THE ASTRONOMICAL OBSERVATORIES AT ANN ARBOR
The earliest indication of a specific desire for astronomical equipment at the University of Michigan is to be found in the Regents' report to the superintendent of public instruction in 1849. The Regents expressed regret for the lack of "philosophical apparatus," and particularly of a "Telescope or Sextant or Orrery, or transit instrument," and hopefully remarked, "A law exists authorizing the Board to purchase apparatus." No steps were taken toward the realization of this hope until the beginning of the Tappan administration in 1852.
In his inaugural address President Tappan outlined plans for developing a true university, in the highest sense of the term, and appealed for assistance. Soon after the address Henry N. Walker of Detroit volunteered and inquired what he could do. The President proposed a campaign in Detroit to secure funds for an observatory. The initial meeting to promote the project was held at the Michigan Exchange, Detroit, December 29, 1852. There President Tappan made an appeal, and $7,000 was subscribed. General Lewis Cass, Henry P. Baldwin, later Governor of Michigan, Senator Zachariah Chandler, and Henry N. Walker were among the twenty-eight prominent Page 466citizens who responded on this occasion. The name "Detroit Observatory" was proposed to stimulate the response and was used until 1931.
The President continued to take an active part in soliciting and collecting subscriptions. One day Mr. A. C. McGraw saw him walking the streets of Detroit in pursuit of funds, hailed him, and contributed the price of a pair of shoes. The Catalogue for 1852-53 announced that $10,000 had been subscribed for the Observatory.
The generous response to the appeal for subscriptions made it possible to expand the original plan, which called for a large telescope only.
President Tappan left for Europe in 1853, chiefly to visit observatories and to secure equipment. Walker accompanied him to New York, where a contract was made with Henry Fitz for a refracting telescope with an objective lens at least twelve inches in diameter and a focal length of 200 inches, to be equipped with eyepieces to give magnifying powers up to 1,200. The cost was to be $6,150 and the date of completion June 1, 1854. This was the first large telescope to be constructed entirely within the United States, and was the third largest refractor in the world. The Harvard College Observatory at Cambridge and the National Observatory at Pulkowa, Russia, each had a giant refractor fifteen inches in diameter. Cleveland Abbe, founder of the United States Signal Service, who studied at the Observatory soon after it was opened, has claimed that "national pride and financial economy" largely determined the selection of Fitz as constructor.
During the President's absence in the spring of 1853 Walker* engaged George Bird of New York to furnish plans for the Observatory building and to superintend construction at a cost of $300. Traveling expenses were added later. Walker also requested the Regents to appoint someone to direct the location of the Observatory on the University grounds.
President Tappan wished to secure in Europe a meridian circle and a sidereal clock equal in excellence to the telescope. For this purpose he had $4,000, which Walker had advanced.
He visited Sir George Airy at the Greenwich Observatory and saw the eight-inch circle constructed by Ransome and May of Ipswich and Simms of London, but considered it too expensive. At Rome Father Secchi of the Observatory of the Roman College gave him a letter to Oertel, instrument-maker of the renowned Optical Institute of Munich.
In Berlin Tappan met Professor Encke, Director of the Royal Observatory, who recommended the instrument-makers Pistor and Martins of Berlin. From that firm on July 15, 1853, the President ordered a meridian circle for 4,000 thalers (about $3,200), with the understanding that Encke and his young assistant, Franz F. E. Brünnow, particularly Brünnow, would supervise its construction and approve it before shipment. It was to be completed by May 1, 1854, and payment was to be made upon its arrival and acceptance in Ann Arbor.
For one month Brünnow thoroughly tested the sidereal clock purchased for the University from M. Tiede of Berlin, and pronounced it an excellent piece of workmanship.
When he was told of the twelve-inch telescope ordered of Fitz, Brünnow responded: "You will have one of the first observatories in the world." President Tappan proudly replied: "Indeed, I contemplate nothing less, and I cannot but be sanguine of the results we shall arrive at under the transparent and serene skies Page 467of Michigan, when we shall have provided an Astronomer worthy of the Observatory we are thus furnishing" (P.R., 1853, p. 6).
This conversation, with its oversanguine reference to Michigan skies, illustrates President Tappan's just personal pride in the project, which he frequently referred to as "our noble Observatory." In his well-known "Historic Statement" just at the close of his administration he wrote: "I cannot speak of the Observatory without emotion. No one will deny that it was a creation of my own."
