The generation of the radio-frequency current is by large-powered tubes which are operated with high voltages in their plate circuits.
The intensity of the oscillations of the current in these tubes is controlled by changing the voltage applied in their plate circuits.
Tubes are rated by the number of watts which can be safely expended in them.
In both types of amplifiers there is, of course, always the chance that the output circuit of one tube may be coupled to and induce some effect in the input circuit of one of the earlier tubes of the series.
In the Arlington experiments, which I mentioned a moment ago, the tubes were cooled by blowing air on them from fans.
In the large tubes used in high-powered transmitting sets it is much less.
Wherever the electrical effect is smaller than desired, or required for satisfactory transmission, vacuum tubes are used as amplifiers.
In recent transmitting sets the tubes are used in parallel for the reasons I have just told, but a different method of modulation is used.
Illustration: Fig 121] The audion amplifiers each consisted of a number of tubes operating in parallel.
In some tubes it may be five or six thousand ohms, and in others several times as high.
When tubesare operated in parallel they are connected as shown in Fig.
There are also small branch tubes leading into the upright gas-tube, and open to the atmosphere.
Thus the holes in the ring are considerably larger, while the three supply-tubes remain of exactly the same capacity as before; by which means the gas is delivered at a much lower pressure.
The products of combustion escape through a chimney; and in so doing give up a portion of their heat to the entering air, which is conveyed to the point of ignition through horizontal tubes that intersect the chimney.
Or the two concentric tubesare closed at the top with a ring, having small perforations, out of which the gas can issue; thus forming small distinct streams of light.
Before entering the chimney, the products of combustion are caused to flow through a number of vertical tubes contained in a cylinder, which is concentric to an inner cylinder containing the gas-supply tubes.
By these means the air is intensely heated; and, passing among the narrow burner tubes through which the gas is conveyed, gives up a portion of its heat to the latter before the point of ignition is reached.
Body somewhat compressed laterally; test thin and covered completely with sand, which is closely adherent; about three quarters of an inch in diameter; tubes short and wide apart.
From the attached end of the /manubrium/ four tubes or canals diverge, and, extending through the animal, open into a circular canal which runs around the margin of the umbrella.
Nearly globular when the tubes are contracted; usually covered with bits of eel-grass, seaweeds, sand, etc.
These worms may easily be mistaken for the mollusks /Vermetus/, which live in similar tubes of larger size, growing in masses.
Pinnixa cylindrica/, a related species, lives in the tubes of large annelid worms as a commensal.
The two tubes unite at the base of the gullet, and from there run as a single canal to the end opposite the mouth, and open to the outside through two excretory pores.
This is a common worm, and its horn-shaped tubes are so plentiful as to attract attention on sandy shores.
This genus, which is deep red in color and very fragile, consists of many tubes slightly separated from [pg152] one another, but connected by horizontal platforms at short intervals.
At a lady's entrance into the play-house, you might see tubes immediately levelled at her from every quarter of the pit and side-boxes.
C and C' are the tubes for putting the vessel about, and DD' the tubes for causing her to run backward.
Upon turning the two mouths of the propelling tubes backward, the boat was thrust forward, and, when they were turned toward the front, she was thrust backward.
All the evolutions were easy, even without the help of the rudder, and the ways in which the propelling tubes could be placed were capable of being varied ad infinitum by a system of levers.
This 'lolo' contains small bamboo tubes an inch or two long, and as thick as an ordinary Chinese pen handle.
In these tubesare fastened a piece of grass and a piece of sheep's wool.
Darting into the soil it frequently forms tubes of vitreous appearance by fusing the earth and stones as it passes.
As a remedy for external use in diseases of the bronchialtubes and lungs, mustard has not, in the author's opinion, any superior.
I consider the body as a system of tubes and glands, or to use a more rustic phrase, a bundle of pipes and strainers, fitted to one another after so wonderful a manner as to make a proper engine for the soul to work with.
The original tubes may have been copper or brass since these were easier to keep tight than the less malleable iron tubes.
This creates a partial vacuum in the smokebox that draws the fire, gases, ash, and smoke through the boiler tubes from the firebox.
Continuing his investigation of the basement, he came to the three huge fifty-horse-power engines, whose duty it is to suck the air from the pneumatic telegraph tubes in the great hall above.
She rose again like a cork, and in a few seconds freed herself from water through the discharging tubes in her bottom.
But tell me, May," said Phil, "do they really suck messages through tubes two miles long?
The chorus of singing birds sounded just like glass tubes being blown through water, and the phonograph simply made a horrid noise, so that you could hardly hear yourself speak.
Yet he could not rejoice in a complete triumph, for the severe inflammation of the bronchial tubes had caused a hoarseness which would yield to none of his remedies.
The bronchial tubes are tree-like branches of the windpipe, and extend to the lungs, which are extremely elastic and, upon being filled with air, become inflated and expand somewhat like a balloon.
It is, moreover, preventive of many affections of the lungs, bronchial tubes and throat.
