530 



SCIENCE. 



[N. S. Vol. VIII. No. 199. 



The Measurement of Thermal Conductivity in 

 Iron. By Professor E. H. Hall,- Cam- 

 bridge, Mass. 



The author pointed out that the method 

 in which thin plates are used is unsatisfac- 

 tory owing to the difficulty of determining 

 the difference of temperature of the two 

 faces. He obviates this by copper-plating 

 the two faces of his iron plate and by using 

 the copper-iron thermocouples thus formed 

 for determining the temperature difference. 

 He finds that the conductivity of iron in- 

 creases as the temperature is decreased at 

 the rate of about one per cent, for eight de- 

 grees Centigrade. 



On the Magnetic Deflection of Diffusely Re- 

 flected Cathode Rays. By Professor 

 Ernest Merkitt. 



On the Electrical Properties of the Vapor from 

 the Arc. By Professor Ernest Merritt 

 and O. M. Stewart. 



Professor Merritt finds that diffusely 

 reflected cathode rays are deflected by a 

 magnet to the same extent as the same rays 

 before reflection. Professor Merritt and 

 Mr. Stewart find that the vapors from the 

 electric arc produce electrical discharge in 

 a manner similar to the action of a gas 

 which has been exposed to X-Eays. Vapors 

 from the negative carbon discharge nega- 

 tive charges more readily than positive 

 charges. 



In their report on the Velocity of Light 

 in the magnetic field Professors E. W. 

 Morley, H. T. Eddy and D. C. Miller de- 

 scribed their interferometer, the two optical 

 paths of which consist of tubes of carbon 

 bisulphide surrounded by very large mag- 

 netizing coils. These coils were wound in 

 halves which could be connected diflfer- 

 entially or directly at will. It was found 

 that the velocity of light in CS^ is not al- 

 tered by one part in sixty millions by a 

 magnetic field of such intensity as to rotate 

 the plane of polarization 180° in 60 cm. 



A Study of Galvanic Polarization. By Barry 

 McNutt, South Bethlehem, Pa. 

 The author finds that the polarization of 

 a Cu— CuSO^ — Cu cell (and the same is 

 true of cells of silver and of zinc) is not 

 zero with infinitesimal (?) current. 

 A Lecture Room Experiment in Electrostatics. 

 By Professor W. S. Franklin, South 

 Bethlehem, Pa. 



The author exhibited an experiment il- 

 lustrating the instability of electrified liquid 

 films. A brass ladle with a sharp lip is 

 nearly filled with melted rosin ; it is then 

 electrified, by joining it with an electrical 

 machine, and tilting until the rosin runs in a 

 thin layer over the lip, when it is blown 

 out in a cloud of silky threads highly elec- 

 trified. 



The Most Efficient Thickness of Transformer 

 Plates. By Professor F. Bedell, E. M. 

 Klein and T. P. Thompson, Ithaca, N". Y. 

 On plotting the curve showing the rela- 

 tion between the thickness of the plate and 

 the total loss due to hysteresis and eddy 

 currents it is found that the curve has a 

 broad, flat minimum extending from about 

 10 to 15 thousandths of an inch in thickness 

 of the plate. 



Proposed Methods of Determining the Frequency 

 of Alternating Currents. By Karl Kins- 

 ley, Falls Church, Va. 

 Mr. Kinsley advised using a clamped, 

 free bar provided with an adjustable rider 

 and set in vibration by an electro-magnet 

 actuated by the current to be studied. 

 A Neio Gas. By Charles F. Brush, Cleve- 

 land, Ohio. (Printed in Science for Oc- 

 tober 14th.) 

 Polarization and Internal Resistance of the Vol- 

 taic Cell. By Dr. Karl E. Guthe, Ann 

 Arbor, Mich. 

 Graphical Treatment of Mutually Inductive Cir- 

 cuits with Special Reference to the Case of 

 Variable Frequency. By Professor H. T. 

 Eddy, Minneapolis, Minn. 



