Henry Andrews Bum stead. i"!"! 



after, lie edited, in collaboration with Dr. Van Name, 

 Gibbs ' collected works. 



Bumstead's interest was greatly excited by J. J. Thom- 

 son's investigations of the properties of cathode rays and 

 it was largely through his efforts that the successor of 

 Maxwell and Rayleigh was persuaded to come to Yale 

 to deliver the first Silliman lectures in May, 1903. AVliile 

 in New Haven Professor Thomson told him of the work 

 being done at the Cavendish Laboratory on a radioactive 

 gas found in Avater coming from deep levels, and sug- 

 gested work of a similar nature at New Havem This 

 Bumstead carried out with the help of L. P. AVlieeler. 

 They found evidences of radioactivity not only in the gas 

 driven off from water obtained from a well 1500 feet deep 

 near New Milford, Conn., but also in that boiled off from 

 surface water drawn from one of the New Haven city 

 reservoirs. A comparison of the rate of decay of the 

 soil-water gas with that of radium emanation showed the 

 two to be identical. The rate of diffusion of the emana- 

 tion through a porous plate was determined, and found 

 to be about four times that of carbon dioxide. This led 

 fo an atomic weight of 180, which was, perhaps, the most 

 reliable value which had been obtained up to that time, 

 and, considering the difficulties of the experiment, sur- 

 prisingly close to the value accepted today. 



The winter 1904-5 Bumstead spent in England carrying 

 on experimental work in the Cavendish Laboratory. 

 This year's work led to the publication of two papers, of 

 which the second, on the heating effects produced by 

 Eontgen rays in metals, excited a great deal of interest. 

 This investigation was undertaken at the time when the 

 attention of the whole world was focused on the brilliant 

 researches of Rutherford on atomic disintegration. 

 Physicists w^ere particularly interested in investigating 

 the possibility of hastening radioactive disintegration by 

 suitable external conditions, and in searching for new 

 sources of radioactivity. However, every effort to 

 control the rate of decay seemed to be in vain. From the 

 lowest_ to .the highest extremes of temperature, under all 

 conditions of electromagnetic excitation, radioactive 

 transformation went on at the same invariable rate. 

 Bumstead's investigation consisted in measuring the heat 

 produced in lead and zinc when Rontgen rays are equally 

 absorbed in the two metals. His experiments seemed to 

 lead to the very surprising result that heat developed in 



