ft 7 2 Different Methods of Mowing np Roils under Wa ter. 



twelfth volume of the Memoirs of the Academy of Stock- 

 holm ; I (kill therefore give a literal transition of it*. 



IV. New Method of blowing up Rocks under Water, by 

 Daniel Tbunberg. 



A profile of the rock which has been hored, and into which 

 the charge fa introduced, is reprefented PI. V. iig. I. 



The charge is contained in a tube of tin plate impermeable 

 to water, a vertical lection of which is reprefented in the fame 

 figure. The lower extremity of this tube muft be adjuiled 

 properly to the hole which has been bored in the rock. 



'J he charge confifts of a paper cartridge filled with gun- 

 powder, and attached to the iron wedge, b with a thread fuch 

 as that ufed for fewing fails. 



To this firft wedge b is applied another c, which adheres 

 to an iron rod that riles above the tube. 



On the plane face of thefe wedges is a groove made with 

 a file which reaches to the powder : this; groove is continued 

 throughout the whole length of the tube of tin plate by means 

 of a wooden rod d, hollow on the fide turned towards the 

 iron rod, to which it is made faft with ftrong packthread. 



Before this rod is attached to the iron one, a match, which 

 proceeds from the upper extremity and communicates with 

 the interior of the cartridge, is pbced in the groove. 



e is a train applied to the end of the match. 



B, C, are two rafts which enable the workmen to bore the 

 rock and blow it up. 



D is a weight which prevents the iron from being repelled 

 too far when the explofion takes place., 



E F G H I are different pieces neceffary for charging. 

 E is the cartridge furnifhed with its wedge, feen fideways; 

 F the wedge ken in front ; G the wooden rule and its groove; 

 11 the upper wedge and its iron rod; I the tube of tin plate. 



When the rock has been bored according to the ufual 

 method by employing a borer pretty ftrong and of fuch a 

 length as the depth of the water may require, introduce into 

 it the tube into which the charge has been put; then apply 

 the train e, and, having placed the weight D above the rod, 

 fct fire to it. The explofion will immediately take place: the 

 wedge b would be expelled but for the wedge c, which can- 

 not give way; and the two wedges being thus united confine 

 the charge, the effect of which will never fail, as has been 

 proved by experience. 



* Details refpe&ing this procefs may be found alfo in a large work en- 

 titled Dcfcriplion des 'irava^x executes a Carijivcnu, par Daniel Tbunberg. 



Four 



