search in its immediate neighborhood for another and, too often to be the result of chance, one is found, apparently connected by physical relations like the binary systems of the double-stars.

In these laborious searches vision is strained to its utmost tension, and, when the wearied eye fails to equal its best efforts, I resort to the less fatiguing work of comet-seeking.

Saving Alaska, Rochester is the most cloudy region in the United States. The three winter months rarely afford over four, clear, moonless nights, and many of the clear nights of summer are, from smoke and haze, useless. Since the appearance of the redlight or after-glow, not one exquisite night has been had. Remembering all these untoward conditions, it will be apparent that the nebula are not all yet discovered and that the efforts put forth at the Warner Observatory have been rewarded with a fair measure of success.

The faintness of some of the nebulæ in my list is inconceivable. Sir William Herschel's class III are bright objects in comparison. With a luminous field and dark wires the largest telescope in the world would not reveal one of them, and it is very doubtful if, even with a dark field and luminous wires, micrometric measures of position can ever be satisfactorily made.

TITLES OF OTHER PAPERS READ IN SECTION A.

By Prof.

A NEW APPARATUS FOR THE STUDY OF BOYLE'S LAW.
LEROY C. COOLEY, Vassar College, Poughkeepsie, N. Y.
THE LUNAR AURORA. By Prof. JOHN HAYWOOD, Otterbein Uni-
versity, Westerville, Ohio.

ON THE MEASUREMENT OF AN INTERNATIONAL ARC OF MERIDIAN
THROUGH THE AMERICAN CONTINENT, FROM CAPE HORN TO THE
ARCTIC REGIONS. By TRELAWNEY SAUNDERS, Surrey, Eng-

land.

RESULTS OF OBSERVATIONS AND EXPERIMENTS WITH AN ALMUCANTAR OF FOUR INCHES APERTURE, AT THE HARVARD COLLEGE OBSERVATORY. By S. C. CHANDLER, jr., Assistant in the Observatory, Cambridge, Mass.

THE GEODETIC WORK OF THE U. S. COAST AND GEODETIC SURVEY. By J. HOWARD GORE, Professor of Mathematics, Columbian University, Washington, D. C.

A CRITERION FOR THE REJECTION OF DOUBTFUL OBSERVATIONS. By Dr. MANSFIELD MERRIMAN, Lehigh University, Bethlehem, Pa. HARMONIC MOTION IN STELLAR SYSTEMS. * By Prof. PLINY EARLE CHASE, Haverford College, Pennsylvania.

ON THE MEAN TEMPERATURE OF THE TWO HEMISPHERES OF THE EARTH. By Prof. H. HENNESSY, Dublin, Ireland.

ON THE CONSTITUTION OF THE EARTH AND PLANETS. By Prof. H.
HENNESSY, Dublin, Ireland.

ON AN INTERNATIONAL STANDARD FOR MEASUREMENTS.
H. HENNESSY, Dublin, Ireland.

By Prof.

SYSTEMATIC ERRORS IN STELLAR MAGNITUDES. By Prof. E. C. PICKERING, Director of Harvard Observatory, Cambridge, Mass.

ON THE MAGNITUDE OF THE ERRORS WHICH MAY BE INTRODUCED IN
THE REDUCTION OF AN OBSERVED SYSTEM OF STELLAR COÖRDI-
NATES TO AN ASSUMED NORMAL SYSTEM BY GRAPHIC METHODS.

By Prof. Wм. A. ROGERS, Harvard Observatory, Cambridge,
Mass.

ANALYSIS OF THE FORMULA FOR THE MOON'S LATITUDE As affected
BY THE FIGURE OF THE EARTH. Вy Prof. JOHN N. STOCKWEll,
Cleveland, Ohio.

ON AN INDIRECT SOLUTION OF THE EQUATION

α d2

a = ao+dar+ 1 1 a 2 + 1.1 14773 + &c.

2 dr2

ds T

2 3 d73
da
ατ

TO THE 6TH POWER OF THE TIME, IN WHICH IS A FUNCTION

OF FOUR VARIABLES. By Prof. Wм. A. ROGERS, Harvard
Observatory, Cambridge, Mass.

* Printed in full in Journal of Franklin Institute, Nov., 1884.

A BRIEF ACCOUNT OF SOME PRELIMINARY EXPERIMENTS IN THE CONSTRUCTION OF CLOCKS OF PRECISION. By Prof. LEONARD WALDO, Yale Observatory, New Haven, Conn.

A COLLECTION OF FORMULE FOR THE AREA OF A PLANE TRIANGLE. By MARCUS BAKER, U. S. Coast and Geodetic Survey, Washington, D. C.

ON THE VISIBILITY OF FAINT

OBJECTS UNDER RED ILLUMINATION.

By Prof. G. W. HOUGH, Director Dearborn Observatory,
Chicago, Illinois.

THE PRODUCTS OF VECTORS. By Prof. SAMUEL EMERSON, University of Virginia, Va.

TEMPORARY STARS.

By Prof. DANIEL KIRKWOOD, Indiana Uni

versity, Bloomington, Ind.

SECTION B.

PHYSICS.