"Far along From peak to peak, the rattling crags among Leaps the live thunder! Not from one lone cloud, But every mountain now hath found a tongue, And Jura answers, through her misty shroud, Back to the joyous Alps, who call to her aloud!"

Franklin found that lightning is just a kind of electricity. No one can tell how it is produced; yet a flash has been photographed. When the flash is from one cloud to another there is sheet-lightning, which is beautiful but not dangerous; but, when the electricity pa.s.ses from a cloud to the earth in a forked form, it is very dangerous indeed. The flash is instantaneous, but the sound of the thunder takes some time to travel.

Roughly speaking, the sound takes five seconds or six beats of the pulse to the mile.

All are now taught at school that it is the oxygen in the air which is necessary to keep us in life. If mice are put into a gla.s.s jar of pure oxygen gas, they will at once dance with exhilarating joy. It occurred to Sir Benjamin Richardson, some time ago, that it would be interesting to continue some experiments with animals and oxygen. He put a number of mice into a jar of pure oxygen for a time; they breathed in the gas, and breathed out water-vapour and carbonic acid. After the mice had continued this for some time, he removed them by an arrangement. By chemical means he removed the water-vapour and carbonic acid from the mixed air in the vessel. When a blown-out taper was inserted, it at once burst into flame, showing that the remaining gas was oxygen.

Again, the mice were put into this vessel to breathe away. But, strange to say, the animals soon became drowsy; the smartness of the oxygen was gone.

At last they died; there was nothing in the gas to keep them in life; yet, by the ordinary chemical tests, it was still oxygen. It had repeatedly pa.s.sed through the lungs of the mice, and during this pa.s.sage there had been an action in the air-cells which absorbed the life-giving element of the gas. It is oxygen, so far as chemistry is concerned, but it has no life-giving power. It has been _devitalised_.

But the startling discovery still remains. Sir Benjamin had previously fitted up the vessel with two short wires, opposite each other in the sides--part outside and part inside. Two wires are fastened to the outside k.n.o.bs. These wires are attached to an electric machine, and a flash of electricity is made to pa.s.s between the inner points of the vessel. The wires are again removed; nothing strange is seen in the vessel. But, when living mice are put into the vessel, they dance as joyfully as if pure oxygen were in it. The oxygen in which the first mice died has now been quite refreshed by the electricity. The bad air has been cleared and made life-supporting by the electric discharge. It has been again vitalised.

Now, to apply this: before a thunder-storm, everything has been so still for days that the oxygen in the air has been to some extent robbed of its life-sustaining power. The air feels "close," a feeling of drowsiness comes over all. But, after the air has been pierced by several flashes of lightning, the life-force in the air is restored. Your spirits revive; you feel restored; your breathing is far freer; your drowsiness is gone. Then there is a burst of heavenly music from the exhilarated birds. Thus a thunder-storm "clears the air."

After the pa.s.sage of lightning through the air ozone is produced--the gas that is produced after a flash of electricity. It is a kind of oxygen, with fine exciting effects on the body. If, then, the life-sustaining power of oxygen depends on a trace of ozone, and this is being made by lightning's work, how pleased should we be at the occasional thunder-storm!

CHAPTER XV

DISEASE-GERMS IN THE AIR

The gay motes that dance in the sunbeams are not all harmless. All are annoying to the tidy housekeeper; but some are dangerous. There are living particles that float in the air as the messengers of disease and death.

Some, falling on fresh wounds, find there a suitable feeding-place; and, if not destroyed, generate the deadly influence. Others are drawn in with the breath; and, unless the lungs can withstand them, they seize hold and spread some sickness or disease. From stagnant pools, common sewers, and filthy rooms, disease-germs are constantly contaminating the air. Yet these can be counted.

The simplest method is that of Professor Frankland. It depends on this principle: a certain quant.i.ty of air is drawn through some cotton-wool; this wool seizes the organisms as the air pa.s.ses through; these organisms are afterwards allowed to feed upon a suitable nutritive medium until they reach maturity; they are then counted easily.

About an inch from each end of a gla.s.s tube (5 inches long and 1 inch bore), the gla.s.s is pressed in during the process of blowing. Some cotton-wool is squeezed in to form a plug at the farther constricted part of the gla.s.s. The important plug is now inserted at the same open end, but is not allowed to go beyond the constricted part at its end. A piece of long lead tubing is attached to the former end by an india-rubber tube.

