the whole heavens, by international cooperation. In the formation of the details of this enormous work and in the practical execution of the observations, its influence has been second to no other observatory. The successful experiments of the Henry Brothers, extending over many years while assistants at the observatory, had enabled them to construct a photographic telescope with which a short exposure would register on the sensitive photographic plate the images of the stars much fainter than had been possible to observe except with the largest telescopes. Their experiments led to the conclusion that by this means could be constructed a map of the heavens which would exceed in accuracy the old method of observations with the eye, and which, with much less labor, would contain all the faint stars in the heavens, as far as it might be desirable to register them. The interest excited in the scientific circles of Paris by these successes led to the assembling at the Paris Observatory in 1887 of the International Astrographic Congress. This meeting resulted in the perfection of measures for the accomplishment of this grand project, forming a new era in astronomy of precision. As a final result of the labors of the Congress and its permanent committees, the work was divided into zones of nearly equal area, and each of these zones assigned to the various observatories volunteering to take part in the international project. The zone assigned to the Paris Observatory is prosecuted by the department of photographic astronomy, under the direction of M. Paul Henry, whose technical work, in conjunction with his brother Prosper, has played so important a part in the origination and perfection of the instruments necessary to carry out the plan. At the present time more than two-thirds of the photographs have been taken; and their measurements are made by an especial bureau organized in this department, under the charge of Miss Klumpke, an American, assisted by four other ladies. The special instruments employed for this purpose, two in number, seem to be models of accuracy and convenience. The interest of the French Government in the prosecution of this zone work has been sufficient to lead it to undertake the photographing of three more zones in the observatories at Bordeaux, Toulouse, and Algiers (in Africa). In the department of astrophysics, time service, and meteorology noteworthy investigations have been made, particularly by means of an instrument invented by M. Delandres for obtaining by spectroscopic-device photographs of the details of the sun's surface. In the general work of the observatory, of the highest importance to its fundamental work is the phenomenal performance of the standard clock of the observatory. The clock is inclosed in a hermetically sealed case, in which the air is practically kept at a constant temperature, pressure, and humidity. It is located in a vault of the main building, where the variation of the temperature is very gradual and small, but where the air is always near the point of saturation. The clock is sealed in the case at the temperature and pressure which may exist at the time, and the humidity, by the introduction of a chemical substance, is reduced to a constant amount, about 50 per cent. It has been found by experience that this humidity gives the best results, for when the air is artificially dried to a condition of low humidity the oil dries up and the performance of the clock is rendered unreliable. Unfortunately, no details of these interesting and valuable experiments have been published, but a careful inspection of the rates for a number of years shows its performance to have been surpassed by none, not even the normal clocks of Pulkowa and Berlin. The annual appropriation for the maintenance of the observatory is 240,000 francs ($46,320). Of this sum, 164,260 francs is for the pay of the scientific personnel, at the present time numbering 31 persons. The remainder ($15, 619) is devoted to the care and maintenance of buildings, instruments and grounds, heating and lighting, and supplies of all kinds; and the pay of all persons not upon the scientific staff of the observatory. [Translation.] "DECREE CONCERNING THE OBSERVATORY SERVICE. "The President of the Republic of France, decrees: "ARTICLE 1. The observatory service, under the minister of public instruction, comprises (titulary) astronomers, adjunct astronomers, and astronomical aids, "ART. 2. The personnel of the observatory of Paris comprises: "1. An astronomical director. "2. Six astronomers. "3. Ten adjunct astronomers. "4. Astronomical aids. "Students may be received into the establishment for securing the future supply of astronomers. "A financial secretary is attached to the establishment. "The director and secretary are lodged in the observatory. "Astronomers, charged with special work at night, by the minister, shall be lodged in close proximity to the observatory buildings. "ART. 3. The astronomers, heads of departments, shall meet monthly in committee, under the presidency of the director. This committee may be called into extra session by the director. "ART. 4. There is instituted at the observatory of Paris a council, composed— “1. Of two members, representing each the minister of war, the navy, of agriculture, and commerce, distinguished for their work. "2. Of four members of the Academy of Sciences and of the Bureau of Longitudes. "3. The astronomical director. "The members of the council are appointed by decree, for three years, upon the nomination of the minister. "ART. 5. The astronomical director is charged with the general administration of the establishment, the correspondence, business arising in the council and in the committee, with the presentation to the minister of the estimates of the annual budget, and with the detailed account of the expenses of the establishment. "He is especially charged to secure the proper coordination and execution of the work requiring the cooperation of the different departments and to secure the regularity of the observatory publications. "No orders can be given without his approval. "ART. 6. The scientific work