"Better sit up for half an hour longer," said the Doctor.

"Why?" asked Jack.

"Because our stomachs are full. They have been seriously weakened by several days of starvation, and are apt to do their work rather badly for a time. Let's give them a chance."

"But, Doctor," said Jack, "I have noticed that all the animals lie down and sleep as soon as they have fed heartily. Why isn't it a good thing for men to do the same thing? Men are after all, animals on one side of their nature."

"Yes, I know," said the Doctor, "and I have known physicians to argue in that way in favor of late suppers. But experience hardly bears out the argument. A man may sleep well on a heavy meal, but often he gets up with a bad taste in his mouth and with a morbid craving for food, which means that he hasn't properly a.s.similated the food that he has already eaten."

"What do you mean by 'a.s.similating' food?" asked Tom, adding: "I'm afraid you'll think me very ignorant."

"Not at all," replied the Doctor. "Most people don't understand that.

You see, there are two distinct processes by which we turn food to account in building up our bodies, making strength and heat, and generally carrying on the processes of life. One of those processes is digestion, and the other a.s.similation. Digestion simply reduces the food which we have eaten to a condition in which it can be a.s.similated. By a.s.similation certain organs of the body take up the food thus prepared for them, convert it into blood and send it through the system to nourish it. In the pa.s.sage of the blood through the arteries and veins, it leaves deposits of muscle here, fat there, bone in another place, and so on. This is a very rude statement of the matter, but it is sufficient to show you what I mean, at least in a general way. Very well. It does a man no good whatever to digest his food if he doesn't a.s.similate it. No matter how perfectly the stomach does its work, the body is not nourished unless the organs charged with the function of a.s.similating the digested food do theirs also. Once, in a hospital, I saw a little baby die of actual starvation, although it had an abundance of food, and digested it perfectly. It simply could not a.s.similate."

"But what has that to do with our going to bed at two o'clock in the morning?" asked Jack, who was disposed to be a trifle cross as the result of the long starvation and strain.

"Only this," answered the Doctor, "that unless we give our weakened stomachs a little chance to digest our food properly before we go to sleep, the process of a.s.similation will be very imperfectly performed and we shall not be as perfectly nourished as we need to be. Still, I think we might safely go to bed now," added the Doctor, "as the half hour is gone, and it is now two thirty"--looking at his watch.

With that the exhausted company prepared for bed. Jim Chenowith was the first to approach the bunks, under which the earthen floor was a little lower than in the rest of the cabin. As he did so, having slipped off his boots, Jim called out:

"h.e.l.lo! What's this? I say, fellows, we have a creek here under our beds!"

A hasty examination confirmed his statement. There was a vigorous stream of water running directly under the bunks, and worse still, as an exploration with torches soon revealed, the water was not only running in under the lower logs of the hut, but was also pouring through every opening it could find in the c.h.i.n.king of the walls above, and streaming into the bunks.

The Doctor hastily went outside to study conditions and, returning, said:

"There's a terrific rain on, boys, and the thermometer stands at fifty.

So the snow is melting rapidly, and the two things together--the rain and the melting snowdrift--are flooding us."

Tired and sleepy as Jack was, he rose instantly to the occasion.

"There's no sleep for us to-night, boys!" he said. "We must go to work at once and dig the house out of the snowdrift. Get some fatwood torches ready and let's go to work."

The boys responded quickly, and presently all of them except Ed, whom the Doctor forbade to do any further work that involved strenuous physical exertion, were engaged in shoveling the snow away from the house and opening a pa.s.sageway around it fully eight feet wide.

By daylight this was accomplished. It put an end to the inflow of water through the c.h.i.n.king of the upper logs; but, as Tom expressed it, there was still "a young river" flowing into the house, from the bottom of the snow bank, underneath the lower logs of the hut. Not only was all the warm rain flowing through the snow bank, but in its pa.s.sage it was dissolving a great deal of the snow, and so the volume of water flowing out at the bottom and running into the house was quite double that which the rain itself would have supplied.

