440 NATURE 

| JUNE 17, 19 15, 

earth and the mean density of the earth as a whole, 
viz. : 2-67 and 5-576, in place of 2:8 and 56-6. 
In August, 1913, two members of Dr. de Filippi’s 
Karakoram Expedition swung their pendulums at 
Dehra Dun, and thus a new independent value for 
gravity at Dehra Dun will be obtained when the 
expedition has returned to Genoa. 
No. officer being available, the determination of 
astronomical Jatitudes was not undertaken during this 
season. 
Work was carried on in the principal triangulation, 
and twenty-two triangles of the Sambalpur series 
were observed, the standard of precision being well 
maintained in spite of the difficult and inhospitable 
character of the country. traversed. A network was 
also observed as the control for a large-scale survey 
of Bombay island, and as a further stage a traverse 
network of considerable precision was utilised. Per- 
manent marks were placed on brass plugs which 
were built into masonry a foot below ground, and a 
special device was introduced for accurately centring 
the theodolite over the mark. Linear measurements 
were made with a too-ft. steel tape, which was 
strained by means of weights suspended over pulleys. 
The precision of the lines of the traverse network when 
adjusted to triangulated poirits is given as 1 in 12,000. 
Some 180 miles of the Indo-Russian triangulation 
connection, which had been reconnoitred in the pre- 
vious year, were observed, and the work satisfactorily 
concluded, 
In levelling details are given of carrying lines, 
of levelling across rivers, both by the ‘target’’ and 
by the “‘vertical angles’’ methods, and their respec- 
tive advantages are discussed. 
In the winter of 1912-13 a delimitation of the boundary 
between Nepal State and Naini Tal district was car- 
ried out. The boundary consisting of three straight 
lines joining four predetermined points in forested 
country, it was found most convenient to run an 
accurate traverse near and approximately parallel to 
the boundary line, so that from the traverse points 
could be located on the boundary line, and be deter- 
mined. The result was quite satisfactory, and 
boundary pillars were erected along the line. 
Dehra Dun having been dispensed with as a 
meteorological station, the forenoon and afternoon 
observations have been discontinued, and others at 
2 p.m. (standard time) have been substituted. With 
similar simultaneous observations taken at Mussoorie, 
it is hoped to gain information bearing on terrestrial 
refraction which will be useful in the work of the 
survey. 
Besides the points which have been mentioned there 
is much detailed information of value and importance 
to surveyors and geodesists in these volumes, which 
represent a large amount of work of a high standard 
carried out during the period under review. 
Gamles 


THE FLY “PROBEEM: 
(s a pamphlet published by the Zoological Society, 
entitled, “‘The Fly Campaign,” and in a public 
lecture delivered at the Zoological Society’s offices, 
Prof. Lefroy has dealt with the problem of the house- 
fly and its allies, less from the purely scientific point 
of view than from the practical and economical 
aspect. 
The pamphlet discusses flies generally, their import- 
ance and occurrence; the life-history of the house-fly 
is dealt with in detail ; the eggs and where they are 
laid, the maggot, its habits, appearance, and _ its 
migration ; the pupze, the adult, its appearance, food, 
reproduction and the total period of its life. 
NO. 2381, VOL. 95| 

A separate section describes the feeding habits of 
the fly, to show why and how it is such a carrier of 
disease, and what a repulsive intruder it is to houses; 
the hibernation and flight of flies is separately dis- 
cussed, and a section deals with other flies than the 
house-fly which are found in houses. 
Dr. C. J. Martin has written a section on flies as 
carriers of disease, which need not be summarised in 
view of the article on this subject in Nature of 
May 13. 
The pamphlet then deals with ‘‘ Methods of Destruc- 
tion,” including the treatment of ‘tips’? and manure, 
the protection of hospitals and houses, and the use of 
fly-traps. It concludes with a bibliography. 
In his lecture at the Zoological Society’s offices on 
June 2 Prof. Lefroy illustrated his remarks with 
lantern slides, largely made from the posters and 
illustrations used in the Fly Exhibition at the Zoological 
Society’s gardens; these bring home vividly what flies 
do, how they actually feed, what the connection is 
between the fly feeding on human excreta and the 
spread of typhoid or summer diarrhcea. 
In the lecture Prof. Lefroy expressed his personal 
opinion on many points, and especially on the question 
of the treatment of manure. Elaborate experiments 
are in progress, and already a method has been 
obtained which is one-third the cost of borax and 
water, and of far more general application. Naturally 
this has to be elaborately tested, but the lecturer was 
extremely hopeful of a solution of this problem, by far 
the most important in regard to the prevention of flies. 
Equally elaborate experiments are in hand with 
regard to baits, with great promise of success; and 
success means a good bait that may be obtained and 
used in the campaign this summer. 
Prof. Lefroy’s lecture was illustrated by more than 
sixty lantern slides, many made from large wall pic- 
tures prepared for the Fly Exhibition by Miss Bertha 
Reid. Arrangements have been made to reproduce the 
lecture with the slides at any town in England that 
wishes it. The exhibition at the Zoological Society’s 
gardens is popular, and will bring home to many the 
importance of flies and the simple ways of dealing 
with them. 
JAMAICA AS A CENTRE FOR BOTANICAL 
RESEARCH IN THE TROPICS. 
O botanist should be content until he has visited 
some tropical area, and studied its flora on the 
spot. _ The tropical region most readily accessible 
from Great Britain lies in the West Indies; and as 
Jamaica now offers special facilities at the Cinchona 
station, recently leased by the Jamaican Government 
to a committee of the British Association, the time 
is opportune for explaining the advantages it can 
provide. 
The public gardens controlled by the Jamaican De- 
partment of Agriculture are seven in number. Of 
these only three are botanic gardens in the strict sense, 
viz., the Hope Gardens near Kingston, the Castleton 
Garden, and the Cinchona Plantation, or Hill Gar- 
dens, in the Blue Mountains. 
The first of these lies on the Liguana Plain, just 
beneath the foothills of the Port Royal range, at an 
elevation of 650 ft., and about six miles from Kings- 
ton. It comprises an area of 200 acres, with a mean 
dnnual temperature of 76° F., and average rainfall 
of 545 in. The gardens contain a large and varied 
collection of typical plants of the tropics, together 
with economic and ornamental plants, and many 
species of academic interest. The office, which con- 
stitutes the headquarters of the Agricultural Depart- 
ment, contains a good working library, and an in- 


