Jet (gemstone)

“ With this jet there is little or no danger of the jet 'snapping' out through a surplus of oxygen, as the greater the flow of this gas, the greater the suction on the coal gas side.
The light is not quite equal to a good mixed jet, but very nearly so, and therefore this jet is deservedly gaining in favour every day. ”

“ Even so, jaded nerves or not, there's nothing else this side of the fourth dimension that for sheer thrill can touch rocket racing. The spectacle of twenty big torpedoes thundering along before the ground-quivering blast impact of their jets, unleashing power better suited to the vastness of space than to a race track, is soul shaking. ”

“ Having made a speedy retreat, I now took my station on the windward side, and was astonished to observe the elevation of the jets, some of them rising higher than two hundred feet; many of the fragments were thrown much higher, and some of considerable size were raised to an invisible height. For some time, every succeeding jet seemed to surpass the preceding, till, the quantity of water in the subterraneous caverns being spent, they gave place to the column of steam, which continued to rush up with a deafening roar for nearly an hour. ”

“ I’ve heard they’re hard on fuel. We’ll have the boys rig up a belly tank on your jet plane. Then you and I will give the ship a good tryout together.”
218
“That’s okay with me, sir,” said Jack.
“It’s not just for fun, or to try out a new toy. I want to warn you,” said the Commander, “that if this jet plane has enough range she’ll be the first scout sent out over Mindanao. It’s going to be very important that we have accurate information regarding ships in the harbor. With this plane you should be able to get that information and come back alive.” ”

“ Jet occurs chiefly in the neighbourhood of Whitby in Yorkshire, the estates of Lord Mulgrave being especially productive. The jet miner searches with great care the slaty rocks, and finding the jet spread out, often in extreme thinness, between the laminations of the rock, he follows it with great care, and is frequently rewarded by its thickening out to two or three inches.
The art of working jet is of very ancient date in this country, for the Romans certainly employed it for ornamental purposes, and probably found it in use among the Britons whom they conquered. ”

“ The steam breath gradually grows and is exhaled with more vigor. Presently he belches up a barrel or so of water which falls back into his throat. Then in a minute come two or three such little spasms, when up lifts a rounded column two or three feet in diameter, rising higher and higher in exact perpendicularity 150 feet high. The jet breaks more or less as it rises into pointed sprays, which, when there is no wind blowing, fall with almost precise regularity about the up going column. ”

“ You feel your grip slipping, know it can't slip, and dig, dig with your knees. You look up and there's the flame of a rocket jet missing you by inches. You look down and there's nothing to maim or sear you—just utter blackness. Believe me, that's worse!
I stared straight across the hull through a spiraling splotch of blue flame toward the stern rocket jets. The flame whorl came from diffuse matter friction. Tiny particles hit the ship, bounced off and set up an electrical discharge in the ether. ”

“ Malachite is found in Russia, France, the Tyrol, England, Scotland, Ireland, Germany, Africa, Chili, Australia, and the United States.
The finest specimens are found in the Urals—a block three and a half feet square, being valued at 525,000 roubles. [Pg 128]
Jet.
The making of jet or mourning jewelry was once a very large industry in France and England, and even now Whitby jet is well known in commerce.
Jet is a species of bituminous coal (cannel coal) which can be cut with a knife. The hardness is 1 to 2.5; specific gravity, 1.35; its lustre is not very high, and color pitch-black. ”

“ If we leave the resistance of the air out of consideration, the water in the horizontal jet has no obstacle to overcome; and it might go on for ever, if its weight did not gradually cause its path to become more and more bent towards the earth, against which it eventually strikes.
When the jet is vertical the case is altered. The water thrown up vertically constantly tends to fall down vertically, as any other heavy body would do, and its momentum has to overcome the obstacle of its gravity. ”

