OP THE EARTH-CURRENTS. 303 



of the current is then nearly the same as at Singapore. At 

 Simla, in the Himalaya, the maximum occurs also at noon ; 

 but the direction of the current of greatest intensity is more 

 southerly, its mean yearly direction being S. 47 W. This is 

 precisely what should happen according to the hypothesis, this 

 being nearly the direction of the line drawn to the nearest point of 

 the coast.* 



The variation in the epoch of the maximum intensity of the 

 current, at different places, is also in accordance with the same 

 principles ; that epoch being earliest in islands, or places nearly en- 

 compassed by sea, and latest in the interior of the great continents. 

 Thus it occurs at noon at St. Helena, and in the southern parts of 

 the peninsulas of Hindostan and the Malaya ; while it takes place 

 at 2 P. M. at Catherinburg and Barnaoul, in the interior of Siberia. 

 This accords with the laws of the sun's calorific action. 



It will be seen, upon an inspection of the diurnal curves 

 of the earth-currents,t that at most of the northern stations, as 

 well as at Hobarton in the southern, the easterly currents are 

 greater than the westerly. I believe this effect to be due to 

 the disturbance-currents, which (as I have already shown) have an 

 easterly tendency. This preponderance of the easterly currents, 

 however, is found to be greater at places such as Greenwich, 

 Dublin, Makerstoun, and Toronto which are near an eastern 

 coast, than at those places such as Petersburg, Catherinburg, 

 and Barnaoul which are in the interior of the continent. The 

 results, therefore, so far confirm the supposition above made. 



There are, unfortunately, very few places situated near the 

 western shore of a great continent, at which continued observations 

 of the two magnetic elements have been made. At Sitka, on the 

 western coast of North America, the results confirm the view above 

 stated, the westerly currents being there greater than the easterly. 



There are probably other circumstances in the configuration 



* These additional results oblige me to abandon the conclusion formerly derived 

 from a more limited induction, that the direction of the current of greatest intensity 

 is connected with the magnetic meridian of the place. From the facts which \v,- 

 now possess, it would appear that the currents affect a meridional direction in the 

 higher latitudes, while they are nearly parallel to the equator within the tropics. Tlii* 

 will be seen in a striking manner by comparing the directions of the maximum current 

 in India, above given, with those of the Russian stations in the northern part of the 

 Asiatic Continent. 



f Transactions of the Royal Irish Acafcmy, Vol. XXIV. 



