MAGNETIC OBSERVATIONS 305 



Owing to the fact that no suitable instrument was available, observations at the observatory 

 simultaneous with the above could not be made. The observations nearest in point of time at 

 the hut are those of June 22 and June 23. Correcting the two-minute readings of June 22 

 between 20 hours and 24 hours for diurnal variation a mean value of 22 51' results. In like 

 manner, the observations on June 23 between 16 hours and 20 hours give a mean value of 

 22 19'. It thus appears, since the average value during the period June 12 to July i is 22 32', 

 that, while the general magnetic conditions preceding the observations at the Italian station by 

 thirteen to fourteen hours were such as to give declinations high by about 19', the conditions 

 six to seven hours later were such as to give declinations low by about 13'. It therefore seems 

 quite probable that between n and 12 A. M. the magnetic conditions were about normal, and 

 hence a direct comparison with the preceding may be made. 



As already noted, Commander Cagni's results at about the same season of year were 

 21 15/6 and 21 25/0 for the epochs 1899.66 and 1900.55, or in the mean 21 20/3 for 1900.10. 

 The result above for epoch 1904.48 is 21 53/3; hence the apparent effect in the elapsed 

 interval of 4.4 years due to secular variation is an increase of east declination of 33'. Assum- 

 ing a linear change over the interval, the secular change in magnetic declination in the region 

 of Teplitz Bay may be taken as about 



+ 7/5 per year. 



It may be noted that this value is of the same magnitude as those deduced by Dr. Solander* 

 for Mossel Bay and Cape Thordsen, Spitzbergen, for the periods 1873.5 to 1899.7 an d 1883.2 

 to 1899.7, viz., 7/3 and 7/8 decreasing west declination respectively. The geographical posi- 

 tions of these stations are : Mossel Bay, 79 53' north latitude and 16 04' east longitude ; Cape 

 Thordsen, 78 28' north latitude and 15 42' east longitude. 



* Missions scientifiques pour la mesure d'un arc de meridian au Spitzberg entreprises en 1899-1902 sous 

 les auspices des gouvernements Su^dois et Russe Mission Suddois. Tome II Determinations magntiques faites 

 au Spitzberg pendent I'e'te 1899, par E. Solander. Stockholm, 1903, p. 50. 



