VOLUME X.

NUMBER 4

THE

ASTROPHYSICAL JOURNAL

An International Review of Spectroscopy and
Astronomical Physics

The University of Chicago Press

WILLIAM WESLEY & SON, 28 Essex St., Strand, London
Sole Foreign Agents

SUBSCRIPTION, FOUR DOLLARS

SINGLE NUMBERS, FIFTY CENTS

Copyright 1899 by the University of Chicago

Where's that towel ?

J. HARTMANN

ON THE RELATIVE BRIGHTNESS OF THE PLANETS MARS AND JUPITER,
FROM MEASUREMENTS WITH A NEW PHOTOMETER
THE VARIABLE VELOCITIES OF B CAPRICORNI AND SAGITTARII IN
THE LINE OF SIGHT.
W. W. CAMPBELL
SUGGESTIONS FOR THE DETERMINATION OF STELLAR PARALLAX BY
MEANS OF PHOTOGRAPHY
FRANK SCHLESINGER
THE DISTRIBUTION OF STARS IN THE CLUSTER MESSIER 13, IN HER-
CULES.
H. K. PALMER
THE PERIODS OF THE VARIABLE STARS IN THE CLUSTER MESSIER 5
S. I. BAILEY
NOTE ON THE RELATION BETWEEN THE VISUAL AND PHOTOGRAPHIC
LIGHT CURVES OF VARIABLE STARS OF SHORT PERIOD

S. I. BAILEY
THE ANNULAR NEBULA H IV. 13 IN CYGNUS
JAMES E. KEELER
ON THE EFFECT OF PRESSURE UPON THE WAVE-LENGTHS OF THE
LINES OF THE HYDROGEN SPECTRUM
J. WILSING
ON THE PRESENCE OF OXYGEN IN THE ATMOSPHERES OF CERTAIN
FIXED STARS
DAVID GILL

MINOR CONTRIBUTIONS AND NOTES:

Corrections to Determinations of Absolute Wave-length, EDWIN B. FROST, 283; Position
of Nova Sagittarii, EDWARD C. PICKERING, 285; The Yerkes Observatory of the
University of Chicago, Bulletin No. 12, GEORGE E. HALE, 287; Results of an Exami-
nation of Spectrograms of a Orionis Obtained during the Recent Irregular Minimum,
HENRY HARRER, 290; Recommendations of the Board of Visitors to the United States
Naval Observatory, 292.

225

241

242

246

255

261

266

269

272

The ASTROPHYSICAL JOURNAL is published monthly except in July and September. Annual subscription, $4.00; foreign, 18 shillings. Wm. Wesley & Son, 28 Essex Street, Strand, London, are sole foreign agents and to them all European subscriptions should be addressed. All papers for publication and correspondence relating to contributions and exchanges should be addressed to George E. Hale, Yerkes Observatory, Williams Bay, Wisconsin, U. S. A. Correspondence relating to subscriptions and advertisements should be addressed to The University of Chicago, University Press Division, Chicago, Ill.

[Entered at the Post Office at Chicago, Ill., as second-class matter.]

Preliminary Table of Solar Spectrum Wave-Lengths

By Henry A. Rowland

ROFESSOR ROWLAND'S important TABLE

PROF

OF SOLAR SPECTRUM WAVE-LENGTHS, which has been generally adopted by spectroscopists as the standard of reference, was first published in the Astrophysical Journal, beginning with Vol. I No. 1, January 1895, and continuing to Vol. V, No. 3, March 1897. The Table gives the waveengths of nearly 20,000 lines, measured from photographs of the solar spectrum made with the concave grating at the Johns Hopkins University.

The eighteen separate parts, together with a table of corrections and additions, have been reprinted in a single volume of 225 pages, copies of which are now offered for sale at $1.50 each.

ALL ORDERS SHOULD BE ADDRESSED TO

The Press Division

The University of Chicago
Chicago, Ill.

Astronomical Photograph

On account of the frequent requests received at the Yerkes Observatory for lantern slides and prints from astronomical photographs, it has been thought advisable to make provision for supplying the very considerable demand. Mr. G. Willis Ritchey, Optician of the Observatory, who has had wide experience in making and copying astronomical negatives, has undertaken to furnish such photographs at moderate expense. He is prepared to supply lantern slides, transparencies, and paper prints from any of the negatives in the collection of the Yerkes Observatory.

Among the subjects available at the present time may be mentioned: Professor Hale's photographs of prominences, faculæ and other solar phenomena, and of stellar spectra; Professor Barnard's portrait-lens photographs of the Milky Way, nebula, comets, and meteors; Professor Burnham's photographs of the Moon, Winter and Summer views of Mt. Hamilton and the Lick Observatory; Mr. Ellerman's photographs of the buildings and instruments of the Yerkes Observatory; and Mr. Ritchey's Kenwood Observatory photographs of the Moon.

A more complete list of subjects may be had on application to G. WILLIS RITCHEY, Yerkes Observatory, Williams Bay, Wisconsin, to whom all orders should be addressed.