July 2, 1909] 



SCIENCE 



31 



Tuesday afternoon (April 20), Lime Sulphur, 

 Its Use and Manufacture. Evening, The Manu- 

 facture of Miscible Oils and Arsenical Insecti- 

 cides. 



Wednesday morning (April 21), The European 

 Elm Scale, and the Codling Moth. Afternoon, 

 The Orange Scale and the Citrus Mealy Bug. 

 Evening, Exhibits of Insecticide Materials, Insect 

 Collections, Apparatus illustrating Methods of 

 Study, etc. 



Thursday morning (April 22), Visit to Oak- 

 land Formicary. Afternoon, Forest Insects and 

 Apiculture. Evening, Medical Entomology. 



Frida3' morning (April 23), Methods Used in 

 the Study of Sensory Reactions, Insect Photog- 

 raphy. Afternoon, permanent organization. 



The meeting was well attended, notwithstanding 

 the enormous distances separating the workers on 

 the Pacific coast. As had been hoped at the out- 

 set, a permanent organization was effected under 

 the name Pacific Slope Association of Economic 

 Entomologists. The constitution adopted requires 

 that active membership shall be limited to the 

 official and professional entomologists of the Pa- 

 cific slope, while associate membership shall be 

 open to agriculturists and to all others interested 

 in the objects of this association. The following 

 officers were elected: 



President — Professor C. W. Woodworth, Uni- 

 versity of California, Berkeley, Cal. 



Vice-presidents (representing each state con- 

 cerned) — Professor R. W. Doane, Palo Alto, Cal.; 

 Professor S. B. Doten, Reno, Nevada; Professor 

 J. Elliott Coit, Phoenix, Arizona ; Professor Fabian 

 Garcia, P. 0. Agricultural College, New Mexico; 

 Professor E. D. Ball, Logan, Utah; Professor A. 

 B. Cordley, Corvallis, Oregon; Professor A. L. 

 Melander, Pullman, Washington; Professor L. F. 

 Henderson, Moscow, Idaho; Professor C. P. Gil- 

 lette, Fort Collins, Colorado; Professor R. A. 

 Cooley, Bozeman, Montana ; Professor Aven Nel- 

 son, Laramie, Wyoming; Hon. Thos. Cunningham, 

 Vancouver, B. C. 



Executive Committee — Mr. R. R. Rogers, San 

 Francisco, Cal.; Mr. H. P. Stabler, Yuba City, 

 Cal.; Mr. L. H. Day, Oakland, Cal. 



Secretary-Treasurer — Professor W. B. Herms, 

 University of California, Berkeley, Cal. 



It is planned to hold the next meeting this 

 summer at Portland, Oregon. 



W. B. Hebms, 

 Secretary-Treasurer 



SOCIETIES AND ACADEMIES 



THE PHIIX)SOrniCAL SOCIETY OF WASHINGTON 



The GGTth meeting was held on May 22, 1909, 

 Vice-president Wead in the chair. Mr. Edwin 

 Smith read a biographical sketch of Mr. William 

 Eimbeck. Two papers were read. 



Investigation of Dip Needle Corrections by Ex- 

 perimental Methods: P. H. Dike, of the Car- 

 negie Institution of Washington. 

 The values of the inclination, or dip of the 

 magnetic needle, as observed by the absolute 

 method with the dip circle, in general still require 

 some correction, and the error is not eliminated 

 by multiplying observations as the correction is 

 a constant one for a given station. The correc- 

 tion is found to vary with the dip and the total 

 force, and it is accordingly necessary to take 

 account of this variation in the reduction of the 

 observations made by the various expeditions of 

 the Department of Terrestrial Magnetism of the 

 Carnegie Institution of Washington covering a 

 large range of the magnetic elements. In the 

 Galilee work on the Pacific Ocean dip circles were 

 compared with observatory instruments over as 

 wide a range of dip as possible ( -f 74° to — 68° ) , 

 and from the corrections thus obtained empirical 

 formulae were established by least square methods, 

 from which the probable corrections for inter- 

 mediate values of dip were derived. 



The purpose of the present investigation is to 

 derive these corrections by comparison with a 

 single standard instrument (an earth inductor) 

 at one station and through the whole range of 

 positive and negative dip. An artificial field is 

 produced by a system of coils, through which a 

 uniform current from a storage battery flows. 

 Two coaxial coils of 80 cm. radius are mounted 

 with axis vertical, 80 cm. apart, each coil having 

 100 turns of wire. A secona pair 90 cm. in radius 

 and 90 cm. apart are mounted with axis hori- 

 zontal, the middle points of the axes of the two 

 pairs of coils coinciding. The second pair has 50 

 turns each of wire. By regulating the currents in 

 the two sets of coils any desired magnetic field can 

 be produced at the center, and this field is ex- 

 tremely uniform over a considerable area. Two 

 systems of coils are set up about 50 feet apart, 

 the horizontal coils of one being in series with 

 those of the other, and the vertical -coils likewise 

 in series with each other. Simultaneous observa- 

 tions with earth inductor and dip circle are made 