“ The lift or descent of the gravitor sufficed for climbing or diving maneuvers. He'd looked like a human fish swimming in the sky.
For the ships, of course, such a jet unit wouldn't do. The ships needed jets which would work while in motion, at speeds exceeding a hundred miles an hour. Thus, they'd had to fly the ship until its gravitors completely polarized its hull. Then they had to determine the air-flow over that hull at flying speeds with flow and pressure indicators mounted on the hull. ”

“ With them were found pottery and stone instruments, mullers and mills of granite. Armlets of bone [79] or ivory also accompany ancient burials, but hardly come within my province.
The use of jet for personal ornaments in pre-Roman times in Britain is quite in accordance with what might be gathered from the testimony of early historians. Solinus (circ. A.D. 80) mentions the abundance in this country of jet, which, he relates, burns in water and is extinguished by oil, and which, if excited by friction, becomes electric like amber. ”

“ The steam thrown into the air is nearly all condensed into little drops which fall back, and this condensation and this fall represent simply the loss of something, an interruption, a deficit. But a small part of the jet of steam subsists, uncondensed, for some seconds; it is making an effort to raise the drops which are falling; it succeeds at most in retarding their fall. So, from an immense reservoir of life, jets must be gushing out unceasingly, of which each, falling back, is a world. ”

“ When the belly tank had been rigged and the jet plane fueled, they took off.
“If I were sure of the oxygen equipment, sir,” said Jack as he set the jet plane climbing, “I’d take you to the stratosphere. There we’d really have distance aplenty.”
“That can wait,” was the answer. “Climb to five thousand, level off, then follow the course the task force has just covered. Our fighters are maintaining a night watch for snoopers, but if our fuel holds out we’ll cover a much greater distance than they.” ”

“ As we rise, the air becomes thinner. Finally a point is reached at which no propeller will ‘bite.’ The ceiling has been attained.
“With jet propulsion, exactly the opposite holds good. The less air there is, the more efficient is the motor. If the ejected gas has an expansion efficiency at rest of 40 feet in one-hundredth of a second—a rate of 4,000 feet a second—the same force exerted in motion would increase the speed up to a point where the maximum efficiency is reached at something like 10,000 miles an hour. Jet propulsion gets better and better as speed and height increase. ”

“ The jet plane began its predawn song. Jack and Stew were off.
The fog was gone, and the moon bright. Jack was astonished as he climbed into the sky. As far as he could see there were white dots telling of ships plowing their way through the dark sea.
“More fighting ships than the world has ever seen in one place,” he said to Stew.
“Sure—carriers, probably a dozen of them; big battle wagons, cruisers, destroyers, cargo vessels, transports, oilers, tankers, repair ships, PT boats—everything. We’re going back to the Philippines, boy! And we’re going back to stay.” ”

“ She was fourteen, and Vicki’s younger sister.
Their mother, Betty Barr, said, “I’m sure if I had your job on a jet-prop—Or is it a jet? Which is it, Lewis?”
Professor Barr looked amused. “You know perfectly well. The all-jet without propellers,” he said, “the Boeing 707, is used more for long hauls—nonstop coast to coast, or across oceans. The Electra 188, with jet engines and propellers, is used mainly for intercity travel. I trust I have the facts correct, Victoria.” ”

“ In one awful surge my big sizzle buggy kicked itself out of the starting tube.
That first magnet bend on the big elliptic is always the worst. Anything can happen when twenty bunched up rockets go into that curve still fighting the blasting surge of their starting momentum.
Automatically I set my repulsion magnets and increased the starboard trimming jets to ride the fence around. It's the only safe way to take that first tight corner. With the magnets of one rocket playing against the next and the last ship cushioned against the fence, you're in a groove as neat and cozy as a baby in a crib. ”

“ In its normal state the jet resolves itself into drops, which even before passing the summit, and still more after passing it, are scattered through a considerable width. When a feebly electrified body (such as a stick of sealing-wax gently rubbed upon the coat sleeve) is brought into its neighbourhood, the jet undergoes a remarkable transformation and appears to become coherent; but under more powerful electrical action the scattering becomes even greater than at first. ”

