228 



SCIENCE. 



[Vol. I., No. 8. 



tulates published in 'The laws of the winds prevail- 

 ing in western Europe,' he claims that three of these 

 have been shown to be incorrect, while the others are 

 confirmed. For these three he would substitute the 

 following: "Mountainous regions, in spite of the 

 copiousness of their rains, are visited by centres of 

 depression more rarely than the surrounding lowlands 

 and seas, — in general, there is not wholly wanting 

 some influence of precipitation upon the depression; 

 but this influence is not yet clearly defined, and in 

 any case is but indirect." 



Recent meteorological investigations justify the 

 enunciation of four new theorems, which the author 

 gives as follows : 1°. Tbe direction of air-currents, in 

 our latitudes, at the distance of from 500 to 3,.500 metres 

 from the earth's surface, is, on the average, nearly 

 parallel to the isobars of that layer; in the lowest 

 stratum it deviates from to 8 points towards the 

 side of the lower pressure, and, in the layer from 3,500 

 to 9,000 metres from the earth, from to 2 points 

 towards the side of the higlier pressure, from the 

 isobars of the respective layer. 2°. Since the press- 

 ure decreases with the altitude more slowly in warm 

 than in cold air, the gradients, independent of their 

 ratio to the pressure, are changed, as we ascend, in 

 such a manner that an excess of pressure exists upon 

 the side of the warmer air-columns. 3°. The advance 

 of the depressions takes place approximately in the 

 direction of that air-current, within it and approaching 

 its path, which has a preponderance of accumulated 

 energy. 4°. Since the conditions of motion at differ- 

 ent heights of the vortex are different, there is re- 

 quired for its onward movement, not the state of 

 motion of the lowest layer, but that of the sum total 

 of layers. As the changes are continuous with the 

 height, the state of motion of a certain mean layer, 

 whose height is still to be determined, can in general 

 be substituted for it. In support of these proposi- 

 tions, the author refers in detail to the worlds pub- 

 lished in recent years by Terrel, Hann, G-uldberg, 

 Mohn, and others, and thus incorporates the results 

 of the leading meteorologists of the present day. — 

 {Ann. hydr. und marit. meteor., 1882, heft xi.) w. u. 



[499 

 Pressure of the iwind. — An apparatus for meas- 

 uring the pressure of the wind, which promises good 

 results, is suggested by Dr. Sprung of Hamburg. It 

 consists essentially of a hollow metallic sphere erected 

 upon the top of a long rod, which is suspended at a 

 point just above the centre of gravity of the appara- 

 tus. Pressure upon the ball is communicated to the 

 rod, and may be recorded by a suitable registering- 

 cylinder. — {Repert. exp. phys., xviii. heft 12.) w. v. 



[500 



PHYSICAL GEOGRAPHY. 



Australia. — The physical structure and geology of 

 Australia is well summarized by Rev. J. E. Tenison- 

 Woods. The southern side is low, or bounded by 

 cliffs three hundred to six hundred feet high; the 

 west is a tableland about a thousand feet in height; 

 the north is a little higher; and the east averages two 

 thousand feet elevation, and, near the south-eastern 

 angle, bears the Australian Alps, with summits from 

 six thousand to seven thousand feet. The interior 

 depression is eccentrically placed near these moun- 

 tains, and from them the slopes are suflicient to form 

 the only large river-system of the continent. Else- 

 where, whatever rain falls on tlie interior plains soon 

 collects in shallow marshes, which are generally salt. 

 Granite occupies most of the border-tablelands, but 

 is sometimes replaced by vertical paleozoic or older 

 slates and schists. These remain from a very ancient 



disturbance which had no connection with the present 

 outline of Australia, and are at places overlaid by 

 mesozoic strata. The great depression contains cre- 

 taceous strata, overlaid along the southern shore by a 

 full series of marine tertiary deposits reaching three or 

 four hundred miles inland, and as much as six hundred 

 feet above sea-level. About contemporaneous with 

 their rapid uplift a subsidence occurred, forming the 

 castellated fiords and diversified scenery of Port Jack- 

 son, Broken Bay, etc. Extensive volcanic overflows 

 are common nearly all around the tableland, and gen- 

 erally determine the direction of modern drainage. 

 Their date is mostly miocene; but west of Melbourne 

 they are much more recent, and ash cones and craters 

 are frequently preserved. There are also scattered 

 isolated masses of cross-bedded sandstone, forming 

 flat-topped mountains, bordered by precipitous cliffs, 

 so characteristic of Australian scenery. These are 

 ranked as tertiary, or' older eollan deposits, and are 

 sometimes a thousand feet thick. Other land-for- 

 mations are the tertiary drifts — often containing gold 

 from the disintegration of the Cambrian and Silurian 

 rocks, and sometimes buried under heavy lava-flows — 

 and the recent sands and clays of the level half-desert 

 regions derived from the weathered granite, covering 

 a great part of the country. The sand lies in ridges, 

 separated by the yellow clay flats, which a little rain 

 makes very boggy. , 



The narrow strip of land between the plateau and 

 the sea is generally well enough watered by streams 

 to possess fertile alluvial plains, occupying most of 

 its area. On higher ground the volcanic rocks, for- 

 tunately of considerable extension, yield the best 

 soils. The colony of Victoria has the greatest share 

 of these. Farther inland the lands are, as a rule, poor, 

 except in river-valleys; and toward the central basin 

 of the continent they are desert, like the Sahara. 

 There seems to be good probability that artesian wells 

 may be sunk here successfully. This is indicated by 

 the occurrence of springs within the central depressed 

 area. Their water is warm, indicating a deep source, 

 and a supply from the slopes of the surrounding 

 tableland. They form travertine deposits, in which 

 the remains of gigantic marsupials are found. The 

 paleontological evidence of the age of the several for- 

 mations above named is given with some detail. — 

 ( Proc. Linn. soc. N. S. Wales, vii. 1882, 371. ) w. M. D. 



[501 



Physical features of the Australian Alps. — A 

 paper with this title, by J. Stirling, gives some intro- 

 ductory particulars of this range, about lat. 37° S., 

 preparatory to further account of its geology and 

 botany. Its culminating peak is Mount Kosciusko 

 (7,256 feet), with companions in Mounts Bogong 

 (6,508), Feathertop (6,308), and Hotham (6,100). 

 These carry snow-patches through the summer. Be- 

 low them are numerous plains at altitudes from 3,000 

 to 6,000 feet, possessing distinctly alpine features. 

 In midsummer (February), when the lower valleys 

 are languishing in excessive dryness, the rich vol- 

 canic soil of these flat highlands bears a luxuriant 

 growth of alpine flowers and snow-grasses, giving 

 excellent pasturage. During the rest of the year 

 their climate is inhospitable, having sudden changes, 

 severe frosts, and heavy snows. The present dividing- 

 range is not regarded as the original axis of elevation, 

 but has assumed its form by the erosion of a great 

 miocene highland north and south of it, now re- 

 maining as isolated peaks, — Wills, Gibbo, Bindi, 

 Baldhead, and others. The basis of this plateau is 

 of crystalline schists and Silui'ian strata, overlaid 

 by deposits containing miocene plants capped with 

 basaltic flows, into all of which the rivers have cut 



