbins and his assistant Elmer Dershem used the 30-inch telescope as a test bed for the selenium photometer as late as 1919. The photoelectric cell photometer being used in the main Observatory was proving to be very sensitive so the work on the selenium cell was eventually ended by the time Stebbins left Illinois in 1922.
Since the original Brashear mirror had proven unsatisfactory, a new mirror was ordered around 1925. The new primary mirror was 29 ½ inches in diameter, 4-inches thick with a 4-inch hole in the center. The missing secondary mirror was 7-inches in diameter. Both were made of borosilicate crown glass figured by John E. Mellish, an amateur telescope maker turned profession located outside of Wilmette Illinois around 1925. As an amateur he discovered six comets and is credited with being the first to see craters on Mars. The new focal length of the primary was 75-inches and the focal ratio of the Cassegrain system was 12.
The original mount from 1915 was an equatorial with a fork mounting. It was later adapted to the new 30-inch telescope in 1925 and to the Ross camera in 1939. The wooden dome was constructed in 1915 with a double slit.
With the new optics and longer focal length, the telescope mount needed to be modified. Six brass rods supported the secondary mirror in its new position. Focus was achieved by racking the secondary along the optic axis of the primary. Slow motion controls and clamps were added as were long counter-balance weight rods. The clock drive was also modified to handle the extra load. The 30-inch observatory's new site was on the south side of Florida Avenue, just east of Wright Street, about a quarter mile south of the Observatory. The site had darker skies courtesy of a cemetery to the north and crop fields to the south. The telescope was operational by December 1927. In 1938 Baker replaced the 30-inch mirror with a 4-inch Ross Fecker camera.
Currently on the Mellish 30-inch mirror remains. The mirror has lost the silver coating and has a 7-inch crack but test have shown it still retains it’s figure.
John Mellish
Baker, Robert H. "The 30-inch Reflecting Telescope and Photoelectric Photometer of the University of Illinois." Popular Astronomy. 122:86-91.
"University buys big telescope" (August 5 1914) Urbana Daily Courier, page 3.
Astronomy Department, University of Illinois, Urbana, Illinois
1927
Michael Svec
Copyright MIchael Svec
image/jpg
English
physical object
University of Illinois Observatory, Urbana, Illinois
Lantern slide 'Photoelectric photometer on 12-inch telescope (1925)'
Astronomy
Photography
Optical instruments
Measuring instruments
Photometry
Lantern slide of the photoelectric photometer around 1925. From the Observatory's lantern slide collection, marked "PE 2." Robert Baker continued Stebbin's photometry work when he arrived at Illinois in 1923. He continued to use the 12-inch refractor for photometer until about 1926 after which time he used the rebuilt 30-inch reflector.
Photographic Department, University of Illinois
Astronomy Department, University of Illinois, Urbana, Illinois
1925
lantern slide
English
still image
University of Illinois Observatory, Urbana, Illinois
Photograph 'Photoelectric photometer'
Astronomy
Photography
Photometry
Measuring instruments
Optical instruments
Photograph of the photoelectric cell photometer attached to the 12-inch refractor. The photograph dates to about 1913-1915. During the summer of 1915, Dr. Stebbins took this photometer to Lick Observatory to study the variable star Beta Lyrae. Photographs of that photometer on the Lick 12-inch telescope match this photograph of the photometer on the Illinois 12-inch telescope.
Astronomy Department, University of Illinois, Urbana, Illinois
circa 1915
still image
English
still image
University of Illinois Observatory, Urbana, Illinois
Lantern slide 'Potassium Photoelectric cell'
Astronomy
Photography
Electrical apparatus
Measuring instrument
Optical instrument
Lantern slide of a photoelectric cell made by Jacob Kunz. Part of the Observatory's lantern slide collection, marked "PE 5."
Photographic Department, University of Illinois
Astronomy Department, University of Illinois, Urbana, Illinois
circa 1925
lantern slide
English
still image
University of Illinois Observatory, Urbana, Illinois