Sky & Telescope May 1983 [antikvár]

Chabot's Century of Science EducationMartin E. Morrison and Allen B. Takahashi, Eastbay Astronomical Society, and Kingsley W. Wightman, Chabot Science CenterPERHAPS they had seen Henry Draper's historic photograph of the Orion nebula or had gotten swept up in the excitement surrounding James Lick's bequest of a 36-inch refractor for nearby Mount Hamilton. Whatever the reasons, J. C. Gilson and W. H. Jordan became steeped in extended discussions about astronomy. More importantly, these two school administrators for the bustling California port of Oakland began to toy with the idea of building an observatory for the school system an impressive undertaking for the 1880's.Their enthusiasm soon led them to Anthony Chabot, a wealthy mining engineer who had designed and constructed the city's municipal water system. Chabot had no particular interest in astronomy, but he was impressed with the educators' proposal and provided them with enough money to fund not only an observatory but to purchase an 8-inch telescope from Alvan Clark Sons in Massachusetts. Lafayette Square in downtown Oakland was chosen as the site, and the construction began on May 21, 1883. The observatory opened its doors to the public five months later, on November 24th.Chabot also financed a double-pier transit telescope and a chronograph, both made by the firm of Fauth and Co. in Washington, D. C. For years these instruments announced noon and 9 p.m. via electrical connections to bells in the city hall and in scattered firehouses. Ironically, Chabot died in 1883, but he willed $10,000 to the observatory for a larger telescope with the stipulations that the Board of Education maintain the observatory on the city's behalf and that the public always have free access to it.Within two years the school board hired Charles Burckhalter to be the observatory's resident astronomer. An insurance broker by profession, Burckhalter had gained astronomical experience through countless hours spent at the eyepiece of his 4y*-inch refractor. In his new capacity as director of the fledgling observatory, he devoted considerable energy toward developing a program of instruction and public viewing while also teaching classes in geography and astronomy at Oakland High School.When clouds interfered withobserving, it was the new director's custom to entertain groups assembled under the dome with lantern slides in lieu of genuine views of celestial objects. He was known to children as the "tall man with a kindly smile," always ready to satisfy their curiosity with help and understanding.Burckhalter's astronomical interests extended well beyond Chabot Observatory. To observe the solar eclipse of January 1, 1889, he led an expedition to a site some 80 miles up the California coast a gathering of professionals and amateurs that soon led to the formation of the Astronomical Society of the Pacific. Thereafter, to photograph the Sun's corona, he developed a unique eclipse telescope that he used on several other expeditions.In 1892, at Burckhalter's urging, the school board had the first Chabot Observatory torn down and a new one, better suited to group viewing, constructed on the same site. Yet by then the aura of electric lights had already become a hindrance, and even though downtown lighting was often shut off for the observatory's benefit,The original Chabot Observatory in Oakland, California, after its completion in 1883. Inside the left dome was a transit telescope, and the larger dome and tower (nicknamed the "mucilage bottle" by early users) housed an 8-mch Clark refractor. Photo courtesy Bancroft Library.it became obvious that a new site would have to be found soon. The director's choice was a spot in then-undeveloped Leona Heights, which benefited from good atmospheric conditions, a nearby trolley line, and best of all reasonable protection from city lights.Like Chabot, Burckhalter dreamed of acquiring a much larger telescope and made little secret of it. "Size is so important," he said, "that I will sacrifice everything to diameter. I want the very biggest I can get." By 1913 the original $10,000 from Chabot's will, with interest and additional funding from the school budget, had doubled, and Burckhalter began thinking in terms of a 20-inch-aperture instrument. He persuaded his good friend, the famous Pittsburgh optician John A. Brashear, to team up with the Warner & Swasey Co. in Cleveland and offer a combined bid of $19,100, which the school board accepted.It was a shrewd bargain. Warner Swasey agreed to assemble the telescope at cost and even ship it to California, in return for the recognition it would bring the company while on display at the 1915 Panama Pacific International Exposition in San Francisco. Burckhalter needed only to transport it across the bay to Oakland.Meanwhile, Brashear had ordered lens blanks from the German firm of Schott and Co., which were shipped through Holland to sidestep export restrictions on optical glass during Worid War I. The grinding began in early 1915, and Brashear wrote to Burckhalter of the blanks' fine characteristics:. . . first, the splendid annealing of both discs [has yielded) no evidence of astigmatism; second, the transparency [is] fully equal to the splendid 30-inch of the Allegheny Observatory; and third, [they are) absolutely free of striae or chords and [have] a minimum of small blisters, usually in evidence in large discs. So the splendid correction of spherical aberration certainly puts your lens in a high class. I believe it is equal to any 24-inch ever made.The 20-inch refractor became the 19th largest of its type in the world. Notably, the convex-con-cave flint element is in front of the double-convex crown element opposite the arrangement found in most refractor objectives.398 Sky & Telescope, May. 1983