4.30 
NATURE 
[Aucusr 31, 1899 
made at Mount Hamilton during 1898 and 1899. The elements 
he gives are the following :— 
System IZ. 
T =1894'0900 7=46° 1''9 
K= —7- 37069 2= 44° 30'°2 (1900) 
P= 488421 years m—Q2=212° 64 
€=0°5875 
The mean value of the distance of the companion is given as 
a=7"'594- 
CATALOGUE OF ASTRONOMICAL INSTRUMENTS.—Sir Howard 
Grubb has sent us a revised edition of his catalogue of astro- 
nomical instruments, observatories, &c., showing the nature of 
the work turned out from his workshops at Rathmines, Dublin. 
The quality and performance of these are well known to prac- 
tical astronomers, the catalogue in its new form will be in- 
teresting to all from the beautiful illustrations with which it 
is furnished, showing in a most convincing manner the capa- 
"bilities of various optical and mechanical contrivances. The 
frontispiece is a reproduction of a photograph of 4 Argus 
taken with the astrographic telescope at the Cape Observa- 
tory. At the end of the volume there are four plates 
showing ‘‘The solar eclipse of 1898,” ‘‘ A specimen of 
work done by a photographic doublet of 15 inches aper- 
ture,” ‘‘The great nebula in Orion,” and ‘‘ The Dumb-bell 
mebula in Vulpecula’’; the two latter being from negatives 
taken by Mr. W. E. Wilson with a reflector of 24 inches 
aperture. 
THE CAPE OBSERVATORY. 
"THE annual report of Her Majesty’s Astronomer at the 
Royal Observatory, Cape of Good Hope, for the year 1898, 
has recently been published. The following is a short 7ésvmdé 
of the chief details :— 
The McClean Telescofe.—The equatorial mounting of this 
instrument, the generous gift of Mr. F. McClean, F.R.S., 
reached Table Bay in good order on April 11, 1898. In six 
weeks all the parts had been mounted and adjusted, the stand, 
however, requiring considerable modification. The fittings for 
electrical illumination of the circles, scales, and micrometers 
had to be made or remodelled at the Cape. 
The hydraulic motor for rotating the dome arrived on July 4, 
the hydraulic ram and valves for automatic clock-winding on 
October 11, and by November 1 all the essentials of the ob- 
servatory and stand were fitted and in good working order. 
The raising and lowering of the floor and rotation of the domeare 
commanded by cords which may be actuated by the observer at 
‘the eye-end of the telescope with the utmost ease and delicacy, 
while the hydraulic clock-winding gear, contrived by Mr. 
McClean, automatically winds up the clock-weight at short 
intervals without communicating the slightest vibration to the 
telescope. 
The 18-inch visual object-glass has proved to be a very 
fine one, both its spherical and chromatic corrections being 
practically perfect, as far as the kinds of flint and crown glass 
at present procurable in discs of that size will allow. 
The 24-inch glass has two faults : the marginal images show 
well-marked coma, and the minimum focus, instead of being 
near to or more refrangible than Hy, is for rays of refrang- 
ibility between H8 and Hy. it is understood that Sir Howard 
Grubb will remedy these defects. The slit spectroscope for 
line of sight work, made by the Cambridge Scientific Instru- 
ment Company, was shipped from London on December 21, 
and the 24-inch glass cannot be returned for alteration until 
tests have been made with this spectroscope in conjunction 
with it. 
he New Transit Circle.—The foundations for the new 
transit circle have been built, and the observatory, of sheet 
steel, is constantly expected from Messrs. T. Cooke and 
Sons, of York. Messrs. Troughton and Simms _ reported 
that the transit circle itself would probably be ready in March 
1899. 
NO. "1557, WOE: 00] 
Astronomical Observations.—The work of the /vanszt circle 
has been chiefly devoted to observations of standard stars for re- 
duction of the measures of the ‘‘ Catalogue Photographic Plates.” 
During the year 10,355 meridian transits and 9863 determin- 
ations of zenith distance have been recorded. 
