\ULet eS T5)| 
NATURE 
493 

OUR ASTRONOMICAL COLUMN. 
Tue Oricin or Comets.—In the Publikationer og 
mindre Meddelelser fra Kobenhavns Observatorium, 
No. 19, Prof. Elis Strémgren publishes a research 
which he has concluded with the help of Mr. J. Braae 
on the subject of the origin of comets. In the intro- 
duction the author refers to the results of previous 
workers, and suggests that the question as to whether 
comets came originally from interstellar space or were 
formed in the solar system, depends on the method 
of discussion adopted. The author describes fully the 
procedure he has used in the present research, which 
involves the backward computation of planetary per- 
turbations for eight comets, and gives the numerical 
calculations. He is thus led to form the conclusions 
that there is not one warranted hyperbolic orbit among 
the comets of the solar system, and that all the comets 
yet observed have their origin in the solar system. 
Companions TO MELLisH’s Comer.—In the Astro- 
nomical Notes of the May-June number of the Journal 
of the Royal Astronomical Society of Canada, refer- 
ence is made to two companion bodies near Mellish’s 
comet discovered by Prof. Barnard. One of these 
bodies was conspicuous and had a distance of 28” and 
position angle of 285° on May 12 at 19h. 36m. The 
other was faint, and occupied an intermediate position 
on the same line. The above confirmation appeared 
in the Harvard College Observatory Bulletin, No. 580. 
THE ABERRATION CONSTANT AND LaTITUDE VARIATION. 
—The floating zenith-telescope designed by the late 
Mr. Bryan Cookson has been in use since 1911 at the 
Royal Observatory, Greenwich, having been lent by 
the Cambridge University. It has been employed in 
the determination of the aberration constant, and a 
preliminary discussion by Mr. H. S. Jones of three 
years’ observations with it appears in the May number 
of the Monthly Notices of the Royal Astronomical 
Society. . This communication represents the results 
derived from observations made between September, 
1g1t, and December 31, 1914, and the discussion is 
based on measures of 479 plates. The value of the 
aberration obtained is given as 20-467”+0-006."” The 
instrument being designed primarily for the deter- 
mination of the aberration, it is interesting to note 
that, as a by-product of the investigation, excellent 
values of the latitude variation have been derived. 
The paper contains a representation in the form of 
curves of the Cookson results, the international results, 
and the latter without the Z or Kimura term. The 
Cookson latitude variation is more in agreement with 
the last-mentioned curve, and it is pointed out that the 
agreement on the whole is improved, and more par- 
ticularly so during the latter half of 1913, when the 
Z term attained its greatest value during this period. 
Tue Henry Draper Memoriat.—In the work of the 
classification of the spectra of stars Miss Annie 
Cannon’s name is well known, and as an able member 
of the staff of the Harvard College Observatory her 
position renders her admirably suited to describe the 
pioneer work and progress of the Henry Draper 
Memorial. Under this title Miss Cannon communi- 
cates to the May-June number of the Journal of the 
Royal Astronomical Society of Canada a most interest- 
ing account of the work that has been carried on at 
both the Cambridge and Arequipa stations of the 
Harvard College Observatory in the name of Henry 
Draper, the memorial having been presented by Anna 
Palmer Draper, the widow of that distinguished inves- 
tigator and astronomer. A very clear survey is given 
of the progress of the many lines of research under- 
taken and successfully accomplished, but these cannot 
be referred to here, for they are too numerous and 
space forbids. The enormous amount of data collected 
NO. 2383, VOL. 95| 

in the form of glass negatives is now being adequately 
dealt with by the generosity of Mr. George Agassiz, 
and the work of identification and reduction placed on 
a scientific basis. To give an idea of the work (other 
than observational) being done at the present time, 
Miss Cannon states that 199,196 spectra have been: 
classified, and about 150,000 of these have been identi- 
fied. It is hoped that the observations for the New 
Draper Catalogue will be finished in six months, and 
that the printing will be started soon after that time. 
It is proposed then to make a very careful study of 
the distribution of the various classes of stellar spectra, 
‘“as a portion of the contribution of the Henry Draper 
Memorial to the greatest of all investigations, the 
constitution of the sidereal universe.’”’ Attention should 
be directed to the excellent reproductions, which in- 
clude a portrait of Henry Draper, views of the Cam- 
bridge and Arequipa stations, types of stellar spectra, 
spectra of stars in region of R Cygni, and many 
others. 
Tue Report OF THE CAMBRIDGE OBSERVATORY, 
1914-15.—In the Cambridge University Reporter for 
June 19 a report is given of the proceedings in the 
Cambridge Observatory for the period May 19, 1914, 
to May 18, 1915. The director states that for various 
reasons not much progress could be made with observa- 
tional work during the first half of the year under 
review, but from the beginning of t915 the conditions 
of work became more normal. The Sheepshanks 
equatorial has been the chief instrument in use, and 
this has been mostly employed in securing photo- 
graphs to complete the series of plates required for the 
parallax programme. At present the exposures at 
each epoch are made on separate plates, but it is hoped 
ultimately to secure the exposures at the two epochs 
on the same plate. The meridian circle has been con- 
fined to observations for time determination. The 
Northumberland equatorial seems to be used only on 
Saturday evenings during term time for the members 
of the University and their friends. As regards pub- 
lications, the printing of the Ledger of the Zone Cata- 
logue is near completion so far as the main catalogue 
is concerned. 
THE DESTRUCTION OF FLIES. 
PAPER on ‘The Destruction of Flies and the 
Disinfection of Corpses in the Battle Line,” by 
M. E. Roubaud, is published in the Comptes rendus 
of the Paris Academy of Sciences for May 25. The 
author remarks that the hot weather will bring with it 
the menace of fly outbreaks and consequent epidemics 
of diseases, and that he has collected the simplest 
methods of dealing with the problem. For house- 
flies, he recommends heavy coal tar oils sprayed on 
the surface of excrement, etc., to prevent access of 
flies; for sanitary purposes he advises the following :— 
Ferric sulphate 2500 grams. 
Heavy tar oil 500 c.c. 
Water sie 1o litres. 
This is stated to be deodorising, larvicidal, and 
protective against flies. 
Heavy tar oils are toxic to plants, and cannot be 
used when the material is to be employed as manure. 
Shale oils (miscible oils) he considers more toxic to 
plants than to larve, and he deprecates their use. 
Cresyl—i.e. miscible cresol—at 5 per cent. in water 
is not harmful to plants, and manure heaps are to be 
treated with 15 litres (four gallons) per superficial 
cubic metre. The exposed areas of the manure heap 
are then to be protected with a watering of Io per 
cent. solution of ferric sulphate. This double treat- 
ment is to be carried out twice, in June and in 
