JuLY 9, 1914] 
88d Tauri respectively, the individual authors being 
Mr. F. C. Jordan and Mr. Zaccheus Daniel. 
THE VARIABLE SATELLITES OF JUPITER AND SATURN.—- 
Astronomische Nachrichten (No. 4741) is composed 
almost wholly of a long communication by Dr. P. 
Guthnick on the variable satellites of Jupiter and 
Saturn, treated as planetary analogies of variables of 
the 6 Cephei type. The photometric observations here 
discussed deal with the observations he has made since 
the end of the year 1904 at the Bothkamp, and later 
at the Berlin, Observatories. The satellites included 
the four old ones of Jupiter, and Enceladus, Tethys, 
Dione, Rhea, Titan, and Iapetus of Saturn, in all ten 
objects, measured with the Zoéllner photometer on re- 
fractors of 6-, 9-, and 11-in. aperture. Dr. Guthnick 
accompanies his paper with thirty-five curves of nine 
satellites, and compares them with each other. Among 
the deductions he draws may be mentioned that the 
inner satellites of both systems, Jupiter I. and II., 
Tethys and Dione, exhibit a principal maximum about 
the time of easterly elongation; in fact, all the light 
curves are very similar in their chief features. The 
outer satellites of both systems, Jupiter IV., and 
especially Iapetus, show, on the other hand, a very 
pronounced maximum in the neighbourhood of the 
westerly elongation. The middle satellites, Jupiter 
III., Rhea, and Titan, belong partly to the first and 
partly to the second group, or, in other words, exhibit 
an uncertain type. Dr. Guthnick refers at some 
length to the observations and deductions of Auwers, 
Engelmann, Pickering, Searle, Upton, Wirtz, etc., 
and gives some interesting tables, including one dis- 
playing the mean brightnesses at opposition, values of 
the albedo, masses and densities of the satellites of 
Jupiter and Saturn. 
THIRD INTERNATIONAL CONGRESS OF 
TROPICAL AGRICULTURE: 
gts congress opened at the Imperial Institute on 
Tuesday, June 23, and sat daily, except on 
Saturday and Sunday, until Tuesday, June 30. The 
number of Governments and societies represented by 
delegates were forty-two and forty respectively, and 
the total number of members and delegates was about 
four hundred. In these respects and also as regards 
the number and quality of the papers read, the London 
Congress showed a very great advance on the previous 
congresses, held in Paris and Brussels. 
Education and Research in Tropical Agriculture. 
Perhaps the most interesting tendency exhibited by 
those who read papers and took part in the discussions 
was that of insisting on the necessity for a better 
organisation of education and research in tropical 
agriculture. This note was struck in Prof. Dunstan’s 
presidential address, but it was particularly satisfac- 
tory to hear it not only from a man of science such as 
the president, but also at meetings afterwards from 
practical planters and manufacturers, and from men 
who have held high administrative posts in the tropical 
colonies. The necessity for higher education in 
tropical agriculture was felt so strongly, that at its 
concluding meeting. the congress passed unanimously 
a resolution instructing the general committee of the 
congress to cooperate with the London committee, 
which is now promoting the establishment of a higher 
Agricultural College in the British tropics. 
On the question of better provision for research in 
tropical agriculture, the congress contented itself with 
appointing a committee to collect. precisé: information 
regarding the organisation, work, and cost of agri- 
cultural departments in the tropics, with a view to 
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more definite recommendations being made at a future 
congress. 
A British Institute of Tropical Agriculture. 
Closely connected with these questions of education 
and research is that of providing a permanent organi- 
sation to promote and safeguard the interests of those 
engaged in the higher branches of tropical agricul- 
tural work, and the congress cordially endorsed the 
suggestion made in the president’s address that a 
British Institute of Tropical Agriculture should be 
founded. At the concluding meeting a resolution in- 
structing the general committee of the congress to 
take the action necessary to this end, was adopted 
unanimously. 
Social and Economic Questions. 
The social and economic problems which arise in 
the practice of tropical agriculture are even more 
difficult and complex than those with which everyone 
in this country is familiar in connection with the home 
agricultural industry. The Brussels Congress gave 
special attention to the question of the supply of native 
labour in the tropics, and the reports on this subject 
collected for that congress are now in the press. The 
London Congress discussed two problems of this kind, 
viz., ‘‘Agriculturai Credit Banks and Cooperative 
Societies,’ and ‘‘ Sanitation on Tropical Estates.’ Sir 
Horace Plunkett took the chair at the former dis- 
cussion, and a very interesting paper was read by 
Sir James Douie, giving an account of his experience 
of the working of such banks and societies in India, 
and more particularly in the Panjab. This formed the 
basis of a discussion which terminated in the adoption 
of a resolution by the congress to collect information 
and prepare a report on the working of such banks 
and societies in tropical countries. A paper on tropical 
hygiene and plantation work in the Federated Malay 
States, by Dr. Sansom and Mr. F. D. Evans, formed 
the basis of the second discussion, at which Sir Ronald 
Ross presided. In this case also the congress decided 
to appoint a committee to collect information and 
prepare a report, on the preventive measures possible 
against ankylostomiasis, cholera, dysentery, malaria, 
smallpox, and other diseases prevalent amongst native 
labourers on tropical estates. 
On the same morning the congress also discussed 
the relation of the Phytopathological Convention of 
Rome to tropical agriculture, on a paper read by Mr. 
A. G. L. Rogers, of the Board of Agriculture. A 
considerable number of entomologists and mycologists 
working in agricultural departments in the tropics 
were present, and some of them were of opinion that 
the convention was not altogether suitable for adoption 
in the tropics. The discussion on this. subject was 
resumed at the concluding meeting of the congress on 
a motion by Mr. E. E. Green (late of Ceylon) and Dr. 
Gough, of the Egyptian Ministry of Agriculture, that 
the congress should appoint a committee to consider 
how far the proposals in question are applicable to 
tropical countries, and on the suggestion of M. 
Brenier, of Indo-China, a rider was added to this 
motion that the Government delegates present should 
communicate this resolution to their Governments as 
soon as possible. 
An interesting discussion also took place on a motion 
by Sir James Wilson and Sir Sydney Olivier on the 
subject of the support of the International Institute 
of Agriculture at Rome by tropical countries, in which 
a large number of members took part. A resolution 
was finally adopted, by which the congress decided to 
ask the committee of the congress to consider the 
whole question of cooperation with the International 
Institute of Agriculture. 
