Test Your Knowledge

Q – How many days can a healthy man live without food, and how many days without water?
– In case of necessity a man can live five days without water, and five weeks without food.

Q – Many men and women, and even children, are fond of singing in the "bath"; which of these voices is the most melodious in song?
– The man's voice, because the tones of his voice are the lowest of tones, and close-set walls, like the walls of a bathroom, are the most effective at echoing back low tones.

Q – How many liters of blood are there in your body? 3 liters, 5 liters, ten liters?
– That depends on the weight of the body; in the average body, however, the blood amounts to 5 liters.

Q – Why do snakes put out their tongues on most occasions?
– Because the snake has no ears to hear with; its instrument of hearing is its tongue. It puts it out so that the nerve endings in it may feel every movement in the air—and sound is one of these movements. Its tongue, then, listens to what is going on around it.

Q – Does drinking coffee in the evening really prevent sleep?
– Yes; coffee contains an element called "caffeine," which is a stimulant to the nerves. But people differ in the degree of their sensitivity to it. In some of them caffeine works on the nerves with extra slowness, so that they fall asleep before its effect can keep them from sleeping.

Q – The Japanese are small of body; is the cause of this the climate, or heredity, or the food they live on?
– The climate has no influence on it... There is no doubt that heredity has its effect, but the first cause of their small bodies is their fixed diet, which is rice and fish. These two foods lack the vitamins that make bodies grow. That is why the Japanese who emigrated to America are taller of stature, and their stature in America increases generation after generation.

Q – Which of these metals is heaviest: iron, lead, mercury, copper, or gold?
– The heaviest of these metals is gold.

Q – Of what is the writing substance in a lead pencil composed?
– The writing substance in a lead pencil is made from a kind of carbon known as graphite, which is kneaded with water together with good kinds of clay, then, after shaping, heated in special kilns that no air enters; after that the wood is fitted around it, and it is usually sidr wood. As for why it is called "lead," though it has no connection with lead or with its compounds, it is that when graphite was discovered they thought it one of the compounds of lead, which it is not. This belief was strengthened by the fact that lead, if one writes with it, makes a line very like the line drawn by a lead pencil.