Mabch 16, 1906.] 



SCIENCE. 



417 



possible by ionization, by incandescence, of 

 carbon, the incandescence being secured by 

 Joule heat. 



Distribution of Gas Pressure in a Closed 

 Tube Rotating on a Transverse Axis: 

 Francis E. Nipher, Washington Univer- ■ 

 sity. (To be published in the Transac- 

 tions of the Academy of Science of St. 

 Louis. ) 



The paper is a mathematical discussion 

 deducing the pressure at the axis, and 

 showing that it is independent of the length 

 I, and angular velocity <a of the tube, if the 

 velocity ti = <oZ is constant. The pressure 

 at any other point is also determined, in 

 terms of its distance r from the axis of 

 rotation. 



The pressure at the free end of the tube 

 due to rotation is greater than the external 

 pressure against the tube due to its mo- 

 tion through the external air. If the outer 

 end terminates in an L with open mouth 

 exposed to the air through which it is ad- 

 vancing the air within the tube is forced 

 out in the teeth of the wind. If the tube 

 be also opened at the axis, the air will pass 

 out in a current through the open end of 

 the L at the free end of the tube. 



A New Type of Frequency Meter: A. S. 

 Langsdorp, Washington University. (To 

 be published in The Electrical World.) 

 Section D. 



Report of Progress in Experiments on 



Ether Drift: Edward W. Morlet and 



Dayton C. Miller, Cleveland. 



At the Philadelphia meeting an account 



was given of experiments to detect ether 



drift. The observations indicated that 



there is no drift of the ether. It has been 



suggested that the negative result was due 



to the influence of the heavy stone walls 



of the building within which the apparatus 



was mounted. The interferometer has 



since been mounted on high ground near 



Cleveland and covered in such a manner 

 that there is nothing but glass in the direc- 

 tion of the expected drift. Observations, 

 though difficult, have been made; but cold 

 weather interrupted them before a definite 

 conclusion had been reached. The obser- 

 vations are to be completed at the first op- 

 portunity in the spring of 1906. 



A Critical Analysis of Methods of Supply- 

 ing Poiver to Branch Telephone Ex- 

 changes on the Common Battery: Karl 

 Kinsley, University of Chicago. Sec- 

 tion D. 



A Neiu Fonn of Mercury Still: Charles T. 



Knipp, University of Illinois. 



This still makes use of the mercury vapor 

 lamp. In it are found, roughly, conditions 

 necessary for the purification of mercury, 

 such as heat by the passage of the electric 

 current, and a more or less perfect vacuum. 

 By fusing to the mercury vapor lamp a 

 properly shaped condensing chamber, mer- 

 cury of a high degree of purity may be 

 obtained. The electrodes of the apparatus 

 are mercury and are in communication with 

 two vessels containing the supply mercury 

 through narrow tubes about 80 cm. long. 

 The condensed mercury flows from the still 

 through a long capillary delivery tube bent 

 in the form of an S at its lower end. The 

 action of the mercury dropping into this 

 tube is that of a continuous mercury piimp. 

 The apparatus is initially exhausted by 

 means of a power Geryk pump (or other 

 equally effective pump). The arc is 

 started by employing a side connection as 

 described by Weintraub.^ 



In this form of still the rate of distilla- 

 tion is about one pound per hour, and the 

 cost is approximately one cent per pound. 



To test the action of the still zinc amal- 

 gams were used. The test for zinc was 



'Phil. Mag., Vol. VII., February, 1904. 



