

Apparatus for Rock Blasting. 357 



these may be considered as separated into two subdivisions by four 

 plates of copper between the letters C C. Of course the box may be 

 considered as comprising four distinct spaces, No. 1, No. 2. No. 3, 

 and No. 4. The circuit is established in the following manner. Be- 

 tween the zinc plates of compartment No. 1 and the copper plates of 

 compartment No. 2, a metallic communication is produced, by sol- 

 dering their neighboring corners to a common mass of solder with 

 which a groove in the wooden partition between them is filled. With 

 similar masses of solder, two grooves severally made in the upper 

 edges of each end of the box are supplied. To one of them, the cor- 

 ners of all the copper plates of space No. 1, and the zinc of space 

 No. 4, are soldered. To the other the zinc plates of space No. 2, 

 and the copper plates of space No. 3, are soldered in like manner. 

 Lastly the zinc plates of No. 3 are connected by solder in a groove, 

 and the copper plates of No. 4 are in like manner connected by sol- 

 der in another groove. Upon the ends, S S, of the solder just men- 

 tioned, the gallows screws are severally soldered, and to these the rods, 

 PP, called poles, are fastened. 



Rationale. 



The zinc and copper surfaces of No. 1 and No. 2, communicating, 

 have iheir naturally opposite electric powers exalted, and induce in 

 the plates with which they are alternated, a like exaltation, still high- 

 er. By the communication of the latter with the surfaces in No. 3, 

 and No. 4, a similar effect is induced, and again by induction the 

 electric powers of the plate alternating with those last mentioned are 

 augmented. Hence a discharge between the latter will have a quad- 

 ruple intensity, and hence the poles, or rods, communicating with the 

 gallows screw, soldered as above described to the zinc and copper 

 plates last mentioned, will make a discharge through any conductor 

 whenever the apparatus is put into operation by raising the acid, so 

 as to enable it to surround and act upon the galvanic surfaces. 



When, agreeably to the project of Mr. Shaw, several masses of 

 gunpowder are to be simultaneously ignited, in as many different 

 holes in the same rock, I purpose to introduce into each hole, a cy- 

 linder prepared as here represented and to secure them by ramming in- 

 to the hole, sand, brickdusl, or other suitable matter, through which 

 the wires are allowed to pass so as to project on the outside. All 

 the wires corresponding with that represented at B in the engraving, 

 we then to be soldered to a rod proceeding from one pole to a calori- 



