BY JOHN TEBBUTT, JUN. 161 



second minimum of the barometer, and the change in the direc- 

 tion of the wind. The principal minimum occurred at Adelaide 

 and Windsor as reduced to the meridian of Windsor, as follows : 

 At Adelaide, October 25 d 5 h 4 m Windsor mean time. 

 Windsor 26 d 3* O m 



The difference gives twenty-two hours as the interval of 

 absolute time occupied by the phenomenon in its propagation 

 over the space separating the two observatories. Again, we find 

 that soon after the principal minimum of atmospheric pressure, 

 the wind at both places veered to the west, and that in about 

 eight hours at Adelaide, and six at Windsor, the barometer 

 again began to fall. We have here a well defined instance of 

 the gradual shifting eastward of the two great air currents in 

 connection with their corresponding atmospheric pressures, and 

 it is evidently in accordance with the rule derived from the 

 consideration of the curves. And the observations recorded at 

 Windsor on this occasion, afford a very striking illustration of 

 the influence of tropical currents of air on the barometer, for no 

 sooner did the tropical current gain a temporary ascendancy over 

 its polar opponent, as shown by the backing of the wind to north- 

 west on the evening of the 26th, than the instrument again began 

 to fall. I have received observations of the same storm from 

 Brisbane and Cape Otway. The observations at Cape Otway are 

 made three times a day, and show that the storm at that place, 

 slightly preceded in point of time the same phenomenon at 

 Windsor. The lowest reading of the barometer occurred early 

 in the afternoon of the 26th, the wind also shifted about the same 

 time. The observations at Brisbane are also made three times a 

 day, viz : at 9 a.m., 3 p.m., and 9 p.m. N.N.E. and N.N.W. winds 

 prevailed there on the 26th, the barometer falling from 29.924 

 at 9 a.m. on the 25th, to its lowest recorded point 29.440 at 

 3 p.m. on the 27th. Strong polar winds from W.S.W. prevailed 

 on the 27th. Thus, it appears, that the principal features of the 

 storm occupied about two days in shifting north-easterly from 

 Adelaide to Brisbane. 



From A what has been said we should infer that if a system of 

 weather warnings were established along our eastern sea-board, 

 Adelaide would form an admirable out-post to warn us of approach- 



