VOL. XLIV.] PHILOSOPHICAL TRANSACTIONS. 341 



On the Formation of Pebbles. By Mr. Wm. Arderon, F.R.S. N° 483, p, 467. 



In all strata of pebbles, that Mr. A. examined, there are some which are 

 broken, and whose pieces lie together, or very near each other ; but as bodies of 

 such hardness could not be broken without some considerable force or violence, 

 their situation implies that they suffered such force or violence as broke their 

 parts asunder, in or near the place where they at present lie. 



Others again have had pieces broken from them, though not the least frag- 

 ment of those pieces can now be found : whence we must conclude, that what- 

 ever might be the cause of their fracture, they must either have been broken at 

 some place distant from where they now lie, or the pieces broken from them 

 must at some time or other have been removed to some distant place. 



Several of these pieces of broken pebbles have their edges and corners so very 

 sharp, that it seems as if they had never been removed from the place where 

 they received the damage. Others have their sides and corners so blunted, 

 rounded, and worn away, that one cannot help imagining they must have been 

 very roughly tossed backwards and forwards against other hard bodies, and that 

 too with great violence, or for a very long continuance ; since without a great 

 deal of friction such hard bodies could scarcely have been reduced to the forms 

 they are now found in. 



Among these strata of pebbles are several fragments of various kinds of marble, 

 various kinds of sand-stone, and various kinds of gypsum, though this part of 

 the kingdom affords no such thing ; most of which have attained the hardness of 

 the very hardest of our pebbles, as it should seem, by lying among them. 



Such pebbles as are found here in strata near the surface of the earth, are 

 much more brittle, and break easier without comparison, than those which lie in 

 deeper strata : for if the first of these fall, but with their own weight, on any 

 other stone, from the height of 3 or 4 feet, they will break very frequently into 

 ten or a dozen pieces ; whereas such as are found deep in the earth will endure 

 being thrown against each other with all the force one can give, and that too 20 

 times perhaps, before the least splinter of them can be broken off. 



On the Distances between Asia and America. By Arthur Dobbs, Esq. of Castle- 

 Dobbs in Ireland. N" 483, p. 47 1 . 



Professor Euler, * swayed by the opinion of captain Behring, seems still to 

 believe that the last land he discovered is joined to California, which country 

 is now known to be part of the continent of America, and not an island; 

 in which fact of its being continuous to California, Mr. D. differs still in opinion 



* See Phil. Trans., N" 482, or Vol. ix, p. 320 of these Abridgments.— Orig. 



