Blowhole

“ Strange to say, he had not advanced more than a few hundred rods before I noticed that there was a strong current of air blowing through the tunnel in the direction Bulger had taken.
Every moment it increased in violence, fairly lifting us from our feet and bearing us along through this narrow bore made by nature’s own hands and lighted too by lamps of her own fashioning. The motion of the air through this vast pipe caused bursts of mighty tones as if peeled forth by some gigantic organ played by giant hands. ”

“ There is a wide choice of apparatus, from a simple mouth-blowpipe and a candle flame to a power-driven blower and a multiple-jet heating device. All are useful, and all have their special applications, but, for the present, we will consider the ordinary types of bellows and blowpipes, such as one usually finds in a chemical or physical laboratory.
The usual, or Herepath, type of gas blowpipe consists of an outer tube through which coal gas can be passed and an inner tube through which a stream of air may be blown. Such a blowpipe is shown in section by Fig. ”

“ On our return, the eye, having had time to accommodate itself to the darkness around, embraced several objects; the roof, sides, and crags in many places, which had before escaped it. Our entertainment also was varied by a blast, as it is termed—the discharge of a small quantity of gunpowder thrust into the rock, occasioning an explosion only to be compared to that sound which the imagination would conceive might be produced, if universal nature were at once to tumble into ruins. ”

“ So much for the strength of the blast; its delicacy is illustrated by this beautiful example of line-engraving, etched on glass by means of the blast.
This power of erosion, so strikingly displayed when sand is urged by air, will render you better able to conceive its action when urged by water. The erosive power of a river is vastly augmented by the solid matter carried along with it. Sand or pebbles caught in a river-vortex can wear away the hardest rock ”

“ Zen answered.
Somewhere outside a man screamed, in terror.
The thing in the sky coughed again, closer now. BRRROOOMMM——BrrroooMMM——BrOOOm!
The blooper struck.
The sound was that of the simultaneous firing of many cannon. The walls of the prospect tunnel seemed to twist and wave. Loose stones dropped from the roof and a fine dust seemed to extrude from the walls. A boulder half as big as a small house hurtled past the entrance, snapping pines like matchsticks. A slide of loose rocks followed it. ”

“ Must he fly until he has ground his very body to such a thinness that the next obstruction will shatter it into ten thousand pieces, and hurl Bulger and me to death?
As these thoughts are flitting through my mind, the flying mass takes one last mad plunge which lands it on an almost level stretch of roadway, and by the different sound given out by the sliding block, I know that we have left the regions of ice behind us, and that our crystal sledge is gliding gently along over a track of polished marble. ”

“ That [Pg 113] foot bellows were employed before the system of working bellows, and producing a continuous blast by means of a water-wheel, is most probable. The foot bellows are known to most primitive people, but in Agricola's illustration of the smelting of tin none are shown. On the contrary, Æolus is represented in the corner as blowing a natural blast.
SLAG-POUNDING HOLLOWS, GOBBETTS.
The book of Agricola, published in 1556, shows that this primitive method was still in practice so late as the middle of the sixteenth century. ”

“ Where gas is not available, an ordinary gasoline blow-torch does very well for all operations requiring a large flame, and a mouth blow-pipe arranged to blow through a kerosene flame does well for a small flame. Several dealers make blow-torches for oil or alcohol which are arranged to give a small well-defined flame, and they would doubtless be very satisfactory for glass-work. Any good bellows will be satisfactory if it does not leak and will give a steady supply of air under sufficient pressure for the maximum size of flame given by the lamp used. ”

“ He went on, stepping across the fissure where the water flowed in, and keeping to the dank rim which widened as he proceeded. Although the walls rose roughly perpendicular with here an outward bulge, there a falling back to a steep incline, there was visible no passage nor even a split, save where the water came sliding down the fissure that was no more than a seam. All along the wall, high up wherever a smooth surface offered, there were the carvings, with little variation in their sinister portent, the great chain of evil, and the death of many. ”

