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[AUGUST 15, I912 
Tue Weekly Weather Report issued by the Meteoro- 
logical Office, which contains a summary of the tem- 
perature, rainfall, and duration of bright sunshine for 
the several districts of the United Kingdom, shows 
that the mean temperature for the first eight weeks 
of summer is generally slightly in excess of the 
average. The rainfall is also in excess of the normal, 
the greatest excess being 4°31 in. in the south of 
Ireland and 364 in. in the north-east of England, 
whilst the north of Scotland is the only district with 
a deficiency. The duration of bright sunshine for the 
first two months of summer is everywhere deficient, 
and in the north-eastern districts the deficiency is very 
large. 
Tue Greenwich observations for July give the mean 
temperature 65°, the mean day readings being 75°, 
and abe. mean night readings 55°. This is rather more 
than 1° in excess of the average, the minima being 
slightly more in excess of the average than the 
maxima. The maxima, or day temperatures, ranged 
from _go° on July 12 to 58° on July 19, and the night 
minima from 63° to 48°. There were ten days during 
the month with the shade temperature above 80°, 
whilst in the corresponding month last year there were 
nineteen days above 80°. There were three days with 
the thermometer in the sun’s rays at 150°, and in July 
last year there were eight days above 150°. Rain fell 
on eleven days, yielding 125 in., which is rather more 
than one-half the average amount; the heaviest fall in 
twenty-four hours was 0°30 in. on July 2. The sun 
was shining for 164 hours, which is 72 hours fewer 
than the average, and is less than one-half of the 
duration of sunshine in July last year. 
Dr. W. E. Britran contributes to The Popular 
Science Monthly for July an article on the house-fly 
and certain other insects which spread diseases. Such 
insects may be divided into two classes: mechanical 
carriers, including the house-fly, and essential hosts, 
such as the mosquito. Rats and fleas are also con- 
sidered, and the author describes the remedial 
measures required for checking both types of pests. 
Tue July number of The Co-Partnership Journal of 
the South Metropolitan Gas Company contains an 
illustration of the upper surface of the reflector of a 
street gas lamp which is completely filled by no fewer 
than four nests of titmice, each with two or more eggs. 
The structure forcibly recalls a collector’s cabinet of 
nests, and the occurrence is probably altogether un- 
precedented. 
Tue June number of Terrestrial Magnetism and 
Atmospheric Electricity contains five tables of mag- 
netic declinations, determined by the Carnegie at 
several hundred positions in the Atlantic during her 
voyages from New York to Porto Rico, Para, Rio, 
Buenos Ayres, and Cape Town, in 1910-11. The cor- 
rections to the declinations as recorded in the British, 
German, and United States charts of the Atlantic are 
also given, and it eet) be noted that these corrections 
generally exceed 0°5°, and often exceed 2° 
Dr. J. R. ASHWORTH announces, 
appears in The Electrician for August 2, that he finds 
the constant P of Frélich’s equation for the magnetisa- 
NO. 2233, VOL. 89] 
in a letter which 
tion of iron is inversely proportional to the absolute 
temperature up to 700° C. If H is the magnetising 
field and I the fraction the magnetisation produced 
is of the maximum magnetisation, Frolich’s equation 
runs H=PI/(1—I), and is only intended to apply to 
cases in which hysteresis is suppressed. As P is the 
value of the magnetising field at which the magnetisa- 
tion reaches half its maximum value, Dr. Ashworth’s 
result is more conveniently expressed by the statement 
that the field for half the maximum magnetisation 
is inversely as the absolute temperature of the 
specimen. 
Pror. P. C. Ray has added to his success in pre- 
paring ammonium nitrite in tangible form a further 
accomplishment in determining the vapour density 
of this very fugitive salt. The salt was vaporised 
in a Hofmann tube at temperatures ranging from 
66° to 100°, and had an average density of 33-5 as 
compared with the value 32 ‘calculated for the 
NH,NO,. During the heating a large part of the 
salt was decomposed according to the equations 
NH,NO,—N,+2H,0 and 
3NH,NO,—-NH,NO,+2N0O +2NH,+H,0, 
but this effect was measured and allowed for. The 
experiments are described in full in the July issue of 
the Chemical Society’s Journal. 
The Builder for August 9 contains an article deal- 
ing with the recent celluloid fire at Moor Lane, E.C., 
the inquiry into which has now been finished. The 
following are some .of the suggestions made for 
handling celluloid, which ought to rank second only 
to absolutely explosive materials and petrol. Storage 
of the material in bulk should not be permitted in 
work-rooms; new buildings for stores or workshops 
should be of fire-resisting materials; the timber parts 
of old buildings should be plastered; celluloid would 
be best dealt with in buildings remote trom towns; 
ample gangways should be arranged in workshops; 
and waste and cuttings of celluloid should be cleared 
away frequently from the floor, Our contemporary 
deprecates any panic legislation, but would like to 
see the duty of examining and pronouncing upon 
plans of such factories in London placed in the hands 
of men possessing wide general experience of build- 
ing and surveying matters, as well as having know- 
ledge of fire and its behaviour under varying con- 
ditions. 
OUR ASTRONOMICAL COLUMN. 
PHOTOGRAPHIC OBSERVATIONS OF COMET I9II¢ 
(Brooks).—Ten excellent photographs of comet 1911¢ 
are reproduced, and, with many others, described by 
Prof. Barnard in No. 1, vol. xxxvi of the Astrophysical 
Journal. Prof. Barnard directs attention to the lack 
of details and variation in the tail of this comet up till 
about the middle of Gctober, 1911; although it was a 
fairly bright object visually, it was very weak photo- 
graphically, being essentially different from More- 
house’s comet in this respect. But later the comet 
became exceedingly active, and Prof, Barnard’s photo- 
graphs show some most interesting changes in the 
structure of the tail, which, on his smaller-scale plates, 
extends to a distance of 17°. A remarkable reduction 
in the size of the head on the comet’s approach to 
Ve se UC 
