Lieutenant Maury led to his resignation after a service of only fourteen months. In 1848 Mr. James Ferguson received the civilian appointment of Assistant Observer, and later that of Assistant Astronomer. He proved an indefatigable observer, and the records of the Observatory show a vast amount of valuable and painstaking work with the equatorial by him. In 1851 Professor Yarnall, U.S.N., was ordered to the Observatory, and in the most untiring and conscientious manner he made substantially all the observations obtained with the mural circle and the Ertel transit instrument during the decade from 1850 to 1860. Professor Keith withdrew from the Observatory in 1853, and Professor Coffin was obliged to give up astronomical observing in 1850 on account of an affection of his eyes. The work of the Observatory as published during Maury's administration is contained in the following volumes: The Observations for 1845, published in 1846; the Observations for 1846, published in 1851; the observations for 1847, published in 1853; the observations for 1848, published in 1856; the observations for 1849-1850 (one volume), published in 1859. It is worth noting that in the published volumes from 1845 to 1848 inclusive the institution is designated as the National Observatory, but on December 12, 1854, the Hon. J. C. Dobbins, Secretary of the Navy, directed that its official designation should be 'The United States Naval Observatory and Hydrographical Office,' and accordingly all subsequent volumes have been issued as the work of the United States Naval Observatory.

The scheme of work arranged by Maury was as follows: To observe regularly in the meridian the positions of the Sun, Moon, planets and moon-culminating stars; to observe a Lyræ regularly with the prime vertical transit, to determine with that instrument the declinations of a catalogue of zenith stars, and to review the Dorpat

Catalogue of double stars with the equatorial telescope.

The meridian observations of the Sun, Moon and planets were commenced in 1845 with some degree of ardor, and kept up with decreasing persistency for several years, but after 1850 only a few scattering observations occur in the published records. The prime vertical transit was also employed for a few years, but soon after 1850 it fell into disuse.

The equatorial was used continuously during the entire period from 1845 to 1861. Assistant Astronomer Ferguson had charge of it during a large portion of this time, and the records show an unbroken series of carefully executed observations of comets, minor planets and occultations of stars by the Moon. The assiduity of Ferguson is attested by his discovery of three minor planets, viz: Euphrosyne, No. 31, on Sep. tember 1, 1854; Virginia, No. 50, on October 4, 1857; Echo, No. 60, on September 14, 1860.

It would be an act of injustice to pass by unmentioned the numerous items of personal work which enrich the published records. In them we find Coffin's refraction tables founded on Bessel; tables for aiding in the reduction of the apparent places of stars to mean places, by Coffin, Keith and Hubbard ; an investigation of the latitude of the observatory and a discussion of the errors of standard thermometers, by S. C. Walker; and last, but not least, we must mention S. C. Walker's discovery, on February 4, 1847, that certain stars observed by Lalande at Paris on May 8 and 10, 1795, were the recently discovered planet Neptune; thus extending the observations of that planet over an interval of fifty years, and thereby making the determination of its elements much more precise.

By far the most ambitious task which Maury set for the new observatory was detailed in his letter to George Bancroft, Sec

retary of the Navy, July 28, 1846. Speaking of the regular work upon the Sun, Moon and planets, he adds: "A regular series of observations is continued on these objects and the time which is not occupied in the round with them has, with your approval, been devoted to cataloguing; to this end a regular and systematic exploration of the whole heavens from 45° south has been commenced, with the intention of penetrating with the telescope every point of space from that parallel of declination up to the north pole, and of assigning position to every star, down to the 10th magnitude, that shall pass through the field of view." The amount of labor involved in this colossal undertaking was entirely beyond the capacity of any one observatory to accomplish in a generation. Maury would never have undertaken it if he had possessed an intimate knowledge of the herculean labor in respect to observation and computation which its execution demanded. The result was that the observation of the zones was continued with some degree of energy through the years 1846, '47, '48 and '49 with the transit instrument, the mural circle and the meridian circle, by some eleven different observers, two of whom were experienced, and the remainder quite inexperienced. The number of observations accumulated unreduced in these four years was fully 38,000. Maury did not publish any results until 1860, when he issued the meridian circle zones observed in 1846, containing about 4,000 observations. The publication of the remaining zone work was delayed until 1873, when it was printed under the supervision of Professor Asaph Hall, who remarks: "On account of the inexperience of some of the observers and the lack of good organization these observations contain many errors, and the whole work needs a careful revision." To furnish material for this revision, four hundred and fifteen zero stars were selected by Professor Hall from

