June 2, 1916] 



SCIENCE 



789 



we ■will take as the inner cylinder; of about 

 one square centimeter in area. Under these 

 conditions the Faraday dark space should be 

 about 8 mm. in length, and the Crookes dark 

 space should be just visible between the vel- 

 vety cathode glow and the cathode electrode. 

 Another prerequisite is that the discharge 

 must not cling to the edge of the aluminum 

 electrodes, but should occupy some intermedi- 

 ate position as shown at 1 in a. Fig. 1. In this 

 position the characteristics of the discharge 

 are shown with exceeding clearness. If now 

 some additional resistance is cut in, the area 

 of the discharge will become less, the Fara- 

 day dark space will shorten, the positive col' 

 umn will move towards the cathode, and the 

 number of strise in it will increase, the extra 

 strise being, as it were, drawn out of the anode. 

 The configuration is perfectly steady except 

 that the discharge, as a whole, is liable to 

 wander. This transition may be continued by 

 a still further increase of the resistance in the 

 circuit, the dark space becoming ever shorter, 

 the positive column lengthening and at the 

 same time shrinking in area and the strise in- 

 creasing in number, all without loss of out- 

 line or brightness. Finally, the discharge will 

 cease. The various stages are suggested at 1, 

 2, 3 in h. Fig. 1. 



In the second method the discharge vessel 

 with its commutator is placed in a derived 

 circuit (Fig. 2). This arrangement enables the 

 discharge potential to be continuously varied 

 over a wide range, and hence for a given 

 vacuum the relation between the length of the 

 dark space and the impressed voltage may be 

 exhibited. Again this arrangement enables 

 the minimum potential to be readily deter- 

 mined that will maintain a discharge. As an 

 example, for a given vacuum with the resist- 

 ance AC equal to 1/3 that of AB the discharge 

 was observed to just pass, indicating that the 

 potential necessary was 330 volts. 



Additional phases of the experiment will 

 suggest themselves to the operator. 



Chas. T. Knipp 



Labobatoky of Physics, 

 TJNrvEEsiTY OP Illinois, 

 March 4, 1916 



UTAH ACADEMY OF SCIENCES 



The ninth annual convention of the Utah Acad- 

 emy of Sciences was held in the chemistry lecture 

 room of the University of Utah. Three sessions 

 were held: one at eight p.m., Friday, April 7, one 

 at ten a.m., Saturday, April 8, and the closing ses- 

 sion at two P.M. of the same day. Dr. Harvey 

 Fletcher presided at all of the sessions. 



Dr. E. G. Peterson, U. A. C, and Professor 

 Carl P. Eyring, B. Y. U., were elected to fellow- 

 ships in the academy. The following were elected 

 members: Professor George B. Caine, U. A. C, 

 Dean Milton Bennion, U. U., Professor Newton 

 MiUer, U. U., Professor A. L. Matthews, U. U., 

 Dr. George S. Snoddy, U. U., Miss Hazel L. 

 Morse, East High School, Salt Lake City, C. Ar- 

 thur Smith, East High School, Salt Lake City, C. 

 Oren Wilson, East High School, Salt Lake City, 

 Professor Estes P. Taylor, U. A. C, Dr. A. P. 

 Henderson, B. Y. U., and Edgar M. Ledyard, Salt 

 Lake City. 



Captain Francis Marion Bishop, a companion of 

 Major Powell in his famous explorations of the 

 Uinta Mountains, was elected to honorary life 

 membership. 



The following officers were elected for the en- 

 suing year: 



President — Dr. Frank Harris, U. A. C, Logan. 



First Vice-president — Dr. L. L. Daines, U. U., 

 Salt Lake City. 



Second Vice-president — Professor Carl F. Ey- 

 ring, B. Y. U., Provo. 



Councillors — Dean J. L. Gibson, U. U., Dr. W. 

 E. CarroU, U. A. C, W. D. Neal, Salt Lake City. 



The following lectures and papers were pre- 

 sented : 



"Industrial Eeseareh in U. S. A.," by Dr. Har- 

 vey Fletcher, B. Y. U. 



' ' The Alkali Content of Certain Utah SoUs, ' ' by 

 Dr. Frank S. Harris, U. A. C. 



"The Agricultural College and Scientific Ee- 

 seareh," by Dr. E. G. Peterson, U. A. C. 



"Selecting Holstein-Friesian Bulls by Perform- 

 ance, ' ' by Dr. W. B. Carroll, U. A. C. 



"Peyote, an Indian Narcotic," by A. 0. Gar- 

 rett, East High School, Salt Lake City. 



"An Epidemic of Colds with Micrococcus catar- 

 rlialis as Causative Agents," by Dr. L. L. 

 Daines, U. U. 



"The First Recorded Case of Rabies in Utah," 

 by Dr. L. L. Daines, U. U. 



"Botulinus Poisoning from a Vegetable 

 Source," by Dr. L. L. Daines, U. U. 



"Comparison of Methods of Treatment for 



