28

egeson’s weather system.

then, be compared with our large extra-tropical cyclones,though they may be with the small but intense tropical ones.Mr. Meldrum and others long since showed that these had aperiodicity similar to the sun-spots, and the zones to whichboth are confined are identical; there are besides many otherpoints of similarity between the two, but I am not surewhether they satisfy the conditions of similar extreme varia-tion, or great range between maximum and minimum, whichdistinguish the sun-spots when compared with rainfall. Onthe whole, it seems most likely that sun-spots if at all identicalwith terrestrial phenomena partake of the nature of a tropicalcyclone. The cyclonic nature of sun-spots is maintained bymany scientists ; the above seems to some extent to supporttheir views.

Reverting now to rain areas of New South Wales , asdetermined for the thirty-one years, 1858 to 1888. If we notethe positions, or time of arrival, of the first four periods in eachyear, we have their variability, which on being projected showa most remarkable likeness to the sun-spot variability. Thediagram is given at the foot of a previous page of diagrams,below which is the corresponding sun-spot curve. The timecovered by the extreme variations of the four periods is aboutfive months.

The maximum or latest appearance of the rain periods areconcomitant or nearly so with the minimum of the sun-spots.It will be remembered that the same result was obtained inthe case of most other parts of the world, using individualstations. (See diagrams.) Here the minimum sun-spots of1856, 1867, 1878, and 1888-9 correspond with the maximumor latest appearance of the rain periods of 1856-7, 1868, 1877,and 1888. The sudden rise from a minimum to maximumand gradual fall thence to the next minimum, which ischaracteristic of the sun-spot curve, is copied by the rainperiods, though apparently reversed, but this is apparent only,as we shall see further on.

As has been before mentioned, the rain periods are mostregular and cyclical in their nature over the time intervening