Read Ebook: Community Property by Coppel Alfred

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Ebook has 107 lines and 9255 words, and 3 pages

THE ENCLOSED FURNACE.

Still, a lot of the heat gets away. In a steam-boiler the burning fuel is enclosed either by fire-brick or a "water-jacket," forming part of the boiler. A water-jacket signifies a double coating of metal plates with a space between, which is filled with water . The fire is now enclosed much as it is in a kitchen range. But our boiler must not be so wasteful of the heat as is that useful household fixture. On their way to the funnel the flames and hot gases should act on a very large metal or other surface in contact with the water of the boiler, in order to give up a due proportion of their heat.

THE MULTITUBULAR BOILER.

The Babcock and Wilcox boiler is widely used in mines, power stations, and, in a modified form, on shipboard. It consists of two main parts-- A drum, H, in the upper part of which the steam collects; a group of pipes arranged on the principle illustrated by Fig. 5. The boiler is seated on a rectangular frame of fire-bricks. At one end is the furnace door; at the other the exit to the chimney. From the furnace F the flames and hot gases rise round the upper end of the sloping tubes TT into the space A, where they play upon the under surface of H before plunging downward again among the tubes into the space B. Here the temperature is lower. The arrows indicate further journeys upwards into the space C on the right of a fire-brick division, and past the down tubes SS into D, whence the hot gases find an escape into the chimney through the opening E. It will be noticed that the greatest heat is brought to bear on TT near their junction with UU, the "uptake" tubes; and that every succeeding passage of the pipes brings the gradually cooling gases nearer to the "downtake" tubes SS.

The pipes TT are easily brushed and scraped after the removal of plugs from the "headers" into which the tube ends are expanded.

Other well-known water-tube boilers are the Yarrow, Belleville, Stirling, and Thorneycroft, all used for driving marine engines.

FIRE-TUBE BOILERS.

Fig. 6 shows a locomotive boiler in section. To the right is the fire-box, surrounded on all sides by a water-jacket in direct communication with the barrel of the boiler. The inner shell of the fire-box is often made of copper, which withstands the fierce heat better than steel; the outer, like the rest of the boiler, is of steel plates from 1/2 to 3/4 inch thick. The shells of the jacket are braced together by a large number of rivets, RR; and the top, or crown, is strengthened by heavy longitudinal girders riveted to it, or is braced to the top of the boiler by long bolts. A large number of fire-tubes extend from the fire-box to the smoke-box. The most powerful "mammoth" American locomotives have 350 or more tubes, which, with the fire-box, give 4,000 square feet of surface for the furnace heat to act upon. These tubes are expanded at their ends by a special tool into the tube-plates of the fire-box and boiler front. George Stephenson and his predecessors experienced great difficulty in rendering the tube-end joints quite water-tight, but the invention of the "expander" has removed this trouble.

The water circulation in a locomotive boiler is--upwards at the fire-box end, where the heat is most intense; forward along the surface; downwards at the smoke-box end; backwards along the bottom of the barrel.

OTHER TYPES OF BOILERS.

In marine boilers of cylindrical shape cross water-tubes and fire-tubes are often employed to increase the heating surface. Return tubes are also led through the water to the funnels, situated at the same end as the furnace.

AIDS TO COMBUSTION.

The most important element in coal is the carbon . Its combination with oxygen, called combustion, is the act which heats the boiler. Only when the carbon present has combined with the greatest possible amount of oxygen that it will take into partnership is the combustion complete and the full heat-value developed.

BOILER FITTINGS.

The most important fittings on a boiler are:-- the safety-valve; the water-gauge; the steam-gauge; the mechanisms for feeding it with water.

THE SAFETY-VALVE.

In principle the safety-valve denotes an orifice closed by an accurately-fitting plug, which is pressed against its seat on the boiler top by a weighted lever, or by a spring. As soon as the steam pressure on the face of the plug exceeds the counteracting force of the weight or spring, the plug rises, and steam escapes until equilibrium of the opposing forces is restored.

On stationary engines a lever safety-valve is commonly employed . The blowing-off point can be varied by shifting the weight along the arm so as to give it a greater or less leverage. On locomotive and marine boilers, where shocks and movements have to be reckoned with, weights are replaced by springs, set to a certain tension, and locked up so that they cannot be tampered with.

