ggg SCIENTIFIC RECORD FOR 1884. 



tensity, total intensity, and dip at St. Petersburg with the sun-spots 

 and shows that all have a parallelism. {Z. 0. G. 3L, xix, p. 415.) 



413 Prof W. Porster has investigated the periodical changes in the 

 azimuth and level of the fundamental bed of masonry established in the 

 Berlin Observatory fortbe support of the meridian instruments. He 

 concludes from the study of 42 years of observations as follows : 



1. Neither the permanent nor the periodical changes show any de- 

 pendence on the water or moisture in the earth. 



2 Those movements that are certainly separated from small move 

 ments in the instrument itself and are plainly to be considered as 

 movements of the whole pier, go through a distinct annual and an 11- 

 year period, and both have a thermal character. 



3. The thermal effect corresponds to a rise of temperature or solar 

 radiation at the time of the sun-spot maxima. 



4 These observations have a general interest, and not purely local. 

 Professor Porster shows that they depend not on local temperatures of 

 the air but on the intensity of solar radiation of which the disturbance 

 of the pier is a sort of summation. He has therefore lately sunk three 

 thermometers into his pier in order to understand better its internal 



temperature. . ^ ^-u 4. 4^ r, -r a 



414 [If we couple Forster's investigation with that ot ur. a. b.. 

 Gould into similar motions throughout the world, we should conclude 

 that these changes take place not in the pier but in the ground on 

 which the observatory stands; but this seems impossible m the case 

 of Berlin, where the observatory is surrounded by trees and buildings. 

 The fact that greater solar heat is radiated at times of sun-spot maxi- 

 mum was clearly shown by the present writer's study of temperatures 

 observed on the Hohenpeissenberg. {Amer, Jour. Sa., 1S69.)] 



415 A similar investigation on the movements of the pillars of thd 

 observatory at Neuchatel, 1859 to 1881, has been made by Hirsch and 

 Faye, showing the same periodical and irregular variations as at Ber- 

 lin. (iVatwre, xxviii, p. 216.) 



416 Prof. Paul Reis has made an exhaustive study of the high ana 

 low waters of the Rhine in connection with the question of a possible 

 sun-Rpot periodicitv. With regard to the floods he finds maxima agree- 

 ing with the principal maxima of sun-spots as given by Wolf's relative 

 nirmbers, and concludes that there is very nearly a period of 110 years, 

 which is twice Fritz's 55-year period, and ten times Wolf's sun-spot 

 period, and which, therefore, would be 111 years. This conclusion 

 based upon observations since 1705, is confirmed by the records of high 

 waters running back as far as the year 14 B. C. He, of course, main- 

 tains that the cause of the overflows is cosmic or extra-terrestrial. 

 Dividing his high waters into four classes, he finds that the prediction 

 of a high water of the first class can be made with greater certainty 

 than a weather prediction. {Z. 0. G. M., xvm, p. 2G1.) 



417. Lieut, v. d. Groeben, of the Engineer Corps in Berlin, endeavors 



