NOTES ^Z7 



on the application of interference methods to astronomical measurements. 

 In this paper he announced that the diameter of a Orionis had been measured 

 and found to be about 260,000,000 miles — a figure which confirms the estimate 

 previously made from theoretical considerations by Prof. Eddington. It 

 appears, however, that the calculations on which the result is based depend 

 on our rather uncertain knowledge of the parallax of the star. 



Dr. F. W. Aston gave an account of his work on the isotopes of the 

 lighter elements at the Royal Institution on February 11. A full description 

 of these experiments by Dr. Aston himself appeared in Science Progress 

 last October. The list of elements given in that paper has now been extended 

 by the addition of iodine, which proves to have only one form. The existence 

 of two isotopes of argon has now been confirmed, and two more possible 

 isotopes of xenon have been detected, making seven in all for this element. 

 Dr. Aston received the first Mackenzie Davidson medal from the council of 

 the Rontgen Society for the paper on this work which he read before the 

 Society. This medal is to be given annually for the best paper presented 

 to the Society during the session. 



In a letter to Science (December 10, 1920) from the Ryerson Physical 

 Laboratory, Chicago, A. G. Dempster announced that he has succeeded in 

 analysing magnesium (atomic weight 24- 36) into three isotopes of atomic 

 weights 24, 25, and 26 present in the metal in relative amounts 6, i, i, and 

 so giving as close an agreement wdth the accepted atomic weight of the 

 element as can be expected at the present stage of experimental work. 



In the Kelvin Lecture to the Institution of Electrical Engineers Sir William 

 Bragg indicated that, by means of improvements he has recently made in 

 his X-ray spectrometer, he has been able to show that atoms have different 

 properties in different directions. This follows indeed from the fact that 

 the atoms in a crystal are not always close packed as they must be if they 

 are not held together in definite positions. Thus some at least of the electrons 

 surrounding the central nucleus of the Rutherford atom must occupy fixed 

 positions relative to the nucleus, a view which accords with the Lewis- 

 Langmuir theory of atomic structure. These " fixed " electrons may describe 

 small closed orbits about fixed points on the " surface " of the atom and so 

 produce magnetic fields which serve as bonds of attachment between the 

 atoms. This is the theory advocated by Dr. A. E. Oxley, who gave an 

 account of some of his work in Science Progress, April 1920. A further 

 account of this subject will appear in the July number of Science Progress 

 from the pen of Prof. W. L. Bragg. 



In a lecture on Helium last July at Toronto, Prof. McLennan expressed 

 the hope that a cryogenic laboratory for low temperature research would 

 be established in the British Empire. It is now stated that a laboratory of 

 this kind has already been constructed, but in the building of the U.S. 

 Bureau of Mines, Washington. It has two 4-stage compressors with a 

 capacity of 75 c. ft. of atmospheric air per minute for liquid air manufacture, 

 a compressor with a capacity of 12 c. ft. of air for liquid hydrogen, and 

 another of 8 c. ft. capacity for use in connection with a liquid helium cycle, 

 together with the necessary gas-holders and mechanical equipment. 



The Technical Review (December 14, 1920) contains an abstract from an 

 article in the Rivista Marittima (July-August 1920) giving some important 

 details concerning the production of helium from the natural gas reservoirs 

 in Texas. It appears that the U.S. Government compelled the companies 

 owning the wells to send all the gas obtained to the establishment at Fort 

 Worth for the helium to be extracted before the gas was distributed for 

 private consumption. This arrangement has caused many complications, 

 and naturally the companies have made heavy claims against the Government, 

 tending to greatly increase the cost of the helium. But a more serious 

 question confronts the authorities operating the extracting plant — namely. 