In Ann Arbor, the committee on the Observatory site met with difficulty. Evidently its members, the Honorable Elon Farnsworth, the Honorable Henry N. Walker, and Professor Silas H. Douglass, did not unanimously approve "the center of the University grounds."
A special meeting of the Board of Regents in July, 1853, was called to decide the question, but a quorum was lacking. The members present visited the proposed country hilltop, then outside the limits of Ann Arbor, discussed the proposition, and adjourned without formal action. However, an agreement was evidently reached. At the November meeting purchase of the balance of the site was authorized, including four acres from the land of a Mr. Benham at $100 per acre. The earliest Catalogue to describe the Detroit Observatory contained the statement: "It is situated half a mile from the University grounds on a hill 150 feet above the Huron river, from which is presented one of the most charming views of the country."
Another difficulty was encountered. The enlargement of the original plan incurred unforeseen expenses. After the return of President Tappan two collimators (small telescopes to adjust the meridian circle) were added to the order of Pistor and Martins at a cost of $375. Other auxiliary instruments were needed.
Another subscription campaign in Detroit in May, 1854, resulted in twenty-three gifts, totaling only $1,150, but President Tappan, backed by Walker and other friends, pushed the project, and in July, 1854, when the new Director arrived, the building was nearly finished. It was soon ready for the arrival of the instruments. The attractive setting, as it then appeared, has been preserved in the famous oil painting made by J. F. Cropsey in 1855, from which an engraving was prepared for the Catalogue of 1855-56. The original painting is now in the University's possession, a gift from the Honorable Andrew D. White.
The superintendent of grounds and buildings was authorized to purchase lumber and enclose the site with a plain substantial fence. A committee applied to the city council to secure the construction of roads to the Observatory. In 1856 the mayor again brought up the question of roads, and the need was soon met in country fashion by a new turnpike.
The Observatory building was soon ready to occupy. (The history of the development and activities of the Observatory staff, except for the construction of new instruments, is omitted from this article. See Part III: Department of Astronomy.) The central part is thirty-three feet square, and there are two wings, each nineteen by twenty-nine feet. The central part is surmounted by a revolving dome twenty-one feet in diameter and contains the pier for the large refractor. The pier extends fifteen feet below the surface and is constructed of solid masonry, twenty-two feet in diameter at the base and six feet at the top, where it is capped by a large circular limestone quarried at Sandusky, Ohio. This carries a vertical limestone monolith, which supports the iron pier cap. The center of motion of the instrument is about thirty-three feet above ground Page 468level. The east wing was designed for the meridian circle and the other for a library and an office for the director. The Walker meridian circle, so called in honor of Henry N. Walker for his interest in the Observatory project and his gift of $4,000 for the instrument and accessories, arrived in September, 1854. It bears the name of the makers, Pistor and Martins, Berlin, and the date, 1854. It has an objective 6.3 inches in diameter and a focal length of 96.8 inches. Its graduated circles, 37 ½ inches in diameter, ruled to ten minutes on one side and two minutes on the other, are read by microscopes to tenths of seconds of arc. One circle was slightly bent in shipment. The collimating telescopes have apertures of two inches and focal lengths of about twenty-four inches. They are mounted on piers, one north and the other south of the meridian circle, on a level with its axis.
The Tiede clock, No. 125, was mounted near the meridian circle and rated to sidereal time. At first star transits were observed by the eye-and-ear method. Soon additional equipment was installed, including a chronograph, originally placed in the west wing, two chronometers, standard barometers, and thermometers to give data for atmospheric-refraction corrections and a four-inch portable comet seeker by Henry Fitz.
The large telescope was not completed on time, so Fitz, the contractor, loaned one in April, 1855. The new one arrived in December, but was rejected, owing, it is said, to the use of cast iron for parts of the instrument and its mounting. A new contract was made at $6,750, an increase in price of $600, and the use of brass and bell metal was specified. The project now faced a debt of about $8,000 and another campaign in Detroit was launched in March, 1856, which raised about $3,500.
