NATURE 
[NovEMBER 20, 1913 _ 
= 
C. Burt; ‘Collective Psychology,’? W. McDougall, 
F.R.S.; ‘‘The Psychology of Personality and Sug- 
gestion,’ T. W. Mitchell; “The Psychology of 
Dreams,” T. H. Pear. In the ‘‘ Cambridge Technical 
Series”? :—‘‘ Automobile Engineering,” A. Graham 
Clark; ‘Electro-Technical Measurements," A. E. 
Moore; ‘Applied Mechanics,” E. S. Andrews; ‘' Alter- 
nating Currents," W. H. N. James; ‘' Chemistry and 
Technology of Oils and Fats,’’ F. E. Weston; “ Paper, 
its Uses and Testing,” S. Leicester; ‘‘ Mining Geo- 
logy,” Prof. G. Knox; ‘Textile Calculations—Mate- 
rials, Yarns, and Fabrics,” A. M. Bell; “Domestic 
Science,” C. W. Hale; ‘‘ Business Methods,” Thomas 
Hart, jun.; ‘‘ Electrical Engineering,” TC, Barllie; 
“Applied Mechanics and Heat Engines,” F. Boulden ; 
“‘Elements of Applied Optics,” W. R. Bower; 
“Physics for Engineers,” J. F. Yorke; ‘‘ English 
Building Construction,’ C. F. Innocent; “Sculpture 
in Relation to Architecture," T. P. Bennett; ‘‘ Electric 
Installations,” C. W. Hill; ‘‘ Accounting,” J. B. War- 
daugh; ‘‘The Theory and Practice of Commerce,” 
J. C. Stephenson. In the ‘Cambridge Health 
Series’: ‘‘The Bacteriological Analysis of Water, 
Sewage and Foods,” Dr. W. G. Savage; ‘Isolation 
Hospitals,’ Dr. H. F. Parsons. In the “ Provincial 
Geographies of. India”: “Bengal and Orissa,” 
L..S. S: O'Malley; ‘The Punjab, N.W. Frontier 
Province, and Kashmir,” Sir J. McC. Douie. 
OUR ASTRONOMICAL COLUMN. 
Comer News.—Miss Anna R. Kidder, of the 
Berkeley Astronomical Observatory, communicates to 
the Lick Observatory. Bulletin, No. 245, the elliptic 
elements and ephemeris of comet rg13e (Zinner). 
The elements she has computed correspond so closely 
to those of comet 1900 II]. (Giacobini) that she con- 
cludes that both comets are identical. The two sets 
of elements are as follows :-— 
Comet 19co IIT. (Giacobini) 
T =1900,: Nov. 28°17 
Com t 1913¢ (Zinner) 
@ =171° 29") 171° 29°1') 
Q.=196 32 19000 195 27°3 ;1913°0 
z= 29 52 | 31 oI! 
g =0°9342 0°97787 
e =0'74168 0'72968 
The average period derived from the dates of peri- 
helion passage in 1900 and 1913 is 6-464 years. 
Two publications, namely the Lick Observatory 
Bulletin, No. 239, and the Lowell Observatory Bul- 
letin, No. 57, contain accounts of photographs secured 
at the respective observatories. In the former, Dr. 
C. C. Kiess describes the observations made on comet 
1g11c (Brooks) and illustrates his descriptions with 
ten excellent reproductions. In the latter communi- 
cation Mr. C. O. Lampland describes fully the photo- 
graphs secured at the Lowell Observatory of the fine 
comet 191oa. A large series of most striking photo- 
graphs is also reproduced. In the addenda to the 
paper he discusses the heliographic positions of this 
comet, and adds some remarks in connection with the 
heliographic latitudes of Donati’s comet (1858 VI.), 
and Chéseaux’s comet (1744 I.) when near perihelion. 
Macnirvinc Powers Usrep py Dovusik-star Op- 
seRveRS.—Mr. T. Lewis, writing in The Observatory 
for November, briags together some very interesting 
facts relating to the magnifying powers used by 
double-star observers. The object of the inquiry was 
to answer the question, “ What is the best magnifying 
NO. 2299, VOL. 92| 
_negative results, for polarisation. 
1913, Nov. 2"1047 G.M.T. ° | 
913s ae Norman Lockyer and Mr, Baxandall in 1905. With — 
power of a telescope in actual practice?” and, in the 
hope of arriving at some definite result, he made 
counts of thousands of observations all over the world 
by various observers. The result of the investigation 
was to produce a formula— a 
Magnifying power=140V A, 
where A is the diameter of the aperture, in inches 
and this formula gives an excellent representation. 
the values derived from the discussion of the actu 
observational data. Thus the formula, as Mr. Lew 
says, ‘“‘may safely be taken as representing the co 
sensus of opinion among experienced observers in 
their choice of the best magnification for a given 
telescope; and it may, therefore, be useful as a guide — 
to others in selecting the eyepieces which will best — 
suit their particular telescope.” a 
STELLAR CLassiIFicaTIoN.—At the Lick Observatory — 
much work has recently been accomplished in the — 
classification ot stellar spectra. Bulletins 237 and 243 
contain two researches in this subject, both of which 
have been carried through by candidates for the © 
degree of doctor of philosophy in the University of — 
California, a fact which indicates the increased atten- 
tion now being devoted to this section of astrophysics. 
The first of these papers deals with ‘Class B Stars 
whose Spectra Contain Brignt Hydrogen Lines," and 
is the work of Mr. Paul W. Merrill. “a 
By using plates stained with Wallace’s three-dye 
stain the spectrograms included He. Five slit- — 
prism spectrographs giving dispersions ranging from 
8-7 A per mm. at Hy, and one grating spectrograph 
giving in the second order at Ha (with that line 
central) 10.9 A per mm. were employed, attached to 
the 36-in. refractor. 
The survey included nearly all the’ stars of the © 
above description north of —40°, and some related — 
stars; also some stars included either because on 
three-prism spectrograms H8 was peculiar, or the 4 
lines were weak and diffuse in order to see whether 
Ha might be bright. The bright components of the 
H8 line of y Cassiopeia and b, Cygni were tested, with — 
The author con- — 
firms the presence of the chromospheric lines AA4g924 
and 5018 in these stars, first pointed out by Sir — 
regard to the doubling of the bright hydrogen lines, — 
complex self-reversal is suggested as the expianation — 
most in accord with the facts. Finally, Mr. Merrill 
divides these stars into four groups, of which the 
types are y Cassiopeie, 6? Cygni, Electra, and ; 
¢@ Persei. The groups contain fourteen, nineteen, — 
two, and three stars respectively, whilst six stars — 
remain unclassified. The variability and distribution — 
of these stars also receives attention. ee 
Bulletin 243 contains a photographic study of 
the visual region of the spectra of the brighter 
Class A stars, by Miss E. Phoebe Waterman. The 
line of greatest wave-length measured was A6517, of — 
unknown origin. Miss Cannon’s proposal to-re- — 
arrange the classification of these stars is supported; — 
the stars now classified as A would thus be divided — 
between classes Ao to A2. In the summary it is — 
stated that the metal lines present are the enhanced — 
or spark lines of the elements represented. They 
coincide throughout in wave-length and intensity with — 
the stronger lines of the solar chromosphere. The 
peculiarity of the spectrum of « Cygni is found ‘to — 
consist in the great intensity of some of the iron — 
lines, and in the narrow and well-defined character oft™ 
all the lines rather than in the presence of lines 
foreign to stars of Class A. Miss Waterman finds — 
that some stars perhaps show bright borders to the — 
absorption lines. 
