186 
There is a suggestive paper by Dr. Mackie, of Elgin, om 
“The Felspars present in Sedimentary Rocks as Indicators of 
the Conditions of Contemporaneous Climate.” 
Messrs. J. J. GRIFFIN AND Sons, Lrp., have issued a new 
edition of their illustrated catalogue of chemical apparatus and 
reagents published under the title ‘‘Chemical Handicraft.” 
Hints on manipulation of instruments and arrangement of 
apparatus are occasionally given, and they assist in making the 
volume a useful catalogue for chemical laboratories and technical 
schools. 
New and revised editions have been received of several well- 
known scientific books. The fourth edition of Prof. Grenville 
Cole’s ‘Aids to Practical Geology” has been published by 
Messrs. C. Griffin and Co. The book is the most helpful guide 
which the student who desires to become intimately acquainted 
with the chagacters of rocks and minerals could possess. It is 
not intended to take the place of a field geology, but to show 
how every specimen obtained may be minutely examined in the 
laboratory or study, and its place among rocks or fossils under- 
stood. Work of this kind is practical geology in as scientific a 
sense as observations in the field. —Messrs. Cassell and Co. have 
published a popular edition of Mr. Richard Kearton’s interest- 
ing book ‘‘ With Nature and a Camera.” The 180 pictures 
reproduced from photographs by Mr. Cherry Kearton have given 
pleasure to many outdoor naturalists.—The valuable text- 
book of ‘* Agricultural Botany,” by Prof. J. Percival, published 
by Messrs. Duckworth and Co. and reviewed in these columns 
in October, 1900 (vol. Ixii. p. 570), has reached a second edition. 
It is satisfactory to know that students of agriculture are using 
a book in which plant structure and growth are dealt with 
scientifically.—The eighth edition of ‘‘ Astronomy with an 
Opera Glass,” by Mr. G. P. Serviss, has been published by 
Messrs. Hirschfeld Brothers, Ltd.—A new edition of Prof. J. G. 
Macgregor’s ‘‘ Elementary Treatise on Kinematics and 
Dynamics” has been published by Messrs. Macmillan and Co., 
Ltd. Few changes have been made, and the book retains its 
character as a comprehensive treatise in which the whole 
subject is treated systematically, without reference to the 
requirements of examining bodies. 
THE additions to the Zoological Society’s Gardens during the 
past week include a Dusty Ichneumon (Her festes pulverulentus) 
from South Africa, presented by Capt. A. Perkins ; two Larger 
Egyptian Gerbilles (Gerbillus pyramidum) from North Africa, 
presented by Col. Momber; a Buffon’s Touracou (Zzracus 
buffoni) from West Africa, presented by Capt. H. A. Thorne ; 
two Long-tailed Whydah-birds (Chera progne) from South 
Africa, presented by the Rev. R. Armitage ; a Richardson’s 
Skua (Stercorarius crepidatus) European, presented by Lt.-Col. 
L. H. Irby; a Sykes’s Monkey (Cercopithecus albigularis), a 
Grant’s Gazelle (Gazella granti), a Banded Ichneumon 
(Crossarchus fasciatus), a Vulturine Guinea Fowl (Acryllium 
vulturinum), a Bateleur Eagle (He/otarsus ecaudatus), three 
White-winged Whydah-birds ( Urobrachya albonotata) from East 
Africa, a Buffon’s Touracou (7wracus buffonz), a Red-faced 
Weaver-bird (Houdia erythrops), seven Orange Weaver-birds 
(Euplectes franciscana), two Pintailed Whydah-birds (Vidua 
principalis), three Paradise Whydah-birds (Vidua paradtsea) 
from West Africa, two Maguari Storks (Dzsswra maguart), two 
Snowy Egrets (Ardea caudidissima), four Black-pointed 
Teguexins (7upinambis nigropunctatus), four South American 
Rat Snakes (Spélotes pullatus) from South America, two 
Brazilian Cariamas (Carzama cristata) from Brazil, deposited ; 
a Black-winged Peafowl (Pavo négripennis) from Cochin China, 
purchased ; a Great Bird of Paradise (Pavadisea apoda) from 
the Arrow Islands, received in exchange; a Brindled Gnu 
(Connochaetes taurina) born in the Gardens. 
