1 The present scientific personnel of the observatory consists of the director, three Salaries of permanent scientific personnel.... Maintenance of instruments, laboratory supplies, etc. $9,375 2,050 495 1,500 500 1, 613 475 875 355 17, 238 The instrumental outfit, from the nature of the work, naturally falls into two classes-astronomical telescopes and auxiliary apparatus for the study of the problems which constitute the aim of the observatory. The telescopes are: 12-inch equatorial, for spectroscopic work; 8-inch equatorial, for observations of sun; 5-inch equatorial, for photometric problems; 6-inch photographic, for photographing sun, and a 13-inch photographic equatorial.' Of instruments for use in connection with these telescopes for physical observation there are all manner of spectroscopes, from the simplest form to the most complete and powerful. The auxiliary apparatus comprises measuring engines for the photographic map of the heavens, apparatus for enlarging photographs of star spectra, and a powerful laboratory spectrometer. The past work of the observatory forms a large part of the history of the new science, and has contributed a number of important inventions and discoveries. Its principal work has naturally been in the application of the spectrum analysis to the study of the physical nature of the stars. The application of photography to the spectroscope, successfully inaugurated in this observatory, has resulted not only in greatly extending the power of the instruments, but in important investigations and discoveries, the most noted of which was the accurate determination, with great precision, of the motions of the stars in the line of sight,2 measurements which had hitherto proven unattainable. Since the date of this report, a 31-inch photographic refractor, with equally powerful spectroscopes and other accessories, has been added to the instruments of this observatory. This telescope, ranking among the most powerful in existence, will be devoted entirely to astrophysical research. The importance of this advance may be realized by the fact that at the present time nearly all the great telescopes of the world are spending large portions of their resources in this important field of astrouomical work. THE IMPERIAL OBSERVATORY OF RUSSIA, AT PULKOWA (NEAR ST. PETERSBURG). Popularly but little known, this observatory stands preeminent amongst astronomers for the extreme accuracy of its observations. The manner in which it came into existence; its instrumental equipment, of the best attainable design and workmanship; its organization and administration deserve careful study, as exemplifying the ideal method of treating such technical subjects. The project of building near St. Petersburg an astronomical observatory "of the highest rank, conforming to the existing state of the science of astronomy and capable of advancing it," was formally recognized in 1833 by an imperial grant of the money to build and equip the observatory and the appointment of a scientific commission of five members to formulate and carry out the plans. The commission adopted for its solution the following problems: 1. To determine precisely the character and aim of the observatory. 2. To formulate a general plan of observations to conform to this aim. 3. To formulate the plan of its organization and administration. 4. To plan the observatory buildings and dwellings for the astronomers. 5. To estimate the annual budget for its maintenance. The general plans formulated by the commission were, in 1834, approved by the Emperor, and Wilhelm Struve, one of the commission, selected as the first director of the observatory. Two distinguished architects, professors of the University of St. Petersburg, were directed to draw up independent plans of the new establishment, which were in all respects to conform to the final judgment of the commission. On account of the peculiar aim of the institution, all contracts were freed from the usual forms of carrying on Government works. The director was ordered to make a scientific journey for the purpose of discussing the work and instruments of the new institution with the distinguished astronomers and artists of Europe, and to invite proposals for the furnishing of instruments "the most perfect which could be built." The list of great astronomers whose opinions were consulted in the realization of the broad scheme adopted by the commission comprises the great names of astronomy of this century-Argeländer, Bessel, Encke, Olbers, Humboldt, Schumacher; and the instrument makers to whom was finally intrusted the task of making the instruments for the observatory are no less renowned-Steinheil, Mertz (successor to Frauenhofer), Ertel, and the Repsold Brothers. The plans of the observatory and its instruments, drawn up with such thorough consideration of the object in view, were carried out with the same care and deliberation. Officially dedicated in 1838, its scientific activity began in 1839, but the provisional control of the commission charged with its construction was continued until 1840. The buildings, with notable additions to meet the requirements of astronomical discovery and advancement, are to-day as perfectly suited for their purpose as any in existence. The principal instruments for astronomical observations, of the highest attainable precision, with no essential alterations or repairs, after more than half a century of active use, have to-day no superiors and but very few equals. The additions to its buildings and instruments, comprising a 30-inch telescope, fitted with spectroscopes and accessories of appropriate power; a 13-inch photographic telescope, and a physical laboratory, represent the same high degree of excellence. ORGANIZATION. The organization adopted by the commission was formally promulgated by imperial edict in 1839, and further extended and improved by a similar decree in 1862. The precise purpose of the observatory and the character and scope of its observations are defined by the decree as follows: (a) Continuous observations of the highest attainable precision for the promotion of astronomy as a science. (b) The perfecting of practical astronomy in its applications to the problems of geography, geodesy, and navigation. (c) The encouragement and support of astronomical work in the other