50 H. C. RUSSELL. 
hence to produce persistent southerly to south-east winds on our 
coast—that is, moisture-laden winds which deposit rain on the 
coast and highlands. The persistence of these anti-cyclones, then 
has been the cause of our persistent coast rains. 
The latitude has been from 35° to 40° south, and the centres of 
the anti-cyclones travel eastward, their average rate of motion has 
been four hundred miles per day—that is to say, they travel from 
the west to the east coast of Australia in six days, but the rate 
varies from two hundred and fifty to five hundred and fifty miles 
per day, the slowest moving anti-cyclones give most rain, and the 
fastest no rain at all. The reason is obvious, when the motion 
forward is rapid there is not time to get up the circulation which 
brings south-easterly winds and rain on our coast, and when it is 
slow these winds most prevail. If we may assume that the average 
daily velocity of a number of these anti-cyclones is the velocity of 
the motion of the atmosphere in latitude 35° to 40° and that the 
variations in speed are due simply to interchanges amongst the . 
masses of air rushing about for adjustment of pressure, then it 
is obvious that these anti-cyclones would, if keeping the same 
latitude, make a circuit of the earth in about 50 days, and bring” 
us a repetition of weather, and we should have in the open 
southern ocean the conditions for foretelling the weather for some 
weeks in advance; it is this point which has rendered the investi- 
gation specially interesting and important, but so far the results 
have not been very promising, because we cannot recognise the 
particular cyclonic centres when they return, if indeed they 
do return at all. But Iam disposed to think from what we see of 
them during their two thousand mile journey over Australia, that 
“they do not preserve special characteristics long enough to be 
recognised on return, after fifty days of a trip round the world. 
The means of forecasting the weather on this principle has been 
sought in the northern hemisphere ; but I think Australia is the 
best postion in the world for testing the merits of the idea, and 
as I have just stated, it does not seem to hold out much promise 
of success, 
