76 RAMBLES OP A NATUEALIST. 



ing point, one is led to ask if this can in truth be 

 the outline of that Etna which Pindar called the 

 column of the heavens. We are apt, on looking at 

 the mountain, to regard the narratives of preceding 

 travellers as fabulous ; we flatter ourselves that we 

 can attain without fatigue the summit, which appears 

 to be so slightly elevated above the horizon; and 

 nothing short of actual experience can rectify this 

 error.* 



The declivities of which we have spoken are 

 moreover variable, and the contour resulting from 

 them consequently presents interruptions which may 

 be easily perceived even by the naked eye. M. Elie 

 de Beaumont f was the first to direct the attention 

 of geologists to this important fact in connection 

 with the formation of Mount Etna. The outline 

 of the volcano forms an irregular circle of consi- 

 derably more than 100 miles in extent, a more or 

 less prominent range of heights separating it at 



* The actual angle of inclination almost always differs consider- 

 ably from the estimate that is formed of it, even by a practised eye. 

 We always exaggerate the inclination of the slopes which -we have to 

 ascend. M. de Beaumont has made this very apparent in his memoir, 

 by means of a table containing a large number of the exact measure- 

 ments of different inclines. We shall here quote only a few examples, 

 in order to afford the reader some idea of these results. The street of 

 the Montagne-Sainte-Genevieve, which is perhaps the steepest in all 

 Paris, has nowhere an incline of more than six degrees ; and roads 

 which have an inclination of ten degrees and a half are impracticable 

 for carts. Loaded mules cannot ascend an incline of more than 

 twenty-nine degrees. Sheep cannot reach grass that grows on an 



ncline of fifty degrees, and a slope of fifty-five degrees is absolutely 



naccessible. 

 f [A brief sketch of the labours of M. Elie de Beaumout is 



given in the Appendix, Note I.] 