the zones, and their places have since been determined, but as yet the revision has not been accomplished. In contrast with this we may recall that during the decade 1850 to 1860 Argelander, of the Bonn Observatory, in accordance with a carefully conceived plan, observed and published the approximate positions of more than 450,000 stars of the first nine magnitudes between 23° of south declination and the north pole of the heavens. Maury failed because his scheme was entirely too herculean to be accomplished with the means at his command, while Argelander achieved success by bringing the scope and precision of his work within the limits possible of execution.

A review of this period would be incomplete without a reference to the invention of the chronographic method of registering star transits and the general application of electro-magnetism to the transmission of time signals for the determination of differences of longitude. Soon after the invention of the telegraph several persons at about the same time conceived the idea of applying its fundamental principles to the transmission of clock signals and the registering of star transits. Among them were Walker, Bache, Bond, Mitchell, Saxton and Locke. Lieutenant Maury became interested in the labors of the last-named gentleman, and induced Congress to appropriate $10,000 on March 3, 1849, to pay Dr. Locke, of Cincinnati, for the construction and use at the National Observatory of a magnetic clock, a fillet chronograph and a cylinder chronograph. These instruments, although not perfect in details, embraced the essential features of the chronographs in actual use at the present time.

We come now to the third period of the history of the Observatory-namely, from Maury's resignation to the removal to the new site. On April 20, 1861, Maury suddenly resigned his commission and went south to join the Rebellion, and on April

23 Commander J. M. Gilliss, who had built the Observatory some sixteen years before, was ordered to assume charge. For ten years previous to his withdrawal Maury had ceased to have an active interest in astronomical work, and had been wholly absorbed in hydrographic studies. Upon the accession of Gilliss new life was immediately infused into the institution. He resumed meridian observations of the Sun, Moon and planets, which had been practically suspended, and made it one of his first tasks to press the completion of all the unfinished work, which had been accumulating since 1852. At the same time he carried on with equal zeal the nautical work of the Observatory, which the Civil War, then just beginning, had very largely increased.

Until June 21, 1866, when the Hydrographic Office was created, an important part of the duties of the Naval Observatory had been to care for and issue to the Navy all charts, sailing directions, compasses, chronometers, sextants, spy-glasses and other nautical instruments. At the date above mentioned the care of all this material, except chronometers, was transferred from the Observatory, but most of it was returned in 1883, and since then the Observatory has had charge of all nautical instruments of the Navy, except charts and compasses. Since January 1, 1884, all chronometers have been regularly subjected to a temperature test ranging from 45° to 95° Fahrenheit.

During the Civil War, from 1861 to 1865, the duties devolving on the Observatory, in connection with the inspection and issue of all varieties of nautical instruments, were especially arduous, and the constant attention of a number of officers was required to supply each of our several hundred war vessels with their needed outfits.

Since August, 1865, in accordance with a plan originated by Professor Harkness, the Naval Observatory has transmitted time.

signals daily, except Sundays and holidays, over the telegraph lines running into the chronometer room. Up to the latter part of the year 1879 these signals were transmitted by hand, but since that date they have been sent by an automatic apparatus in connection with the transmitting clock devised by Professor J. R. Eastman. Time balls in a large number of the principal cities of the country are dropped by them.

In 1862 Congress authorized the appointment of three civilians, called aids, to assist in meeting the increased demands on the Observatory on account of the war. Some of the changes in the personnel during this period were as follows:

Simon Newcomb was appointed Professor of Mathematics, U. S. N., in 1861; Asaph Hall, William Harkness and J. R Eastman received appointments as aids in 1862. Hall and Harkness were promoted in 1863, and Eastman in 1865, to be Professors of Mathematics, U. S. N. In 1863 the Observatory lost by death the gifted Professor Hubbard, whose labors had been restricted for years by a frail body.