shall be divided into several departments (services), each under the direction of an astronomer. "The subordinates placed under the orders of a head of department shall perform the duties which may be assigned to him. "The material of each department is placed under the charge of the head of the department. "Requests having for their object the use of an instrument, either within or outside of the observatory, are referred to the committee. They may be referred to the council, who transmits them to the minister with its recommendation. "Each head of department is required to submit to the director a monthly summary of the progress of his work. He reports directly to the committee scientific questions arising in his work. "All matters requiring a permanent or temporary expenditure are submitted to the committee through the director. "The heads of departments shall communicate to the director the condition of the reduction of his work at such time that the observations of the current year may be prepared for publication within the year following. They will supervise the printing of the same. "In the last fifteen days of January, or later, they shall submit to the director a general report of the work of their respective departments during the past year on the work proposed for the ensuing year and of the needs of their departments. "ART. 7. These documents shall be communicated to the council with the personal report of the director; the latter report, with the approval of the minister, shall be printed and distributed. "The assignments of the head of Departments shall be made annually; they may be indefinitely renewed. "ART. 8. The council of the Observatory of Paris is required to meet three times per year at fixed dates. It may be called in extra session by the minister. "The president, vice-president, and secretary are appointed by the minister upon the nomination of the council. "The council advises upon the annual assignments of the heads of departments the plan of work to be followed, and the distribution of the personnel and material among the departments, upon the estimated budget prepared by the director, from the report of the heads of departments, on the construction of buildings and instruments, on the nomination and promotion of subordinates, on disciplinary measures. "The action of the council, upon approval of the minister, form a part of the regulations of the observatory. "After the distribution of the annual reports mentioned in the preceding article the council inspects the observatory establishment, designating two of its number to assist in the inventory of the material. Copies of the inventory are to be furnished to the minister. "ART. 9. The directors are appointed for five years by the President of the Republic, upon the nomination of the minister, from a double list of two candidates presented by the Academy of Sciences and the observatory council. "The minister may, besides, propose directly to the President of the Republic a candidate distinguished for his scientific works. "ART. 10. In case of a vacancy in the position of astronomer (titulaire) the members of the observatory appointed by decree shall present two candidates. The corresponding class of the Institute of France shall also present two. The minister may besides present directly to the President of the Republic a candidate distinguished for his work. "ART. 11. The adjunct astronomers and astronomical aids are appointed by the minister, upon the nomination of the director, approved by the observatory council. "Done at Paris the 21st of February, 1878. (Signi) "M' DE MCMAHAN, "President of the Republic." BERLIN OBSERVATORY. Although a state institution, the Berlin Observatory is strictly a university organization. Its director is the professor of astronomy in the University of Berlin. For this reason its organization and work has not the special interest which attaches to the Government observatories of England, France, and Russia and the Royal Observatory of Potsdam. Its present situation in the midst of a populous section of the city, in close proximity to a large iron manufactory, restricts its work to a limited field. Although its able astronomical corps and the possession of instruments suitable for the exacting requirements of fundamental observations fit it for such work, it has not, for the above reason, in recent years attempted work of this character. Its personnel consists of the director and three astronomical observers, dwelling in Government quarters close to the observatory. They are all paid from the university funds. The principal instruments consist of two meridian circles, a universal transit, and a 9-inch equatorial, by Frauenhofer. The principal meridian circle, by Pistor and Martins, is interesting from the fact that it is an almost exact duplicate of the one in use for years in the old Naval Observatory at Washington, and which has been recently subjected to radical alteration. The Berlin instrument, built in 1868, with no essential alterations or repairs, is still in excellent condition for work of the highest accuracy, in fact its original value is greatly increased by the continuous and careful investigation of its constants during the years in which it has been in use. The universal transit is an instrument designed by Professor Foerster, the director of the observatory, for a wide variety of observations. It has brought considerable celebrity to the observatory, through the discovery in 1888 of the periodic variation of the latitude by Dr. Küstner as an accidental result from a careful series of observations to determine by a new method the constant of aberration. Since that time the director of the observatory has exercised much influence in the attempt to organize, by international cooperation, a series of observations at suitably situated points for the systematic study of this important phenomenon. At the late geodetic conference in Berlin (October, 1895) methods were completed to carry this project into execution. The instrument to be used was designed by Professor Foerster, and will record all the observations photographically, thus