Part 92

A trained ship captain can take his ship from any port in the world to another port. He can start at New York City and in a given number of days, according to how fast his ship can travel, land his passengers and cargo in the port of London or Johannesburg, South Africa, or at any desired port in China, Japan or any other country. But he cannot do this by any kind of instinct. He takes his directions from information that was furnished him by some one who went that way before him--some other captain of a vessel who made marks in his book of his position in relation to the sun and stars. This is practically the same as the traveler in the forest who made marks on the trees to make a map of the way back and forth. Even with these charts, compasses and other guiding marks, however, man, even though he is the most intelligent of all the animals, makes very grave mistakes and sometimes brings disaster upon himself and the lives in his care.

Why the Birds Come Back in Spring?

The birds, however, have no charts or compasses to guide them. We do not know as yet absolutely what it is that enables the bird to find its way back and forth to the same spot year after year. As nearly as we have been able to ascertain, the birds after they mate and build their first nest and bring up their first family, develop a fondness for that particular spot which is much the same as the instinct in man which we call the “homing instinct.” Man becomes attached to one particular spot which he calls home and wherever he is thereafter, he is very likely to think of the old locality when he thinks of home, and there are very few of us but have yearnings to go back to the old “home locality” every now and then. The environment in which a bird or human being is brought up generally becomes to a greater or less extent a permanent part of him in this sense.

Why Do Birds Go South in Winter?

We know why birds go south in the winter. The necessity of finding food to live upon has everything to do with that. As food grows scarce towards the end of summer in the farthest northern places where birds live, the birds there must find food elsewhere. They naturally turn south and when they find food, they have to divide with the birds living there. The result is that soon the food becomes scarce again and both the new-comers and the old residents, so to speak, are forced to seek places where food is plentiful. So both of these flocks, to use a short term, fly away to the south until they find food again and encounter a third flock or group of the bird family crowding the locality and exhausting the food supply. So in turn each flock presses for food upon the one in the locality next further to the south until we have a general movement to the south of practically all the birds until they reach a point where the food supply is sufficient for all for the time being.

Why Don’t the Birds Stay South?

The result of all this is that the south-land is crowded with birds of all kinds and the food supply is enough for all. But soon in following the laws of nature in birds, as in other living things, comes the time for breeding. The south-land is warm enough for nesting and hatching, but it is so crowded that there wouldn’t be enough food for all the old birds and the little ones too and so the birds begin to scatter again. Just think of what would happen in the south-land if all the birds that stay there in the winter built their nests there and brought up a new family. A bird family will average four young birds, so that if all the bird families were born and raised in the south the bird population would quickly multiply itself by three and there would be the same old necessity of traveling away to look for food. To avoid this the birds begin to scatter to their old homes before the breeding season begins.

How Do They Find the Old Home?

The return of the birds to their old homes and how they find their way back to the same spot every year, to do which they must sometimes travel thousands of miles, is one of the most marvelous things in nature and has not as yet been satisfactorily determined. The nearest approach we have to a satisfactory answer to this is that birds do have a memory, that they can and do recognize familiar objects, and that their love for the old home causes them to fly to the north until they recognize the landmarks of their former habitation. In this it is said that the older birds--those who have gone that way before--lead the flocks and show the way.

There is no doubt that birds have a more perfect instinct of direction than man. They can follow a line of longitude almost perfectly, i.e., they can pick out the shorter route by instinct, and this is, of course, a straight line. They just keep on going until they come to the familiar place they call home and then they stop and build their nests. That it is not memory and sight of places alone that guides the birds is shown by the fact that some birds when migrating fly all night when there is no light by which to recognize familiar objects.

Why Do Birds Sing?

The song of the birds is a part of the love-making. The male bird is the “singer,” as we call them at home, when we think of the canary in the cage near us. The male bird sings to his mate to charm her and to further his wooing. This wooing goes on after the eggs have been laid in the nest and while the mother bird is keeping them warm until they hatch out, but almost instantaneously with the birth of the little birds, the song of the male bird is hushed. Take the case of the nightingale. For weeks during the period of nest-building and hatching he charms his mate and us with the beautiful music of his love song. But as soon as the little nightingales come from the eggs, the sounds which the male nightingale makes are changed to a gutteral croak, which are expressive of anxiety and alarm, in great contrast to the song notes of his wooing. And yet, if you were at this period--just after the birds are born, and when his song changes--to destroy the nest and contents, you would at once find Mr. Nightingale return to his beautiful song of love to inspire his mate to help him build another nest and start all over again to raise a family.

