OF NATURAL PHILOSOPHY. 47 



twenty-four hours. Accordingly, making all secure, 

 fastening down his trap -door, and provided with all 

 necessaries, as well as with the means of making 

 signals to indicate his situation, this unhappy victim 

 of his own ingenuity entered and was sunk. No 

 signal was made, and the time appointed elapsed. 

 An immense concourse of people had assembled to 

 witness his rising, but in vain ; for the vessel was 

 never seen more. The pressure of the water at so 

 great a depth had, no doubt, been completely under- 

 estimated, and the sides of the vessel being at once 

 crushed in, the unfortunate projector perished before 

 he could even make the signal concerted to indicate 

 his distress. 



(39.) Ex. 4*. (35.) III. In the granite quarries 

 near Seringapatam the most enormous blocks are 

 separated from the solid rock by the following neat 

 and simple process. The workman having found a 

 portion of the rock sufficiently extensive, and situ- 

 ated near the edge of the part already quarried, lays 

 bare the upper surface, and marks on it a line in the 

 direction of the intended separation, along which a 

 groove is cut with a chisel about a couple of inches 

 in depth. Above this groove a narrow line of fire 

 is then kindled, and maintained till the rock below is 

 thoroughly heated, immediately on which a line of 

 men and women, each provided with a pot full of 

 cold water, suddenly sweep off the ashes, and pour 

 the water into the heated groove, when the rock at 

 once splits with a clean fracture. Square blocks of 

 six feet in the side, and upwards of eighty feet in 

 length, are sometimes detached by this method, or 

 by another equally simple and efficacious, but not 



