Cabin sidereal clock
Astronomy
Clocks
Aluminum, brass, glass
There are two sidereal clocks, both are electric. The first is 9 ½-inch diameter with a 8-inch dial, black metal base, brass and glass, 3 hands.
The second smaller clock 5 ¼-inch diameter, tag indicates a date of 1966.
A 1953 ad shows the electric sidereal clock with a rating of less than one minute slow in 16 years. Cast aluminum case with bronze bezel for $40.
Haines Scientific Instruments, Englewood, New Jersey
Astronomy Department, University of Illinois, Urbana, Illinois
about 1966
Michael Svec
copyright Michael Svec
image/jpg
English
physical object
University of Illinois Observatory Collection A225.1, A225.2
University of Illinois Observatory, Urbana, Illinois
Master clocks
Astronomy
Clocks
Measuring instrument
Wood, glass, metal
They are model 25 IBM Master clocks. There are two 60 beat with a Graham dead-beat escapement with micrometer adjustment. Magnet wound, spring drive, self-regulating movement, 63 1/6” x 19 ¼” x 7 5/8”, plain glass door, 12” Arabic dial, white with black numbers, separate hours and smaller seconds circle. There is a one second switch as well as a 59 second switch. Pendulum is a mercurial compensating pendulum, 45 5/16 inches long and approximately 11.5 pounds, accurate to 10 seconds over a 30-day period. The standard time clock has the original mercurial pendulum with two cylinders. The sidereal clock pendulum is a replacement Invar pendulum with one cylinder. Clocks are automatically wound with reserve power for approximately 12 hours. Clocks are housed in a walnut wood case with a glass door and two locks.
A=central standard time (south side of pier), B=local sidereal time (east side of pier). Clock serial numbers are 462905 and 462904.
Included in the purchase order was the new switching wiring and metal storage cabinet and control panel outside the clock room. Paper instructions included.
These clocks replaced the original 1896 Clemens Riefler clocks both of which are now part of the Alder Planetarium collect.
IBM
Astronomy Department, University of Illinois, Urbana, Illinois
1954
Michael Svec
Copyright Michael Svec
image/jpg
English
physical object
University of Illinois Observatory Collection A211.1, 211.2
University ID 196631A, 196631B
University of Illinois Observatory, Urbana, Illinois
Sidereal clock, no. 22
Astronomy
Clocks
Measuring instruments
Wood, metal, glass
Wooden mahogany case, there was a spare wooden case, height 59.25 cm, width 44 cm, depth 20 cm. There are two front glass doors, one for the dial and one for the pendulum. The sides are wood paneling for the pendulum and glass for the top portion showing the mechanism. Details on Riefler clocks can be found on page 36 of this catalog. On the left of the dial it reads; “C Riefler, DRP No 50739 no 22” and on the right side of the dial “Munchen DRP No 60059 1896.” The number DRP 50739 is the German patent number for the escapement and DRP 60059 is the German patent number for the mercury compensating pendulum. The pendulum consisted if a steel tube filled 2/3 with mercury and a thin steel bob weighing several kilograms. The dial for the large hand is for minutes. The top smaller dial is for seconds marked in 0-60. The bottom dial is for hours, marked 1-12 in roman numerals.
The clock is now in the collection of the Adler Planetarium in Chicago
"The Riefler clock has two interesting characteristics. The first consists in the peculiarly simple and effective compensating pendulum, and the second in the mode of suspending the pendulum.
“As is well known, any good compensating pendulum should have as few parts as possible, should take up changes of atmospheric temperature with equal rapidity in all its parts, should have its compensating material extending as nearly throughout the length of the pendulum as possible, and finally should be heavy and have an appropriate form. How nearly Riefler's pendulum satisfies these conditions can be inferred from the following description:
“Its consists of a hollow steel tube 4 ft. 2 in. long, 0.65 of an inch inside diameter, with its wall 0.04 an inch thick. The tube is filled with mercury to a height of about two-thirds of its length. At the lower end is attached, by a screw with a milled head, a heavy lens-shaped mass of brass whose form permits it to cut its way through the air with almost no resistance. Below the lens are smaller disk-shaped masses whose number and position may be varied for somewhat finer regulation of the rate than can be effected with the milled head. These disks are also used for regulating either to sidereal or mean solar time. At about two-thirds of the height of the pendulum is a light brass cup for the reception of small weights that may be put on or taken off for the most delicate alterations or rate, without disturbing the vibrations of the pendulum.
“The second special feature is the peculiar mode of suspending the pendulum. Its weight is carried by a frame resting by knife edges on agate surfaces. By means of a pair of thin steel springs the two parts into which the pendulum tube is divided near its point of suspension are connected at a distance about one-half inch apart. Through these springs the oscillations of the pendulum communicate a rocking motion to the frame and also to an arm extending downward, terminating in a fork either prong of which carries an agate pin. These pins engage alternately into the tooth wheel of the escapement. The rest of the mechanism of the escapement offers no features especially different from the ordinary form. By means of a pair of screws at the extreme top of the pendulum, the relative lengths of to and fro vibrations may be regulated. The clock is also provided with break circuit attachments and chronographic connections."
The first Riefler clock was designed in 1890 in consultation with Hugo von Seeliger, director of the Munich Observatory. Professor G.W. Myers did his dissertation research under Seeliger in Munich between 1894 and 1896. By 1900, 230 of the mercury compensation pendulums had been sold.
Clemens Riefler of Munich, Germany
Myers, George W. "The Astronomical Observatory of the University of Illinois." Popular Astronomy. 6 (1898) 319-321.
Special catalogue of the joint exhibition of German mechanicians and opticians. (1900). Berlin: Reichsbruckerei.
Adler Planetarium, Chicago, Adler: Accession number A-189
1896
graphic image from catalog
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