“ We could not imagine, We had work enough trying to extricate the man before us, When the blow-out occurred, he was knocked senseless for a time, but then the black water and mud flowing in through the opening made by the outpouring air ran down over his face, and restored him to consciousness. ”

“ Jets of several sizes to fit the air-tubes of blow-pipes may be obtained with them, and will serve for regulating the supply of air to the flame.
The Bellows.—The usual blowing apparatus is some form of foot-blower. These may be obtained fitted to small tables with sheet-iron tops. But a much less expensive apparatus is the large foot-blower made by Mr. Fletcher of Warrington, which can be used at an ordinary table or laboratory bench. Good foot-blowers can also be obtained from makers of furnace bellows.
Fig. 2
No part of the glass-blower’s equipment exceeds the bellows in importance. ”

“ Blasting.—In some hydraulic claims, the dirt, in dry seasons, is blasted, so as to loosen it. A drift or hole is cut into the bottom of a hill, one or two hundred feet high, and a number of kegs of powder (from twenty to two hundred) are introduced, and they are fired with a slow match. The explosion makes an earthquake in the vicinity; and the ground is loosened to such an extent that there is a great saving of labor. The breaking up of the dirt and the exposure to the air are supposed to facilitate the washing greatly. ”

“ They tear off great masses of stone, which the resultant energy disturbances, pressure, gas, and friction, redden with heat. The mixture of gases from the decomposed water is in large amount, is burning and exploding, and in this fiery furnace amid such convulsions as have been described, the adjacent earth substance is fused, and even clay is melted, and carried on with the fiery blast. Finally the current reaches the earth's surface through the funnel passage, the apex of which is a volcano—the blast described a volcanic eruption. ”

“ A quick-burning explosive is all right in soft rock, or in soil with rock and earth mingled. But in rock that is harder than flint if you use a quick explosive, only the outer surface of the rock will be scaled off.
"If you take a hammer and bring it down with all your force on a hard rock you may chip off a lot of little pieces, or you may crack the rock, but you won't, under ordinary circumstances, pulverize it as we want to do in the tunnel. ”

“ A blast of air is supplied to it generally from two bellows, placed behind a wall of wattle well coated with clay, by which they and the men working them are protected from the heat. The blast is led from each bellows by a bamboo tube, terminating in a very long nozzle of clay, which rests on the edge of the furnace cavity. ”

“ Take a clay pipe, fill up with cotton wadding loosely and keep in place at mouth of bowl by a wire screen. Wet cotton with gasoline. Let the bubbles float in air and light them with candle, and they will explode with a big flame. Smoke-bubbles may be made by blowing in smoke after the bubble has been well started.
Rebounding Bubbles. A good game is to have a small sheet held by a number of children and blow the bubbles upon this, then they can be sent flying by drawing the sheet taut. Many ways may be devised to make blowing soap-bubbles attractive. ”

“ For blasting, a hole is generally drilled to receive the charge of explosive. The depth and diameter of the hole and the quantity of explosive used are all variable, depending on the character of the rock and of the explosive, the shape of the mass to be blasted, the presence or absence of cracks or fissures, and the position of the hole with respect to the free surface of the rock. The shock of a blast produces impulsive waves acting radially in all directions, the force being greatest at the centre of explosion and varying inversely as the square of the distance from the charge. ”

“ A young man who was tamping a hole in a rock, with an iron bar an inch in diameter and three feet seven inches long, had the bar blown through his skull by the premature discharge of a blast. The explosion drove the bar completely through his head, and high in the air. ”

“ Bellows now cut a great figure in the newspapers. An ass, poisoned by way of experiment, was restored to life by continual blowing into his lungs; and the Houses of Parliament are going to be furnished with pure air during the whole sessions by means of a great pair of bellows. As an infallible remedy against suffocation, nothing more is necessary than to hold the patient by the nose, and blow common atmospheric air into his lungs, with the bellows out of the chimney corner. There will therefore be a greater number of puffed-up people in England now than ever. ”

