M. Arago on Graham or Julia Island. 205 



found a number of soundings taken round the new island, on 

 the 29th September 1831. With tliese observations M. Arago 

 was able to calculate the mean inclination, in reference to the 

 horizon, of the immersed portion of the islet, comprehended be- 

 tween its shore, and the corresponding points at which the sound- 

 ings were effected. The following table contains these results, 

 and the calculated inclinations : — 



The Calculated Inclinations. 



47r 



62^" 



54i'* 



54i» 

 49^" 



Other observations and other calculations, which we shall not ad- 

 duce here, give to the emerged sides of the new island, declivities 

 which diminish as they recede from the shore ; and the varia- 

 tion is even considerable. It appears, then, evident, that if M. 

 Lapierre, instead of sounding at horizontal distances from the 

 coast extending to 30 and 40 fathoms, had taken them at 8 or 

 10 fathoms, he would have found inclinations amounting to 70, 

 and even perhaps to 75 degrees. I leave it, said M. Arago, to 

 those who have most attentively studied the configuration of the 

 globe to decide if moving ground, without cohesion, and inces- 

 santly beaten by the waves of the ocean, if ashes, and above 

 all small stones, in the supposition that Graham or Julia Island 

 has been formed from them, could have maintained itself for 

 whole months under such great inclinations.* 



But a few additional figures will put every one in a capacity 

 to appreciate the value of the remarks which have just been 

 made. 



Inclination with the horizon of the slope of the cone of Vesu- 

 vius, according to Elie de Beaumont, . . . 33' 



That of the slope of the upper cone of Etna, . 32° & 33° 



• At the time that M. Constant Prevost gave an account of his interesting 

 investigations, I learned from him that in a certain point, at the distance of 30 

 or 40 feet from the shore, he found a depth of 200 feet. The two numbers 

 40 and 200 coriepond to an inclination of 7fcT 5 and 30 and 200 vield 81i°. 



