"You see," said Mr. James, "the expansion of the contents of the can under heat makes the cover bulge, and when the Chinaman taps it with the mallet he can tell at once by the sound, whether the solder is perfectly tight or not. If, when the mallet strikes it, the cover yields much, he knows that there is an escape for the air and the can is thrown out. There, see him throw that one out? When the Chinaman taps the cans it seems as if he were paying little attention to the work, but when a defective can comes along he detects it at once and casts it aside, just as he did that one." This happened to be the only one rejected of this lot, and the operator at once reversed his mallet and began to tap them over again.
"What is he doing now, Mr. James?" asked Jack. "Is he going over them again?"
"No," said Mr. James; "look closely at the mallet and you will see that he has reversed it; and in this end of the mallet there is a little tack. Each time he strikes a can he punctures it, allowing, as you see, air, water, and steam to escape. As soon as this is done, the other workmen, with their soldering irons seal up these little bits of holes, and the work is done. Now the only thing to do is to label the cans, box them, and ship them to the markets."
"How many fish do they put up here in a day, Mr. James?" asked Jack.
"About five hundred cases," said Mr. James. "It's a lot, isn't it?"
"I should say so," said Jack, "it makes my head swim to think of it, and that is being done all along the river, isn't it?"
"Yes," said Mr. James. "It is, and it keeps up for weeks and sometimes for months. The run of sockeye salmon usually lasts from four to six weeks, and during that time the factories run from four in the morning to seven or eight at night; and the work goes on constantly, Sundays as well as week days."
"Well," said Hugh; "I don't see how there are any salmon left in the river. I should think you would catch them all. There must be a lot of factories just like this all along the river; what becomes of the people living farther up the stream?"
"I can't answer that very well, myself," said Mr. James, "except that I know that there are plenty of them. Here comes a man, though, who can tell you. He is an old fisherman, and has been in the canning business for years. Oh, McIntyre!" he called out to a raw-boned, weather-beaten man who passed not far from them. Mr. McIntyre looked at him, came over, and was introduced to Hugh and Jack as the proprietor of the cannery. He was glad to see them, and readily talked about salmon and salmon canning.