4:66 Scientific Intelligence. 



from the hot filament after passing through a small hole in the 

 main cathode are accelerated in a strong field and may be brought 

 to a very sharp focus on the target which is inclined at an angle 

 of 45° to the path of the beam. 



The authors of this paper, J. E. Lilienfeld and F. Rother, 

 report the formation of a luminous ring of light, blue-gray in 

 color, and of elliptical form, just at or above the surface of the 

 anticathode. The size of the ellipse increases with higher poten- 

 tial discharges but remains similar in form. Examined with a 

 polariscope the light is almost completely plane-polarized with 

 the electric vector parallel to the line of intersection of the plane 

 of symmetry of the tube with the surface of the target. 



The spectrum was similar to that which would have resulted 

 from a high temperature but with limits dependent somewhat 

 upon the conditions of excitation of tlie tube. The intensity of 

 the short wave end compared to the long wave end was so very 

 much greater than with ordinary light sou.rces as to imply an 

 exceedingly high temperature. It is their idea that the radiation 

 arises in an electron layer just at the front of the anticathode, 

 which is excited by the cathode rays and that the connection 

 between this layer and the electrons lying a little deeper in the 

 plate is so close that the visible spectrum probably passes over 

 uninterruptedly into the continuous Roentgen spectrum. The 

 paper is illustrated with pliotographs of the spot and its spec- 

 trum together with comparison spectra from helium and a metal 

 filament.— P/?.?/5. Ztschr. 21, 249, 1920. f. e. b. 



6. Ohservations on Soaring Flight. — Although the exact nature 

 of soaring flight still remains an unexplained problem of physics 

 a summary of observations by Dr. E. H. Hankin extending over 

 a period of ten years and recently communicated to the Cam- 

 bridge Philosophical Society is deserving of attention. The obser- 

 vations were carried on in a tropical countr}^ where the meteor- 

 ological conditions are more stable than in temperate latitudes, 

 and were made not only upon birds, but also upon dragon flies 

 and flying fishes. 



The two points of novelty in the author's view are, (1), that 

 the wing sections of the best soaring birds and in. the soaring 

 dragon flies are characterized by transverse ridges projecting on 

 the under side of the wing. A similar feature is significantly 

 present in the puttying, a form of Indian kite which flies verticall}^ 

 over its string ; (2) , that the slow soaring flight in all three classes 

 of animals is seemingly dependent upon the presence of sunshine, 

 while fast soaring fl-ight is always dependent upon the presence 

 of wind. 



That soaring flight is not due to undiscovered wing movements 

 is a conclusion drawn from the means used to brake the flight in 

 the case of dragon flies and of flying flshes. Arguments are pre- 

 sented that soaring flight is neither due to lateral gusts of wind, 

 to ascending currents nor to turbulencies whose presence could 



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