Juty 30, 1914] 
enough to be timed. Two of those which occurred in 
eastern Mindanao (on March 14 and April 18) were 
registered all over the world, and were followed by 
after-shocks too numerous to chronicle. Two other 
earthquakes (on August 23 and September 4) were also 
recorded at Formosa and Zikawei. 
No. 8 of vol. ii. of the Economic Proceedings of 
the Royal Dublin Society contains a lecture delivered 
by Prof. G. T. Morgan before the Royal Dublin 
Society on ‘‘Modern Dyes and Dyeing.” This gives 
an interesting review of the history of modern dyes 
and synthetic colouring matters. Amongst other 
matters, it is stated that more than go per cent. of 
the world’s demand for indigo is now met by the 
synthetic product. A recent discovery of great in- 
terest is that made by Friedlander, who has shown 
that the antique dye, ‘“‘Tyrian Purple,’? which was 
extracted by the ancients from several species of sea- 
snails, found in the Mediterranean, and was highly 
prized in Italy and Greece, is in reality dibromoindigo. 
_ A VALUABLE contribution to our knowledge of the 
distribution of radium emanation in the earth’s atmo- 
sphere is made by Messrs. J. R. Wright and O. F. 
Smith, of the University of the Philippines, in the 
February number of the Philippine Journal of Science. 
Working in Manila and on Mount Pauai at an alti- 
tude of 2460 metres, they found by the charcoal ab- 
sorption method that the average amounts of emana- 
tion present during the eight months of observation 
in terms of its radium equivalent were 82x 10-12 
grams at sea-level and 19 x 10-!? grams on the moun- 
tain. In both cases the ratio of the greatest to the 
least amount observed was 4 to 1, and the changes 
were closely related to the weather. Fair weather 
gave high, and heavy rain low content which was 
especially low during typhoons. As the authors pro- 
pose to continue their observations, it is to be hoped 
that they will attempt to trace the paths traversed by 
the winds which give the high and low values 
respectively previous to their arrival at the islands. 
WE learn from the Engineer for July 24 that work 
on the reconstruction of the Quebec bridge over the 
St. Lawrence River is making very satisfactory pro- 
gress. The entire substructure was completed last 
season, and the coming season will see considerable 
progress on the erection of the superstructure. The 
superstructure is constructed partly of carbon steel and 
partly of nickel steel, the floor members being con- 
structed of the former, and the truss members of the 
suspended span, together with the greater part of the 
cantilever arms, of the latter material. Drawings 
giving the arrangement and principal dimensions of 
the superstructure are included in the article. The 
bridge is designed for 5000 lb. per lineal foot. Wind 
load is assumed at 30 lb. per square foot of exposed 
surface of the two trusses and 1-5 times the elevation 
of the floor, and 300 Ib. per lineal foot as a moving 
load on the exposed surface of the train. In consider- 
ing temperature stresses, the following conditions 
were assumed: a variation of 150° F. in the tem- 
perature of the whole structure. A difference of 50° F. 
between the temperature of steel and masonry. 
NO. 2335, VOL. 93]| 
NATURE: 569 
difference of 25°F. between the temperature of a 
shaded chord and the average temperature of a chord 
exposed to the sun. A difference of 25°F. between 
the outer webs exposed to the sun and the inner webs 
of the compression members. 
Messrs. E. Merck, of 66 Crutched Friars, London, 
E.C., have issued a pamphlet containing a list of the 
Merck chemicals now stocked in London. Consider- 
able additions have been made to the number of 
articles which are kept regularly in stock, especially 
as regards ‘‘ Merck’s Guaranteed Reagents.”’ Special 
labels are attached to the latter, which show the 
impurities from which these reagents have been shown 
to be free, when tested according to the well-known 
Merck standards. The list of stock now includes 
about 650 articles, and about goo subdivisions, so that 
immediate delivery can be guaranteed for all the more 
important pharmaceutical and analytical preparations. 
' OUR ASTRONOMICAL COLUMN. 
Comet 1913f (DELAvAN).—The ephemeris of Dela- 
van’s comet (1913f) given below is the continuation 
of that published by Dr. G. van Biesbroeck in Astro- 
nomische Nachrichten, No. 4739 :— 
a (true) Decl. (true) Mag. 
July go... «9559 63. «... +38 18 445 63 
av cess, nOsr, Bie Se 38 41-9 
Aug. I 2; 5 82 58 45:2 
2 8 146 39 18 54:3 
3 Ir 24:8 39 «86 6:2 
4 14390 59 2777 
5 YT 5G Sh. 22 4 TOS O9 
6 6 21 19-9 . +40 40 17-9 6-1 
The comet is situated in the region about @ Aurige. 
AstRONOMICAL Notes FOR AuvuGusT, 1914.—The 
planet Jupiter will be a fine object for observation, 
being in opposition to the sun on August 10, and 
visible during the whole night. 
‘The great red spot and hollow in the southern 
equatorial belt should be observed and the times of 
their transits across the central meridian of Jupiter 
taken. These may be expected to occur at the follow- 
ing approximate times :-— 
he) mM: hay sim: 
AMIE ui, 2.2, O30 Aug. 20 Q, 125 
10 Gr io 22 it 
13 8 38 25 8.27 
15 10 16 27 9 
17 Tis 54 29 E47 
18 yess) BOi, Kiss af) oe 
The spot is now in longitude about 205°. Its 
accelerated motion since the middle of the year 1914 
has caused it to lose 153° of longitude, which repre- 
sents a westerly drift of about 105,000 miles. The 
rotation period derived from the motion of the spot 
was in 1910 equal to 9h. 55m. 37°4s., in 1913 it was 
gh. 55m. 35°9s. 
Tue Meteoric SHOWER OF PerRsEIDS.—During the 
past few years not many of the Perseids have been 
observed. This year they commenced early, Miss 
Cook at Stowmarket saw them on July 14. The 
maximum will probably occur on August 11, but there 
will also be many meteors on August 12. The moon 
will somewhat interfere with the success of the obser- 
vations, as she rises on August 11 at 9.1 p.m., and on 
August 12 at 9.14 p.m., but she will be nearing third 
quarter, and her light will therefore not be strong. 
A ! Observers should ascertain, by counting the horary 
