114 On Dove's Law of the 



In closing this subject, I cannot pass over in silence one 

 remarkable fact, viz., that the positive electricity-rose — [vide 

 Plate II.] — nearly coincides with the pressure of air, which 

 fact may perhaps lead to some clue for the solution of this 

 remarkable, but still mysterious agency in nature. 



Allow me to read a passage from a log kept by Captain 

 Gilfillan, late master of the schooner " Yarra," which illus- 

 trates in a most striking manner the general course of the 

 wind and weather on this coast. He states as follows : — 



" It will be seen that we had some heavy weather during 

 this voyage. The first breeze was when off Cape Otway, 

 which lasted up to midnight of the 9th, when the wind shifted 

 from northward to south by the west, and taking its regular 

 course after falling light round the east to the north, being 

 lightest at east. It continued to haul round to S.W. again, 

 and fell calm, and was lightest when E.N.E., continuing to 

 follow round to west by the north, and it blew hardest when 

 between W.N.W. and S.W., from which quarter we expe- 

 rienced some very heavy hail squalls. It then continued 

 sometime at S.W., and then hauled back by the west to the 

 north, after which it fell light and came to N.E. There the 

 breeze increased, and hauled round to N.W. by the north, 

 and blew hard. It then gradually became calm, again 

 sprung up from N.W. light, fell then calm, and in the calm 

 shifted to S.W. light, when we reached Adelaide." 



The question may be raised, why does the wind at all go 

 back, and not pursue its course continually according to the 

 law ? To this I may reply, firstly, why does a balance not 

 come at once to a state of rest after an oscillation? Secondly, 

 the retrograde motion may also be caused by hurricanes, in 

 which the vane may turn with or against the sun, according 

 to the side of the storm on which we are. Furthermore, the 

 land and sea breezes, hot winds, and local influences must 

 necessarily cause irregularities ; and if in spite of all these 

 interferences we can prove such a surplus of direct revolu- 

 tions, we cannot but feel surprised that the law makes itself 

 manifest so clearly as it does. 



Another objection which may be raised is, how is it to be 

 proved that the alternating currents are passing each other 

 sideways ? Why do they alternate at all ? Why does not 

 one prevail for ever ? And what law rules this change in 

 winds ? 



. These are questions containing problems which to attempt 

 to solve would be rather premature. A system of meteoro- 