The other end of the lead tubing is connected with an exhausting syringe.

Sixty strokes of the 18 cubic inches syringe will draw 1080 cubic inches of the air to be examined through the plugs, the first retaining the organisms.

The impregnated plug is then put into a flask containing in solution some gelatine-peptone. The flask is made to revolve horizontally until an almost perfectly even film of gelatine and the organisms from the broken-up plug cover its inner surface.

The flask is allowed to remain for an hour in a cool place, and is then placed under a bell-jar, at a temperature of 70 Fahr. There it remains, to allow the germs to incubate, for four or five days. The surface of the flask having been previously divided into equal parts by ink lines, the counting is now commenced. If the average be taken for each segment, the number of the whole is easily ascertained. A simple arithmetical calculation then determines the number of organisms in a cubic foot, since the number is known for the 1080 cubic inches. That is the process for determining the number of living organisms in a fixed quant.i.ty of air.

No less than thirty colonies of organisms were counted in a cubic foot of air taken from the Golden Gallery of St. Paul's Cathedral, London, and 140 from the air of the churchyard. An ordinary man would breathe there thirty-six micro-organisms every minute.

Electricity has a powerful effect in destroying these organisms. Ozone is generated in the air by lightning, and it is detrimental to them. In fine ozoned Highland air scarcely a disease-germ can be detected. Open sea air contains about one germ in two cubic feet. It has been found that in Paris the average in summer is about 140 per cubic foot of air, but in bedrooms the number is double. During the twenty-four hours of the day the number of germs is highest about 6 A.M., and lowest about mid-day.

Raindrops carry the germs to the ground. Hence the advantage of a thunder plout in a sanitary way. A cubic foot of rain has been found to contain 5500 organic dust-germs, besides 7,000,000,000 of inorganic dust-particles. In a dirty town the rain will bring down in a year, upon a square foot of surface, no less than 3,000,000 of bacteria, many of them being disease-bearing and death-bearing. No wonder, then, that scientific men are using every endeavour to protect the human frame, as well as the frame of the lower animals, from the baneful inroads of these floating nuclei of disease and death.

CHAPTER XVI

A CHANGE OF AIR

For weakness of body and fatigue of mind a very common and essentially serviceable recommendation is "a change of air." Of course, the change of scene from coast to country, or from town to hillside, may help much the depressed in body or mind; and this is very commendable. But, strange to say, there is a healing virtue in breathing different air.

At first one is apt to think that air is the same all over, as he thinks water is--especially outside smoky towns; but both have varied qualities in different parts. You have only to be a.s.sured that in a cubic inch of bedroom air in the denser parts of a large town there are about 20,000,000 of dust-particles, and in the open air of a heathery mountain-side there are only some hundreds, to see that there is something after all on the face of it in the "old wives' saw."

Not that the dust-particles are all injurious; for most of them are inorganic, and many of the organic particles are quite wholesome; yet there is a change wrought, often very marked, in going from one place to another for different air.

Even in the country, especially in summer-time, one distinctly notices the great difference in the air of lowland and highland localities. The ten miles change from Strathmore to Glenisla shows a marked difference in the air. Below, it is close, weakening, enervating; above, it is exhilarating, invigorating, and strong.

So people must have a change--at least those who can afford it--for health must be seen to first of all, if one has means to do so. Oh! the blessing of good health! How many who enjoy it never think of the misery of its loss! In fact, health is the soul that animates all enjoyments of life; for without it those would soon be tasteless. A man starves at the best-spread table, and is poor in the midst of the greatest treasures without health.

In these days half of our diseases come from the neglect of the body in the overwork of the brain. The wear and tear of labour and intellect go on without pause or self-pity. Men may live as long as their forefathers, but they suffer more from a thousand artificial anxieties and cares. The men of old fatigued only the muscles, we exhaust the finer strength of the nerves. Even more so now, then, do we require a change of air to soothe our overwrought nervous system.

And when that magic power, concealed from mortal view, works such wonders on the health, surely it is one's duty to save up and have it, when it is within one's means. For is not health the greatest of all possessions?

