76 COSMOS. 



restrial magnetism, and of the conjectured soli-lunar in- 

 fluence. 



1840. Horary magnetic observations with one of Gambey's 

 declination compasses during a ten years' residence in Chili, 

 by Claudio Gay (see his Historia fisica y politica de Chile, 

 1847). 



1840 1851. Lamont, Director of the Observatory at 

 Munich. The results of his magnetic observations, compared 

 with those of Gottingen, which date back as far as 1835. 

 Investigation of the important law of a decennial period in 

 the alterations of declination (see Lamont in Poggend. Ann. 

 der Phys., 1851, Bd. 84, s. 572582, and Relshuber, 1852, 

 Bd. 85, s. 179 184). The already indicated conjectural con- 

 nection between the periodical increase and decrease in the 

 annual mean for the daily variation of declination in the 

 magnetic needle, and the periodical frequency of the solar 

 spots was first made known by General Sabine in the Phil. 

 Transact, for 1852, and four or five months later, without 

 any knowledge of the previous observations, the same result 

 was enunciated by Rudolf Wolf, the learned Director of the 

 Observatory at Berne. 73 Lament's manual of terrestrial mag- 

 netism, 1848, contains a notice of the newest methods of 

 observation as well as of the development of these methods. 



18401845. Bache, Director of the Coasts' Survey of the 

 United States, Observ. made at the Magn. and Meteorol. Ob- 

 servatory at Girard's College, Philadelphia (published in 

 1847). 



18401842. Lieutenant Gilliss U. S. Magnetical and Me- 

 teorological Observations made at Washington, published 1847, 

 pp. 2319 ; Magnetic Storms, p. 336. 



1841 1843. Sir Robert Schomburgk's observations of 



73 The treatise of Eudolf Wolf, referred to in the text, contains 

 special daily observation of the sun's spots (from January 1st to June 

 30th, 1852) and a table of Lament's periodical variations of declination 

 with Schwabe's results on the frequency of solar spots (3835 1850). 

 These results were laid before the meeting of the Physical Society of 

 Berne, on the 31st of July, 1852, whilst the more comprehensive 

 treatise of Sabine (Phil. Transact. 1852, pp. 116 121) had been pre- 

 sented to the Royal Society of London in the beginning of March, 

 and read in the beginning of May, 1852. From the most recent 

 investigations of the observations of solar spots, Wolf finds that be- 

 tween the years 1600 and 1852 the mean period was 11.11 years. 



