must have plenty of fuel aboard. It is one of the rules that the men cannot go under pneumatic pressure except on a full stomach.” So we repaired to the nearest restaurant, and filled our bunkers with broiled steak and apple-pie.
“Now we shall see the doctor,’ said Mr. Squires.
“The doctor!’ we both exclaimed; “why, we are not ill!”
“Certainly. Every one has to undergo a physical examination before entering a caisson.”
All this preliminary was most impressive. For the first time it occurred to me that there might really be some danger, but, shucks! what did I care about dangers as long as I could feel good, solid earth beneath me.
The doctor was such a serious-looking man that we never, for a moment, imagined he might play a joke on us. He felt of my pulse, looked at my tongue, listened to my heart, and then thumped and pounded me unmercifully all about my chest and back, to see if I were perfectly sound. I tell you I was sore before he got through with me! I ached all over, but found some consolation in the thought that Will’s turn was coming next. After Will had stood the test, the doctor began in a clerical tone to sermonize on the awful hazard we were inviting upon ourselves. He told us that we were to enter a chamber where the air was compressed to over three times the density of the atmosphere. “On every square inch of your body,” he said, “there will be a pressure of thirty-five pounds above the ordinary pressure of the air, and thirty-five pounds on every inch means 5000 on every square foot, or about fifty tons on your whole body. Think of that, young men, fifty tons! Why, that would smash you as flat as a griddle-cake if you did not take air of the same pressure inside your body, so that it would press out and counteract the outside compression. The weakest spots are your ear-drums. You will have to look out for them. They are liable to burst unless you can get compressed air up your Eustachian tubes. The only way to do it is to take a long breath, and then, holding your nose and keeping your mouth shut, blow for all you are worth.”
I began to suspect that we were providing a lot of fun for these men, but they were both so insistent about it, that we had to practise blowing so that we should know how to do it when in the air-lock. I learned afterward that that bit of practice was the only really important item in the whole farcical examination. The doctor explained how men who did n’t heed instructions were affected with a dreadful malady known as the “caisson disease.”
“In its very mildest form,” he said, “you are seized with cramps and shooting pains from which you can get no relief. Every bone in your body will ache so that you cannot sleep. In the more serious stages, you become paralyzed. There is one simple test of your condition. Can you whistle? Yes? Well as long as you can whistle, you are all right, but if, after you have been in awhile, you experience any difficulty, it means trouble. Your lips are losing their sensitiveness, a slow paralysis is coming on.”
At this, Mr. Squires had a terrific coughing-spell, but there was not even the flicker of a smile on the doctor’s face as he waved us off.
Mr. Squires led the way up a ladder to a platform surrounding one of the cylinders we had seen. Just as we reached it, there was a sudden blast of air, the trap-door at the top opened, and out came a load of sand. We climbed into the lock, and the lock-tender closed the upper door. The lock was a large chamber about ten feet in diameter, lighted by an electric bulb. At the bottom, there was a trap-door. Mr. Squires warned us against standing on it. The lock-tender turned a valve and let the compressed air rush into our chamber with a loud, hissing noise. The noise was so deafening, we could n’t talk, but Mr. Squires motioned to us to follow his example of taking in deep breaths, and blowing with nose and mouth tightly shut. I felt a little queer as the pressure came on, but was in no distress. The pressure on my ear-drums was far from pleasant. I looked at Will, and could n’t help laughing. He was following directions so conscientiously, taking in copious breaths, and blowing until his cheeks were distended like balloons.
Suddenly, the trap-door below us dropped open with a clang that echoed and reëchoed down the yawning well that seemed to run to the very center of the earth. The well was pear- shaped, with a latticed partition dividing it into two shaftings, the smaller one for the workmen, and the other for the sand bucket. The trap-door opened into a chamber with a narrow ledge to stand upon, and we had to climb down into it and then over to the workmen’s shafting. Mr. Squires then pulled a whistle cord, in response to which the lock-tender swung the bottom door shut.
A ladder led down the workmen’s shafting, which was lighted with a few electric lamps. We could see the shafting tapering with the perspective until it formed but a tiny hole where it passed into the workmen’s chamber, a hundred feet below. In the murky darkness, we could barely make out the forms of men in the cham-Vol. XL.—68.