The new telescope arrived in Ann Arbor in November, 1857. In December it was ready for use. By this time the building and equipment had cost about $22,000. Citizens of Detroit contributed about $15,000, and for many years the name "Detroit Observatory" was used in recognition of their generosity. President Tappan frequently referred to it as an observatory of the first rank and said that he knew of no other instance of one of its class erected at so little cost. The main expense was due to the instruments and as little as possible was spent on the building. In spite of the President's zeal in soliciting and collecting subscriptions and his carefulness in expenditures an annoying debt was incurred, part of which was carried on personal account, which remained open and unpaid for several years, adding to the friction between him and members of the Board of Regents. At one time (October, 1856) the treasurer of the University, John M. Chase, made a loan of $4,900 to President Tappan on the Observatory account, holding the President's personal notes and a chattel mortgage on the equatorial telescope as security. An auditing committee requested by the President made a satisfactory report in 1859. Not until December, 1863, however, after the close of the period of Tappan and Brünnow, were the Regents able to record: "The old Observatory debt has been paid."
Brünnow, while at Dudley Observatory during the year 1859-60, retained the directorship of the Observatory in Ann Arbor, but James Craig Watson, Professor of Astronomy and Instructor in Mathematics, was in charge. Watson secured appropriations from the Regents for constructing a room and furnishing the west wing of the Observatory in 1860.
In the autumn of 1863, under the presidency of Erastus O. Haven, Watson became Director of the Observatory.
Early in the administration of President Page 469Haven there was agitation to move the Observatory to the campus (p. 448). In the course of the discussion attention was drawn more and more toward what would be the requirements of operating the Observatory efficiently on its established location. In the end, $500 was appropriated for roads by Ann Arbor citizens, and an addition was made to the Observatory building. The enlargement, completed in 1868, included a residence for the director on the west side of the original building. It was further repaired and enlarged in 1905-6.
The records show that new instruments were requested from time to time, but were not furnished. In 1870 the Regents were asked to provide the Observatory with a spectroscope. Among the requests not granted this is perhaps the most significant, for the instrument has been of fundamental importance in the later development of astronomy.
A small, separate building was constructed on the occasion of the transit of Mercury, May 8, 1878, when the Observatory was made temporarily a United States Government station. This building, which was located about one hundred feet southeast of the main Observatory, was later remodeled and equipped for the use of students. It contained a six-inch equatorial refractor and a three-inch transit, with zenith telescope attachment.
In 1878 H. A. Wetzel gave a 2 ½-foot hemispherical cast of the moon, representing its elevations and depressions, which was of "great usefulness in the teaching of astronomy."
A new director, Mark Walrod Harrington, took charge on October 1, 1879. In response to his request soon after arrival, $850 was appropriated for meteorological instruments. He secured a Hough's barograph, a Hough's thermograph, and an anemograph of St. Gibbon's pattern for wind velocity and direction. From the United States Signal Service he obtained a standard thermometer, a psychrometer, a terrestrial-radiation thermometer, and a solar-radiation thermometer.
In the spring of 1880 Harrington appealed for more astronomical instruments to be used in instruction. He reported that some loaned by the Navy Department had been recalled and that the large instruments (the twelve-inch refracting telescope and the Walker meridian circle) were not available for student use. A total of $3,050 was appropriated — $1,800 for a six-inch equatorial telescope, $1,000 for a three-inch transit, and $250 for a chronometer. Reports previous to Harrington's administration indicate that a six-inch telescope and a three-inch transit with zenith telescope attachment were in use in the Students' Observatory. Apparently these were among the instruments "recalled" by the Navy Department, and new ones were obtained.
Near the end of this administration, upon Harrington's request for a good astronomical globe, Bailey's cosmosphere was demonstrated before the Regents by a Mr. Morley, but the question was referred to a committee, and we find no record of purchase of the globe.
Harrington left at the end of June, 1891, and for one year the Observatory was managed by William Joseph Hussey, Instructor in Astronomy and Acting Director of the Observatory. No changes of importance were made in the physical equipment during that year. Hussey then left the University for some years, and Asaph Hall, Jr., became Director.
