That was really enjoyable - very well written and quite funny. The bit about the benefits of 'constant physical exertion' being particularly apt surrounded by fatties 111 years later!
There's a very similar account by Puttrell in a collection of his newspaper articles in Sheffield Local Studies Library, written about the same time. They also let off a rocket, which they claimed revealed the roof of the Great Shack to the miners for the first time.
Mind you, they may have just said that to all the mine explorers to make them feel more important, especially if they had to stop work to show another lot around 😉