We see that a man may exercise his brain so intensely as to reduce the power of nervous control elsewhere, and that in such a case nerves cannot compel muscles to do their usual amount of work. The following, then, is the first great lesson of fatigue.

Hard brain work lessens the muscular power of the body. Later came a test which proved another point. Again it was examination time for Dr. Maggiora, and we have a tracing which shows how the muscles felt when the last examination was over. Dr. Mosso now wished to know how promptly the brain could recover itself and improve the record. Accordingly, Dr. Maggiora went out of town for three days of idleness. During these days he did no brain work whatever, and when he came back to Turin not a word was necessary about his feelings. The tracing of the ergograph told the story.

The startling contrast in the two records shows that even a brief rest may do wonders for the nerves and the muscles of a man whose brain is tired.

Another valuable fact about Dr. Maggiora's record is that in June and July, 1890, other tracings were made showing wonderful improvement. He now raised a heavier weight with his finger and raised it much oftener than before. The explanation turned out to be the state of his general health. He was heavier, stouter, and stronger. "Never before quite so well," as he told

Dr. Mosso. Moreover, he had been resting and not teaching. Even in this condition, however, there was the same astonishing contrast between the tracings which his finger was able to make before and after carrying on a long oral examination.

These facts which Dr. Mosso gave to the world were astonishing to all brain workers. They teach lessons of great importance.

is

1. Muscular work done by an over-tired brain poor in quality.

2. The surest and quickest way to rest an overtired brain and to make muscles do good work again is to give both brain and muscles nothing to do for a season.

In view of these facts, if my friend is anxious to win a college boat race, shall I encourage his plan to take a hard examination just before he starts on the race? By no means, for, as proved by the ergograph, his muscles will not do their best work for him if he starts with a tired brain.

If children feel tired out after a hard examination in arithmetic or hygiene, shall we urge them to go out of doors and take vigorous exercise? Get them out of doors, by all means, but encourage them to postpone violent action for a season. Rather let them stay quietly in the sunshine and in the open air; let them occupy themselves with simple games and quiet sports.

Work the muscles vigorously when the brain is not too tired, but when it is exhausted deal kindly with your whole body; relax your muscles, let your thoughts wander at such times, let nature help you. Use your sense and good judgment always. Energetic exercise of the brain, hard thinking, is most wholesome. Without it you will never gain mental power; but constant overwork, a constant feeling of being tired, is quite another matter. It is nature's way of calling for rest, and nature is a stern ruler. It is not safe to persist in breaking the laws of the nervous system.

CHAPTER V

TIRED MUSCLE AFFECTING BRAIN POWER

It was quite as important for Dr. Mosso to know how the brain acts when muscles feel tired as to know how muscles act when the brain is tired, and for this purpose he studied swift-flying birds.

He went to Palo, near Rome, in Italy, and waited for the quails to arrive from Africa. The distance they fly in crossing the Mediterranean Sea is three hundred and forty-one miles. Their rate of flight is about thirty-eight miles an hour, and they make the trip within something like nine hours. Surely no muscles could work harder than the wing muscles of these small voyagers, and such work as this must bring great weariness. But how does the weariness show itself? How do birds act when they are tired?

Dr. Mosso says that he found some of these birds so tired that when landing time came they seemed to pay no attention to the high obstructions in their pathway. They had crossed the wide stretch of water, they had reached their destination; but now, instead of dropping safely to the ground or alighting on some tree top or

roof, many of them in their swift flight dashed their heads against trees and houses and were killed at once. It looked very much as if they were so tired that they could not recognize things and had with dazed vision flown against the obstacles without seeing them. No wonder the birds were killed, for they were moving as fast as many a local railroad train ever travels.

But we wonder why tired muscles should interfere with eyesight. Carrier pigeons help answer the question, and Dr. Mosso pressed them into service for the special purpose of making discoveries.

He began his work in 1885 with fifty young pigeons. Each pair was located in a small dovecote of its own fastened to the wall, and each dovecote was numbered as carefully as your home is or mine, for no pigeon ever cares to leave its own pleasant habitation. It was, therefore, just as well to number each home as to call each bird by a name which belonged to no other.

Since these fifty pigeons were all young, each had to be trained, for only after training is a carrier pigeon able to find its way across land and sea to its home. Fortunately it is not a difficult matter to train these birds, yet before the training begins there are three important requirements: the dovecote must be pleasant in itself and pleasantly located; the surroundings must be peaceful and quiet; the pigeons themselves must have such food as pleases them best.