Smoke signal

“ I wonder what it means, and who is making it?”
“It is a common signal among uncivilized people,” replied Jim. “Savages the world over use smoke for signaling. They use it especially as a warning against the approach of an enemy or of strangers.”
“Well, what do you find of interest?” asked Berwick, joining them, the captain following a moment later.
[Pg 172]
“We were just looking at that column of smoke over there,” replied Tom. “Do you think it is a signal of some kind?” ”

“ The Indians of the West used it much, and whenever an army detachment or other strangers traversed the plains and the hills their course was marked by the smoke signals of Indian scouts. To make smoke signals, first a moderate blaze is started; then damp or green stuff is piled on, for a smudge; and the column of smoke is cut into puffs by a blanket or coat held over like a cup and suddenly jerked off. A high place should be selected for the smoke signal, so as to distinguish it from the ordinary camp-fire, which is not as a rule made on a high place,—that is, in hostile country. ”

“ If there is none, again shout the lost signal and continue the calls every little while for quite a time. Another call for help is the ascending smoke of three fires. This, of course, is for daylight. Build your fires some distance apart, twenty-five feet or more, that the smoke from each may be clearly seen alone, not mingled with the rest. Aim to create smoke rather than flame; a slender column of smoke can be seen a long distance, therefore the fire need not be large. ”

“ Where flames had been there were now streamers of smoke; but the countless ruins of shattered and gutted houses and blasted and blackened trees that the night had hidden stood out now gaunt and terrible in the pitiless light of dawn. Yet here and there some object had had the luck to escape—a white railway signal here, the end of a greenhouse there, white and fresh amid the wreckage. Never before in the history of warfare had destruction been so indiscriminate and so universal. ”

“ Exposures of this kind obviate to a great extent the difficulty of sun haze and should be secured when this difficulty is encountered and it is impracticable to change the azimuth of the station.
Altitude.—The location of signal stations at high altitudes will tend to obviate difficulties arising from smoke, haze, and dust. The undulation of the atmosphere noticeable on a hot summer's day is always less at a distance from the earth's surface, and it is often practicable to read signals from a tree or housetop when they would be unintelligible from the ground. ”

“ Far below on the ground a missle fell. A dull boom came up. A cloud of smoke rising from the spot indicated that the missle had been a bomb remarkably well aimed. They realized that only by a narrow margin had it missed them.
"Plenty close enough," gritted Jimmie between his teeth. "Rise, if you can, Ned, and give us a chance at them with our guns."
From his seat Ned glanced quickly downward and observed the cloud of smoke about the spot where the bomb had landed.
"Give them another one, Dave," he cried, righting the Eagle and altering the rudders so as to drive the machine higher. ”

“ This use of smoke, coupled with the deadly fire of machine guns and high explosives, forced men to take shelter in deep shell holes, in deep trenches and other places that were safe, but which made it nearly impossible to see signals along the front of battle.
Every man can readily be taught to read a few signals when clearly indicated by definite, sharply defined colored smokes. At first these were designed for use on the ground and will be used to a certain extent in the future for that purpose, particularly when it is desired to attract the attention of observers in aeroplanes or balloons. ”

“ If the air-channel is too small for the extent of the grate, it does not bring the quantity of air necessary for combustion; the fire languishes, it heats the flue imperfectly, and the lukewarm smoke does not ascend rapidly enough. If the air-channel is too large, or brings in too considerable a volume of air, the oxygen of which is not completely taken up, then a part of the cold air enters the flue and does not stimulate the draught; or, if there are changes in the temperature, the air-channel attracts the air from the chimney instead of bringing in air from the outside. ”

“ The usual way of signalling with smoke is to make a smudge fire of browse or grass and use a blanket as an extinguisher. By covering the fire with the blanket and suddenly removing it, a large globular puff of smoke is made to suddenly appear, and is certain to attract the attention of anyone who happens to be looking toward the site of the fire. ”

“ A good deal of scientific work is being done in the way of clearing away fog and smoke; and this, through time, may have some practical results in removing a great source of annoyance, illness, and danger in large towns. Sir Oliver Lodge and Dr. Aitken have been throwing light upon the deposition of smoke in the air by means of electricity.
If an electric discharge be passed through a jar containing the smoke from burnt magnesium wire, tobacco, brown paper, and other substances, the dust will be deposited so as to make the air clear. ”

“ Signal stations should be convenient for messenger service and hence as near commonly traveled roads as the physical contour of the country will permit. Locations for signal stations should be so selected that the visual lines do not cross traveled roads, camps, etc., as dust and smoke in the daytime and lights at night are factors in determining the visibility of signals. Signal stations can if necessary be artificially concealed by erecting screens constructed of limbs of trees, etc., about the flanks and rear. Sheltered positions should be utilized in windy weather. ”

“ Where does it get fresh air from now? There can be no current down the chimney. Let us search it out with this smoking taper. Ah, here it is coming down through the ventilator from the very top of the house. We will soon stop that by this cap. But see, it still burns as brightly as ever. Let us try again. Ah, do you see the smoke rushing down the second story chimney and across to the stairway, and down the stairs, and across the room again to this fire?
There is a valuable hint. Have you not noticed frequently gas in the room from the fire-place or stove, and especially at night? ”

“ The proper fire for pipes is one in a cheerful blaze. If your spill is carelessly constructed the flame runs up into your fingers before you know what you are doing, so that it is as well to marry and get your wife to make spills for you. Before you begin to smoke, scatter these about the fireplace. Then you will be able to reach them without rising. The irritating fire is the one that has burned low—when the coals are more than half cinders, and cling to each other in fear of death. With such a fire it is no use attempting to light a pipe all at once. ”

