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GEOLOGICAL MEMOIRS. 



becomes considerably diminished by thawing in the summer months ; 

 and the glacier-streams are fed in the winter by the continual supply 

 from the gradual emptying of the canals and cavities in the ice : — 

 2. the currents of air at the exits of the streams are the principal 

 cause of the greater terminal cavities of the glaciers ; their formation 

 is favoured by the presence of a second, contrary aperture : — 3. small 

 bodies strewed singly over the surface favour the wasting away, but 

 heaped up together in greater masses they hinder it, causing thereby 

 a considerable increase of bulk in their neighbourhood : — 4. the 

 yearly amount of waste is in a great part repaired by the motion of 

 the glacier, combined with its specific inclination ; at the same time 

 local accumulations, arising from unequal movement, appear to have 

 considerable influence in this respect. 



The geological division of the work commences with a chapter on 

 Hypsometric Observations* on the Alps (pp. 163-197), written by 

 MM. Schlagintweit conjointly. Their method of determination and 

 the several stations for corresponding observations are first noticed, 

 and the authors who have established previous determinations are 

 enumerated. They then proceed to explain the elaborate Table of 

 Altitudes that succeeds. This Table comprises 191 determinations 

 in topographical arrangement, from which we extract some of the 

 most important. 



Altitude. 



Numbers of the Table. Metres. Paris feet. 



I. Northern limestone Alps. 



1. Munich 518*77 1597*0 



54. Lavatschjoch 2084*4 6416-8 



II. Central Alps. Tauern. 



70. " Firn-meer " of the Pasterze gla- 

 cier on the Todtenlocher 3358*9 10340*2 



83. Johannishutte(whereMM.Schla- 



gintweit resided some months) 2462*6 7581*1 



92. Heiligenblut 1300*8 4004*4 



103. Salmshohe 2671*1 8222*8 



104. Salmshutte 2729*8 8403*6 



105. Firn-line on the Leitergletscher.. 2813*1 8660-4 



106. Hohenwarte 3187*7 9813*1 



107. Adlersruhe 3388*8 10432*3 



108. Grossglockner, First Peakf 3926*8 12088*4 



109. , Second Peak 3949*5 12158*2 



116, Summit of the Kacher 3365*9 10361*6 



117. Summit of the Wasserradkopf ... 3190*6 9822*2 



III. Central Alps. The Oetz Valley Group. 



134. Vent 1881*3 5791*4 



143. Gurl 1788*0 5504*2 



149. Similaun 3617*2 11135*4 



150. Wildspitze 3732*0 11489*1 



151. Vernagt glacier, the lowest part 



of the 2100*0 6464*8 



* Determined partly by means of a siphon barometer, and partly by a hypso- 

 meter (thermo-barometer). 



f Of the method of reckoning used by the authors in determining heights, an 

 example (that of the Grossglockner) is given at page 166. The notices of the 

 Grossglockner and the neighbouring heights were originally communicated to 

 Haidinger's Jahrbuch d.d, K.K. Geologischen Reichsanstalt, 1850, p. 125. 



