594 



SCIENCE 



[Vol. LVI, No. 1456 



diagram is symmetrical about a line approxi- 

 mately in the direction of the Magnetic North 

 Pole. 



(e) The extreme diurnal range of the Ebro 

 earth currents reaches its highest values near 

 the equinoctial months, and lowest near the 

 solstitial months. Earth currents, atmospheric 

 electricity, the Aurora Borealis, and the earth's 

 magnetic disturbances, all show similar annual 

 variations in the ranges of their fluctuations. 



(/) The potential gradients of earth cur- 

 rents and of atmospheric electricity apparently 

 vary during the sun-apot cycle, the former de- 

 creasing in the direction of normal flow of cur- 

 rent, and the latter increasing with increased 

 sun-spot activity. The diurnal ranges of the 

 potential gradients of earth currents, as well 

 as of atmospheric electricity, just as is the ease 

 for the diurnal variation of terrestrial mag- 

 netism, increase with increased sun-spot activi- 



ty. 



(g) There is evidence of a similar six-hour 

 wave in atmospheric electricity, earth currents 

 and terrestrial magnetism. 



The analyses referred to in (c) are chiefly 

 those by Schuster, Fritsohe, Chapman, Walker, 

 and Mass van Vleuten, the method of investiga- 

 tion employed by them being that first suggest- 

 ed by Gauss, iwhieh is based on the well-known 

 Amperian rules of deflection of a magnetic 

 needle by an electric current. The general re- 

 sult reached by these investigators, as stated in 

 (c), has been accepted by every modern mag- 

 netioian; it post-dates the investigations by 

 Airy and Weinstein quoted by Dr. Sanford in 

 his recent article^. In this connection it may be 

 pointed out that the conclusions drawn by Dr. 

 Sanford do not depend upon simultaneous 

 earth-current and magnetic data at the same 

 station, as was the case in my investigations. 



As stated above, my present conclusions ap- 

 ply only to possiible relations between the di- 

 urnal variation phenomena of earth currents 

 and of the earth's magnetism. It does not ap- 

 pear that definitive conclusions can 'be safely 

 reached until we have at the same station un- 

 questioned coincident magnetic and electric 



2 Earth currents and magnetic variations, 

 Science, October 27, 1922, p. 466. 



data, and until we can furthermore consider 

 in our comparisons only that portion of the 

 magnetic diurnal variation caused by systems 

 of forces below the earth's surface. 



A fresh examination is also being made re- 

 garding the relations between earth currents 

 and severe disturbances of the earth's mag- 

 netism, such as occur during the so-called mag- 

 netic storms. There are some indications which 

 may support the views recently advanced' by 

 Satyendra Ray*, though I am not prepared 

 just now to make a definite statement. 



With the view of giving renewed stimulus 

 to systematic earth-current investigations, a 

 special committee, "to consider and report on 

 best methods and instruments," was formed at 

 the Rome meeting of the International Section 

 of Terrestrial Magnetism and Electricity last 

 May. The chairman of the committee is Sir 

 Arthur Schuster, and the secretary, Dr. S. J. 

 Mauchly, of the Department of Terrestrial 

 Magnetism. 



Louis A. Bauer 



Department or Teekestrial Magnetism, 

 Caeneqie Institution op Washington 



COLLABORATORS IN THE STAND- 

 ARDIZATION OF BIOLOGICAL 



STAINS 



From time to time reports from the Com- 

 mittee on Standardization of Biological Stains 

 have appeared, dealing with the investigations 

 in progress. Many congratulations have been 

 received by the chairman of the committee on 

 the results accomplished; but as these accom- 

 plishments would have been impossible but for 

 the very hearty collaboration of a long list of 

 investigators, credit for the work should be 

 given where it belongs by publishing the fol- 

 lowing list of committee members and collab- 

 orators : 



committee membees 

 F. W. Mallory, Boston City Hospital, Boston, 



Mass. 

 P. G. Novy, University of Michigan, Ann Arbor, 



Michigan. 



3 Eay, S., ' ' Ueber parallele Storungen von 

 parallelen erdmagnetisehen und erdelektrisehen 

 Elementen," Zs. Physik, Berlin, v. 7, 1921 (201- 

 205). 