freeing them from danger of systematic personal errors. The Royal Astrophysical Observatory at Potsdam was designated at first as a branch of this observatory, but the necessity of removing it far from the deleterious influence of a large city, and the radically different character of the investigations, led to their entire separation. One of the most important works of this observatory is its thorough study and investigation of its normal clocks. A fine clock by Tiede has been for many years kept at a constant atmospheric pressure by inclosing it in an air-tight case in which the air has been previously dried and reduced to a pressure of about one-half the normal pressure of the atmosphere. The temperature of the basement has a very small daily variation, but the annual variation is considerable. The clock was removed in 1894 for cleaning and repairs after running continually for eight years with a rate of remarkable uniformity. The performance of this clock has for many years been the subject of frequent articles in the astronomical and scientific journals. Another Tiede clock is provided with a barometric compensation, which largely frees the rate of the clock from the effect of variations in the atmospheric pressure. During the long administration of its present director, beginning in 1863, the following important catalogues have been observed: Catalogue of 521 Bradley stars (1881). Catalogue of 622 right ascensions of the Berlin Jahrbuch stars. Catalogue of 2,100 stars observed between 1893 and 1896 (in press). Zone catalogue of 9,200 stars (zone 25° to 20°) (in press). 71 ROYAL ASTROPHYSICAL OBSERVATORY OF POTSDAM, GERMANY. The first Government institution established solely for researches in the field of astrophysics, is a monument to the liberality of the German Government and to the thorough manner in which the organization and building of its technical institutions is conducted. From the time of Kirchoff's brilliant discovery of the meaning of the dark lines in the solar spectrum, the importance of an observatory especially equipped for the study of the problems of solar physics was a subject of frequent discussion in the various scientific societies of Germany, but the realization of such an institution first became financially practicable with the foundation of the German Empire. The first outlines of such an establishment, to form a branch of the Berlin Observatory, were presented in a memorial to the minister of public instruction by the director of the latter observatory. This memorial was referred to the Royal Academy of Sciences of Berlin for its consideration and advisory action. This body emphasized the importance of the subject, and advised the founding of such an observatory equipped for astrophysical research in its widest extent. This favorable report was followed in the next year by the appointment of a special commission of eight members to formulate a precise plan for the buildings, instrumental equipment and organization of an astrophysical observatory of the highest rank. Among this commission are seen the distinguished names of Helmboltz, Kirchoff, Auwers, Foerster, and Siemens. The plans submitted by this commission were approved and the necessary funds secured at the winter session of the Landtag in 1873-74. The commission was continued in existence for the practical execution of the project, and the services of a distinguished architect assigned for the technical plans of the buildings and the supervision of their construction. At this early stage three of the personnel of the new observatory were appointed, two of them, Professors Vogel and Sporer, were assigned the designing and ordering of the instruments, and the third to the supervision of the details of the observa tory buildings. For a more complete utilization of the opportunity, Professor Vogel made a protracted visit to Great Britain for consultation with the astronomers and physicists concerning the instrumental outfit. A permanent subcommittee was named for the consideration of important questions arising in the building, and for the further organization of the observatory upon its completion. With the enlargement of its scope the idea of the new observatory forming a branch of the Berlin Observatory was abandoned, and a favorable site chosen near the city of Potsdam. The site was located on a hill some 600 feet in height, in the midst of a wooded region, and within a convenient distance of the city. The frequent train service between the city and Berlin, a distance of 14 miles, removed any inconveniences arising from its situation entirely beyond the deleterious influence of a large city. The first buildings erected were the dwelling houses for the observers and the engineers of the water plant. The observatory buildings were begun in the fall of 1877, and finally completed in 1879, although sufficiently advanced for beginning observations the year previous. The provisional administration of the permanent subcommittee continued, however, until 1882, when it was formally turned over to the director, Professor Vogel. In the meantime the personnel of the observatory had been selected, and its scientific activity fully begun. The main building contains the office rooms of the scientific staff, four laboratories, and the library. The subbasement contains the dwelling rooms of the janitor, a thoroughly equipped workshop, and a 6-horsepower gas engine and dynamo for charging the storage battery used in lighting the observing rooms and instruments, and for electric currents for laboratory experiments. The power house contains the machinery for pumping the water supply from a well 180 feet deep, and a complete Pintsch gas-generating plant. This plant also supplies the water and gas for the geodetic and meteorological institutes, which are located a short distance on either side of the observatory. Since that time there has been added to the observatory dwelling houses for the director in 1883, for the fireman and gate porter in 1889, and a detached observatory for the 13-inch photographic telescope for the observation of a zone of the international photographic star chart. |