Upon his arrival at Ann Arbor in 1892 Hall first gave attention to the condition of the instruments, which had been surpassed in size and efficiency by those installed at other institutions and which were in need of being cleaned and read-justed. He reported that the instruments Page 470were in bad condition. It was necessary to take the objectives apart and clean them. The Tiede clock had an irregular rate. As far as he could find out the driving clock of the twelve-inch telescope had never been of any use, and Watson had not made regular use of the Walker meridian circle. Hall had the object glass of the meridian circle taken to Clarke and had a spring put into the cell to act against the glass. He obtained a new micrometer from Repsold, a chronograph from Saegmüller, and a clock from Howard. With these improvements and accessories the instrument was remounted; it was then subjected to a very complete investigation.
The condition of the Observatory and of the Department of Astronomy was subjected to serious criticism in 1903. The Fitz objectives for large telescopes were surpassed in quality and size by Clarke. The twelve-inch telescope, once the pride of Michigan and third largest refractor in the world, was small compared with many newer ones, notably the forty-inch telescope at Yerkes and the thirty-six-inch telescope at Lick. The Meridian circle was antiquated. Instruments for work in astrophysics were lacking, and the Observatory was rapidly being surrounded by buildings. An enthusiastic alumnus, after calling attention to its brilliant past, concluded with the appeal, "Michigan and her alumni should not allow her observatory to fossilize" (Abbe, p. 421).
The only important purchases made about this time were a sextant instrument at $150 in 1902 and in 1904 a surveyor's transit, for which $375 was appropriated.
When Hussey returned as Director of the Observatory in October, 1905, he found the Observatory building and equipment in need of repairs and improvements. Instruments for research in modern astronomy were lacking. The Observatory library and residence were reconstructed and enlarged during the winter of 1905-6. The Regents appropriated $5,000 for this work, and, in addition, the heating and lighting were provided from the general fund.
In 1906 the Observatory Shop was established, furnished with tools for the repair of old instruments and the construction of new, and provided with a staff headed by a skilled machinist.
The reconstruction of the instruments, including the twelve-inch refractor, was begun. Changes to this historical telescope included a new steel tube to replace the old pine one, a new 3 ½-inch finder in place of the 2 ½-inch finder, the addition of a coarse circle in right ascension, the addition of a coarse circle in declination, a new worm and worm wheel, a new driving clock, a new slow motion and clamp in right ascension, a new slow motion and clamp in declination, a new counter-weight arm and weights, and a new right-ascension circle. This work, including the construction of the new parts, was done at the Observatory Shop. A new micrometer for the reconstructed twelve-inch refractor was obtained in 1907 from Warner and Swasey Company. Alterations to the micrometer, including better illumination of the wires and a quick motion in position angle, were made by Colliau of the shop staff.
A new telescope with accessories for spectrographic work was one of the chief requirements. In June, 1906, the Board of Regents made an initial appropriation of $15,000 toward the construction of a new reflecting telescope and an addition to the Observatory in which it could be housed. Much of the work was done in the Observatory Shop. In August the optical parts for the reflector were ordered from the John Brashear Company, Pittsburgh. A clear aperture of at least thirty-six inches was specified. The glass was cast at Saint-Gobain, France, and after being ground and polished at Pittsburgh Page 471reached Ann Arbor in December, 1907. The diameter of the reflecting surface is 37 inches. With the eleven-inch hyperbolic secondary the equivalent focal length is sixty feet.
Among the needs which Hussey presented to the Regents in January, 1907, were additional shelves for Observatory books, seismological instruments, and drainage of the Observatory. President Angell and the Regents favored these inprovements.
In order to make room for the addition to the main Observatory the old Students' Observatory was moved in 1908 to a location about three hundred feet west of the main building. In the Students' Observatory three rooms were provided, an entrance, an equatorial room, and a transit room. The six-inch telescope was provided with a new driving clock, a new worm and worm wheel, and an electrically driven slow motion in hour angle. A camera was provided for use with the six-inch telescope, having a lens of 4 9/16 inches' diameter and 19 ½ inches' focal length. In the same year, 1908, a new comet seeker, which was larger and more convenient than the old one, was constructed at the Observatory Shop. It has a lens of 4 ½ inches and an altazimuth mounting. Parts of the old Fitz comet seeker, including tube and lens, were used in the short focus finder for the 37 ½-inch reflecting telescope.
