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Physics. — "A hypothesis relating to the origin of RöNTGEN-rays." 

 By Prof. ü. H. Wind. 



W. Wien l ) has measured the energy of RöNTGEN-rays, converted 



into heat in a bolometer or in a thermo-element, and has compared it 



with that of the cathode-rays, likewise converted — with exception 



of the small fraction transformed in energy of R.-rays — into heat 



in the anti-cathode. He finds for the proportion of the total quantities 



of energy of the two kinds of rays 



jp 



— = 2,18 . 10-3 n 



Supposing that the R.-rays are the radiation of energy, emitted 

 by cathode-ray electrons being brought to rest, and that this stoppage 

 may be considered as a continually decreasing motion, he proceeds 

 with the aid of the theory of M. Abraham to deduce the duration 

 of the stoppage and from it the thickness of the R-waves. For the 

 latter he finds 



;. — 1,15 . lO-io cm . 



Results of the same order of magnitude have afterwards been 

 attained by Edna Carter 3 ) in an investigation, also made at the 

 laboratory directed by Wien. 



These results do not very well agree with the values, derived by 

 Haga and myself for the wave-length of R.-rays from diffraction- 

 experiments : 



X — 270 to 12 . 10- 10 cm 4 ) 

 and 



;. = 160 , 120 , 50 . 10- 10 cm. 6 ) 



If the R.-rays have to be considered as disturbances in ether of the 

 single pulse character assumed by Wien in accordance with the 



3.7 

 current conception, the same numbers must be divided by — or 



1\ 8 ) in order to represent the corresponding values of the thickness 

 of the pulse- waves, which consequently become 



t = 110 to 5 . 10-10 cm, 



ft — 64, 48, 20 . 10-10 cm. 



i) W. Wien. Wüllners Festschrift, Leipzig, 1905; Ann. d. Ph. 18, p. 991, 1905. 

 2 ) L. c. p. 996. The number is doubled here, on account of the remark made 

 regarding it on page 1000. 



») E. Garter. Ann. d. Ph. 21, p. 955, 1906. 



4 ) H. Haga and G. H. Wind. These Proc. I. p. 426. 



5) Id. Ibid. V. p. 254. 



6 ) G. H. Wind. Physik. Zschr. 2, p. 96. Fussnote 2), 1901. 



