of intensity in the dipping and horizontal needles , &c. 187 
amount of the variation, but the year in which the magnetic 
pole arrives at its maximum westerly position. He also 
states, that in 191 2-§- the magnetic pole will again be on the 
meridian of London, and that it requires 505 years, 215 days, 
8 hours, and 24 minutes, to make a complete revolution 
round the pole of the world. 
