Historical Highlights of
The Buhl Planetarium and Institute of Popular Science
Pittsburgh, Pennsylvania

By Glenn A. Walsh

October, 1998

I. The Buhl Planetarium and Institute of Popular Science building -

B. Unlike other cities where planetaria were constructed adjacent to existing Natural History museums, such as in New York(American Museum of Natural History) and later in Cleveland(The Cleveland Museum of Natural History), Pittsburgh chose to build an Institute of Popular Science, with presentations and exhibits from many Scientific disciplines, along with the Planetarium. Although several cities had Natural History museums by the 1930s(including Pittsburgh: The Carnegie Museum of Natural History opened in 1895), only a few cities, such as Chicago(Museum of Science and Industry: 1933) and Philadelphia(Franklin Institute: 1934), had museums which provided a greater emphasis in the Physical Sciences. Thus, in 1939, Buhl's Institute of Popular Science joined these select few museums in explaining the Physical Sciences to the public. Buhl really was an early pioneer in interactive Science exhibitry and in the concept that would later be referred to as the "Science Center." The fifty-two years of operation of The Buhl Planetarium and Institute of Popular Science/Buhl Science Center are an important part of the history of the City of Pittsburgh, and an important part of the history of development of Planetaria and of Science museums/Science Centers.

C. At the building's opening, Buhl employed a state-of-the-art(1939) "talking exhibit" system; the visitor would push a button to activate a phonograph recording, from a special audio room.

D. In 1939, the Buhl building was the first public building in the city(and, possibly, the state) to be built with air conditioning.

II. The Buhl Planetarium and the "Theater of the Stars" -

B. It was the last Zeiss projector to be built before World War II. Once the war began, the Zeiss Optical Works in Jena, Germany was converted to make bombsights for German military aircraft; the Allies later bombed the factory.

C. The Zeiss II projector is the only Model II projector, in its original condition, still in operation in the world. The only other Model II projectors, that may still be in operation(one in India and one in Japan), have been extensively modified.

D. With a 65-foot diameter dome and a seating capacity of 425(including 381 permanent seats), the "Theater of the Stars" is one of the largest planetarium theaters in existence.

E. Buhl's Zeiss II was the first planetarium projector to be placed on an elevator; Westinghouse built this huge worm-gear elevator, in 1939. This gave additional flexibility to enhance the performances. Worm-gear elevators of this size are rare. Engineers visiting Buhl have often requested to see the actual elevator equipment and are amazed at the size of the four worm-gears.

F. It was the first planetarium theater built with a stage for theatrical performances. The main stage can actually be extended into the planetarium theater; originally, this was accomplished using electric motors. The planetarium theater actually was constructed with two stages. After the elevator takes the projector completely below the floor level, a second stage can be created above the projector(again, using electric motors), for theater-in-the-round-type presentations.

G. In 1939, it was the first planetarium theater(and, perhaps, the first theater!) to install a special sound system specifically for the use of the hearing-impaired. Both air-conduction and bone-conduction headsets were available(for a one dollar, returnable, deposit fee) for the use of hearing-impaired, Sky Show attendees.

H. Buhl's planetarium theater provided courses in Celestial Navigation to military pilots, bound for service in World War II.

III. The Ten-Inch, "Siderostat"-type, Refractor Telescope and "The People's Observatory" -

B. Although it was built specifically for use by the public, a limited amount of research has been conducted using this telescope. The most recent instance occurred in the mid-1980s. Former Planetarium Lecturer Francis G. Graham(Founder of the American Lunar Society, who now teaches at the East Liverpool, Ohio Campus of Kent State University) photographed the Moon through the "Siderostat"-type telescope, as part of a project to provide a more accurate map of the Moon. Up until this time, there was an area near the Moon's southern pole that was not well mapped.

C. The telescope(ten-inch refractor mounted in a "Siderostat" arrangement) is the second largest(primary lens aperture) "Siderostat"-type telescope now in use(third largest that ever existed). It is the only "Siderostat"-type telescope, now in operation, that has been used by the public on a regular basis.

D. The "Siderostat" or "Sidereal Coelostat" telescope arrangement was designed in the mid-nineteenth century by the famous French Scientist Jean Leon Foucault. In poor health, Foucault died before constructing a "Siderostat"-type telescope.

Foucault also invented the Foucault Pendulum. In the Great Hall of the original Buhl building, a Foucault Pendulum displayed the classic demonstration of the Earth's rotation on its axis, in a beautiful pendulum pit made of marble with a brass railing. This Foucault Pendulum is now on display on the second floor of The Carnegie Science Center. Buhl's original pendulum pit continues to display the true cardinal points of the compass.

The "Siderostat" telescope arrangement has several advantages, particularly for public viewing:
1. It allows the public to remain in a heated Observing Room, during cold weather-thus, exposing more members of the public to the wonders of Astronomy.
2. Since the refractor telescope tube(and eyepiece) is fixed(only the flat, first-surface, "Siderostat" mirror, that reflects one-power light into the telescope, moves), observers do not have to risk neck strain, or keep moving, to view objects.
3. Accidental bumping(and misaligning) of the telescope, by members of the general public, is eliminated-allowing more people to observe during a shorter period of time.
4. It presents an excellent view of sunspots and other phenomena on the surface of the Sun, utilizing the safe projection method of observation.
5. This Observatory was specifically designed so that it could operate, for short periods of time without an attendant, during evening observing sessions only. Before the closure of the Buhl Planetarium building as a Science Center on August 31, 1991(the building closed completely in February of 1994), this capability was updated by The Carnegie Institute maintenance staff.

E. The keynote address, at the Observatory dedication, was given by Harlow Shapley, Ph.D., one of the most renowned Astronomers of the twentieth century. At the time, he was Director of the Harvard College Observatory.

F. Historic Anecdote: On the same evening of the Observatory dedication, Buhl started a new Planetarium Sky Show and opened a new gallery exhibit. The Sky Show, regarding Celestial Navigation, was titled "Bombers by Starlight." The new exhibit, in Buhl's lower-level Octagon Gallery(which encircles the planetarium projector pit, below the planetarium theater) was titled "Can America Be Bombed?" This exhibit opened two and one-half weeks before the Japanese bombed Pearl Harbor, Hawaii!

Glenn A. Walsh
633 Royce Avenue
Pittsburgh, PA 15243-1149 U.S.A.
Telephone: (412) 561-7876
Telefacsimile: (412) 276-9472
Electronic Mail: incline@trfn.clpgh.org