IV 
CONTENTS 
PAGE 
Transformations of Applicable Conjugate Nets of Curves on Surfaces 
By Luther Pfahler Eisenhart 637 
On Bilinear and N-linear Functionals By Charles Albert Fischer 640 
On the Deformation of an N-Cell By Oswald Veblen 654 
A Theorem on Series of Orthogonal Functions withan Application to Sturm- 
LiouviLLE Series By George D. Birkhoff 656 
ASTRONOMY 
Studles of the Magnitudes in Star Clusters. IV. On the Color of Stars in 
THE Galactic Clouds Surrounding Messier 11 By Harlow Shapley 25 
The Color of the Standard Polar Stars Determined by the Method of Expos- 
ure-Ratios By Frederick H. Scares 29 
Relation of the Apex of Solar Motion to Proper Motion and on the Cause 
of the Differences of Its Position from Radial Velocities and Proper 
Motions f .By C. D. Perrine 38 
The Meteor System of Pons-Winnecke's Comet By Charles P. Olivier 47 
Axes of Symmetry in Globular Clusters. . .By Francis G. Pease and Harlow Shapley 96 
The Parallax of the Planetary Nebula N. G. C. 7662 .. . .By Adriaan van Maanen 133 
The Ninth Satellite of Jupiter By Seth B. Nicholson 147 
Photographic Magnitudes of Stars in the Selected Areas of Kapteyn 
By Frederick H. Scares 188 
Preliminary Note on the Distribution of Stars with Respect to the Galactic 
Plane By Frederick H. Seares 217 
Studies of Magnitudes in Star Clusters. V. Further Evidence of the Absence 
OF Scattering of Light in Space By Harlow Shapley 267 
Studies of Magnitudes in Star Clusters. VL The Relation of Blue Stars and 
Variables to Galactic Planes By Harlow Shapley 276 
A Search for an Einstein Relativity-Gravitational Effect in the Sun 
By Charles E. St. John 450 
Studies of Magnitude in Star Clusters. VIL A Method for the Determi- 
nation- OF THE Relative Distances of Globular Clusters 
By Harlow Shapley 479 
The Principal Axes of Stellar Motion By H. Raymond 485 
Relation of Preferential Motion and of the Spectral-Class and Magnitude 
Velocity Progressions to Proper Motion By C. D. Perrine 491 
Further Evidence on the Concentration of the Stars Toward the Galaxy 
By Frederick H. Seares 558 
Absorption Effects in the Spiral Nebulae By Heber D. Curtis 678 
PHYSICS AND ENGINEERING 
Inferences Concerning Auroras By Elihu Thomson 1 
The Resistance of Metals under Pressure By P.W. Bridgman 10 
Hydrology of the Isthmus of Panama By Brig. Gen. Henry L. Abbot 41 
The Mass of the Electric Carrier in Copper, Silver and Aluminium 
By Richard C. Tolman and T. Dale Stewart 58 
The Silver Voltameter as an International Standard for the Measurement of 
Electric Current By E. B. Rosa and G. W. Vinal 59 
On Moseley's Law for X-ray Spectra By Horace Scudder Uhler 88 
Refractivity Determined Irrespective of Form, by Displacement Interfer- 
OMETRY By Carl Barus 117 