"We ought to have made a bank of earth around the lower part of the cabin," said the Doctor, after studying the situation for a time.

"True," said Jack, "but we had no tools with which to do it. Neither have we any now. So I don't see what is to be done."

"I do!" said Tom, the alert of mind. "I do, and it is perfectly simple."

"What's your idea, Tom?" asked Jack.

"Why, to make the snow protect us against itself."

"But how?"

"Why, by building a little snow bank between the big snow bank and the house, hammering it into solid ice, with our mauls, and in that way making a ditch that will carry off the water around the end of the house and down over the cliff."

"That's a superb idea, Tom," said Jack, "and we'll get to work at it at once. I'd give the proceeds of all my winter's work for a head half as good as yours, Tom."

"Oh, pshaw!" said Tom. "My head isn't of much account. It is only that I look straight at things and try to use common sense."

"Yes," said the Doctor, "and that is what we call 'genius' in science.

It is the men who 'look straight at things and try to use common sense'

who do the great things in science. Darwin did that, and so did Asa Gray, and Edison, and Aga.s.siz, and all the rest of them. Scientific genius is nothing in the world but common sense, reinforced by a habit of observation."

But there was no further time for talk. The boys quickly built a low snow embankment between their house and the great snowdrift, and beat it down with their mauls, into a condition of solid ice. With this barrier to aid them they succeeded in compelling the water from the rain and the melting snow to flow in a sort of ditch around their house, and to cease flowing through it.

Inside, however, the condition of things was deplorable. The earthen floor under the bunks was a mud hole. The broom straw that const.i.tuted the beds was soaking wet, and the task of drying it promised to be no easy one.

"We've simply got to sleep on hard clapboards for two or three nights,"

said Ed.

"Well, what of that?" asked Tom, "I've often slept on much harder beds than clapboards make."

"For example?" asked Jim.

"Well, I've slept on big rocks for one thing."

"Why did you do that? Why didn't you sleep on the softer ground?"

"Because the softer ground was much too soft, being mud. I've slept on two rails placed about eight inches apart, with one end stuck into a fence so as to keep me out of the mud, and a pretty good bed rails make.

Finally, I have slept on the worst bed there is in the world."

"What is that?"

"Why, a pile of pebbles. That's the very worst there is, but you can sleep on it, if you've got to. Now, let's have some breakfast, Ed, and after devouring a proper quant.i.ty of bear steak, I'll show you fellows how a healthy fellow who has worked all night can sleep on clapboards in spite of the daylight that the Doctor's rag windows are letting in, now that we've shoveled the snow away from them."

Ed had breakfast already well under way. It was to consist solely of bear steak and coffee, for coffee was their one supply which was not exhausted, and during the starving time they would hardly have endured their hunger but for that resource.

"But," said Jack, as they ate their breakfast, "what are we going to do with that bear meat? It won't keep long in this soft weather. By the way, Jim, throw another stick on the fire. It's cold."

"So it is," said the Doctor, who had just come in after a consultation with his scientific instruments. "The thermometer has sunk twenty degrees within the last hour, and stands now at two degrees below freezing. It will go much lower, for the barometer is rising and the wind has shifted to the northwest. We're in for a trip to the Arctic regions without doing any traveling to get there."

"Let's hang the bear out of doors, then," said Jack. "It will freeze there."

"Yes, and every carnivorous animal in these woods will come and eat for us," said Tom, whose authority on the habits of wild creatures was accepted by all the boys as final.

"Besides," said the Doctor, "it isn't necessary. Our bear will freeze hanging just where he is, by the door there."

With that he arose, went outside, and brought in a thermometer, which he pinned to the bear's carca.s.s.

"We're down to twenty-six degrees outside now," he said, "and it is growing steadily colder." Then, after waiting for five minutes, he consulted the thermometer that he had hung upon the bear, and announced:

"It stands at thirty-three degrees--fruit-house temperature."