56 OBSERVATIONS ON THE CAUSES OF ELEVATION, ETC. 



the surface pressed ; and whose height is equal to the vertical 

 depth of the centre of gravity of the surface pressed below the 

 surface of the water. It is a natural mistake among young 

 students of hydrostatics to fall into the error that the magni- 

 tude of the horizontal expanse of any body of water intensifies 

 the pressure upon its limiting surfaces ; but the determining 

 factors of pressure given hereinbefore shows that the 

 horizontal pressure upon the vertical face of any wall or 

 embankment, say 100 feet oeep and 100 feet wide, would just 

 be the same if the width were extended 1,000 miles or to any 

 conceivable extent so long as the area pressed and the vertical 

 depth of its centre of gravity below the level surface remain 

 unchanged. That Mr. Danvers-Power has fallen into this 

 elementary error as regards the lateral pressure of oceanic 

 water is beyond doubt, for there is no escape on the plea of 

 misconception or ambiguity in the following statement intended 

 by him to show that greatness of expanse or area of ocean 

 intensifies lateral pressure upon coast lines. Thus in account- 

 ing for the parallelism of high chains of mountains with 

 great ocean basins, he states — " We almost invariably find that 

 the highest mountain ranges have been developed more or less 

 parallel to the past or present sea coasts that are washed by 

 the largest bodies of water. Thus, in South America, we find 

 the Andes on the west higher than the mountains of the east 

 coast ; also that the western shores of America are washed by 

 the Pacific Ocean, which is greater in area and depth than the 

 Atlantic. Coming nearer home for an example we find the 

 highest Australian Mountains on the East Coast, the Pacific 

 again being larger than the Indian Ocean. In Tasmania, 

 however, matters are somewhat different, for there is an un- 

 broken stretch of water from its West Coast to South 

 America ; while on its East Coast some twenty degrees 

 distant New Zealand acts as a breaJcivater, and braces up the 

 ocean so to speak, relieving the East Coast of Tasmania of 

 much pressure from the main body of water ;" and further on 

 he again states : — " We not only have the horizontal pressure 

 of the ocean, but also the vertical pressure." In his reference 

 to Tasmania he is extremely unfortunate, for there is nothing 

 more probable than that Tasmania, as a ivhole, forms but a 

 southern prolongation of the Eastern Alps of Australia, and 

 the causes which led to the original determination of the main 

 chain operated in the formation of its southern extremity. 

 And again he does not recognise the fact that the highest Alps 

 of the Australasian region run along the Western Coast of 

 New Zealand in a line north easterly and parallel to the 

 south eastern coast of the mainland of Australia, and are not 

 found on the eastern border, which is washed by the full sweep 

 of the South Pacific Ocean, to whose influence he ascribes the 

 smaller Alps of the Eastern border of the mainland of 



