Chase.] 



370 



[February. 



According to the second edition of the " Admiralty Manual 

 for ascertaining and applying the deviations of the compass 

 caused by the iron in a ship" (1863), the magnetic equator 

 crosses the meridian of 49° E. (3h. 16m. E.), in (geographical) 

 latitude 10° N. The above average latitude is therefore nearly 

 an arithmetical mean between the corresponding magnetic lati- 

 tude and the magnetic dip. 



The " ranges of the mean diurnal variations of the needle 

 freely suspended in the direction of the magnetic inclination," 

 are given in the following table (op. ciL, p. 684). 



By combining these values in various ways the general means 

 in the first column of the following table are obtained. Those 

 of the second column are derived in a similar manner, from 

 Kaemtz's table of the barometric means at Paris, Strasburg, 



Halle, Berlin, and St. Petersburg, 

 is given in millimetres. 



The heioht of the barometer 



January, 

 February, 

 March, . 

 April, . 

 May, 

 June, . ' 