Boilers are tested by filling the boilers quite full and by heating the water, which expands slightly, but with great pressure; by forcing in additional water with a powerful pump. In either case a rupture would not be attended by an explosion, as water is very inelastic.

The days when an engineer could "sit on the valves"--that is, screw them down--to obtain greater pressure, are now past, and with them a considerable proportion of the dangers of high-pressure steam. The Factory Act of 1895, in force throughout the British Isles, provides that every boils yellow painted face. "And dance?"

I smirked happily at Pancho. "And dance. At 1,000 prots each."

If Pancho had any reply for that, I don't know, for Gleda came in. She was wearing her hair blue and she wore a really striking pattern of iridescent blue paint with a double snake pattern coiling up her legs and torso.

The party got under way very quickly. Gleda supplied the alkie and treacle and everyone nibbled their own synthetic protein out of their pouches. The combination soon had an hilarious effect on the gathering and a couple that I didn't know, a boy and girl in particolored green and blue, starting throwing small articles of furniture at the Eyespy over my head.

Couldn't hurt the Eye, of course, but I was kept pretty busy dodging. Then Thais suggested a quick game of Clobber. I must confess, not without satisfaction, that I cheated a little and peeked through the bandage so I could land a real lulu on Pancho's long pointed nose.

Lyra tore down a drapery and staggering a bit from two or three too many alkie-and-treacles, wrapped herself in it from head to foot. There was a shocked sort of gasp from the watchers. Professor Cripps turned red under his yellow paint.

Gleda put a tape on the MusiKall and Lyra went into her act. I've never seen anything like it. Swaying like a cobra, her bare feet pounding out the beat on the plastic floor, she raised the temperature about ten degrees in that room. Her green painted lips twisted in agony, her eyes rolled in the chromatic mask of her face. An old folk tune--not the sort of thing she generally did. Something that really tore at the heartstrings. A song that dated centuries back. History and the sense of our way of life lived in that room for a few short moments. Her voice was a blood-stirring trumpet--

"Mairzy Doats and Lammsy Doats And little kiddsie Divy-- A Kiddlee Tivy Tooo Wouldn't you--?"

When it was over, there was a breathless hush in the room. I wondered where in the world Gleda had gotten that MusiKall tape--It had probably cost her plenty.

The Venerians trooped in and squatted on the floor while Gleda made the introductions. The room began to smell very like an embalming room must smell.

"May I present Clare, Vivian, Gail, Evelyn and little Jean. They're going to sing for us." Cheers from the guests. I glanced triumphantly at Pancho. The Professor seemed fascinated. "And," added Gleda archly, "they may even tumble for us." The Venerians looked at one another, tittered and flushed dark green. I was glad to see they were all on friendly terms with Jean.

Clare struck an attitude, crest erect, and waited until everyone quit shuffling around. Presently, they sang. I think it was singing. Very cultural. Very esoteric. Also very noisy. It sounded rather like they were all in pain.

After what seemed to me a very long time, they grew silent. There was a smattering of discontented applause. Gleda glared at me. I looked at Thais in dismay. "They also dance," she said weakly.

"Yes," Pancho said. "Let's see them dance!"

"Dance, fellows," I said hopefully.

Jean came over to me and whispered: "Are you sure it will be all right?"

"Do you want to ruin me? Dance. Tumble. Do something."

Jean shrugged and went back to where the Venerians squatted. "He says dance."

Evelyn and Gail stepped properly, I should say primly, aside and the other three began stomping about. The rhythm was infectious. The movements became more heated and shouts of approval began to ring out.

"Dance, Gookie!"

"Whapperoonie!"

"Go go go Gook!"

Pancho was delighted. So was the Professor. In the middle of it, the prof raised his hands and made a signal. An earsplitting clangor broke from the Eyespy.

The Venerians stopped.

Everyone stared at the Eye.

And at me.

The Professor stepped forward and flipped his Loyalty Oath over, it opened like a poison-ring. The engraving inside said TBI Morals Division.

"The Interlocutory Decree, if you please," he commanded.

Stunned, I fished it out and handed it over.

He glanced at it. "You realize of course that this is immediately invalidated."

"You know--as any Legal Eagle should know--that any re-stablishment of--uh--connubial rights abrogates an interlocutory."

"Of course I know that."

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