Science for the School and Family, Part I. Natural Philosophy

[1] I take the following from Dr. Arnot:

The reasons that so many people are drowned in ordinary cases, who might easily he saved, are the following:

1. Their believing that continued exertion is necessary to keep the body from sinking, and hence their generally assuming the position of a swimmer, in which the face is downward, and the whole head must be kept out of the water to allow of breathing. Now as a man can not retain this position without continued exertion, he is soon exhausted, even if a swimmer, and if not, the unskillful attempt will scarcely secure for him even a few respirations. The body raised for a moment by exertion above the natural level, sinks as far below when the exertion ceases; and the plunge, by appearing the commencement of a permanent sinking, terrifies the unpracticed individual, and renders him an easier victim to his fate.

2. From a fear that water entering by the ears may drown as if it entered by the nose or mouth, a wasteful exertion is made to prevent it; the truth being, however, that it can only fill the outer ear, or as far as the membrane of the drum, and is therefore of no consequence.

3. Persons unaccustomed to the water, and in danger of being drowned, generally attempt in their struggle to keep their hands above the surface, from feeling as if their hands were tied while held below; but this act is most hurtful, because any part of the body kept out of the water, in addition to the face, which must be so, requires an effort to support it which the individual is supposed at the time incompetent to afford.

4. Not having reflected that when a log of wood or a human body is floating upright, with only a small portion above the surface, in rough water, as at sea, every wave in passing must cover the head for a little time, but will again leave it projecting in the interval. The practiced swimmer chooses this interval for breathing.

5. Not knowing the importance of keeping the chest as full of air as possible; the doing which has nearly the same effect as tying a bladder of air to the neck, and without other effort will cause nearly the whole head to remain above the water. If the chest be once emptied, and if from the face being under water the person can not inhale again, the body is then specifically heavier than water, and will sink.

[2] This is true except when the tube is so small that capillary attraction exerts considerable influence.

[3] I was once consulted in regard to a smoking stove. It was an open Franklin stove, the pipe of which went through a fire-board into a monstrous chimney. I recommended that a pipe with a knee should extend from the pipe of the stove a little way up the chimney. The expedient was successful, because but a small body of air, that in the pipe, needed to be heated to establish an upward current.

[4] As in the case of many other inventions, so here the same idea was originated and put to practical use by more minds than one. George Stephenson, who from being a common engine-wright in a colliery rose step by step till he invented the locomotive, constructed a lamp which illustrated in another way the same principle as the lamp of Davy does—in other words, he invented another safety-lamp. But this does not in the least detract from the glory which the invention has given to the name of Davy, for each acted independently of the other. In Davy's case, it is to be remarked, there was a long course of scientific reasoning and investigation which led him at length to the invention, the record of which is exceedingly interesting. No invention or discovery is made without thought, though accident may suggest the thought; but here is an invention which, without any suggestion by accident, was evolved by laborious and long-continued thought, proceeding step by step to its conclusion.

[5] I will mention here a contrivance that I once adopted for a small conservatory, which I wished to keep warm from the heat of a room to which it was adjoining. In each space of the window-frames were put two panes of glass, there being nearly half an inch of space between them. In this way I secured all the benefit of double windows with less expense and a less cumbrous arrangement. In mentioning this contrivance now and then, casually, I have found that a few others have thought of it, and adopted it with the same success that I did.

[6] We are in entire ignorance of the nature of electricity, and we use the term fluid merely as a matter of convenience.