594 NATURE 
[JANUARY 22, 1914 
tains the oils of clove, pimento, and bay. Mention is 
made of the fact that there is a systematic manufac- 
ture of bodies designed solely for the purpose of 
adulterating perfumes; the adulterants include gly- 
ceryl acetates, ethyl citrate, laurate, succinate, and 
phthalate, and methyl phthalate. Some stress is laid 
on the bactericidal properties possessed by certain of 
the essential oils; for example, origanum oil, the most 
effective of those referred to, is stated to have a 
“carbolic acid coefficient’ of 25-76, attributable to the 
high proportion of carvacrol it contains. Other 
examples of such coefficients are given, ranging down 
to 4-94 for lavender oil and 1-0 for oil of cade. It is 
stated that the protective power of lemongrass in 
keeping off the tsetse-fly has led to the cultivation of 
the plant and the distillation of lemongrass oil in 
Uganda. 
Wirn reference to Dr. Rosenhain’s letter in Narurk 
of January 8, upon a new method of etching steels, 
Dr. C. H. Desch directs attention to papers by Prof. F. 
Giolitti (Gazz. chem. ital., 1906, vol. Xxxvi., ii., p. 142; 
1908, vol. Xxxviii., ii., p. 352) upon the use of the 
electro-chemical deposition of copper in the etching of 
bronzes. Prof. Giolitti’s work does not, however, 
anticipate the use of the new reagent for steel de- 
scribed by Dr. Rosenhain, and particularly for the 
study of phosphorus distribution, although it seems 
probable that the banded structure of phosphoritic 
steel is a direct consequence of core formation during 
the first solidification of the steel. 
A PAPER dealing with commercial tests of internal- 
combustion engines was read at the Institution of 
Mechanical Engineers on Friday last, January 16, 
by Mr. W. A. Tookey. In such tests, it is usually 
not possible to obtain measurements other than the 
gas consumed or liquid fuel used, indicator diagrams, 
bore and stroke of the cylinder, and the valve settings. 
From this information, advice has to be tendered re- 
garding possible improvements in the engine, and 
Mr. Tookey advocates the use of a factor obtained by 
dividing the mean pressure, as shown by the indicator 
diagram, by the mixture strength. The mixture 
strength is defined as the calorific value, in British 
thermal units, of one cubic foot of stuff in the effec- 
tive cvlinder volume, and may be calculated with good 
approximation from the cylinder dimensions and the 
information to be obtained from ordinary and light- 
spring indicator diagrams. ‘The author uses the index 
1-3 for the compression curve, and has found his factor 
to be of great service in dealing with more than 700 
gas engines which he has tested during the last few 
years on behalf of London gas companies. 
The Morning Post has published an exhaustive list 
of congresses of learned societies and other bodies to 
be held dufing the present year, and some which have 
been announced for future years. The list is arranged 
conveniently on a large card for hanging on the wall, 
and should prove very valuable as a source of reference 
to forthcoming events. 
Messrs. J. AND .\. CHURCHILL write to point out 
that the price of ‘‘ Who’s Who in Science,” which was 
briefly noticed in_last week’s Nature (p. 553), was 
incorrectly given as 2s., whereas it is ros. net. 
NO. 2308, VOL. 92] 
OUR ASTRONOMICAL COLUMN. 
SPECTRA OF STARS NEAR THE NortH Pore.—In the 
Harvard College Observatory Circular, No. 180, we 
are informed that in the preparation of the revised 
Harvard Catalogue Miss Cannon has now classified 
the spectra of 110,000 stars covering more than one- 
half of the sky. As Prof. E. C. Pickering has re- 
ceived numerous requests for the spectra of stars near 
the pole the present circular contains a special list, 
prepared by Miss Cannon, of stars within 10° of it. 
All stars are included which have a magnitude in the 
Durchmusterung of 8-3 or brighter, and the table 
consists of three columns giving the number in the 
Durchmusterung, the photometric or Durchmusterun 
magnitude, and the type of spectrum. The number o 
stars included in this list is 825. 
CuHaNnGE IN Lunar Crater Ermmart.—Prof. W. H. 
Pickering, writing from the Harvard Astronomical 
Station at Mandeville, in Jamaica, records, in a recent 
number of the Astronomische Nachrichten, No. 4704, 
a change in the lunar crater Eimmart which has 
lately taken place. The change in appearance, he 
states, is so noticeable that he considers it desirable 
to direct the attention of astronomers, and especially 
of selenographers, to it at once, as it is the most 
marked non-periodic change that he has ever observed. 
The crater lies on the north-western border of the 
Mare Crisium in long. 295°, lat. +24°, and is about 
twenty-five miles in diameter. The general nature of 
the change is shown in the two illustrations which 
accompany his communication. While formerly, at 
each lunation, the crater apparently gradually filled 
up and overflowed with a white material, the source 
of which was at a point at the foot of the northern 
interior slope, this change no longer occurs. The last 
regular eruption observed, if, as Prof. Pickering 
states, it is considered proper to use this term, occurred 
in January of last year. Observations in February 
and March of last vear indicated a reduction in 
activity, while in April and May of the same year the 
activity was scarcely noticeable. The point Prof. 
Pickering desires to be settled is this :—When the 
moon is just past first quarter, Eimmart was distinctly 
brighter than any area of similar size between it and 
the limb. This is not the case at present, and the 
question is, Will this condition ever occur again? 
Details of his observations are given in_ his 
paper, and he indicates other differences in appear- 
ance of this crater, in addition to that above men- 
tioned. 
Tue Maprip OpsErvatory ANNUAL FOR 1914.—The 
first portion of this annual is continued on the same 
lines as in previous issues, and consists of the different 
forms of calendars, ephemerides of the members of the. 
solar system, and useful astronomical tables and the 
explanations of them. These occupy about 200 pages. 
Then follows a series of sections relative to other astro- 
nomical matters. The first is devoted to practical 
rules for the installation of an equatorial and the 
study of the correction of the objective. An account 
is next given of the proveedings of the International 
Solar Union meetings at Bonn. The observations of 
solar prominences made during the years 1907-12 are 
next studied and described in some detail, succeeded 
by the observations of spots, prominences, flocculi, and 
radiation made for the first two phenomena during 
the year 1912, and for the last two for the twelve — 
months ending September and August, 1913, respec- 
tively. These take up about another 200 pages. The 
last portion is devoted to the meteorological observa- 
tions made during the year 1912, with an annual 
‘ summary, and occupies about 150 pages. 