The addition to the Observatory building at Ann Arbor, begun in 1908, was completed the following year. The main floor contained offices for the Director and his secretary, a vault, clockroom, and classroom. On the second floor were additional offices and a photographic room. The basement provided, in addition to utility space, rooms for new seismological equipment, which was installed in August, 1909. These instruments include two Strassburg tromometers of the Bosch-Omori type for north-south and east-west components respectively; also a Wiechert, inverted-pendulum, astatic seismograph, which records both components, and a Wiechert vertical seismograph, which has not proved successful. Continuous records of the two horizontal components have been kept since August, 1909, except during brief periods when the instruments were being cleaned and readjusted.
Work on the 37 ½-inch reflector continued in the Observatory Shop, and additional annual appropriations were made by the Regents to cover the expenses of the telescope and accessories, which totaled about $24,000. The single-prism spectrograph by Brashear, Pittsburgh, used with the new reflector, arrived on January 18, 1909. This instrument followed in general the type of the Mills spectrograph of the Lick Observatory, with some changes which had been introduced in the Mellon spectrograph of the Allegheny Observatory, and further modifications proposed by Ralph H. Curtiss. The forty-foot dome for the new telescope, constructed by the Russell Wheel and Foundry Company of Detroit, was completed and erected in 1910.
In January, 1911, the large mirror was placed in the cell, and all accessories were ready.
In 1922-23 the 37 ½-inch reflector was overhauled, and the driving was improved. A new two-prism spectrograph designed by Curtiss was constructed in the Observatory Shop in 1923-24. This instrument was intended for use with a new and larger reflecting telescope, which was part of the plan under consideration for a new site, new buildings, and equipment. The optical parts were by J. B. McDowell. The dispersion is about twice that of the single-prism spectrograph. A Hartman spectrocomparator was purchased the same year.
Attempts to prevent nuisances near the Observatory have been frequent. In Page 472April, 1908, grading was begun on the west end of the Observatory lot for a women's athletic field. Appeal to President Angell stopped the work and that encroachment. In 1910 Robert P. Lamont purchased twenty-six acres of land east of the Observatory for its protection in that direction.
The encroachment of University buildings began to receive serious consideration in 1912. On April 24 Hussey prepared a statement for presentation to the Regents regarding the question of putting the power plant of the University in the "cat-hole" location. The proposed site for the power plant was considered so valuable for that purpose that it seemed advisable to look for a new site for the Observatory and its research instruments. "Huddy Hill," just east of the city, was considered. Sufficient land could have been obtained at an estimated cost of from $50,000 to $70,000.
The proposed new Hospital site just north of the Observatory raised the question again in the spring of 1915, and Huddy Hill received further consideration, but no action was taken.
In 1919 the question of the effectiveness of the Observatory on its present site was before the Regents and was referred to the buildings and grounds and Hospital committees, and Hussey recommended to the Regents that the Observatory and equipment be moved to Huddy Hill. This site, however, was not well protected from future encroachments, and action was again delayed when the question was referred to a special committee consisting of the committees on buildings and grounds, the Medical School, and the Observatory. A communication regarding the same question, including the purchase of new equipment, was before the Regents in December of that year; but in 1920 the Board declined further consideration of the question of additional equipment.
The issue regarding site became prominent again in 1922, when the western part of the Observatory grounds was proposed as a site for Couzens Hall, a new dormitory for nurses. Hussey made this record:
Conference with President Burton, Regents Clements and Hubbard, Dean Effinger, Shirley W. Smith, and Professor Shepard concerning Observatory plans, etc., at President Burton's office. At this time President Burton stated that it was not the plan to use any part of the Observatory grounds for other purposes. Two days later the Regents voted to place the proposed Nurses Home on the west end of the Observatory Grounds.
In the President's Report for 1922-23 special attention was called to the urgent need of moving the Observatory because of the power plant, the University Hospital, and the projected nurses' home. A high hill about three miles west of the city on Liberty Street was then considered. It seemed advisable that the removal of the Observatory and the increase of equipment, including a new and larger telescope, should be incorporated as a part of the building program advocated by President Burton. The land of the Observatory site, including the twenty-six acres east of the building, if released for other uses, would provide a large amount toward a new site, new buildings, and improved equipment. Again the project was postponed, but the need remained. An article in the Michigan Alumnus (31 : 533) mentioned, in addition to other nuisances, "an earthquake every time a train passes."