With the He/zome‘er systematic observations of the major ex- 
terior planets have been made, the year’s work including fifty- 
three measures of Jupiter, forty-four of Saturn, forty-five of 
Uranus, and seventy-two of Neptune, all during opposition. 
This instrument has also been employed in the triangulation of 
twenty-one stars surrounding the South Pole, and for investiga- 
tion the possibility, first suggested by Dr. Rambaut, of atmo- 
spheric chromatic dispersion affecting the accuracy of heliometer 
observations. The seven-znch equatorza/ has been employed for 
observations of occultations, revision of star-lists, and Codding- 
ton’s comet ; and the s¢x-znch telescope, in conjunction with a 
Zollner photometer, for the comparison of photographic and 
visual magnitudes in areas near the pole and equator of the 
Milky Way. 
With the astrographic telescope, 469 plates have been ob- 
tained, 200 of these being ‘‘revision plates,” as it is pro- 
posed to repeat the whole series of catalogue plates, in order 
to bring the epoch at which the plates were taken nearer to 
that at which the comparison stars were observed on the 
meridian. 
Geodetic Survey of South Africa.—The field operations in 
connection with the geodetic survey of Rhodesia were resumed 
in May at the close of the rainy season, the early part of the 
year having been spent in training the observers in the use of 
the Jaderin base-measuring apparatus, the constants of which 
were accurately compared with the Cape measuring bars. The 
difference of longitude between Buluwayo and the Cape Observ- 
atory was determined by exchange of telegraphic signals on four 
nights, the astronomical latitude and azimuth being also ob- 
served. After the selection of a site, a base line of 117 miles in 
length was measured, and during the year seventeen stations 
were occupied and measurements taken therefrom. 
An arrangement for the delimitation of the Anglo-German 
boundary between British Bechuanaland and German South- 
west Africa having been approved by both Governments on 
January 1, Lieutenant Wettstein and Major Laffan, R.E., 
after some months’ sojourn at the observatory for practice in 
astronomical observations, commenced operations at Reitfontein 
(long. 20° E., lat. 26° 47’ S.) on November 19, by determinations 
of astronomical latitude and azimuth and the selection of 
stations. 
The existing triangulation in the Cape Colony on the meridian 
of 20° E. long. is at present limited to the northern triangles of 
Sir Thomas Maclear’s arc and to Bosman’s accurate triangula- 
tion of Bechuanaland from Vryburg to the 20th meridian, and 
along that meridian from the Orange River to Reitfontein. There 
thus remains to complete the chain from Cape Agulhas (the 
southern point of Africa) to Reitfontein, a distance of only 140 
miles to be filled in. The triangles for this work have been 
selected, and are about to be measured with the Repsold 
theodolite by Mr. Alston. 
In connection with the survey of Rhodesia, Mr. Rhodes has 
promised that when he is in a position to commence the ex- 
tension of the railway from Buluwayo to the Zambesi, he will 
place at the disposal of Her Majesty’s Astronomer the funds 
necessary to carry on thearc of meridian from Southern Rhodesia 
to Lake Tanganyika. Thus there is in prospect the completion 
of the following valuable geodetic data :— 
(1) A geodetic are along the meridian of 20° E. long. from Cape 
Agulhas (lat. 34° 49’ S.) to the parallel of 22° S. lat., perhaps 
to 18° S. lat., ze. an are of 12” 49’, or possibly of 16° 49’ in 
length. 
(2) An arc along the meridian of 30° E. long. from the 
south of Rhodesia (lat. 22° S.) to the southern extremity of 
Lake Tanganyika (lat. 8° 40’ S.), an arc of 13° 33’ in length. 
Both of these important operations ‘will be under the direction 
of Her Majesty’s Astronomer. 
It is also hoped that the German Government will carry the 
latter work along the eastern border of Lake Tanganyika to 
Uganda, whence the way is now clear for a triangulation along 
the Nile to Alexandria, z.e. practically along the same meridian 
as above, 30° E. long. This latter work should for various 
reasons be commenced at its northern extremity. 
Longitude of Lake Nyassa.—The longitude of Nkata Bay 
a ll lg 
