104 
his student days in Milan, Turin and Rome, and 
his professional days in the universities of Genoa, 
Malta, Ravenna, Cremona and Rome, and while 
getting wider experience in Paris and Greenwich 
preparatory to beginning his long period of astro- 
nomical observations at Palermo, where he built an 
observatory on the royal palace. 
The method of his observing for the large 
catalogue of stars, his discoveries of certain 
stellar proper motions, his wide range of observa- 
tions and of writings on astronomical and geo- 
detic subjects, are narrated to elucidate the influ- 
ence which this Theatine priest exerted on the 
science of his and later days, and inversely to 
exemplify the influence which had been exerted on 
him by his environment and by his intercourse 
with Laplace, Lagrange, Delambre, Bailly, Cassini, 
Herschel, Wollaston, Oriani, Cagnoli and other 
notable men of astronomy. It is further shown 
how his discovery of Ceres was not altogether an 
accident, nor by any means his greatest achieve- 
ment, but was the natural by-product of his plan 
of work and his persistent diligence; and that all 
the many and valuable fruits of his quarter-cen- 
tury of labor were but the outgrowth of an un- 
selfish devotion that had adopted as its motto the 
words of Seneca: ‘‘At mehercules non aliud quis 
aut magnificentius quaesierit aut didicerit utilius, 
quam de stellarum siderumque natura.’’ 
(This paper will be published im extenso in 
‘‘Makers of Astronomy,’’ soon to be issued by 
the Fordham University Press, New York, as com- 
panion to ‘‘ Makers of Electricity.’’) 
The Astronomischer Jahresbericht (an Annownce- 
ment): H. S, Davis. 
A brief historical summary of the founding and 
maintaining of this review of astronomical pub- 
lications, its plan and scope, and to what extent 
its purpose has been attained. Its future, since 
assumption of the editorship by Professor Dr. 
Fritz Cohn, on the retirement of Dr. Berberich, 
who succeeded to the editorship on the death of 
Professor Dr. Wislicenus, its founder. 
The Variability of Polaris: JOEL STEBBINS. 
The variation in the light of Polaris was de- 
tected by Hertzsprung and confirmed by King. 
Assuming the spectroscopic period of 3.9681 days, 
Hertzsprung found the light-curve to be approxi- 
mately a sine-curve with double amplitude 0.17 
mag., and King found a similar curve with varia- 
tion greater than 0.10 mag. Both of these results 
were from photographs. Observations by the 
writer with the selenium photometer give a similar 
SCIENCE 
[N.S. Vou. XXXV. No. 905 
curve of the same phase, but of much smaller 
amplitude, the approximate range being 0.057 mag. 
It is highly probable that the amount of the visual 
variation is likewise about 0.06 mag. 
The Asteroid Problem: JoEL H. METCALF. 
In ninety years from January 1, 1801, to 1891, 
323 asteroids were discovered. In the last twenty 
years about 427 have been added. The rapid mul- 
tiplication of discoveries and the probable exist- 
ence of 1,500 brighter than the 14th magnitude 
demands greater cooperation and division of labor 
in this field. Except for special investigations the 
work should be photographic, which gives great 
facility for observation of old asteroids as well as 
the discovery of new ones. The importance of the 
investigation in the light of the discovery of Eros 
and the Jupiter group of asteroids and the prob- 
able existence of still more interesting bodies is in- 
creasingly obvious. 
Magnitudes, Colors and Spectra of Standard Stars 
within 17° of the North Pole: J. A. PARKHURST. 
This paper describes the determination of the 
‘‘visual’? and photographic magnitudes, color- 
indices and spectral classes of all the stars down 
to the B. D. 7.5 magnitude, from declination 
-+ 73° to the north pole. There are 666 stars 
within these limits. The instrument used was a 
camera having a Zeiss doublet of ‘‘ultra-violet’’ 
glass, also a 15° prism of the same material. The 
aperture of each is 145 mm. and the focal length | 
of the lens 814 mm. 
The photographie magnitudes were taken from 
Seed plates exposed 6.5 mm. inside the focus, and 
the opacity of the images was measured with a 
Hartmann ‘‘mikrophotometer.’’ To obtain the 
‘¢visual’’? magnitudes images were taken in focus 
on Cramer trichromatic plates through a ‘‘visual 
luminosity’’ filter, and the diameters of the 
images measured under the microscope. The spec- 
tral classes were estimated on the Harvard system 
from the objective prism plates. The magnitude 
scale was determined on the ‘‘absolute’’ system, 
directly by sensitometer squares on the extra-focal 
plates, and indirectly through the Pleiades stars 
on the focal plates. The measures were reduced 
by using the Miiller and Kempf Potsdam visual 
magnitudes of the white stars in each field, and 
reduced to the Harvard system by subtracting 0.29. 
Curves were shown giving comparisons with the 
results of Schwarzschild, Muller and Kempf and 
Mrs. Fleming; also the relation between color- 
index and spectral class, and between the color- 
index and Miiller and Kempf’s estimates of color. 
