158 re;ports of investigations and projects. 



for the Institution to prepare such charts itself at the present time, but instead 

 it will be better to wait until the general completion of the work. However, 

 all institutions and persons interested are being furnished with the manu- 

 script results. 



MAGNETIC SURVEY OF LAND AREAS. 



In pursuance of the policy of the Department not to undertake in general 

 magnetic work in the regions where there are institutions charged with such 

 work, or where persons with the aid of special grants from scientific societies 

 have already in hand the desired investigations, the work during the past 

 year has been conducted in localities where data were greatly needed and 

 would not soon be acquired. 



Besides the work enumerated below, arrangements are in progress for the 

 undertaking of systematic work in Africa under the joint auspices of the 

 governments concerned and of the Department, beginning, it is hoped, in 

 1909 or earlier. The Department is fortunate in being able to avail itself of 

 the cooperation of Prof. J. C. Beattie, of the South African College, at Cape- 

 town, during his furlough u\ 1909. 



Alaska. — The Director, in connection with his inspection of the Galilee 

 at Sitka, made magnetic observations at Sitka, Juneau, and vicinity. Assisted 

 by Magnetic Observer J. C. Pearson, he furthermore made a special investi- 

 gation of the anomalous magnetic conditions existing in the neighborhood 

 of the local magnetic pole at Treadwell Point, found by him at this place in 

 1900. Here a source of local attraction exists affecting the marmers' com- 

 passes, a mile distant in Gasteneau Channel, about ^ point (about 8°), 

 a quantity large enough to put a ship on the rocks were it not allowed for in 

 the navigation of the vessel. Because of its extreme localization and intense 

 concentration, whereb)^ changes of point of observation by but few inches in 

 a horizontal or in a vertical direction cause considerable changes in the mag- 

 netic elements, this anomaly afforded opportunity for investigations of 

 extreme interest along various lines of inquiry. While stronger magnetic 

 anomalies have been found elsewhere, the published results have not revealed 

 anywhere as steep gradients of the magnetic elements, i. e., changes in these 

 elements with variation of horizontal or vertical distance from the points of 

 attraction as found here. Thus, for example, within a distance of 2 to 3 feet, 

 at a height of about 5 feet above the surface, the compass would change its 

 direction by nearly 180°. This region, furthermore, gave opportunity to 

 make some interesting tests as to how closely in such a region of disturbance 

 the earth's magnetic forces are "coupled," i. c, whether in addition to a 

 couple there is a resultant magnetic force producing a motion of translation 

 of the magnetic needle either in a horizontal or in a vertical plane. The 

 special report on this work shows that some interesting results along this 

 line of inquiry have been obtained. 