Russian observatories. (d) To furnish opportunity for the officers of the Government services to perfect themselves in the methods of practical astronomy applicable to their duties in geographical, geodetic, and nautical work. The present administration of the observatory, in accordance with these decrees, is in its essential features the same as at Paris and Greenwich, consisting in the general control of the observatory committee and the direct control of the observatory administration by the executive head—the director. The observatory committee consists of the president of the Imperial Academy of Sciences (ex officio presiding officer); the president of the Imperial Geographical Society; director of the military topographical survey; chief of the Nicolia Academy (military); president of the Marine Committee; director of hydrography; permanent secretary of the Imperial Academy of Sciences; four members of the Imperial Academy of Sciences (chosen by ballot officers of observatory staff not eligible). The personnel of the observatory is at present as follows: The director; four senior astronomers (one to be vice-director); six adjunct astronomers; two computers; one instrument maker; one financial secretary; and one scientific secretary. The committee is charged with the supervision of the scope and character of the observations and the consideration of questions especially affecting the attainment of the aims of the observatory. It is required to meet annually at the observatory at a fixed date, when the director submits his annual report of the finances of the observatory, of the scientific work accomplished in the past and the plans for the ensuing year, together with the needs of the observatory for the prosecution of its work and the increase of its efficiency. After consideration of the report, with the necessary verbal explanations of the director, and inspection of the buildings and instruments, the committee submits its recommendations to the minister of public instruction. The director is chosen by the Imperial Academy of Science of St. Petersburg, according to the regulations defining the election of its own members. He is required to devote his energies entirely to the duties of his office and to see that all the resources of the observatory are directed to the accomplishment of the declared aim of the observatory as defined by the statute. As the executive head of the observatory he distributes the scientific work among the astronomers and is himself required to take a part in the same. The senior astronomers must be chosen from persons distinguished for their work in astronomy. They are appointed by the minister of public instruction upon the recommendation of the director approved by the Imperial Academy of Sciences. They are charged by the director with the responsibility of the proper execution of the work which constitutes the special aim of the observatory. The adjunct astronomers and computers are appointed by the minister upon the recommendation of the director. The director may further take into the observatory, for the higher study of astronomy, students who have finished certain prescribed work. The director may then pay them for such work in the observatory as he may assign them and permit them to carry on some special work under the direction of some member of the permanent scientific staff. They are paid from the scientific contingent fund, and may not exceed at any one time four in number. The financial secretary ("ekonom") assists in the financial management of the observatory and is responsible to the director for the proper care of the buildings and grounds. The director, or with his approval the astronomers, may from time to time visit other Russian and foreign observatories for the purpose of keeping advised upon the improvements in astronomical methods. The principal instruments of the observatory, and assignment of astronomical staff: The Ertel meridian transit, two astromomers; the Ertel vertical circle, two astronomers; the Repsold prime vertical transit, one astromomer; the Repsold meridian circle, one astronomer; 30-inch equatorial (object glass by Clark, mounted by Repsold Brothers), one astronomer; 13-inch photographic telescope, one astronomer; 15-inch equatorial, one astronomer; 7-inch heliometer, and 4-inch photometric equatorial (Frauenhofer), one astronomer. The Ertel meridian transit and vertical circle are engaged exclusively on fundamental observations-the sun and a small list of the principal fixed stars. The transit instrument is provided with two collimators, a fine spirit level, a special telescopic collimator for studying the variation of the level at different zenith dis tances, and with two meridian marks for the control of its azimuth. These last two accessories deserve special mention on account of their importance, and the further fact that, although this has been generally conceded, it is only in recent times that they have been adopted in any other government observatory. The Repsold prime vertical transit is not equalled by any other instrument of its class for perfect design and workmanship, and the satisfactory manner in which it has fulfilled all the requirements of extreme accuracy. The objects observed with this instrument are limited to a very few stars, for the investigation of the constants of aberration, nutation, and the variation of the latitude. The Repsold meridian circle is engaged in the formation of star catalogues and other miscellaneous work, referring all observations to the fundamental positions derived from the observations of the three preceding instruments. It is the work of these instruments which has given the Pulkowa Observatory decided preeminence for the extreme accuracy of its observations. The right ascensions of its fundamental catalogues are practically free from systematic and periodic errors, a preeminence shared in a lesser degree by but one other, Argelander's catalogue of 1830. While their absolute determinations of declination are not free from systematic error, they are not equaled in accuracy by those of any other observatory. The thorough and scientific treatment of their astronomical clocks, especially in recent times, deserves special mention. Some twenty years ago the Tiede clock was placed in the basement of the observatory, where the