Photographs have been received through the Solar Physics Committee from Dehra Dûn, India, up to 1907 December 25, and these have been further supplemented by photographs from the Observatory at Kodaikanal, India, and from the Royal Alfred Observatory, Mauritius. The daily record thus made up is complete, for the year 1907, up to 1907 December 25, the date of the last photograph received from Dehra Dûn. The last photograph received from Kodaikanal is dated 1907 August 12, and the last from Mauritius 1907 January 26. The photographs taken at Greenwich have been measured up to 1907 May 21, those from Dehra Dûn up to the end of May, those from Kodaikanal and from Mauritius as far as they have yet been received.

The solar activity throughout 1907 has shown no diminution as compared with the previous year, the months of January and February being indeed two of the most active during the whole of the present maximum. The work of measurement and reduction, therefore, still continues to be very heavy.

The copy for press of the photoheliographic results for 1906 is complete for the daily record, and is in the hands of the printer as far as the end of June. The copy for press of the sun-spot ledger is nearly ready.

During the past year the volume of supplementary photoheliographic results, 1874 to 1885, has been completed and published. The ledgers of the spot-groups, and the computation of the areas of spots and faculæ as "projected," as well as corrected for foreshortening, are therefore now complete from the beginning of the Greenwich photographic record of the state of the solar surface.

Printing. The copies of the volume of Greenwich Observations for 1905 were distributed in July 1907. The Heliographic Results 1874 to 1885 have been printed, and will be distributed with the second volume of the Astrographic Catalogue and the Measures of Photographs of Eros for determination of the Solar Parallax, which are just on the point of completion. The printing of the 1906 observations is in progress.

At the request of the Hydrographer, Captain Monro, R.N., and Lieutenant Gibson, R.N., were attached to the observatory from September 16 to October 14 to practise observations with one of the portable transits, in view of a determination of the longitude of the Island of Ascension, and indirectly of the Cape Observatory, to be made in February,

Royal Observatory, Cape of Good Hope.
(Director, Mr. S. S. Hough, H.M. Astronomer.)

After twenty-eight years' service as H.M. Astronomer, Sir David Gill retired from the observatory on February 20, and was succeeded by Mr. S. S. Hough, Chief Assistant. The vacancy

in the staff thus created was subsequently filled by the appointment

of Dr. J. K. E. Halm, of the Royal Observatory, Edinburgh, to the post of Chief Assistant, who arrived at the Cape on July 1. Transit-Circles.-The new reversible transit-circle has been in use throughout the year, principally in observations of the list of fundamental stars commenced in January 1905. To this list were

added a number of circumpolar stars, and throughout the winter months consecutive transits of the latter, above and below pole, were observed as frequently as circumstances permitted. The method of observing employed has been the Repsold-Struve method, with travelling wire driven by hand.

The discussion of the observations of circumpolars in conjunction with the observations for azimuth determination in the preceding years, while exhibiting unmistakable evidence of the stability of the azimuth marks, indicated a significant and apparently increasing discordance between the azimuth determinations made with Clamp East and those made with Clamp West. Attempts to account for these discordances led to the detection of a slight mechanical defect in the end-bearing of the micrometer-screw, which has now been rectified. Since September 13, observations have been directed to the further testing of the instrument under its altered condition, and to the determination of the personality of observers in observing slow-moving circumpolar stars. These observations appear to indicate that the defects previously shown have now been completely remedied. Regular observation of the Sun and minor planets have been made throughout the year.

The old transit-circle has been employed in observing miscellaneous stars used in connection with the Geodetic Survey of S. Africa, those of which occultations have been observed, or of which places were required for various purposes.

The total number of observations secured with both instruments was as follows:

In each case the day observations include observations of the Sun taken on 116 days, observations of Venus on 89 days, and of Mercury on 55 days. The lunar crater Mösting A has been observed on 13 nights with the old transit-circle and on 31 nights with the new transit-circle.

Heliometer. The systematic observation of the major planets at the time of opposition has been continued and the following observations secured :

:

In connection with the triangulation of the comparison stars used for the planetary observations, 478 measures of distance have been made during the year, and the following zodiacal areas have now been completely triangulated :—

During the transit of Mercury of November 14 a series of measures of the distances of Mercury from the Sun's limbs, comprising in all 48 pointings, were secured, and in connection therewith observations of 5 standard pairs for the determination of instrumental corrections were made on 3 nights.

The Victoria Telescope.-This instrument has been almost exclusively used throughout the year in the photography of stellar

* Still under observation.

19 8

-25 7

19 40

19 55

-22 29

20 24

21 34

23 10

23 30

- 7 30

spectra for the determination of radial velocities and the solar parallax. The instrument was in use on 103 nights, and 231 plates of the spectra of 18 stars were secured. 246 stellar spectra have been measured, mainly in connection with the determination of solar parallax.

The radial velocities of the following stars, specially selected for the determination of solar parallax, are completely reduced and await final discussion:

A considerable number of experimental plates for the examination of the focal adjustments have also been secured and carefully measured. A discussion of these plates has resulted in a distinct improvement in the focal adjustments, while their permanence has been further secured by an improved arrangement for circulating the air surrounding the prism box. Whereas formerly a practically perfect temperature and focal control was secured so long, but only so long, as the instrument remained undisturbed in one position, under the improved circulatory system no appreciable change in focus occurs as the result of moving the instrument from one position to another.

Astrographic Telescope. This instrument has been chiefly used in the photography of selected regions, in accordance with the plan proposed by Professor Kapteyn. The number of plates secured is as follows:

During the year 199 Catalogue plates, containing 101, 136 stars, including 2282 standard stars, have been measured, both in direct and reversed positions of each plate. The total number of plates now measured is 1285, containing about 700,000 star-images, corresponding to nearly 300,000 different stars.

The actual state of the work on December 31 was as follows:

Plate constants have been derived for plates in zones - 41°, - 42°, and 43°, and applied to all rectangular co-ordinates in zone - 41°, and to 112 plates in zone - 42°.

Occultations. Twenty-four separate phenomena of occultation have been observed, viz.—

The observations up to November 14 have been completely reduced and results communicated in advance to Professor Newcomb.

Transit of Mercury.-On the occasion of the transit of Mercury of November 14, in addition to observations with the transit-circle and heliometer, the times of ingress and egress were observed by six different observers with the various equatorials.

Comets.-Comet 1907 a was observed with the Victoria telescope on 6 nights, and the results have been communicated to the Astronomische Nachrichten. The results of observations of Comet Finlay (d 1906) and Metcalf (b 1906), made during 1906, have likewise been communicated to the Ast. Nach., and published during the year.

Vol. ii. part 5 of the Cape Annals, containing "Meridian Observations of the Sun, Mercury, and Venus during the years 1884-1892," and vol. ii. part 6, containing "Results of Occultations observed during the years 1896-1906," have been passed through the press and issued during the year.

Vol. viii. part 1, containing "Heliometer Observations of the Major Planets during the years 1897-1904," has been passed through the press and will shortly be issued.

The Cape Catalogue 1905-6, based on meridian observations made with the 8-in. transit-circle during the years 1905-6, and reduced to the equinox 1900, has been printed and issued.