6o 



BIRKELAND. THE NORWEGIAN AURORA POLARIS EXPEDITION, 1902 1903. 



A list of the perturbations that will be treated in the following chapter is given below in Table IX. 

 The great generosity and interest shown by the heads of all the previously-mentioned observatories, 

 without which the exceptionally valuable material relating to magnetic storms contained in these twenty- 

 one plates could not have been collected, would be worthy of emulation in all branches of science. 



TABLE IX. 