What a rich colour clothes the countenance of the young after a month's outing in the hill country! How fine and pure has the blood become! All stagnant humours, acc.u.mulated in winter town life, have been dispelled by the ozone-brightening charm. The weary looking office or shop man is now transfigured into a sprightly youth once more, ready with strongly recuperated power for another winter's labours. The pale wife, who has been stifled for months in close-aired rooms, has now a healthy flush on her becoming countenance that speaks of gladly restored health. And all this has been brought about by a "change of air"!

For a thorough change to a town man, he should make for the Highlands.

There he is never tired of walking, for the air which he breathes is full of ozone. This revivifying element in the air is produced by the lightning-bursts from hill to hill. There is in the Highlands a continual rush of electricity, whether seen or not. Hence the air is very pure, free from organic germs, intensely exhilarating and buoyant.

Sportsmen are livingly aware of the recuperative power of the Highland air. Perhaps these city men do not benefit so much by the easy walking exercise on the grouse moors as in breathing the splendidly delight-inspiring air. What a change one feels there in a very few hours!

"A change of air" is an old wives' adage. But much of the weather-lore of our forefathers was based on real scientific principles only now coming to light. Nature is ever true, but it requires patience to unravel her secrets. We therefore advocate an occasional "change of air" to improve the health--

"The chiefest good, Bestow'd by Heaven, but seldom understood."

CHAPTER XVII

THE OLD MOON IN THE NEW MOON'S ARMS

After the sun's broad beams have tired the sight, the moon with more sober light charms us to descry her beauty, as she shines sublimely in her virgin modesty. There is always a most fascinating freshness in the first sight of the new moon. The superst.i.tion of centuries adds to this charm.

Why boys and girls like to turn over a coin in their pocket at this sight one cannot tell: yet it is done. No young lady likes to look at the new moon through a pane of gla.s.s. And farmers are always confident of a change of weather with a new moon: at least in bad weather they earnestly hope for it.

But, banishing all superst.i.tion, we welcome the pale silver sickle in the heavens, once more appearing from the bosom of the azure. And no language can equal these beautiful words of the youthful Sh.e.l.ley:--

"Like the young moon, When on the sunlit limits of the night Her white sh.e.l.l trembles amid crimson air, And while the sleeping tempest gathers might, Doth, as the herald of his coming, bear The ghost of its dead mother, whose dim form Bends in dark ether from her infant's chair."

That is a more charming way of putting the ordinary expression, "the old moon in the new moon's arms." We are regularly accustomed to the moonshine, but only occasionally is the _earthshine_ on the moon so regulated that the shadowed part is visible. This is not seen at the appearance of every new moon. It depends upon the positions of the sun and moon, the state of the atmosphere, and the absence of heavy clouds. I never in my life saw the phenomenon so marvellously beautiful as on May 7th, 1894, at my manse in Strathmore. I took particular note of it, as some exceedingly curious things were connected with it.

At nine o'clock in the evening, the new moon issued from some clouds in the western heavens, the sun having set, about an hour before. The crescent was thin and silvery, and the outline of the shadowed part was just visible. The sky near the horizon was clear and greenish-hued. As the night advanced the moon descended, and at ten o'clock she was approaching a purple stratum of clouds that stretched over the hills, while the position of the sun was only known a little to the east, by the back-thrown light upon the dim sky. Through the moisture-laden air the sun's rays, reflected by the moon, threw a golden stream from the crescent moon, for the silvery sh.e.l.l became more golden-hued.

The horns of the moon now seemed to project, and the shadowed part became more distinct, though the circle appeared smaller. By means of a field-gla.s.s I noticed that this was extra lighted, with points here and there quite golden-tinged. The darker spots showed the deep caverns; the brighter points brought into relief the mountain peaks.

Why was the surface brighter than usual? I cannot go into detail about the phases of the moon; but, in a word, I may say that, while the sun can illuminate the side of the moon turned towards it, it is unable to throw any light on the shadow, seeing that there is no atmosphere around the moon to refract the light.

If we, in imagination, looked from the moon upon the earth, we should see the same phases as are now noticed in the moon; and when it is just before new moon on the earth, the earth will appear fully illuminated from the moon. We would also observe (from the moon) that the brightness of the illuminated part of the earth would vary from time to time, according to the changes in the earth's atmosphere. More light would be reflected to the moon from the clouds in our atmosphere than from the bare earth or cloudless sea, since clouds reflect more light than either land or sea.

Accordingly, we arrive at this curious fact--that the extra brightness of the _dark_ body of the moon is mainly determined by the amount of _cloud in our atmosphere_.