Hussey continued the search for a more suitable site. On June 19, 1925, Regent Beal, Secretary Smith, Dr. Ruthven, Mr. Paul Buckley, Professor Leigh Young, and Professor Hussey visited the Page 473hills near Portage Lake adjacent to the University's forest preserve in that vicinity. All seemed well pleased, and action to secure a part of "Peach Mountain" for the new Observatory site was begun. An appropriation of $1,525 was authorized in September to secure the site, but real-estate complications delayed the purchase. Tentative plans were being developed for the construction of a large reflecting telescope (seventy-five inches), the refiguring of the 37 ½-inch reflector to adapt it for photographic rather than visual work, and the return of the twenty-seven-inch Lamont refractor from South Africa (see Part III: Lamont-Hussey Observatory) for double-star work in the North after completion of the southern survey. This program, it was thought, would again bring the institution and its equipment to a prominent position in the astronomical world.
Another project begun but not completed during Professor Hussey's administration was the Angell Hall Observatory and astronomical laboratory for student use. The need of more adequate facilities for this purpose had long been felt, as the number of students electing astronomy had increased rapidly since 1905. The Students' Observatory, previously described, was discontinued in the fall of 1923, when it had to be removed from the site of Couzens Hall. To meet this need the entire fifth floor of Angell Hall was originally designed for the use of the Department of Astronomy, although parts of that floor have temporarily been relinquished for other purposes.
Two twenty-four-foot domes were included in the plans, and later constructed by J. W. Fecker. A ten-inch refracting telescope was ordered from Warner and Swasey to occupy one part, and a reflecting telescope for the other was left to be provided in the future. The two domes by Fecker were erected, and the ten-inch refractor was installed in the first year of the directorship of Ralph Hamilton Curtiss, 1926-27.
The two-prism spectrograph constructed during Hussey's administration was first used on the large telescope at the main Observatory for about two months early in 1927, but since then has not been put into frequent use.
In 1927-28 a three-inch transit was added to the Angell Hall equipment, and a fifteen-inch pyrex mirror was ordered from J. W. Fecker. Work on the mounting for the reflector was carried on in the Observatory Shop. The mirror arrived on January 24, 1929, and the fifteen-inch reflector was added to the Angell Hall equipment and was ready for student use in 1929-30.
Some progress was made during the administration of Curtiss toward the acquisition of a new site and new instruments for research. The ridge north of Dexter, Michigan, known as Peach Mountain, is cut into two parts by the Huron River. On the west is the site tentatively selected by Hussey; on the east is a slightly lower spur that extends south of Base Lake, on which available space could be obtained.
In November, 1928, Curtiss requested the Regents to secure an option on land in Dexter Township covering this site and extending to the shore of Base Lake. Favorable action was taken, and a part of the land recommended was afterward purchased. The new Observatory project was placed first on the Regents' list of the University's most urgent needs which was presented to the state legislature in 1929. Attention was called to the success of the Observatory under Brünnow, Watson, Hall, and Hussey, and to the impossibility of carrying on scientific work meeting modern improved standards on the old site and with instruments surpassed in size and efficiency at other institutions. The removal of the Observatory, Page 474it was also pointed out, would turn over to the Regents thirty acres of land owned chiefly by Lamont, the value of which would be greater than the amount proposed for the new Observatory and telescope. The request was approved, but the financial depression prevented an appropriation for the project.
In the meantime drawings were in progress for a seventy-five-inch reflecting telescope, based upon the plans of the seventy-two-inch reflector of the Dominion Astrophysical Observatory at Victoria. Inquiry was also made as to the possibility of securing a disk of the fused silica quartz used in the experimental work on the 200-inch reflector for the Carnegie Institution; this program was being developed by steps, in the course of which disks sixty inches and 100 inches in diameter had been used.
The purchase of a Howard sidereal clock and of a Hale spectrohelioscope for the Angell Hall Observatory was authorized in 1929-30. A Moll microphotometer from Kipp and Zonen was added to the instruments for research at the Observatory, and a Brown and Sharpe No. 13 universal grinder was obtained for the Observatory Shop.
About two hundred acres south of Base Lake, fifteen miles northwest of Ann Arbor, was secured that year for the new Observatory site. A survey was made and a preliminary layout was proposed for the location of the main buildings. Correspondence was continued regarding means of obtaining the material for a large mirror.