NO. 1703, VOL. 66] 
NATURE 
[JUNE 19, 1902 
OUR ASTRONOMICAL COLUMN. 
Tue Sunspor CurVE AND Epocus.—The great importance 
-| of collecting as many facts as possible regarding solar activity, 
and revising them from time to time as new information is 
gathered, is clearly shown by the paramount ré/e that the sun plays 
in causing the numerous variations in meteorological phenomena. 
Wolf’s relative numbers have been, and are now, so commonly 
used when reference has to be made to solar activity that it is 
of the first importance that such a series of values should be as 
near correct as possible. It is with great satisfaction, therefore, 
that we note that Wolfer has so diligently continued the useful 
work, ably begun by Wolf, that he has now published 
(Meteorologische Zeitschrift, May, 1902) a new set of values 
carefully revised and brought up to date. As he remarks, an 
examination of the original manuscript at the observatory with 
various published tables has shown that a great number of 
differences and printer’s errors have crept in, suggesting that it 
is time that a new edition was published. This reduction has 
been very carefully made by Wolfer and his assistant, each making 
the computations twice. In addition to the observed relative 
numbers, the paper gives smoothed relative numbers, while a 
third table shows the epochs of maxima and minima with their 
corresponding weights ; the addition of the weights to the dates 
of these epochs is a very valuable piece of information which 
will add to the utility of the earlier epochs. 
METHOD OF OBSERVING ALTITUDES AT SEA DURING 
NIGHT-TIME.—In a paper read before the Royal Dublin 
Society, Prof. Joly introduced recently a method for observing 
the altitude of a celestial body at sea which may prove ex- 
tremely useful for taking bearings at night-time or when the 
horizon is obscured. Assuming that the vessel is provided with 
the usual Board of Trade rescue signals, one of these is per- 
forated and dropped overboard. This will furnish a bright 
white light visible in clear weather up to five miles, and burning 
for about halfan hour. To the signal is attached a suitable 
sinker, so that it will not drift appreciably. Selecting a star, 
the observer takes its bearing and then alters his course to the 
opposite bearing, thus bringing the star right astern. The 
signal is then dropped overboard, and at the same time a reading 
of the log is taken. After the vessel has travelled a distance of 
about a mile from the signal, as indicated by the log, the 
observer takes the angular elevation of the star over the signal, 
using the sextant in the usual manner. Corrections will have 
to be applied for the relative motion of the star from east to west 
at the rate of 1° in four minutes of time, for the larger angle of 
“dip,” and also for the state of the water surface. In very 
rough water this last correction becomes of special importance, 
and formule with reduction tables are given to show the in- 
fluence of waves of varying heights. The routine to be followed 
in observing two altitudes for a ‘‘Sumner” position is also 
described (Sctentijic Proceedings of the Royal Dublin Society, 
vol. ix., n.s., part v., No. 46, pp. 559-567)- 
LIQUID FUEL FOR STEAM PURPOSES. 
THE possibility of burning a liquid fuel with very great 
advantage in most circumstances as compared with a solid 
fuel has been so long recognised that it is astonishing the practice 
has not been more generally adopted. The success which has 
been gained in the last few years, however, will undoubtedly 
lead to a greatly extended use in the near future. 
Naturally the choice of a fuel for steam raising is not altogether 
dependent upon the evaporative efficiency and other advantages 
which a particular one may possess, but will, of course, be 
largely influenced by relative market prices, and this, no doubt, 
has had considerable influence against the adoption of liquid 
fuel on a large scale in this country. The fuel natural to the 
locality will always have great advantages dVer an imported 
fuel, and England, having such valuable coal supplies to hand, 
whilst on the other hand having no great natural sources of 
liquid fuel, gives preference to that material which renders it 
most independent of outside supplies. Although gas tar and 
oil gas refuse may be frequently employed in a very economical 
manner, yet there is little doubt that with a greatly extended 
use of liquid fuel the prices of suitable bye-products would be 
so enhanced that imported liquid fuel would remain practically 
in possession of the field. 
For this reason engineers who have perfected the methods of 
