Transactions and proceedings and report of the Philosophical Society of Adelaide, South Australia . follows: —Selecting an arbitrary point torepresent the position for the year 1895 (curve B, fig. 11),the amount by which the 1896 Lowan rainfall is less than19 in. is plotted below the level selected for 1895. Similarlythe amount by which the 1897 rainfall is less than 19 in. isplotted as a further downward movement below the levelshown for 1896, and so on, so that for each year the differencebetween the actual rainfall and 19 in. is plotted fig. 11, the bottom line A represents
Transactions and proceedings and report of the Philosophical Society of Adelaide, South Australia . follows: —Selecting an arbitrary point torepresent the position for the year 1895 (curve B, fig. 11),the amount by which the 1896 Lowan rainfall is less than19 in. is plotted below the level selected for 1895. Similarlythe amount by which the 1897 rainfall is less than 19 in. isplotted as a further downward movement below the levelshown for 1896, and so on, so that for each year the differencebetween the actual rainfall and 19 in. is plotted fig. 11, the bottom line A represents the actual curve ofthe variation in the water level at Blue Lake. The line B 202 represents the curve drawn by the above method, showing thecumulative effects of variation from the rainfall of 19 in., con-sidering the County of Lowan (Vict.) only. The line C,which has been arbitrarily placed above that of A and B, repre-sents a similar curve to that of B, and as based on the rainfallof the south-eastern counties of South Australia, but with20J in. as the basis of calculation instead of 19 1895 1900 1905 1910 1915 1920 Fig. 11. Graphs showing the relationship between the variationcurve of the lake levels and the curve of the cumulativeeffects of the annual rainfall above or below certainselected bases. The vertical units represent 2 inches forcurves B, C, and D, and 1 foot for curve A. It will be noted that the nature of the curves coincides ina remarkable way and demonstrates the correctness of theassumptions upon which the curves are based. Various othercurves have been drawn taking other annual rainfalls asproviding the equivalent to x, and these curves are, in alicases, similar to those shown in fig. 11, but bearing a lessclose coincidence with the curve A than the ones selected. Mention has been previously made of the fact that thelake levels, on the whole, show a distinct rise in Decemberas compared with June. Since this is an area of winter rainsit seems clear that
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1878
