546 
NATURE 
[APRIL 21, 1923 

of this work, and some new experiments by the | engineering, and early medical works. 
authors are given. The report will prove useful 
to all who are interested in this very important 
subject. 
Messrs. DuLAu AND Co., Ltp., 34 Margaret Street, 
W.1, have just issued a valuable catalogue ‘No. 100) 
of upwards of 2600 second-hand science books and 
serials which they have for disposal. The list is 
conveniently arranged under the headings—ornitho- 
logy, entomology, conchology, the lower inverte- 
brates, general zoology, botany, horticulture, agricul- 
ture, geology, mineralogy, astronomy, mathematics, 
It should 
interest many readers of NATURE. 
Amonec the books shortly to be published by the 
Oxford University Press is ‘‘ The Glass Palace 
Chronicle of the Kings of Burma,” which has been 
translated for the Burma Research Society by Pe 
Maung Tin and G. A. Luce. The chronicle is the work 
of the committee of “‘ learned monks, learned brahmans, 
and learned ministers ’’ appointed in 1829 for the 
purpose by King Bagyidaw of Burma. The title is 
taken from the Palace of Glass, in a chamber of which 
the compilation was made. 

Our Astronomical Column. 
GREECE ADOPTS THE GREGORIAN CALENDAR.—The 
Gregorian Calendar was adopted for civil purposes 
in Greece from the beginning of March. As Russia 
has apparently taken the same step, the old or Julian 
style becomes practically obsolete. M. D. Eginitis, 
director of the Athens Observatory, contributes a 
paper to the Comptes rendus of the Paris Academy of 
Sciences, March 12, in which he notes that the finding 
of the decree of Nicwa, A.D. 325, shows that, far from 
prohibiting such a change, it in reality rather demands 
it. The decree simply directed that Easter should 
everywhere be kept on the same day ; by implication 
this day was the first Sunday after the 14th day of 
the first lunation after the spring equinox, which was 
assumed to occur on March 21. When it was found 
that the Julian Calendar did not maintain the equinox 
at this date, the reform at once became appropriate. 
The causes that for so long retarded its acceptance in 
eastern Europe were largely removed by the War, 
and M. Eginitis addressed a memorandum to the 
Greek Government in December 1918, which has now 
been followed. 
The Greek Church is not at present adopting the 
reform, the reason being the expectation of the 
speedy adoption of other calendar changes in the west, 
for which it prefers to wait. 
Some of these reforms are being discussed by the 
International Congress of Chambers of Commerce 
now meeting in Rome; but experience shows the 
extreme difficulty of persuading the world to adopt 
changes in their fixed habits, however desirable in 
themselves, so that we can scarcely share the sanguine 
view of M. Eginitis, who shares the expectations just 
mentioned. 
THE E1GuTH SATELLITE OF JuPITER.—Prof. E. W. 
Brown contributes an article on this satellite to 
Astronom. Journ.No.817. He makes use of Delaunay’s 
algebraical expressions for the various terms, which are 
theoretically available for any satellite ; however, in 
cases of such large eccentricity and inclination as 
those of J. VIII the terms do not converge rapidly 
enough to be used straight away. Prof. Brown, 
whose great experience gained in his new lunar theory 
comes useful, shows how estimates may be made of 
the remainders, and in particular finds a solution for 
the mean motion of the perijove. The general rule 
both with planets and satellites is that the apse moves 
in the same direction as the body, but in the case of 
J. VIII the higher terms of the series reverse the 
earlier ones, and produce motion in the opposite 
direction, Prof. Brown refers in his work to G. W, 
Hill’s paper on the motion of the lunar perigee ;_ it is 
interesting to recall that it was this work of Hill’s 
that gave Brown the idea that he afterwards followed 
so successfully in his lunar theory. 
_ The period of revolution of the perijove of J. VIII 
is about 800 years, an unusually long period for a 
NO, 2790, VOL. I11] 

satellite. It is welcome news that Prof. Brown proposes 
to continue his work till he has arrived at expressions 
which will enable the place of the satellite to be pre- 
dicted without the tedious method of mechanical 
quadratures. Mr. J. Jackson has also been at work on 
the satellite, using a combination of observed and 
calculated positions, and gives an ephemeris for the 
present apparition in the Observatory for March. The 
chief importance of observing this satellite and the 
still fainter J. IX is that they will ultimately give a 
better value of Jupiter’s mass than any other method. 
ASTRONOMY IN THE UNITED STATES.—The section 
of Year Book, No. 21, of the Carnegie Institution 
of Washington, dealing with astronomical work 
catried out in departments of the Institution in- 
cludes several items of general interest. The so-called 
K-term in radial velocities, that is, an average motion 
of recession shown by all spectral types, but especially 
by type B, where it amounts to 4 km. /sec., is discussed. 
More than half of this is removed by adopting newly 
determined wave-lengths for the lines of oxygen, 
nitrogen, silicon and helium that were used; it is 
further pointed out that certain lines formerly used 
were double, and therefore unsuitable. A small residual 
recession may be due to the Einstein effect. Work 
on the proper motions of the red stars has shown that 
these are generally small in the case of types M and N ; 
M stars have large radial velocities, they are there- 
fore mainly giants, and very distant. The radial 
velocities of type N stars are small, indicating that their 
average mass is high. Both types give much the 
same direction for solar motion as that generally 
adopted. 
Studies have also been made on the progressive 
differences of spectra from type Bo to B8. In B8 
the oxygen and nitrogen lines disappear, while a 
number of enhanced metallic lines appear; it is 
anticipated that discussion of these facts may advance 
the theory of ionisation, and our knowledge of the 
constitution of matter. 
The meridian observers seem to be worked very 
hard; they are on duty for a week at a time, and 
observe time-stars at intervals not exceeding 6 hours, 
besides circumpolars at both culminations. What 
would the advocates of an 8-hour day say to this ? 
The object is to eliminate personality, but it is 
found that when an observer is fatigued he observes 
differently than he does when fresh. One of the 
objects of this series of observations is to deter- 
mine the laws of differential refraction both in Right 
Ascension and Declination, and if possible to con- 
nect it with the meteorclogical conditions. 
is little doubt that differential refraction is the cause 
of the perplexing variations in time-determinations 
from different observatories, and that its determina- 
tion would mean a marked increase of accuracy in 
meridian work. 
There - 
CE 