It was a vacuum tube set with two tubes and power enough to send messages out over the whole county.
The main idea seems to be to make one tube do as much as three tubes did before.
The tubes are angular-sided instead of round, and much larger than in the B.
Tube surface:= Yellow or yellowish green, becoming bluish when bruised; opening of tubes large and angled.
The tubes beneath are covered by the veil in the younger specimens, but this at length breaks, leaving ragged fragments hanging from the rim of the pileus.
If your skin is chilled, the tiny mouths of the perspiration tubes are sometimes closed and can not throw out the waste matter.
The alcohol has made the hot blood rush into the tiny tubes near the skin, and he thinks it has warmed him.
Waste matter is all the time passing out through the perspiration tubes in the skin.
Those tubeswhich bring the blood back again to the heart, are called veins (vānz).
If you could piece together all these little perspiration tubes that are in the skin of one person, they would make a line more than three miles long.
These tubes are encased in black walnut, and each labeled with the name of the county from which the strata have been taken.
The strata, undisturbed, have been transferred to glass tubes six inches in diameter and six feet in length.
One of the girls making tubes said she was paid by the hundred, and could not earn $1 a day.
Casts of living persons are taken by having the individual breathe through iron tubes placed in the nostrils.
Replacing aqualung tubes with snorkels, they swam on the surface, faces down, alert for sharks.
The snorkels used by the boys were plastic tubes curved at both ends.
Though the Stardust was damaged too badly to return to earth, little of her equipment was harmed except for the rocket tubes themselves.
All the landing party wore light armour of steel coated with duralite, and carried ray-tubes at their belts.
Even the Earth-men of the landing party had drawn together in a compact group, ray-tubes ready and eyes alert.
The whole western wall has come down, carrying all the ray-tubes with it.
The short hand-tubes were soon exhausted, but the heavy ray-guns carried by two of the men fired steadily.
Even from this distance Gerry could see the hopelessly crumpled rocket-tubes at the stern, and the gaping holes where plates had been ripped away to make the submarine that had brought them out of the city of Larr.
He did not doubt that her duralite hull could withstand the explosive bullets of even the heaviest caliber gas-guns, nor that her three-inch ray-tubes could blast a way into these underground dungeons in a few minutes.
Then the forward rocket-tubes began to let go for the braking effect, and the flame of the discharges filled the control room with a flickering yellow light.
The big space-ship dropped down over the beleaguered city, her powerful ray-tubes flashing.
In one corner stood a compact two-way radio telephone set with its tubes still intact.
Her duralite hull would withstand either rays or explosives, and her own powerful ray-tubes should be able to blast the attacking artillery out of existence and thereby raise the siege.
The subdued blast of only two rockettubes began to drive the Viking forward at a slow speed of about 300 M.
Gerry stepped out into the clearing with his ray-tubes swinging free in his hand.
I saw the tubes on the walls," Gerry said, "but why is it that your mobile forces are armed only with primitive weapons like bows and arrows?
As the members of the landing party filed on board and turned their ray-tubes in to the Ordnance Officer to be recharged, the other members of the crew came out to stare at the visitors.
The blood vessels are elastic, and the study of the effect of a liquid pumped rhythmically into elastic tubesexplains with simplicity the various phenomena associated with the circulation.
These tubes are large near the heart, but smaller at their ends, where they flow into the veins, so that the blood does not flow out into the veins so readily as it flows in from the heart.
Within thetubes is the blood, which, from its liquid nature, is easily forced around the body through the tubes.
Instead, then, of playing with tops and dolls, her time was occupied in cleaning evaporating dishes and test tubes and in assisting her father to prepare for his lectures and experiments.
The same motion of the chambered receiver causes the divisions between the tubes and the chambered receiver to pass under and sustain the balls in the magazine.
These tubes are also open at their lower ends, so that the balls may pass from them into a chambered receptacle, l l, similar to that for the powder.
There are tubes called blood-vessels which carry the blood to all parts of the body.
By means of these tubes the blood is carried into every part where it is required.
The back part of the mouth joins the two tubes which lead from the mouth to the lungs and the stomach, and is called the throat.
The air-tubes and air-cells are well shown on the following page.
There has been provided a wonderful system of tubes running through every part of the body.
The tubes through which the blood is carried are called blood-vessels.
The saliva produced by the salivary glands is sent into the mouth through little tubes called ducts.
When the heart beats, it forces the blood through the tubes just as water is forced through a pipe by a pump or by a fire-engine.
The arteries and veins are connected by small tubes called capillaries.
The coiled parts of the tubes are called sweat glands, because they separate from the blood the fluid which we call sweat or perspiration.
In the chest the airtubes and lung of each side are enclosed in a very thin covering, called the pleura.
Involuntarily he changed it to 'computer logic' with the result that the question was utterly meaningless and caused Giac's tubes to short circuit.
Then there were the preliminary synthesizers, each of which unified in vapor-plutonium tubes the findings of its three separate feeders.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "tubes" in a variety of sentences. We hope that you will now be able to make sentences using this word.