annual variation of temperature was 4° to 5° C. To protect it against the variations of the pressure of the atmosphere it was inclosed in an air-tight metallic case in which the annual variation of pressure has been about 0.10 of an inch. Another fine clock, by Kessel, was provided with a barometric compensation designed by Professor Krueger. This compensation proved of unexpected efficiency and so exactly performed its function that in the course of several months not the slightest trace of variation in the rate of the clock due to barometric changes could be detected." Both these clocks are at the present time in good condition and maintain the same uniformity of rate for which they have been distinguished in the past. All the instruments are thoroughly equipped with electric lights, furnished by a storage battery of 30 cells. The dome of the 30-inch equatorial is turned by an electric motor, the current for which is supplied by a storage battery of 40 cells. The latter battery has been in use for ten years with no repairs, while the electric lighting plant has performed well for two years with no repairs. They are charged from once a week to once in two weeks, depending upon the weather. The dynamos for charging the cells are run by a 25-horsepower engine, which, with the steam pumps for the water supply, is run by the same boiler. The whole plant is attended by one mechanic. The observatory has in its present mechanician an assistant of great value in such an institution, having served in that capacity for fifteen years at the Imperial Magnetic Observatory, Pavlovsk, under the direction of Professor Wild, one of the most eminent investigators in the field of terrestrial magnetism. Provided with a thoroughly equipped machine shop, the mechanician is competent to keep in thorough order all the varied apparatus of the observatory. The annual budget of the observatory is 70,000 rubles ($35,000), of which 37,000 rubles ($18,500) is for the permanent staff of the observatory. For the expenses of the temporary scientific staff, of special researches, and the increase of the instrumental equipment, a special contingent fund of 12,000 rubles ($6,000) is assigned. For the maintenance and repairs of buildings, grounds, and instruments, heating and lighting, pay of temporary and permanent laborers, 20,000 rubles ($10,000) is assigned. These items, with 1,000 rubles ($500) for the library, make up the expenses of the observatory. Unexpended money is carried to the future credit of the observatory as a fund for the purchase of new instruments and accessories. When it is remembered that all the staff of the observatory, including watchmen and permanent laborers, are domiciled with their families in the buildings of the observatory, the economy of its administration is strikingly shown. Besides observatory publications, sixteen large quarto volumes, many important investigations are contained in the memoirs of the Imperial Academy of Sciences, with which the observatory has always had the most friendly relations. The important constants of aberration and precession used in the American and British almanacs are adopted from Struves's discussion, while Peter's value of the nutation is used. The constant of atmospheric refraction determined by Gylden is now generally used. In the new field of astrophysical research the 13-inch photographic telescope and the 30-inch equatorial have contributed some valuable results, most of which are published in current scientific periodicals. 1 My experience since the date of this report has only deepened my conviction that the principles and methods adopted in this observatory sixty years ago for prosecuting their fundamental work are still far in advance of those existing even at the present day in any other government observatory: First. By the determination of right ascensions and declinations with separate instruments, each of which, by its proper design, is best adapted to secure the highest precision. Second. By the design and successful application of accessories for controlling or studying the azimuth and level of the transit instrument. Third. By the installation of its normal clocks, so as to free them largely from the effects of atmospheric variations. THE ROYAL OBSERVATORY OF HOLLAND, AT LEYDEN. The National Observatory of Holland stands in intimate connection with the University of Leyden, the professor of astronomy in the university being the director of the observatory. The modern observatory dates from the year 1860, when the present buildings were completed and the principal instruments mounted, consisting of a 6-inch meridian circle and two equatorials, one of 7 inches aperture, by Mertz, and the other of 6 inches aperture, by Frauenhofer. The meridian circle of 6 inches aperture and 8 feet focal length followed the wellknown model of its makers, Pistor & Martins. In the beginning it was supplied with the two principal accessories necessary for properly undertaking fundamental work-a carefully mounted normal clock and two meridian marks, after the wellknown design of those in use at the Pulkowa Observatory since 1840. The constants of the instrument have from the beginning been made a subject of continuous and thorough investigation, as well as the rate of the normal clock by Höwü, which has shown a rate of remarkable uniformity. The proper temperature to be used in computing the atmospheric refraction, a factor of great importance in determination of the absolute declinations of the stars, has also been an object of thorough and valuable research for a number of years. The thorough study of these essential factors in fundamental work has given the observations of this observatory a high reputation for their accuracy. Some years ago the instrument was thoroughly overhauled by the Repsold Brothers, of Hamburg. Its pivots, worn by the constant use of the spirit level, were reground, and the illumination of the instrument altered in conformity with the well-known method of the Repsolds. The instrument is now in excellent condition, and is still engaged in the field of fundamental work. The force of the observatory consists of the director and two assistants. The instrument maker is a fine mechanic, and not only keeps in repair the various instruments, but adds many new accessories. S. Doc. 4 -8 77 |