218 Description of the Great Chimney at St Rolloz. 
climb to the top safely and very cheaply. A man was got 
who undertook to carry out the suggestion, and actually 
went up the outside of a chimney 112 feet high, threw down 
a loose coping-stone from the top, and descended; the 
whole job occupying two days. Working upon this sugges- 
tion of Mr Colthurst, we contrived the Climbing-Machine, for 
examining the rent in the great chimney, at a height of 280 
feet from the ground. The drawings are a correct represen- 
tation, and shew the details of the machine, in which two 
men worked themselves up 280 feet on the chimney in the 
course of nine days, including the time occupied in filling up 
the rent. 
Instead of the AA staples on which the climber set his 
foot, and held on by means of a band with a hook to it, 
which, passing round his waist, or rather under his arms, 
supported him while driving in a new staple at the level of 
his head, or nearly so ;—instead of this, in the original, the 
new machine is so arranged, that two men working in it, 
bore or ‘‘ jump” two holes in the brick-work, to receive two 
lewises. The ropes being hooked on to the lewis on each 
side, the machine is moved up by means of the ratchets and 
pall worked by the men. A movement of about 5 feet is thus 
made. The safety-chains are then put on to the pins, or 
lewises, besides the hooks of the ropes. The men, thus se- 
cure, go to the top stage of the machine, and, working"there, 
drive each a new hole to receive a new pair of lewises ; 
which being well fixed, the ropes are taken off the first 
lewises, and put on to the new pair. While the machine és 
in motion, the men were at first dependent on the ropes alone, 
but by attaching the vertical racks, which constantly press 
outwards against the pins, it was very improbable, or scarcely 
possible, that, even should the ropes break, the machine 
could fall more than 2 inches before being brought up by the 
ratchets catching on the pins. 
On gaining the position of the rent, a strong pulley was 
fixed in the chimney, through which a rope was passed, ex- 
tending to the ground; and to this point an ascent can 
very easily be made at any future time. The persons em- 
ployed were s/aters by trade, an old and a young man. It was 
