xii MINUTES. [April 19, 



William Duane, Ph.D., late of the Curie Radium Laboratory, 

 University of Paris (introduced by Professor Arthur W. 

 Goodspeed). Discussed by Dr. H. C. Jones, Mr. E. C. 

 Franklin and Mr. Joseph Willcox. 



" Some Diffraction Phenomena ; Superposed Fringes," by 

 Charles F. Brush, Ph.D., LL.D., Cleveland, O. 



" Matter in its Electrically Explosive State," by Francis E. 

 Nipher, A.M., LL.D., Professor of Physics, Washington 

 University, St. Louis. 



" New Investigations of Resonance Spectra," by Robert Wil- 

 liams Wood, A.B., LL.D., Professor of Experimental Physics, 

 Johns Hopkins University. Discussed by Professor Schuster. 



"Application of Recent Studies on the Origin of the Earth's 

 Magnetic Field to the Possible Magnetic Fields of Rotating 

 Bodies in General" (illustrated), by Louis A. Bauer, Ph.D., 

 Director of the Department of Terrestrial Magnetism of the 

 Carnegie Institution, Washington. 



"The Determination of Visual Stellar Magnitudes by Photog- 

 raphy," by Edward C. Pickering, D.Sc, LL.D., F.R.S., Di- 

 rector of the Harvard College Observatory, Cambridge. 



" Some Problems in Connection with the Milky Way, as Shown 

 by Photographs Made with Portrait Lenses," by Edward E. 

 Barnard, Sc.D., LL.D., Astronomer of the Yerkes Observa- 

 tory, Williams Bay, Wis. 



" The Spectroscopic Detection of the Rotation Period of 

 Uranus," by Percival Lowell, LL.D., and V. M. Slipher. 

 Ph.D., of the Lowell Observatory, Flagstaff, Arizona. 



"On the Spectrum of the Nebula in the Pleiades," by V. M. 

 Slipher, Ph.D., of the Lowell Observatory, Flagstaff, Arizona. 



"Eclipsing Variable Stars," by Henry Norris Russell, Ph.D., 

 Professor of Astronomy and Director of the Observatory, 

 Princeton University (introduced by Professor William F. 

 Magie). 



" Progress of New Lunar Tables," by Ernest W. Brown, M.x\., 



Sc.D., F.R.S., Professor of Mathematics, Yale University. 



Dr. John Mason Clarke, elected to membership in 191 1, Dr. E. C. 



