131 
Bombay and at Greenwich, namely, at four in the afternoon 
and between seven and eight in the morning. It is curious, 
moreover, how very quickly the current turns through the 
meridian at Bombay; at three o’clock it flows at an angle of 
15° from the east, and at five already it flows due west, and 
remains almost unaltered in direction till five o’clock in the 
morning. At Greenwich the currents turn much less 
sharply, but they always flow east when the currents at 
Bombay flow west. The system of currents indicated by 
these numbers is that approximately shown by the equations 
given above, the phase, however, being different. Along 
the meridian, on which the local time is four, the currents 
flow from the equator towards the north, they tend round 
in one latitude towards east and west, join on either side 
again to go south, where the local time is half-past seven 
in the morning, and come back along the equator. 
The numbers given in the columns as intensity become 
Amperes when multiplied with 10“®. They are approxi- 
mately of the same magnitude as the currents we are 
accustomed to send through our vacuum tubes, but as the 
thickness of layer through' which they are distributed must 
be very large compared to that on which we experiment, 
the current intensity at such place is very small, far too 
small to cause luminosity. The currents on the whole are 
weaker at Greenwich than at Bombay, but while they 
almost vanish at one time at Bombay, making the ratio of 
the strongest to the weakest current equal to 78, that ratio 
is only 3J at Greenwich. The minimum at Greenwich in 
the early morning is as pronounced at the afternoon mini- 
mum, but much less so at Bombay. 
On the whole the numbers both as regards direction and 
intensity show such a remarkable regularity that there is 
good hope of obtaining a good mathematical representation 
of their distribution. 
But more detailed investigations will require much time 
