622 
two wooden floats. After a general review of the 
development of the compass card, Prof. Thompson 
gives a classification of the principal forms which 
appeared prior to 1600. Beautifully coloured illustra- 
tions appear in five of the six plates at the end of the 
paper. From an artistic point of view it is to be 
regretted that, as has been the case with ordinary 
male attire, colour has now disappeared from compass 
cards. At first almost universal, it seems to have 
died out before the end of the seventeenth century. 
In the Quarterly Review for July, Mr. George 
Forbes, in a review of Sir David Gill’s~ “‘ His- 
tory and Description of the Royal Observatory, 
Cape of Good Hope,” gives a sympathetical account 
of the life and labours of ‘‘this great man, who will 
live in the hearts of all who knew him, not only as 
among the greatest of astronomers, but also as one 
of the noblest and most lovable of men.’’ Special 
attention is naturally given to his work at Capetown 
between 1879 and 1907. The comments on his career 
by the most eminent astronomers of the day, included 
in this article, show the great scientific value of his 
work, and the impression left on his contemporaries 
by his unselfish devotion to science and by the nobility 
of his character. 
Buttetin No. 11 of the Indian Association for the 
Cultivation of Science consists of three papers by Mr. 
Cc. V. Raman on the dynamics of vibration, which 
are well illustrated, and cover fifty-two pages. The 
first deals theoretically and experimentally with the 
vibrations of a silk thread attached at its two ends to 
the prongs of two tuning-forks of different periods 
the directions of motion of which are parallel to the 
string. If M and N are the frequencies of the forks, 
it is shown that the string will be set into vigorous 
transverse oscillation if the tension of the string is so 
adjusted that the natural period is nearly 3(Mm+Nn), 
where m and n are integers. The second deals in 
the same complete manner with the possible fre- 
quencies of oscillation or speeds of synchronous rota- 
tion of a soft iron wheel with thirty teeth mounted 
between the two poles of a small electromagnet fed 
by an alternating current of frequency 24 or 60 per 
second. The third describes new methods of studying 
the relation between the motion of the bow and that 
of the bowed point of the string it sets in motion, 
and of recording the motion of each point of the 
string. It appears from the author’s observations 
that in all cases in which the displacement time curve 
of the bowed point is saw-toothed, the velocity of 
forward motion of the bowed point is identical with 
that of the bow. 
Tue Government have taken over two battleships, 
one completed and the other shortly due for comple- 
tion, which had been ordered in this country by the 
Turkish Government, also two destroyer leaders 
ordered by the Government of Chili. Reference is 
made to the battleship Sultan Osman I., now H.M.S. 
Agincourt, in the paper read at the joint meeting of 
Naval Architects at Newcastle by Mr. J. R. Perrett, 
chief of the shipbuilding department at Elswick, 
where the ship was built. The vessel is 632 ft. long, 
with a beam of 89 ft. and a displacement of 27,500 
NO. 2337. VOLe ga 
NATURE 
em, 
| October. 
[AUGUST 13, 1914 
tons. She carries fourteen 12-in. guns, twenty 6-in. 
guns, and a number of small guns. Her main 
armour belt is 9 in., and the upper belt 6 in. She 
has various armoured decks and extensive magazine 
protection. She is designed for a speed of 22 knots. 
Messrs. LONGMANS AND Co. have in preparation 
“The Year Book of Radiology for 1915.’’ It is to be 
edited by Dr. R. Knox and J. H. Gardiner, and its 
object is to give an account of the more recent 
advances in our knowledge of radium, X-rays, and 
the allied phenomena, both from the medical and 
physical point of view. The volume will comprise a 
series of authoritative articles by specialists working 
in radiology, and a directory of qualified medical men 
practising in radiography, X-rays, radium and 
electro-therapeutics, both at home and abroad, also a 
list of hospitals and institutions where such treatment 
is carried out. 
OUR ASTRONOMICAL COLUMN. 
Comer 1913f (DELAVAN).—The following ephemeris 
and chart give the positions of Delavan’s comet for 
the remainder of the present month and September. 
This ephemeris is given by Dr. Crommelin in the 
July and August numbers of Knowledge :— 
Greenwich, Midnight. 
R.A. Dec 
likes Pits AS 3 j 
Aug. 15 6 54 2 +43 44 
28 Tea tehy 4 46 22 
i 31 8 15 43 48 35 
Sept. 8 9 8 35 49 56 
16 10 8 6 49 51 
24 TT -9u33 +47 56 
During the present month the comet is_ travel- 
ling in the constellation of the Lynx, passing 
then into The best time for observation 
Ursa Major. 
is the early hours of the morning, and Dr. Crommelin 
thinks ‘‘that the prospects are hopeful for this comet 
being an interesting spectacle in September and 
There is already no doubt that it will be 
visible to the naked eye.”’ 
THE Perrserps.—The progress of this shower up to 
and including August 10 was watched by Mr. 
Denning at Bristol, and he reports it as fairly active, 
though on August 10 the number seen was decidedly 
scanty. ’ 
The shower first gave intimation of its oncoming 
on July 14, and there has been a gradual increase 
since that date. On August 10 the radiant point was 
very exactly defined at 43°+56°. On nights when 
the position could be determined from a_ sufficient 
number of meteors it showed the usual displace- 
ment. 
alae ae 
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