Part 24 (1/2)
”Hullo!” he said, seeing a young man at work making a copy of a mining plan; ”who are you?”
The young man rose--
”Jack Simpson, sir. I work below, but when it's my night-s.h.i.+ft Mr.
Williams allows me to help him here by day.”
”Ah! I remember you now,” Mr. Brook said. ”Let me see what you are doing. That's a creditable piece of work for a working collier, is it not?” he said, holding up a beautifully executed plan.
Mr. Hardinge looked with surprise at the draughtsman, a young man of some one or two-and-twenty, with a frank, open, pleasant face.
”Why, you don't look or talk like a miner,” he said.
”Mr. Merton, the schoolmaster here, was kind enough to take a great deal of pains with me, sir.”
”Have you been doing this sort of work long?” Mr. Hardinge asked, pointing to the plan.
”About three or four years,” Mr. Brook said promptly.
Jack looked immensely surprised.
Mr. Brook smiled.
”I noticed an extraordinary change in Williams's reports, both in the handwriting and expression. Now I understand it. You work the same stall as Haden, do you not?”
”Yes, sir, but not the same s.h.i.+ft; he had a mate he has worked with ever since my father was killed, so I work the other s.h.i.+ft with Harvey.”
”Now let us look at the plans of the pit,” Mr. Hardinge said.
The two inspectors bent over the table and examined the plans, asking a question of Mr. Brook now and then. Jack had turned to leave when his employer ceased to speak to him, but Mr. Brook made a motion to him to stay. ”What is the size of your furnace, Mr. Brook?” asked Mr. Hardinge.
”It's an eight-foot furnace,” Mr. Brook replied.
”Do you know how many thousand cubic feet of air a minute you pa.s.s?”
Mr. Brook shook his head: he left the management of the mine entirely in the hands of his manager.
Mr. Hardinge had happened to look at Jack as he spoke; and the latter, thinking the question was addressed to him, answered:
”About eight thousand feet a minute, sir.”
”How do you know?” Mr. Hardinge asked.
”By taking the velocity of the air, sir, and the area of the downcast shaft.”
”How would you measure the velocity, theoretically?” Mr. Hardinge asked, curious to see how much the young collier knew.
”I should require to know the temperature of the shafts respectively, and the height of the upcast shaft.”
”How could you do it then?”
”The formula, sir, is M = h(t'-t)/480+x, h being the height of the upcast, t' its temperature, t the temperature of the exterior air, and x = t'-32 degrees.”