JUNE 23, 1923] 
Tuesday, visits will be paid to Thorvaldsen’s Museum 
and the Museum of Applied Art. In the afternoon 
the National Art Gallery and the Zoological Museum 
will be visited, and later there will be a trip in the 
Danish Expeditionary ship Dana, which is under the 
charge of Dr. Petersen. On Wednesday, July 18, there 
will be a visit to the Open-Air Museum at Lyngby, 
a visit to the Natural History Museum in Frederiks- 
borg Castle, where the members will be entertained 
to lunch, and later a visit to the famous castle at 
Elsinore. On the following day the members will 
visit the Glyptotheke, returning to Hull by the 
s.s. Spero on the same evening. 
Mr. I. H. N. Evans, of the Federated Malay States 
Museums, Taiping, has written, for appearance with 
the Cambridge University Press, ‘‘ Studies in Religion, 
Folk-lore, and Custom in British North Borneo and 
the Malay Peninsula,” giving the results of research 

NATURE 
857 
carried out in the years 1910-21. The same house 
will publish in the summer ‘‘ The Banyankole,” by 
the Rev. J. Roscoe. It will form the second part of 
the report of the Mackie Ethnological Expedition to 
Central Atrica. 
In the chairman's report of the National Ilumina- 
tion Committee for 1922, now issued in pamphlet 
form, it is stated that the provisional definitions of 
photometric terms and units have now been adopted, 
and form the basis of a series to be issued shortly by 
the British Engineering Standards Association. The 
latter body has been invited to form a sectional com- 
mittee on illumination. Reference is also made to the 
committee which is investigating the subject of motor- 
headlights, and, as a preliminary to suggestions, is con- 
sidering the recommendations already made in other 
countries. The pamphlet contains an official transla- 
tion of the French text of the photometric definitions. 

Our Astronomical Column. 
ANNOUNCEMENT OF A NEw Comet.—Mr. W. N. 
_ Abbot, the British schoolboy in Athens who recently 
announced the brightening of Beta Ceti, now reports 
the discovery of a comet on June 12. The Right 
Ascension is given as 15" 13™ 4°, and the Declination 
53° 26’ N., in the constellation Draco. As the tele- 
is not quite in the regular form, there is some 
doubt whether the Declination may not be the com- 
plement of the above, that is, 36° 34’. No further 
information is at present to hand. 
PROPOSED SOLAR OBSERVATORY IN AUSTRALIA.— 
This observatory has now been planned for several 
years ; a message, dated April 17, from Melbourne to 
the Times indicates that the arrangements are making 
considerable progress. The site has been chosen at 
Mount Stromlo, near Canberra, the federal capital. 
Prof. Duffield, of University College, Reading, was 
then in Australia and was being consulted, together 
with the Astronomer Royal and Prof. Turner, on the 
question of the selection of a director. It was ra 
posed that the new director, when selected, should be 
given an opportunity of visiting, among other observa- 
tories, the solar observatory on Mount Wilson, As that 
observatory takes the leading place in researches on 
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3 
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7 
solar physics, it is obvious that the director of the 
new observatory should be intimately acquainted with 
its methods, and should arrange a programme of work 
that would supplement the results obtained there. As 
the two observatories are some 90° apart in longitude, 
the Australian station could continue the record of 
interesting outbursts after sunset in California. 
PHOTOMETRIC OBSERVATIONS OF THE PLANET 
Mercury.—It is of considerable importance to 
measure the brightness of this elusive little planet, 
since the result has a considerable bearing on the 
estimate we form of the condition of its surface. The 
conditions for doing so are much easier in the tropics, 
owing to the shorter twilight, the prevalence of 
clearer skies, and the greater altitude of the planet. 
Mr. J. Hopmann, who visited Christmas Island for 
the recent eclipse, utilised the occasion to compare 
Mercury with neighbouring stars (Arcturus, Spica, 
Procyon, Regulus, Deneb, Denebola, etc.) and the 
lanets Saturn and Jupiter. On September 5 it was 
righter than Saturn by a whole magnitude, on 
November 5 even brighter than Jupiter, which was, 
however, lower down. It was seen at Malta on 
November 15 when only 12° from the sun. 
NO. 2799, VOL. 111 | 
Mr. Hopmann has reduced his observations to 
distance of Mercury from the sun 0°3871, from the 
earth ro, and obtains the formula -o'71I mag. 
+0°03582 mag. (a -50°), a being the phase angle 
sun-Mercury-earth. The first term was given as 
-o-998 mag. by Miiller and Jost, their second term 
being practically the same as his. In other words, he 
makes the planet a quarter of a magnitude fainter, 
thus indicating a still lower albedo, and a condition 
of surface probably approximating to that of the moon 
(Astr. Nachr. 5220). 
PHOTOGRAPHIC STUDIES OF NEBUL&.—Mr. J. C. 
Duncan contributes his third paper on the studies 
of the form and structure of nebule from photo- 
graphs made with the roo-inch and 60-inch reflectors 
and the 1o-inch Cooke refractor in the years 1920 to 
‘1922 to the Astrophysical Journal (vol. 57, No. 3). 
The previous papers appeared in volumes 51, p. 4, and 
53, Pp. 392, of the same journal. The present com- 
‘munication is accompanied by eleven excellently 
reproduced plates. Evidence of the existence of 
dark nebulosity is found in N.G.C. 1977, M 78, the 
‘Trifid nebula, the dark objects Barnard 72, 92, 93, 
and 133, and the American nebula. Of great interest 
is N.G.C. 4038-4039, a bright spiral of unique form 
with faint extensions of extraordinary appearance. 
In a field the size of the full moon in Coma Berenices, 
the 100-inch telescope photographs no less than 319 
small nebula. The object N.G.C. 6822 is found to be 
a mixture of stars and small nebule resembling the 
magellanic clouds. 
In examining these reproductions taken with the 
great roo-inch mirror, one cannot but recall and 
admire the fine photographs which Dr. Isaac Roberts 
took with his small mirror of only 20-inches aperture. 
To take a case in point, it is interesting to com- 
pare the reproduction of the nebula N.G.C. 1977 
in Orion taken with the t1oo-inch mirror with 
Roberts’s reproduction in plate 17 in his volume of 
‘Photographs of stars, star-clusters and nebule,’’ 
taken in 1889 and published in 1893. The exposure 
for Roberts’s photograph was 3 hours 25 minutes, 
while that with the roo-inch was 5 hours 40 minutes. 
There is very little difference between these photo- 
graphs except the sharpness of the details and the 
greater contrast in light and shade, which in the 
1oo-inch reproduction has been secured purposely by 
repeated copying. 
