Why does water take a spiral motion when running?

Because in rubbing against the sides of the pipe, it is diverted from the forward motion, while the water in the center of the pipe flows faster, there being less friction there.

What is specific gravity?

Specific gravity is the relative weight of one body to another, which is taken as a standard. For solids and liquids, water is the standard. For gases, air is the standard.

Of what is air composed, and in what proportions do those elements exist?

Air is composed of oxygen and nitrogen; about one-fifth oxygen and four-fifths nitrogen. It also contains a small amount of carbonic acid gas.

Why is it necessary that there should be so much more nitrogen than oxygen in the air, when nitrogen is detrimental to life?

It is necessary in order to dilute the oxygen. Otherwise fires would burn out too quickly, life would be too rapidly exhausted, etc.

What is the effect on animal life of oxygen and nitrogen?

Oxygen tends to assist and preserve life, while nitrogen destroys it.

How much air is consumed by a person in one hour?

A human being consumes about 15 cubic feet of air per hour.

What is centrifugal force?

It is that force which tends to make the particles of an object that is revolving fly away from its circumference.

How is centrifugal force applied in plumbing?

In the centrifugal trap. The inlet being taken off as near a tangent as possible to the body of the trap, gives the waste a swirling motion which thoroughly scours the trap.

What is gravitation?

The natural force which tends to draw everything toward the center of the earth.

What is fusion?

The passage of a body from a solid into a liquid state, as, for instance, the melting of lead.

What is a flux?

A substance or mixture used to help the joining of two metals, as rosin, borax, etc.

What is an alloy?

Any compound of two or more metals, as copper and zinc, to form brass.

What is superheated steam?

It is steam removed from contact with water, and heated until it resembles a gas, when it becomes dangerous.

Describe the principle of circulation.

To illustrate, we will take a piece of ice, and place it so that it is exposed to heat. We would call the ice solid matter, but if we could magnify it or any other substance sufficiently, we would find it composed of innumerable small particles or molecules, each one in constant motion. Now, as the ice is heated, these molecules commence to expand, and the vibrations increase in rapidity. In a short time these vibrations increase to such an extent that the particles no longer hold together, but separate from the solid, and form water. As the heat continues, expansion also continues, each heated molecule striving to rise, which of course, forces the colder molecules to drop, and fill the space thus left vacant. Up to this point, the action has been exactly what takes place in the circulation of hot water. At last, however, the water has become so heated that expansion is even stronger than atmospheric pressure, the molecules separate from the original mass, and being lighter now than the air itself, pass off in the form of steam. Being lighter than the air, they of course rise, and here again we have circulation, that is, circulation of steam. These principles then, underlie all circulation work.