172 
NATORE 
ful, it is considered that no failure of supply is likely 
to occur in the immediate future. 
Tue April issue of Mr. C. Baker’s list of ‘‘ Second- 
hand Instruments for Sale or Hire”’ is now available, 
and can be obtained post free on application to 244 
High Holborn, London. The catalogue contains de- 
scriptions of nearly 2000 pieces of scientific apparatus, 
amongst which modern microscopes and objectives, 
telescopes and spectroscopes, take a prominent place. 
The preface to the catalogue points out that every 
instrument is guaranteed to be in adjustment, and 
that customers may in certain circumstances have 
instruments for three days on approval. 
Messrs. DuLau AND Co., LTp., 37 Soho Square, 
London, W., have just issued their Catalogue 65 deal- 
ing with works on recent and fossil ichthyology which 
they are offering for sale. The list contains 1740 
entries, and includes periodicals as well as books on 
every branch of the science concerned. 
OUR ASTRONOMICAL COLUMN. 
APRIL SHOOTING StTars.—Mr. W. F. Denning 
writes :—On Tuesday night, April 21, there may occur 
a rich return of the April meteoric shower. It is un- 
certain, however, what this year’s aspect of the dis- 
play will be, as the periodic time is not known. There 
were brilliant returns in 1803 and 1851, and there is 
indication that the brighter and more abundant exhibi- 
tions of this stream occur at intervals of sixteen years. 
If so, it ought to be well seen in 1915, but in view 
of the doubts remaining, the phenomenon should be 
watched every year, for negative evidence is sometimes 
useful. The Lyrids probably form a moving radiant 
like the Perseids, the motion being to the eastward 
one degree a day. This feature should be attentively 
looked for, but the shower is usually a very brief one, 
and meteors directed from it are rarely seen before 
April 19 or after April 22. This year the moonlight 
will be almost absent from the sky at the time of the 
maximum, so that with a clear atmosphere the cir- 
cumstances will be highly favourable for its observa- 
tion. 
Nova GEMINORUM No. 2.—A number of observations 
has recently come to enrich the general store of data 
regarding this nova, and some of these later con- 
tributions possess a high degree of importance. ‘This 
applies especially to a memoir appearing in Bulletin 
No. 3 of the Imperial Academy of Sciences, St. 
Petersburg, communicated by M. N. V. Vojtkevié- 
Poliakova, of the Pulkova Observatory. Unfor- 
tunately for English students. this memoir is printed 
in Russian, but it contains an excellent plate giving 
reproductions of eight spectrograms of the new star. 
It is at once apparent that evidence has been obtained 
regarding the transient proemial phase during which 
the nova exhibited a dark-line spectrum showing char- 
acteristics resembling that of Procyon. Although the 
Harvard spectrograms had established beyond any pos- 
sibility of doubt that this nova had indeed passed 
through this so much questioned stage, the value of 
independent confirmatory evidence need not be in- 
sisted on. The series of thirty-six spectrograms dis- 
cussed in the paper extends from March 15, 1912, to 
October 8, 1913, and inciudes two excellent plates 
taken on the first date, ard others for March 16, 17, 
and 18. The wholly dark-line stage so happily caught 
at the Harvard College Observatory was missed at 
Pulkova, but the leading Procyonian features are still 
NO; (2320;..ViOrenO 3] 
[APRIL ‘16, 1914 
predominant in the first two spectra, although: the 
bright-line spectrum is making its appearance, and 
on March 16 predominates, but the H and K lines 
may still be seen quite plainly. 
Another spectroscopic paper comes from the Catania 
Observatory, and is the work of Dr. Vittorio Fontana. 
It appeared in the Memoirs of the Societa Spettro- 
scopisti Italiani, vol. ii., series 2, pp. 201-10. 
Additional observations of the light changes of this 
nova are given in two papers published in No. 4720, 
Astronomische Nachrichten. In the first of these 
von J. Kasansky, Moscow Observatory, presents fifty- 
seven determinations, ranging from the time of the 
discovery (March 14, 1912) to March 27, 1913. The 
observed magnitudes range from 3:58 (H.R.) on the 
former to 8-76 on the latter date. By March 16 the 
brightness of the nova had fallen nearly two mag- 
nitudes to 5-54. The magnitudes for the greater part 
of the series are also stated in terms of the Potsdam 
scale, and can thus be at once compared with the 
values given in the other paper, which is by Sig. 
Eugeni Guerrieri, Capodimento Observatory. | This 
series includes 139 determinations of magnitude be- 
tween March 28, 1912, and April 29, 1913. The light 
curve exhibits the typical characteristics of nova 
variability. For the few common dates the two series 
show good agreement. 
DiuRNAL VaRIATIONS OF LatiruDE.—During last year 
M. Jean Boccardi, in discussing the results of his 
observations for latitude made -by the method of 
Struve, drew the conclusion that an effect of lunar 
attraction was suggested by displacements from the 
vertical. As these displacements were considerably 
greater than those which he could calculate by theory 
he was led to conclude that these latitude variations 
were caused by geological conditions special to the 
place of observation. Having subsequently become 
acquainted with M. Schumann’s researches on latitude 
variations in which he could trace undulatory curves 
showing diurnal variations of latitude, M. Boccardi 
has completed some diagrams showing the march of 
the latitude values. These diagrams are not pub- 
lished in the communication which he sends to the 
Comptes rendus of the Paris Academy of Sciences 
(February 9, 1914, No. 6); tables only are given, but 
he states that the maxima and minima values of the 
latitude obtained with the four stars which he has 
observed follow one another at intervals which corre- 
spond to the movement made by the moon in right 
ascension during the corresponding intervals of right 
ascensions between the stars. Thus the action of the 
moon seems to be demonstrated. 
A PERPETUAL CALENDAR.—We have received a neat 
perpetual calendar, ‘‘Alle Jahreskalender auf einem 
Blatt,” by ‘‘Dr. Doliarius,”’ of Leipzig (B. G. Teub- 
ner). It is of postcard size, and seems well adapted 
to the requirements of clergymen and others. Three 
tables are given: (1) the dates of Easter according to 
the Gregorian calendar, 1582-2000; (2) the correspond- 
ing Julian dates, 1470-2004; and (3) a double enumera- 
tion of the days of the year arranged in thirteen 
columns in such a way that any seven consecutive 
columns are complete in themselves. A separate card 
frame is supplied having a slit which fits over the 
width of seven columns, and as the top of the slit is 
marked with the seven days of the week an annual 
calendar is displayed when the frame is placed over 
table (3). The correct position of the frame is deter- 
mined by a marked space which is adjusted to the 
date of Easter for the year required according to the 
indication of table (1) or (2). The manipulation of 
| the calendar is quite simple, and furnishes the dates 
) of the principal church festivals very readily. 
