Garden and Agricultural Structures. 



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about them you will consider more as hints to work upon, 

 than as any thing more valuable. 



I am, Sir, yours, &c. 

 94. Capel Street, Dublin, Dec. 1832. Robert Mallet. 



Since we received the above communication, Mr. Mallet 

 has sent us another (which we have forwarded to the Me- 

 chanics' Magazine) ; by which we find that, to his numerous 

 other inventions, he has just added a most beautiful and most 

 important one, viz. that of splitting all stones that can be 

 separated into laminae, by the application of male and female 

 screws, instead of blasting, as heretofore, with gunpowder. 

 The process is as follows : — Jumper holes are formed in the 

 direction of the proposed fracture, as at present; but, instead 

 of filling them with gunpowder, a split female screw is inserted 

 in each hole, and the fracture is effected by the insertion of 

 conical male screws. The success of this mode was proved 

 before the Commissioners of Public Works at Dublin ; and 

 the advantages which would result from it, if it were gene- 

 rally adopted, are so great as scarcely to be foreseen. Not 

 only all risk of accident from the blasts would be avoided, but 

 the operation would be performed more cheaply, and, from its 

 slowness, incomparably better. What can be clumsier than 

 separating slate or other rock, for useful purposes, in such 

 a manner as to reduce at least half of it to useless fragments ? 

 We congratulate our esteemed friend Mr. Mallet on his 

 having made so important a discovery. We recommend our 