The later additions to the personnel were as follows: Edgar Frisby was appointed Assistant Astronomer in 1868; A. N. Skinner in 1870 and H. M. Paul in 1875. Frisby was promoted to be Professor of Mathematics, U. S. N., in 1878, on the retirement of Professor Yarnall.

Soon after Gilliss' accession to the superintendency it became apparent that in order to meet the demands of science the Observatory needed a first-class meridian circle, and he took steps to remedy this defect in its equipment. The result was the sale. of the small Ertel meridian circle, and the mounting in 1865 of a Pistor and Martins meridian circle 8.52 inches' aperture. The Ertel transit instrument was moved to the east wing and the new meridian circle took its place in the west wing.

In 1873 the Observatory received the

great 26-inch eqtatorial refractor by Alvan. Clark & Sons, which was then the largest telescope in the world.

A continuous series of Sun, Moon and planet meridian observations was carried on from 1861 to 1865,with the mural circle and the transit instrument. In the beginning of 1866 the new Pistor and Martins meridian circle was put in service, and observations were made with it in the old west transit room until 1869, June 5. It was then removed to the new transit room, where it was used from February 2 to August 15, 1870, when observations were suspended for some repairs on the instrument. They were resumed in 1871, August 1, and then continued until 1891, June 28, when the instrument was dismounted for removal to the new Observatory. In connection with the Sun, Moon and planet observations, there were made on this instrument extensive determinations of the positions of the Ephemeris stars and of large numbers of miscellaneous stars. When the mural circle and transit instrument were relieved of the planet work, Professor Yarnall devoted them to the completion of the determination of the positions of all miscellaneous stars which had been observed with them since 1845. These collected observations form Yarnall's catalogue, which was published later. The equatorials were assiduously employed on the observation of asteroids, comets, occultations, double stars, satellites, and other work for which they were especially adapted.

The annual volumes of observations were published regularly from 1861 to 1890, and the principal memoirs and researches of greater or less extent appearing in them. during this period are as follows:

The solar parallax; from equatorial observations of Mars, 8.8415" by Professor Hall, Washington Observatory 1863, p. XI; from meridian observations of Mars, 8.8310" by Assistant Astronomer Ferguson, Washington Observations, 1863, p. XI.

Discussion of the solar parallax by all known methods, 8.848'' by Professor Newcomb, Washington

Observations, 1865, App. II.

A catalogue of the positions of 151 stars in Præsepe by Professor Hall, Washington Observations, 1867, App. IV.

Reports on the solar eclipse of 1869, August 7; Washington Observations, 1867, App. I.

Reports on the solar eclipse of 1870, December 22; Washington Observations, 1869, App. I.

Reports on the solar eclipse of 1873, July 29; Washington Observations, 1876, App. III. Reports on the solar eclipse of 1880, January 11; Washington Observations, 1876, App III.

The following embrace all of Hall's double-star work with the 26-inch equatorial; Washington Observations, 1876, App IV., and Washington Observations, 1888, App. I.

The time of rotation of Saturn on its axis was determined by Professor Hall by means of an equatorial spot which was visible from 1876, December 7, to 1877, January 2. The period deduced was 10h14m 23.8 mean solar time. The paper may be found in the Astronomische Nachrichten No. 2146.

On the right ascensions of the equatorial fundamental stars, by Professor Newcomb, Washington Observations, 1870, App. III.

Researches on the motion of the Moon, by Professor Newcomb, Washington Observations, 1875, App. II. The Uranian and Neptunian systems, Professor Newcomb, Washington Observations, 1873, App. I. The central parts of the nebula of Orion, Professor Holden, Washington Observations, 1878, App. I.

A catalogue of 10,964 stars from observations on the mural circle and transit instrument, by Professor Yarnall, revised edition by Professor Frisby, Washington Observations, 1884, App. I.

A catalogue of 1963 stars observed by Gilliss, at Santiago, Chili, edited by Professor Harkness, 1868,

App. I.

Observations and orbits of the satellites of Mars, Washington 1878. This memoir is bound with some copies of Washington Observations, 1875.

