BY T. GRIFFITH TAYL0K. 523 



diversities in temperature and rainfall which will be discussed in 

 the remainder of this paper. 



It has been stated that the rainfall of New South Wales is 

 due primarily to horizontal movements of the atmosphere. This 

 in general holds true, but the local distribution of rain in this 

 State is wholly due to its stereography, i.e., to the distribution of 

 positive and negative land-forms. 



To bring about rain it is necessary to cool air containing water 

 vapour below a definite temperature (known as the saturation 

 point, which is critical for the given proportion of water). This 

 cooling generally arises in one of two ways, (1) by elevation of 

 moist air into cooler and rarer regions; (2) by horizontal motion 

 to cooler regions. 



A glance at the stenothermal chart (Plate xlv.) shows strikingly 

 the distribution of mean annual temperature. [This has been 

 adapted from a temperature chart of some years back by Mr. H. C. 

 Russell, B.A.] Four facts are noticeable— 



(1) The general concavity (of the isotherms) directed towards 

 the Central Australian area of higher temperature, and the 

 broadening of the isotherms towards the Wimmera and Broken 

 Hill districts. (2) The cool loops surrounding the New England 

 and Kosciusko massifs. (3) The interesting looping of the coastal 

 isotherms, indicating, as first pointed out by Professor David, a 

 hot " hinterland " where the temperature is neither lessened by 

 elevation nor materially lowered by proximity to the sea. (4)The 

 bulging of the isotherm up the Goulburn valley, indicating (as the 

 loop is towards cool elevated regions) heating above the normal. 

 This bulge is directed towards the Cassilis Geocol. A similar 

 interesting bulge up the Peel River valley* (towards colder 



* This bulge up the Peel River valley is probably due to river-erosion, and 

 may be explained as follows : — The crescent-shape of the Liverpool Range is 

 a further confirmation of the theory advanced. It will benoticed (fig. 2) that 

 the southern tributaries of the Peel River (Mooki Creek, etc.) rise in the 

 Liverpool Range. Their course lies for some considerable distance within 

 the northern portion of the Coal Measure area near Gunnedah. They have 

 thus been able to cut back rather more rapidly than other less advantageously 

 situated streams in the north-east. The concave Liverpool Range thus 

 reproduces on the northern slope a characteristic shifting of the divide similar 

 to that due to the Goulburn River on the southern slope. 