“ Another reason for locating stations at high altitudes is because the cool night air, the smoke and dust of the day, and heavy mists lie close to the ground, filling the depressions and lowlands, while the higher points remain in view. ”

“ When open, there will be a strong draught of air through it into the chimney, which will presently carry off a cloud of smoke, and keep the room clear: if the room be too hot like-wise, it will carry off as much of the warm air as you please, and then you may stop it entirely, or in part, as you think fit. By this means it is, that the tobacco smoke does not descend among the heads of the company near the fire, as it must do before it can get into common chimneys.
[241] ”

“ Sir Isaac Newton defines flame to be fumus candens, considering all smoke as being of the same nature, and capable of ignition. But the smoke of common fuel consists of two very different things. That which rises first is mere water, loaded with some of the grosser parts of the fuel, and is hardly more capable of becoming red hot than water itself; but the other kind of smoke, which alone is capable of ignition, is properly inflammable air, which is also loaded with other heterogeneous matter, so as to appear like a very dense smoke. ”

“ They put spurs to their horses’ flanks, and gallop for their lives. Every instant the column of smoke increases in width, till it extends directly across the horizon. It grows denser and denser. Now above the tall grass flashes of bright light can be seen. The traveller almost fancies he can hear the crackling of the flames as they seize all combustible substances in their course. Now they surround a grove of aspens, and the fierce fire blazes up more brightly than ever towards the sky, over which hangs a dark canopy of smoke. ”

“ A slight dusting with tobacco powder will generally make an end of green fly or aphis without harm to the leaves dusted, but when all the plants in a house are covered it will be well to fumigate, and any machine will answer the purpose that will quickly diffuse an impenetrable cloud of cool smoke, the fuel being the strongest shag tobacco. ”

“ If the oil in the stampers’ forges is worse than usual the dense clouds of nauseating smoke hang over you like a pall so thickly that you cannot see your fellows a few paces away, making it intensely difficult to breathe and adding a horrible disgust to the unspeakable weariness. Then the bright flashing metal and the white gas-jets show a dull red. Even the sound seems deadened by the smoke and stench, but this is merely the action of the impurity upon the sense organs; they are so much impaired with the grossness of the atmosphere as to fail in their functions. ”

“ When the air of a room is very calm, have you ever noticed that tobacco smoke rises slowly and in a nearly vertical direction? Have you never watched with interest the grayish or bluish streaks of smoke issuing from the smoke of a cigar or pipe? ”

“ Toxic Smoke Candles. To-day we have poisonous smokes that exist in solid form and that are perfectly safe to handle until a fuse is lighted. The so-called candles will be light enough so that one man can carry them. With these, cloud gas can be put off on an hour’s notice when wind and weather conditions are right, no matter how fast the army may be moving and whether on the advance or in retreat. Cloud gas will usually be put off at night because the cloud cannot be seen, because then men are tired and sleepy, and all but the most highly trained become panicky. ”

“ The visibility of a gas cloud arises from the fact that when a large amount of liquid is suddenly evaporated, the air is cooled and moisture condensed, thereby creating a fog. With gases such as mustard gas and others of slight volatility, a visible cloud is not formed. For purposes of identification of points struck by shell, smoke substances are occasionally added, or a few smoke shell fired with the gas shell. ”

“ In manufacturing districts where soft coal is extensively used as power fuel the smoke pall may be dense enough to hide the outlines of large objects at a distance of 4 or 5 miles. A low-lying lid holds the smoke pollution close to the ground and impairs seeing very materially. The airman may fly above the lid into a region of clear air; the marine pilot, except in harbors, is out of the way of smoke; the locomotive engineer, who cannot avoid the smoke pall, sometimes finds it disconcerting. ”

“ I then open the cock and put fire to the gas, which makes its escape through the small tube, and immediately a most beautiful flame ensues, perfectly free from smoke or smell of any kind. A larger light, but not so vivid or clear, will be produced without passing the gas through water, but attended with a smoke somewhat greater than that of a lamp charged with common oil. ”

“ He gave another pull, and blew out another cloud. The white smoke lay above the heads of the company in a thick mass; it grew thicker, so that he could not see through it; it began to move, as if in a high wind. He drew on the pipe once more, and blew out another cloud of smoke. He knew what was coming, and in fact the same thing happened that had happened to him before. The white cloud churned about, with its barber-poles and jets of fire, coming down closer and closer upon him, and in a jiffy he was sitting in midair on his hassock, and then he felt himself falling, falling ”

“ When this is the case, our most sensitive flames fall far behind them in delicacy; and though less striking than the flames, the smoke-wreaths are often more graceful. Not only special words, but every word, and even every syllable, of the foregoing stanza from Spenser, tumbles a really sensitive smoke-jet into confusion. To produce such effects, a perfectly tranquil atmosphere is necessary. Flame-experiments, in fact, are possible in an atmosphere where smoke-jets are utterly unmanageable.56
§ 15. Constitution of Liquid Veins: Sensitive Water-jets
Fig. ”

“ Two methods of measuring the effectiveness of a smoke cloud have been devised, one, the smoke box, which measures the obscuring power directly by observing at what distance a lamp filament is obscured by intervening smoke, the other, the Tyndall meter, which measures the intensity of the scattering of the light. ”

“ It is not to the flame, as such, that we are to ascribe these effects. Effects substantially similar are produced when we employ jets of unignited coal-gas, carbonic acid, hydrogen, or air. These jets may be rendered visible by smoke, and the smoke jets show a sensitiveness to sonorous vibrations even greater than that of the flames.
When a brilliant sensitive flame illuminates an otherwise dark room, in which a suitable bell is caused to strike, a series of periodic quenchings of the light by the sound occurs. Every stroke of the bell is accompanied by a momentary darkening of the room. ”