What Causes an Arrow to Fly?

It is caused by the power generated when you bend the bow and string of the bow and arrow out of shape. The bow and string have the quality of elasticity which causes a rubber ball to bounce. When you force anything elastic out of shape, this quality in it makes it try to get back to its natural shape quickly. In doing this it acts in the direction which will take it back to its normal shape most quickly. The arrow is fixed on the string in a way that will not interfere with the bow and string getting back to its shape and, when they bounce back, the arrow goes with it. The real cause for the arrow’s flight, however, comes not from the bow, because the bow cannot put itself out of shape, but comes from the person who causes it to be out of shape and, therefore, the person who pulls the string back really causes the arrow to fly.

Why Do Children Like Candy?

Children crave candy because the sugar which it contains largely is in such a condition that it is the most suited of all our foods for quick use by the body. It is actually turned into real energy within a few minutes after it is eaten.

All the things we eat are for the purpose of supplying energy to our bodies to replace the energy that our daily activities have dissipated. Nature takes the valuable parts of the foods we eat and changes them into energy. The waste parts she throws off. Many things we eat have little real value as food and many also nature has to work upon a long time before their food value is available in energy. Sugar, however, represents almost energy itself.

Children are, of course, more active than grown-ups. They are never still. They are, therefore, almost always burning up or using up their energy. They are also, therefore, almost always in need of food that can be made into energy, and as sugar does this almost more quickly than any other food, nature teaches the children to like candy or sweets.

Why Does Eating Candy Make Some People Fat?

Eating as much as one can of anything at any time will produce fat, provided you do not do sufficient physical work or take enough exercise to counteract the effect of generous eating. When you see a person who eats a great deal and is growing fat, you may know that he or she is not taking sufficient bodily exercise to work off the energy produced by the body from the food that has been eaten. When this happens the energy in the form of fat piles up in various parts of the system. Candy will do this more quickly than any other thing we eat because it contains so much sugar and because sugar is so easily changed by our system into usable energy. You generally find a fat person who eats much candy to be a lazy person.

What Makes Snowflakes White?

A snowflake is, as you are no doubt aware, made of water affected in such a way by the temperature as to change it into a crystal. Water, of course, as you know, is perfectly transparent. In other words, sunlight or other light will pass through water without being reflected. A single snow flake also is partially transparent, i.e., the light will go through it partially, although some of it will be reflected back. When a drop of water is turned into a snowflake crystal, a great many reflecting surfaces are produced, and the whiteness of the snowflake is the result of practically all of the sunlight which strikes it being reflected back, just as a mirror reflects practically all the light or color that is thrown against it. If you turn a green light on the snow, it will reflect the green light in the same way. When the countless snow crystals lie on the ground close together, the ability to reflect the light is increased and so a mass of snow crystals on the ground look even whiter than one single snowflake.

What Makes the White Caps on the Waves White?

In telling why the snowflake is white we have practically already answered this question also. Instead of little crystals formed from the water, the foam produced by the waves of the ocean are tiny bubbles which have the same ability to reflect the light as the snow crystals.

What Good Can Come of a Toothache?

Very few of us realize that an aching tooth is a good thing for us, provided we have it attended to and the ache removed. Any one who has had toothache will hardly agree that there can be a blessing attached to this excruciating pain.

But the good comes from the warning it gives us of the condition of our teeth on the inside of our mouths. The arrangement of the interior of the mouth and the use we make of it in passing things into our systems, favors very much the development and increase of microbes, and when they once get in they are difficult to remove. It is said that the greatest percentage of cases of stomach trouble come from teeth which are in bad condition and that a very large percentage of people who have bad teeth are in grave danger of blood poisoning or other troubles due to the microbes. When these microbes lodge in the mouth, they find conditions favorable to their development when there are bad teeth, and spread through the system.

How Can Microbes Spread Through the Body?