204 



SCIENCE. 



[N. S. Vol. XIX. No. 475. 



of lag between this current and the induced 

 B.M.P. as the load in the secondary is in- 

 creased. ( & ) In the primary. There is an 

 apparent decrease in the loss of energy in 

 the iron, the magnitude of the exciting cur- 

 rent and the cosine of the angle between, 

 as the load increases. (2) If the load is 

 increased in the secondary of a transformer 

 in which there is little magnetic leakage, 

 not only the loss of energy in the iron, but 

 the exciting current and its phase with re- 

 spect to the induction remain constant. 



A Method for the Determination of Mutual 

 Induction Coefficients: Augustus Trow- 

 bridge, University of Wisconsin. 

 The method is based on the fact that 

 when a pair of coils are joined in series so 

 that the magnetic tiibes of force form one 

 thread through the other in the same direc- 

 tion as those due to it the self-inductance 

 of the pair is L^ + 2M -f i,. When the 

 current is reversed through the one coil but 

 not through the other the coefficient of 

 self induction of the pair is L^ — 2M + L,. 

 By a bridge method each of these quan- 

 tities may be determined in terms of a 

 standard self inductance and thus M (the 

 coefficient of mutual induction) is obtained. 

 A careful comparison of the results obtain- 

 able with this method with those by other 

 known methods seems to be considerably in 

 favor of this method, the probable error 

 being about 1 part in 800. 



The Influence of Occluded Hydrogen on 

 the Electrical Resistance of Palladium: 

 W. E. McElfresh, Williams College. 

 To be published in full in the Transac- 

 tions of the American Academy of Arts and 

 Sciences. 



On Hydrogen-charged Palladium: E. H. 



Hall, Harvard University. 



This paper is a review of the main facts 

 known in regard to the properties of 



hydrogen-charged palladium and an ex- 

 amination of the various suggestions which 

 have been made as to the nature of the 

 union between the two elements concerned. 

 The point is made that previous estimates, 

 by Graham and by Troost and Haute- 

 feuille, of the density of the hydrogen in 

 the combination gave values very much 

 greater than the observed value of liquified 

 hydrogen. These estimates practically 

 neglected the possibility of spaces between 

 molecules of palladium sufficiently large to 

 admit molecules of hydrogen with little 

 expansion of the solid. The evidence in 

 favor of a definite chemical combination 

 between the palladium and the absorbed 

 hydrogen is, on the whole, inadequate. 



A New Form of Frequency Meter, Pre- 

 liminary Note: A. S. Langsdorf, Wash- 

 ington University. 



The paper described a type of instrument 

 to indicate frequency on alternating-cur- 

 rent circuits, the readings to be independ- 

 ent of fluctuations of voltage on the line, 

 the connections similar to those of an in- 

 dicating wattmeter. 



A Bemarkable Distribution of Carbon on 

 the Btdb of a 'Hylo' Incandescent 

 Lamp: Arthur L. Foley, University of 

 Indiana. 



In the 'Hylo' turn-down incandescent 

 lamp there are two filaments, one of 16 c. p. 

 {F) and one of 1 c. p. (/), the former 

 consisting of two and the latter of three 

 turns. AVhatever be the direction of the 

 current, the filament coils are of opposite 

 polarity. 



When / is burning F is in series with it, 

 but the current is insufficient to render the 

 latter luminous. When F is burning / 

 is short-circuited. Let P and P' be points 

 on the globe at the ends of a diameter 

 through the plane of the filaments, and 

 NS and sn be points on the globe where 



