MAGNETIC OBSERVATIONS 321 



OBSERVATIONS AT AI,GER ISI.AND 



SiTB AND ObSBRVATORY 



The stay at Alger Island (Camp Ziegler) being of uncertain duration, dependent upon the 

 arrival of the relief expedition, the observing quarters were of less permanent character than 

 those at Teplitz Bay. The site of the magnetic station is, as shown in figure 21, some 289.5 

 meters due north of the astronomic pier. To test for local disturbance observations were made 

 at four points to the magnetic north, east, west, and south, respectively, and each distant about 

 91 meters from the site proposed. These gave indications of local magnetic attraction, in the 

 maximum, about 30'. Apparently, therefore, the local conditions are more uniform than is 

 the case at the Teplitz Bay site. The construction and dimensions of the observatory are 

 shown in detail by the plan and sections of figure 22. The construction proved very serviceable 

 despite its temporary character. The central pier is of coniferous drift-wood about 20 centi- 

 meters in diameter, 1.75 meter long, and is sunk some 0.4 meter in frozen gravel, thus leaving 

 a clear height of about 1.3 meter. Towards the close of the work a second and similar pier 

 was erected, as shown in the figure, the intention being to mount the dip circle on the same. 

 No use was, however, made of it, the central pier serving for all of the observations. Great 

 care was exercised that no magnetic material was used in building the observatory. The pier 

 will undoubtedly remain in good condition for a long time, so that the station may be reoccupied 

 if future opportunity offers. 



The geographical position of this station is latitude 81° 21' 30" N and longitude 3" 44°" 22" 

 (56° 05.'5) E. 



DECI/INATION 



Methods 



The methods of observation and record were substantially the same as for the Teplitz Bay 

 series. The regular declination work was begun June 26, 1905, and continued, so far as 

 possible, in accordance with the program of observation outlined on page 17, until July i, 1905. 



The azimuth mark used was the south astronomic meridian mark, distant about 3,910 

 meters. From sun observations with the Repsold circle at the astronomic station on July 16, 

 19, 20, 26, and 28, 1905, on which days ten determinations were made (see astronomic notes), 

 the azimuth of this mark as referred to the magnetic station pier is 359° 59. '27. 



So far as this short series of observations goes there is no very decided evidence of pier 

 twist with changes in temperature, as was the case for the Teplitz Bay series. 



The observers are indicated by their initials as per list on page 17. 



As for the later observations at Teplitz Bay a suspension of four fibers was used (see 

 page 19). 



The following values for axis are used in the final reductions (see page 1 8) : 



Week ending at Number of Mean 



8 A. M. Sunday determinations axis value 



d 



July 2, 1905 9 53.54 



July 9, 1905 7 53.62 



July 16, 1905 8 53.10 



July 23, 1905 8 53.13 



July 30, 1905 8 53.50 



Records 

 The original notes and results have been tabulated in the same manner as the Teplitz Bay 

 series (see pages 19 and 20). The readings of azimuth mark will be found on page 322. The 

 readings corresponding to the position of the telescope appear under the heading, Circle reading 

 of magnet. Where the telescope with circle has been shifted during declination observations 

 this fact has been denoted in the table of resulting declinations by an asterisk at the time of 