The two satellites of Mars were discovered by Professor Hall in August, 1877, with the 26-inch equatorial.

The six inner satellites of Saturn, by Professor Hall, Washington Observations, 1883, App. I.

Saturn and its rings, by Professor Hall, Washington Observations, 1885, App. I.

Observations for stellar parallax, by Professor Hall, Washington Observations, 1883, App. II.

The solar parallax and its related constants, by Professor Harkness, Washington Observations, 1885, App. III.

Reports on the observations of Encke's comet during its return in 1871, by Professors Hall and Harkness, Washington Observations, 1870, App. II.

Chronometer rates as effected by changes of temperature and other causes, by Commander C. H. Davis, Jr., Washington Observations, 1875, App. III.

The following differences of Longitude have been determined between Washington

and

Havana, Cuba, Professor Harkness, Washington Observations, 1867, App. I.

St. Louis, Professor Harkness, Washington Observations, 1870, App. I.

Detroit, Mich. Carlin, Nev.

Professor Eastman, Washington
Observations, 1872, App. II.

Austin, Nev. Ogden, Utah, Professor Eastman, Washington Observations, 1874, App. II.

Sayre Observatory, South Bethlehem, Pa.; Professor Eastman, Washington Observations, 1875, App. I. Cincinnati Observatory, Professor Eastman; Washington Observations, 1876, App. IV.

Morrison Observatory, Glasgow, Mo.; Professor Eastman, Washington Observations, 1876, App. V. Observatory Princeton, N. J.; Assistant Astronomer Paul, Washington Observations, 1878, App. II.

The zone observations made in 1846-1849 were published as follows:

Meridian circle zones observed in 1846 (a separate publication) contains 4,054 stars, 1860.

Mural circle zones 14,804 stars, Washington Observations, 1869, App. II.

Transit zones, 12,033 stars, Washington Observations, 1870, App. IV.

Meridian circle zones observed in 1847, '48, '49, 7,390 stars, Washington Observations, 1871, App. I.

Results of observations made with the transit intrument and mural circle, 1853 to 1860 inclusive, Washington Observations, 1871, App. II.

Report of Lieut. A. G. Winterhalter as delegate of the United States Naval Observatory to the Astrophotographic Congress held in Paris 1887; with a report on European observatories, Washington Observations, 1885, App. I.

Announcement of the discovery in April 1888, and the subsequent determination of the elements, of a new short-period variable star, S Antliæ No. 3407 of Chandler's catalogue; by Assistant Astronomer H. M. Paul, Astronomical Journal No. 215.

A magnetic observatory was arranged by Maury in 1845, but its construction was so faulty and inadequate that its use was soon discontinued. Nothing further was done

In

in reference to magnetic observations until 1887, when the Bureau of Navigation erected on the grounds of the Naval Observatory a complete magnetic outfit which was provided with facilities for obtaining continuous photographic records of declination, inclination and horizontal force. struments were also provided for the necessary absolute determinations of the magnetic elements. This magnetic outfit was turned over to the Observatory in July, 1887. Observations were commenced soon after that date, and continued until September, 1892, when the instruments were removed to the new site.

The preparations for the observations of the transits of Venus of 1874 and 1882, by the United States Transit of Venus Commission, were made at the Naval Observatory as the headquarters of the operations of the Commission, but although this work was done principally by Professors Newcomb and Harkness, it was entirely distinct from the work of the Observatory.

During the years 1885, 1886 and 1887 Professor S. J. Brown, U. S. N., was permitted by courtesy of the Superintendent of the Naval Academy to use its 4-inch Repsold meridian circle as an adjunct of the Naval Observatory in making a series of determinations of the positions of the 303 stars which had been selected to serve as the basis of the German Astronomical Society's southern zones.

When it became known that the work of the Naval Observatory would be interrupted by its removal to a new site the trustees of the Washburn Observatory, of Madison, Wis., very considerately offered the free use of the instruments of the Washburn Observatory to the staff of the Naval Observatory during that period. In acceptance of this invitation Professor S. J. Brown went to Madison on the conclusion of his Annapolis work, and from October, 1887, to October, 1890, conducted a series of