“ The old Sonoranian told me it contained no more pockets. His theory about the blow-hole is by no means confined to his own wild imagination; a man by the name of Black, who is one of the most successful gold-hunters in the ravine, is guided, in his researches, by the same seemingly absurd theory. It is possible that these blow-holes, as they are called, were the vents of volcanoes, performing the same functions as those found beneath the shaking cone of Etna. ”

“ But if once a blast is shewn, and they have to hoist out the rock, their obstinacy succumbs, and in three months, men, who knew it was poison, and so dangerous it was wicked to ask them to drill holes to receive it, have positively refused to descend a shaft if powder was attempted to be used merely in a comparative experiment, alleging, that the powder was unhealthy and not fit to be used at the bottom of a shaft, where the air was confined. ”

“ A blow like thunder followed; and, seeming to fall upon the locks and bolts of the door, dashed them at once to pieces, driving a part of the wood-work into the dungeon itself. Two more blows cast the whole mass wrenched from its hinges to the ground. A multitude of people rushed in, some of them bearing lights, all armed to the teeth, some bloody, some begrimed with smoke and gunpowder; fierce excitement flashing from every eye, and eager energy upon every face. ”

“ And now it strikes a stretch of way piled here and there with clumps and blocks of ice.
With a mad fury it springs upon the lesser ones with a growl of rage, grinding them to powder, which, like showers of icy foam, it hurls upon Bulger and me seated on its back. But some of the blocks resist its terrible onslaught and our mighty steed is hurled from side to side with crash and creak, as it drives its crystal corners fiercely against the jutting rocks, leaving marks of its white flesh on these black heads of adamant. ”

“ They had not then anything to fear from a disastrous encounter, when all at once a sudden explosion was heard, the silk of the balloon quivered, the car received a violent shock, and seemed to be shot suddenly into the gloomy abyss. A second explosion and a third succeeded, accompanied each time by this fearful shock to the car. The travellers soon found out that, owing to the great altitude, the gas had expanded, and the rope which surrounded it, saturated with water, and frozen with the intense cold, had yielded to the pressure, in jerks which caused the report and the shock. ”

“ Dry blowing is now much in vogue on the West Australian fields owing to the scarcity of water; but the great objection is first, the large amount of dust the unfortunate dry blower has to carry about his person, and secondly, that the peck of dirt which is supposed to last most men a life time has to be made a continuous meal of every day. ”

“ I concluded it was either leakage of gas into the manhole, or else the acid used in pickling the casting had given off hydrogen, and air had leaked in, making an explosive mixture. As this was a pretty serious problem, and as we had a good many of the manholes, it worried me very much for fear that it would be repeated and the company might have to pay a lot of damages, especially in districts like that around William and Nassau, where there are a good many people about. If an explosion took place in the daytime it might lift a few of them up. ”

“ When the blower places his incomplete bottle, still attached to the blowpipe, into the mold, he closes the mold with his foot, and blows through the pipe until the plastic glass is everywhere forced against the sides of the mold, and has impressed upon it the form of its prison. Then with a quick motion the blower detaches his blowpipe from the projecting neck of the bottle—the glass is still plastic—hands it over to the gatherer, and with a fresh blowpipe repeats his labor. Such constant blowing largely develops the muscles of the cheek, but the exercise is not unwholesome. ”

“ With a good blowpipe the air projects the entire flame, forming a horizontal, blue cone of flame, which converges to a point at about an inch from the wick, with a larger, longer, and more luminous flame enveloping it, and terminating to a point beyond that of the blue flame. ”

“ Heat in the blowpipe flame the point at which you wish to make the hole, and blow a slight bulge (1, Fig. 75) . Then heat the top of this bulge until it is red hot over an area about equal to the size of the hole you wish to make, and blow hard to make a thin bubble (2, Fig. 75) . Break away the thin glass of the bubble, smooth the edges, and the hole is made. The edge of this hole will project beyond the side of the tube (3, Fig. 75) . If you wish to make the edge even with the side of the tube, heat it in the blowpipe flame until it shrinks back level with the tube. ”