18 NATURE 
as a test for nitric acid. The lists are most complete, 
and so far as we have been able to refer to them are 
accurate, and are not confined to recent work; e.g. 
Beale’s carmine stain and injection fluids are given. 
The volume will be of the greatest service in the 
chemical and the biological laboratory. 
OUR ASTRONOMICAL COLUMN. 
ASTRONOMICAL OCCURRENCES FOR SEPTEMBER :— 
Sept. 8. 20h. 46m. Jupiter in conjunction with the 
Moon (Jupiter 4° 56’ N.). 
ro. 17h. om. Saturn at quadrature to the Sun 
(go° distant). 
» 20h. om. Venus in the ascending node. 
» 22h. 14m. Uranus in conjunction with 
the Moon (Uranus 3° 35’ N.). 
14. 20h. om. Juno in conjunction with the 
Moon (Juno 0° 20’ N.). 
15. oh. 48m. Moon eclipsed, 
Greenwich. 
16. 3h. om. Mercury in superior conjunction 
with the Sun. 
22. gh. 2m. Saturn in conjunction with the 
Moon (Saturn 6° 59’ S.) 
23. 3h. 53m. Sun enters Sign of Libra; 
autumn commences. 
,, 8h. 22m. Mars in conjunction with the 
Moon (Mars 5° 6’ S.). 
25. oh. 7m. Neptune in conjunction with the 
Moon (Neptune 5° o’ S.). 
8h. 34m. Venus in conjunction with the 
Moon (Venus 1° 21’ S.). 
29. 16h. 46m. Sun eclipsed, invisible at 
Greenwich. 
30. 12h. om. Saturn stationary. 
5» 13h. 2m. Mercury in conjunction with the 
Moon (Mercury 2° 36’ N.). 
Tue SPECTRA OF THE Stars.—After many years of 
patient labour by such pioneers as Rutherfurd, Secchi, 
Huggins, Vogel, Pickering and his co-workers, Lockyer 
and McClean, the subject of stellar spectra has at- 
tracted during the last decade the attention of an 
ever-increasing number of students in astronomy, 
astrophysics, physics, and chemistry. This is no 
doubt thanks in a great measure to the enormous 
number of spectra classified in connection with the 
Draper catalogue, but also largely to the simple 
nomenclature developed by Miss A. J. Cannon, further 
simplified by the suggestions of Dr. Hertzsprung. 
Although classification merely has received a great 
amount of attention of recent years, perhaps partly 
due to the prominence given to the matter by the Solar 
Union making it the work of a special committee, 
yet many important pieces of work have been accom- 
plished beyond. Such are Campbell’s and Kapteyn’s 
work on the relations between radial velocities and 
type of spectrum, the similar work of Lewis Boss on 
the relation between proper motion and type, the work 
of Pickering and others on the distribution of stars of 
particular type of spectrum with reference to the Milky 
Way, &c. It is perhaps fitting that the import- 
ance of the subject should have led to the publication 
of a summary in the Memoirs of the Society of 
Italian Spectroscopists, No. 6, from the pen of Signor 
G. Abetti. It is, however, passing strange that this 
writer makes no mention of the work of Rutherfurd, 
Huggins, Lockyer, or McClean, except perhaps that 
some of them may be referred to in an ‘&c.”" Signor 
Abetti does not deal at all adequately with the litera- 
ture on the chemical constitution of the stars. He 
does state, however, that titanium stars are on a level 
nearer to the helium stars than are the iron stars— 
a statement for which we know no justification. 
NO. 2288, VOL. 92] 
invisible at 
[SEPTEMBER 4, 1913 
EXHIBITION OF THE ROYAL PHOTO- 
GRAPHIC SOCIETY. 
‘THE Royal Photographic Sociéty’s annual exhibi- 
tion at the Gallery of the Royal Society of British 
Artists, Suffolk Street, Haymarket, is well worth a visit 
by anyone interested in photography and its applications 
before it closes on October 4. Besides an excellent 
collection of works that are notable for their pictorial 
quality, and that will be examined by technicians as 
illustrations of the possibilities of the processes that 
they represent, there is a larger than usual number 
of colour transparencies, and also exhibits that are 
of specially scientific interest. The colour trans- 
parencies are chiefly autochromes, but there are many 
on the new Paget plate and a few ‘‘ Dufays,’’ both of 
which latter will quite well bear comparison with the 
autochromes for the quality of their colour and detail. 
In the scientific section, Lt.-Col. J. W. Gifford shows 
a large number of original photographs of spectra of 
the metals taken with a quartz optical train of large 
aperture. Mr. G. Reboul shows that cuprous 
chloride, produced by exposing a polished copper plate 
to chlorine gas, will furnish photographs by treatment 
somewhat similar to that employed in the production 
of daguerreotypes. The. insecurity of intaglio plate 
printing for monetary documents is again demon- 
strated by Mr. A. E. Bawtree in his copies of stamps, 
the genuine stamp and the forgeries being indistin- 
guishable. The photo-micrographic séction is par- 
ticularly strong. ‘The method of discovering a differ- 
ence in the colloids present in jams, and of detecting 
various adulterations, is excellently shown in a series of 
low-power photo-micrographs by Mr. E. Marriage. 
Of other series, the ‘‘ Histology of the Optic Nerve 
of Sheep,’ by Mr. J. T. Holder; the ‘‘Corpuscular 
Elements of Human Blood,” by Dr. D. H. Hutchin- 
son; and Mr. J. M. Offord’s ‘‘Diatoms under High 
Power,” deserve special notice. There is a fine col- 
lection of radiographs by Dr. Bela Alexander, Dr. 
G. H. Rodman, Dr. Gilbert Scott, Dr. Robert Knox, 
and Dr. Thurstan Holland, some taken in a small 
fraction of a second. In this direction the most novel 
work is by M. Pierre Goby, who by the use of ultra- 
soft rays secures quite full details in the most delicate 
transparent membranes, such as insects’ wings, at the 
same time as showing the internal structure of the 
insect. But more wonderful are his micro-radio- 
graphs, made by using the fine pencil of Réntgen rays 
that passes through a small hole in a lead screen. The 
detail in parts of small vertebrates only a fraction of 
an inch in length, is so well reproduced that a fifteen 
or seventeen times enlargement would be considered 
excellently sharp for a direct radiograph. M. Goby 
applies his method to foraminifera and other minute 
objects with similar success. Among the other ex- 
hibits there are a process with examples of a method 
of producing colour transparencies by the absorption 
of dyes in fish-glue, by Mr. Bawtree, and good col- 
lections of natural history photographs, lantern slides, 
and stereoscopic transparencies. 
THE ARCHAOLOGICAL INVESTIGATIONS 
IN THE MISSISSIPPI REGION. 
| the publication referred to below Mr. Clarence B. 
Moore gives us another of his very careful de- 
scriptions of the systematic excavations he is under- 
taking in the Mississippi valley, and, as usual, it is 
profusely illustrated with most excellent photographs 
and coloured plates. By these investigations and the 
superb way in which he publishes his results, Mr. 
Moore is laying a sure foundation for future general- 
1 ‘*Some Aboriginal Sites on Red River."’ By Clarence B. Moore. 
Journ. Acad. Nat. Sci., Philadelphia, xiv., 1912. 
ee 
