Revieivs — Dr. A. Pench — Geographical Morphology. 87 



is no English, geographical manual which gives it adequate notice. 

 In this section much useful information is given in a concise and 

 simple form, upon various branches of geodesy, which can elsewhere 

 be only found in such works as Giinther's Geophysik (1885), or 

 Handbuch der mathematischen Geographic (1890). Penck gives 

 the latest conclusions upon the earth's form, and the methods and 

 results of morphometry. Thus in regard to the former, he states 

 that the question of the amount to which the form of the earth 

 deviates from a true ellipsoid of revolution is now reduced to from 

 ± 200 to ± 250 metres. As an example of the latter may be noticed 

 the care with which the altitude systems adopted by different countries 

 in Europe are tabulated and compared ; some of these are based ou 

 a supposed natural line, such as the British " sea-level," and others 

 on a recognizedly artificial standard, such as the German "Normal 

 Null." No two nations adopt the same standard : thus the levels in 

 Belgium are all 3'39m. lower than in Gei'many, and the standard 

 in Ireland is more than 7 feet lower than that of Great Britain. 

 The uncertainties both in the accepted longitudes and altitudes are 

 clearly pointed out. Thus we are warned that even when the latter 

 are based on trigonometrical observations they are not absolute ; 

 for the error of refraction cannot be altogether eliminated. The 

 considerable amount of this is shown by two cases quoted : thus 

 Harti found that the difference of altitude of two points 28 kilometres 

 apart, varied from 18-6 metres at 5 a.m. to 36'2 m. at 10 a.m. And 

 Bauernfeind found that the difference between the summit of the 

 Dobra and the Kapellenberge in Bavaria increased from 25 m. at 

 3 a.m. to 35-6 m. at 11 a.m. 



This part of the book discusses the methods and formulte used in 

 the determination of the principal measurements of the earth's 

 surface, and also gives the results : thus there are tables of the latest 

 estimates of the ratio of land to water, the area and cubic contents 

 of the different continents and oceans, the lengths of coast-line, 

 the proportions of the continents at given distances from the sea, etc. 

 Two of the most interesting chapters are those on the geographical 

 homologies, which have been recently so graphically illustrated by 

 Prof. Lap worth, and that on the question of the permanence of 

 oceans and continents, of which discussion a useful bibliography is 

 given. In regard to the latter it is interesting to note that the 

 author fully maintains that the specific gravity of the earth below 

 the oceans is greater than below the continents. 



In the second part of the work the surface of the earth is described. 

 It is regarded as made up of a number of " land-forms," which are 

 grouped into eight classes : these are plains ; heaped up masses, such 

 as dunes and sinters ; valleys ; highlands (thallandschaft) or the 

 masses cut up by valle3's, including plateaux, and some types of 

 mountains ; basins or " wannen " ; mountains ; areas of subsidence ; 

 and finally caves and ravines. The agents that produce and mould 

 these various forms are also described. This part of the work is of 

 value as a digest of the classifications and literatui'e of structural 

 geography. It uses throughout the terminology of Eichthofen and 