The administration of Heber Doust Curtis as Director began in September, 1930. During the ensuing year the Hale spectrohelioscope, previously ordered, was added to the Angell Hall equipment, and the fifteen-inch reflector for student use was completed, although it was not installed until a year later, when the Howard clock rated to sidereal time was also ready.
The old name "Detroit Observatory," used in honor of the Detroit contributors from the time when the Observatory was founded, had long given rise to confusion as to its location. Investigation disclosed the fact that this name had never been officially adopted; therefore, in November, 1931, it was dropped by regental action and the name "Observatory (or Observatories) of the University of Michigan" was formally accepted. The collective name now includes the old Observatory in Ann Arbor, the Angell Hall Observatory for students, the Lamont-Hussey Observatory in South Africa, and the McMath-Hulbert Observatory at Lake Angelus, Michigan, a notable gift received from the founders in January, 1932 (see Part III: McMath-Hulbert Observatory).
Improvement in the slow-motion guiding of the 37 ½-inch reflector was made by H. D. Curtis. In the spring of 1934 a motor-driven silvering carriage was constructed and necessary alterations were made to permit the removal of the mirror and its cell from the telescope for silvering the mirror and preparatory to the work of aluminizing. A steel bell-jar of forty-two inches' inside diameter was ordered, to be equipped with necessary pumps and auxiliary apparatus. Williams, who joined the staff of the Department of Astronomy in 1935, was a specialist in the process and supervised the work of aluminizing the mirror in March, 1936. An increase in efficiency in the ultraviolet region of the spectrum was realized as expected.
The present reflector is now far excelled by the larger instruments of many American observatories, and it is probable that no observatory of like rank in America is so unfavorably located for scientific work as is that of the University of Michigan at Ann Arbor.
Page 475The future plans for the Observatory definitely involve its removal to the Base Lake site and the installation there of a new and powerful reflector in addition to the 37 ½-inch reflector now in use. When the work in the Southern Hemisphere is completed the excellent twenty-seven-inch Lamont refractor also may be brought there from South Africa. Only the equipment necessary for instruction will be left in Ann Arbor.
The Base Lake site will eventually comprise over two hundred acres. It is some fourteen miles northwest of the city, well away from any village or community. This makes it especially favorable for scientific work, since astronomy is now at least 95 per cent photographic, and artificial light is the principal enemy of modern astronomical research. When the Observatory was built in 1855 the science was 100 per cent visual, but the growth of Ann Arbor, with its brilliantly lighted streets, has completely cut out many lines of photographic research. Scientific work at Ann Arbor is further hampered not only by the proximity of the railroad and of the large Hospital and other medical units, but also by smoke from the power plant less than one thousand feet to the southwest, for the prevailing winds of this locality come from that quarter.
Curtis accepted the directorship in 1930 with the understanding that the new Observatory project would be steadily pushed to completion. Although the depression necessitated delay, and although some special gift or legislative appropriation must be secured before the building can be constructed and the new telescope completed, at least a beginning has been made.
Curtis drew the plans for the new telescope, and a rough disk for its mirror has been provided through the generosity of the late Tracy W. McGregor, of Detroit. Under this gift a pyrex disk measuring 85 ½ inches in diameter was cast by the Corning Glass Works, but some fault developed in the long annealing process. A second and larger disk was later most successfully cast. The new disk, now stored near the Observatory, is 98.5 inches in diameter in its unfinished state and 18 inches thick. It weighs about 5 ½ tons. With the exception of the disk for the 200-inch reflector to be built in California it is the heaviest disk of pyrex yet cast. The finished mirror will exceed 96 inches in diameter, which is surpassed by the 100-inch telescope at Mount Wilson. Even after the completion of the 200-inch disk, the Michigan reflector will rank third in size in the world.
Eventually a plant adequate for astronomical research will be provided, and the work done by the Observatory of the University of Michigan will be commensurate with that which has given it such high rank in the past.
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Curtis, Heber D."Observatory Is Gift to University."Mich. Alum., 38 (1932): 347-48.
Curtis, Heber D., "Mammoth Disk Cast for University."Mich. Alum., 40 (1934): 341-42, 353.
Curtis, Heber D."Eighty Years of Astronomy at the University of Michigan."Mich. Alum. Quart. Rev., 41 (1934): 244-49.
Curtis, Heber D."James Craig Watson, 1838-1880."Mich. Alum. Quart. Rev., 44 (1938): 306-13.
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