“ It was while gliding through these latter waters that one serene and moonlight night, when all the waves rolled by like scrolls of silver; and, by their soft, suffusing seethings, made what seemed a silvery silence, not a solitude; on such a silent night a silvery jet was seen far in advance of the white bubbles at the bow. ”

“ Some years ago experimental water-jet vessels were built in New York in which a jet only 5⁄8 inch in diameter with a pressure of 2,500 pounds per square inch was used, but the experiment proved a failure. The propelling force of a jet is the reaction of the stream of water against the orifice from which it issues. The action is just like Hero’s reaction steam turbine referred to on page 143. The propulsion would be the same were the jet discharged in the open air or in a vacuum or against a solid stone wall. ”

“ The exact design of this jet varies considerably, but all are alike in this, that a jet of coal gas is burned at the orifice of a more or less open nozzle, and a stream of oxygen blown through it on to a cylinder of lime which it thereby renders incandescent. Fig. 15 represents the various designs chiefly adopted for this jet, that marked A being perhaps the most usual, though C is also frequently met with.
In light-giving power there is not much to choose between the various types ”

“ Intermittent illumination, however, with frequency equal to that of the fork shows at once that the jet is really broken up into drops, one for each vibration, and that these move over in a steady procession. The cylindrical form of jet is unstable if its length is more than ir times its diameter, and usually the irregular disturbances it receives at the orifice go on growing, and ultimately break it up irregularly into drops which go out at different rates. ”

“ I flew it through all the maneuvers I wanted for twenty minutes, then landed, and taxied up to the line.
“‘I wanted to check the fuel before resuming flight, so before turning on the main switch to read the electrical fuel gauges, I stuck my head out of the cockpit and shouted, to warn the mechanics to stay clear of the propeller, completely forgetting that I didn’t have any propeller.’...
“Jet propulsion is necessary if we are to exceed the possibilities of propellers. A propeller literally screws its way through the air. The blades cause a partial vacuum. ”

“ A small jet is fitted for starting and running without load. The channels cast in the crank chamber, already alluded to in connection with oil-cooling, serve to warm the air before it reaches the carburettor, of which the body is water-jacketed. ”

“ The softer kinds, not capable of being freely worked, are known as bastard jet. A soft jet is obtained from the estuarine series of the Lower Oolites of Yorkshire.
Much jet is imported from Spain, but it is generally less hard and lustrous than true Whitby jet. In Spain the chief locality is Villaviciosa, in the province of Asturias. France furnishes jet, especially in the department of the Aude. Much jet, too, occurs in the Lias of Württemberg, and works have been established for its utilization. In the United States jet is known at many localities but is not systematically worked. ”

“ A jet scorch it was, and a few hundred yards away the sunlight glittered on a round lump that couldn't be anything but a Mitchell blister. Of all the rocks in the Belt, I would bump into one with a station on it. Nice catch, Denby!
I crawled into the bulger again in case I might set her down a little heavy, and got at the controls. Landing on the steering jets is tricky, especially when there is no atmosphere to help you brake down. I never would have made it if it had been a full-sized planet. ”

“ A small wire-wound jato for jet-assisted-take-off will weigh a hundred and forty pounds and deliver a thousand pounds of thrust for fourteen seconds. And that is for rockets using nonpoisonous compounds. The jatos of the pushpots used the beryllium-fluorine fuel that had lifted the Platform and that filled the take-off rockets of Joe's ship. These jatos gave the pushpots themselves an acceleration of ten gravities, but it had to be shared with the cage and the ship. ”

“ White jet comes from Norway, black jet comes from England, black glass jewellery comes from Germany. Jet is the lightest, the most precious, the most costly. Imitations can be made in France as well as in Germany. What is needed is a little anvil two inches square, and a lamp burning spirits of wine to soften the wax. The wax was formerly made with resin and lampblack, and cost four livres the pound. ”