IC1ENT1PIC NEWS. 227 



SCIENTIFIC NEWS. 



Mr. JessopV Method of blasting Rocks. 



JL HE information respecting the blasting of rocks given. 

 in our Journal, vol. IX. p. 230 *, has not only been con- 

 veyed to France, but the process has been followed there, 

 and different experiments made on it. Mr. Baduel, an en- Rocks blasted 

 gineer employed in executing that part of the road from Switzerland" 

 Simplon, which extends along the south shore of the Lake 

 of Geneva, has availed himself of it on that occasion. He 

 used the common charge of powder there, which is sufficient 

 to fill one third of the hole, and at first filled the rest of the 

 hole with sand. This quantity of sand he diminished gradu- 

 ally, till he found, that two thirds as much as the powder 

 were sufficient. Bran, saw-dust, ashes, and other light Bran, saw-dust, 

 pulverulent substances, substituted instead of sand, P™- swercd nice-*"" 

 duced the same effect. wise. 



Several mines thus charged, and made with various de- 

 grees of inclination, in single blocks of stone, and knotty 

 trunks of trees, succeeded as completely, as if they had 

 been stemmed with the greatest care. But the success was Failed in the 



not so uniform in the mass of the mountain itself, com- solKlrockoflke 



* .,,..,.,... ,. T ,. , mountain. 



posed of a blackish siliciferous limestone. In this case the 



explosion frequently took place without affecting the rock, 

 though the hole was sometimes filled with gunpowder two 

 thirds, or even three fourths of its height + 



These results are scarcely consistent with those obtained Succeeded 

 by Mr. de Candolle, in the works carrying on over jtf ottdt Jwuat^cSa 

 Cenis. This gentleman has seen the blasting with sand ex- 

 ecuted with success repeatedly, not in separate blocks, but 

 in immense rocks of a micaceous lime-stone schist. Some with a small 

 of these mines, charged with two ounces of powder only, $™ r °~ po *~ 

 produced as much effect as if they had had the usual charge, 

 which is double that quantity. 



* See also, Vol. XII. p. 60. 



f The failure in these instances may obviously be ascribed to so 

 large a portion of the hole being filled with gunpowder, the sand 

 feeing forced through the remaining short space, before the resist- 

 ance offered by the solid rock could be overcome. The next para- 

 graph confirms this, W. N, 

 9 w This 



