October 28, 1898.] 



SCIENCE. 



583 



with Section A at the Museum. The Con- 

 ference was opened witli an address by its 

 President giving a short historical review 

 of the present organization, and setting 

 forth as the object of the meeting the need 

 of a closer association for guidance to future 

 well directed and concerted ei3fort in the field 

 of terrestrial magnetism. 



Among the questions submitted for de- 

 liberation and expressions of opinion were 

 the following: In presenting monthly means 

 of hourly tabulation of differential observa- 

 tions shall simple means only be given or 

 shall they be accompanied by means derived 

 from undisturbed values ? In this question is 

 involved the difiBculty of recognizing a ' dis- 

 turbed ' observation, that is, of fixing a 

 limit separating normal from apparently 

 abnormal values. The discussion respect- 

 ing the desirability of publishing, besides 

 the usual values for declination, dip and 

 horizontal intensity, at least for the months 

 of January and July, the components of 

 the magnetic force towards the north, the 

 west and the vertical, involved also the 

 the question of uniformity in notation as 

 advocated by Professor F. Bigelow, i. e., 

 whether right or left-handed rotation re- 

 specting the axes would be preferable and 

 whether the potential of the magnetic force 

 should be regarded as affected with a posi- 

 tive or a negative sign. 



A discussion was had respecting the 

 relative value of long and short magnets. 

 The principal work of the Conference, how- 

 ■ever, centered in the wider question involv- 

 ing magnetic observatories, their present 

 ■unsatisfactory distribution over the globe 

 and their inadequacy as regards numbers. 

 It is here that the United States is in a 

 •condition to take a most important step in 

 ithe advancement of knowledge by establish- 

 ing and maintaining a well equipped mag- 

 netic obsevatory either on Oahu or one of 

 the other Hawaiian Islands. This position 

 is unique, being central to a vast unexplored 



or magnetically unknown region and well 

 adapted for the special study of the modi- 

 fications which it is supposed the diurnal 

 and secular variations may undergo in con- 

 sequence of a surrounding ocean as con- 

 trasted with a continental surface. The 

 destructive effect of electric tramways or 

 trolley lines, when passing within a fraction 

 of a mile or even within several miles of a 

 magnetic observatory installed with sensi- 

 tive self-registering instruments, was com- 

 mented on and pointed out as an evil 

 specialljr to be provided against in any new 

 magnetic establishment. In considering 

 the selection of positions for new observa- 

 tories, attention was given to their greater, 

 need in the southern than in the northern 

 hemisphere, aiming necessarily at as regular 

 a distribution of all establishments as prac- 

 ticable. 



Of special papers brought before the Con- 

 ference may be mentioned : ' An account of 

 the late Professor John Couch Adams' deter- 

 mination of the Gaussian magnetic con- 

 stants,' by Professor W. Grylls Adams. 

 ' Sur le mouvement diurne du pole nord 

 d'une barreau magnetique suspendu par le 

 centre de gravite,' par. J. B. Capello. ' On 

 the influence of altitude above the sea 

 on the elements of terrestrial magnet- 

 ism,' by Dr Van Ryckevorsel and Dr. 

 W. Van Bemmelen. ' On the interpre- 

 tation of earth current observations,' by 

 Arthur Schuster, F.E.S. ' On magnetic 

 observations in the Azores,' by Albert, 

 Prince of Monaco. ' On a simple method 

 of obtaining the expression of the mag- 

 netic potential of the earth in a series of 

 spherical harmonics,' by Arthur Schuster, 

 F.R.S. 'Eeport of Professor von Bezold 

 and General Eykatchew on the establish- 

 ment of temporary magnetic observations 

 in certain localities, especially in tropical 

 countries. ' On the relations between the 

 variations in the earth currents, the elec- 

 tric currents from the atmosphere and the 



