Bruce MacDonald"The security of the ladder depends on the dog which is a slender steel hook.
"A hole is nicked out of the chimney brickwork a mere one inch deep. Into it goes a wooden plug and then the dog is hammered home.
"If it's not properly done, then the ladder isn't secure. And each man does his own laddering.
"This is his lifeline and he wants his lifeline to be in his own hands."
https://www.youtube.com/watch?v=fsBD4E4t1ck
