in the Diving-Bell. IS 
any direction, as it is suspended from an outrigger, at some 
height from the vessel's deck. 
The men at Howth are principally occupied in clearing the 
entrance to the harbour. They are paid by the ton weight for 
what they quarry and send up, viz. 6s. 6d. per ton for very 
hard rock, that has chiefly to be blasted with gunpowder; 
5s. 5d. per ton for easier quarried rock ; and 4s. per ton for 
detached stone, gravel, and mud. At this rate, they are able 
to earn on an average 20s. per week all the year round. Their 
tonnage of rock averages 3\ tons per day, and detached stone 
5 J tons for four men. 
The method of blowing up rocks by aid of the diving-bell, as 
practised in Ireland, is as follows. For an account of this pro- 
cess, I am entirely indebted to Mr Bald’s kindness. 
Three men are employed in the bell; one holds the jumper 
or boring-iron, the other two strike alternately quick, smart 
strokes with hammers. When the hole is bored of the requi- 
site depth, a tin- cartridge, filled with gun-powder, about two 
inches diameter, and a foot in length, is inserted, and sand placed 
above it. To the top of the cartridge a tin-pipe is soldered, having 
a brass-screw at the upper end. The diving-bell is then raised up 
slowly, and additional tin-pipes with brass-screws are attached, 
till the pipes are about two feet above the surface of the water. 
In the old practice, the tube was filled with powder as a 
train, and fired ; but, in many instances, the heat melted the 
solder of the pipe, and the water entering extinguished the fire. 
The improved method is to leave the tube empty. The man 
who is to fire the charge is placed in a boat, close to the tube, 
and to the top of the tube a piece of cord is attached, which he 
holds in his left hand. Having in the boat a chofler with small 
bits of iron red-hot in it, he, with a pair of nippers, takes one 
of the bits of red-hot iron, and drops it down the tube, which 
instantly ignites the powder, and blows up the rock. A small 
part of the tube is destroyed next the cartridge ; but the great- 
er part, which is held by the cord, is reserved for future ser- 
vice. The workmen in the boat experience no shock by the explo- 
sion ; the only effect is a violent eruptive ebullition of the wa- 
ter, arising from the explosion ; but those wlio stand on the 
shore, and upon any part of the rocks connected with those 
which are blowing up, feel a very strong concussion, similar to 
