KXI'KIHTION TO POINT I'.AHHOV*. ALASKA. 



531 



from the fundamental relations H = .Fcos #and V= Fsin 6 we find by differentiation and elimina- 

 tion, the variation in the dip A 6 and the variation in the total force (in parts of the force) i viz: 



/"JF AH\ AF AH A V 



J0=sin # cos { V ~ II ) ' F =cos2 ^ ~Jf +m 2 9 



Solar-diurnal rtuitititins In tin: winituitic dip and in the total magnetic 'intensity, inclusive of disturb- 

 ances ; annual mean values 188li-'83. 



In presenting the foregoing results of the three variation instruments I had two objects in 

 view, viz, to be in a position to form a close estimate of the character and value, of the whole series 

 of observations preparatory to their full analysis and -discussion, and, secondly, to give at once, 

 but preliminarily, such leading results as could be deduced without waiting for the publication of 

 the results of the conference for the uniform treatment of the magnetic work at the international 

 Polar stations. What has been presented will, in general, enable the reader to form a judgment 

 of the magnetic outfit of the tJglaamie station, and of the value of the work done. 



As lias been already pointed out, there were no well-adapted magnetic variation instruments 

 available in the first year; the range of the collimator scale was very limited, and the declinometer 

 had frequently to be turned in azimuth in order to secure readings on days of disturbance; besides, 

 the great changes in the torsion of the suspension renders it impossible to produce a uniform series 

 with respect to a fixed direction. The record of the bifilar magnetometer has not yet been suffici- 

 ently examined to form an opinion as to its value, and at present I am still waiting for notes bearing 

 on the adjustment and scale value of the instrument.* There was then no vertical force magnetome- 

 ter, but hourly observations were made with a dipping needle deflected by a constant weight; corre- 

 sponding values for the true dip or deflections by the same needle were only made on two or three 

 days each month, so that the value of this series, as a. differential measure of the total force, may 

 be regarded as small. It has, however, enabled me independently to verify the fact brought out 

 by the balance magnetometer of the greater total intensity during the morning than in the after- 

 noon hours. There is no record of the effect of temperature changes on the angle of deflection of 

 the loaded needle. 



In the year 1881-'82 there were but few stations with which to compare results, and to publish 

 the above-mentioned records in extenso would seem to me an expenditure of time and labor hardly 

 to be recommended, and probably not warranted by the ?neager results the series may be capable 

 of yielding. If this early record is to be published at all I would propose to set down the mean 

 of the 10 readings (5 with scale extreme left and 5 with scale extreme right) for each instrument, 

 viz, the declinometer and bifilar, and the mean of the 10 readings of the dipping needle (5 for south 

 and 5 for north end); for each observing hour and during term days it would suflice 1o give only 

 the mean of the two extreme scale readings. But on these and other points the result of the 

 deliberations a! Vienna may be awaited. 



I conclude this report with a table of frequency of the aurora a.s .seen and recorded in connec- 

 tion with the magnetic work at Uglaamie. 



".No further iiil'oniintioii r 'iiiil !><! nlifciiiu'd V 



