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Portable Wireless Tele. anced in the first case by a countergraph Stations

weight consisting of about 6 square

meters (64.7 sq. ft.) of copper gauze W IRELESS TELEGRAPHY is stretched out at a height of about 3972

being widely used at the present inches from the ground; while the moment in the Russian Japanese conflict. amount necessary in the second case is In order to show the convenience of this as high as 24 square meters (258.3 sq. means of communication in time of war, ft.). The antenna is supported either by it will be sufficient to state that a safe

kite balloons or by linen kites. connection up to more than four days'

Each station comprises three twomarching is possible when working with wheel carts-namely, the power cart, the the Morse apparatus, while in the case

apparatus cart, and the utensil cart. of acoustical records a distance even

The power cart contains the source twice as great may be covered.

of current, that is, a 4 horse-power benWe illustrate herewith the portable zine motor direct-coupled to an alternatwireless telegraphy stations designed by ing-current generator having an effective the Gesellschaft für Drahtlose Telegra- output of about i kilowatt, and to the phie, of Berlin, Germany.

exciting machine. In a special reservoir The stations are arranged for 2-wave

is carried the benzine necessary for about lengths, namely for a short wave of 350

30 hours' continuous telegraphic service. meters (1.148 feet), and a long wave of The balloon is pulled in by means of a 1,050 meters (3,444.8 feet), the antenna conical friction clutch, causing a cable remaining the same. for both. In the drum on the outside of the protective case of the short wave, the latter will casing to rotate. oscillate in 34, and with the long wave The apparatus cart, separated into two in lá, of a wave. The antenna is outbal- compartments, contains both the sending

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and receiving apparatus ; while the utensil cart contains the gas reservoir and the necessary intrenching tools, as well as the balloon and a reserve benzine reservoir.

Steel Tanks vs. Stand

pipes STEEL TANKS elevated high on posts w are rapidly taking the place of standpipes in cities where natural elevations are not available. To obtain satisfactory pressure, water must be stored above an elevation of 100 f.et. Thus, in a standpipe located on level ground much of the water contained therein is useless in affording pressure. The advantage of the elevated tank over the standpipe is that, for the same cost of construction, from two to three times as much water can be stored at the desired elevation.

One of these tanks recently built at College Hill, near Cincinnati, Ohio, is shown herewith. It is 154 feet high, and holds 100,000 gallons of water. This tank stands on top of four steel posts, and is reached by lofty stairs winding about the water-pipe. At the top of the stairs is a space around the tank, banistered off for an observatory. The tank not only has proved very serviceable to the suburb, but is an ornament to the land on which it stands.

At Galion, Ohio, the old standpipe proved so unsatisfactory that the city council required the Water Company to increase its storage capacity by building a tank. This has been erected, and now the pipe leading to the bottom of the tank as its central support is the old Galion standpipe. The Water Company claims that a saving of $1,500 per year in operating expenses has been achieved

The tanks are made with hemispherical bottoms, which design is said to be ideal.

Steel tanks are also gradually supplanting the wooden structures used by railroads. It is not necessary to keep them full in order to prevent shrinkage or collapse; and a portion of the bottom may be used as a receptacle for sediment, which can be drawn off without emptying the tank or interrupting its use.

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Grain-Bucket Tram

ways AWAY out at the town of Wawawai,

on the Snake river, in Whitman County, Washington, is a “bucket tram

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Grain-Bucket TRAMWAY IN OPERATION.

scending loaded, and 64 ascending empty. A man sits at the upper terminal, and by means of a lever operates the brake that regulates the speed.

This tramway has proved very successful. It saves a haul of from 15 to 25 miles over a rough, rolling country, down to the nearest railroad station.J. M. B.

way” that is used in conveying grain from a lofty bluff down to the steamboat landing.

Bucket tramways out West are not infrequently used for conveying ores in connection with mining operations; but this, so far as known, is the only "grainbucket tramway” in use in the world.

At the top of the bluff stands one immense grain warehouse. At the foot of the bluff on the river's bank, stands another. The elevation of the upper warehouse is 1,700 feet above the stream, and the distance between the two warehouses is 5,150 feet. The endless cable of steel wire is thus nearly two miles long.

The upper terminal of this cable tramway is a cast-iron wheel eight feet in diameter, furnished with a patent ratchet grip through which the cable passes, and a smooth, band-iron grip brake for regulating the speed. The lower terminal is constructed in the same manner.

The grain delivered at the upper warehouse is placed on “carriers” and sent down by cable to the lower terminal. The tramway is operated by gravity, the loaded carriers drawing up the empty ones.

The receiving cable terminal is placed in the tower of the lower warehouse; and the grain is conveyed in chutes from this tower, either to separate sections of the warehouse, or to the steamers in waiting

This tramway has a capacity of handling 200 tons of grain per day of ten hours, or a total of 75,000 sacks during the wheat season. The "carriers” or frames are placed along the cable at intervals of eighty feet. There are 128 of them, so that 64 are constantly de

Better Railway Sanita

tion. ANGERS of railway sleeping cars and plush seats in day coaches have been the objects of

special condemnation by the State of Kentucky, which thereby has won the approval of every railway traveler in America. The Kentucky State Board of Health places the plush seat under state ban, declaring it to be one of the most dangerous receptacles of filth and disease germs. Either leather or cane is permitted as a substitute. Linen would also make a good seat covering in that it could be taken off and cleaned at frequent intervals.

CHALK

TALKS

by CARL S. DOW.

Number Ten_The Condenser

The Steam Engine

sure. This back pressure is sometimes HE piston in the cylinder of

called the “exhaust pressure." a steam engine is compelled . Steam Engine Without Condenser to move back and forth by the The first sketch on the blackboard

expansive force of the steam, (Fig. 1) illustrates the cylinder of an which is admitted alternately to either engine, showing the piston, etc. The end of the cylinder. As the steam numerous small arrows indicate the highis under great pressure (from 80 to 200 pressure, or entering, steam; and the pounds per square inch), the force act- few arrows on the other side of the pising on the piston at a given instant is ton represent the low-pressure, or exenormous. After the steam has forced haust, steam. After having done the the piston to the end of the cylinder, a work of pushing the piston through a valve opens and allows the steam to es- stroke, the steam is driven out of the cape. This steam is called “exhaust cylinder by the piston on the return steam” because it is at low pressure and stroke, and thus forced into the atmosmuch of its energy has been exhausted phere.

Since the steam exhausts into the atPressures

mosphere, the back pressure must be

greater than atmospheric; if this were Let us understand at the outset that

not so, the steam would not be forced into the force causing the piston to move is

the air. In actual practice, the back presnet pressure, or the difference between

sure is about 2 pounds greater than atthe pressures on the two sides. In other

mospheric. words, if steam at 100 pounds per square

It is a well-known fact that the atmosinch is pushing the piston, and a pressure

phere exerts a pressure of 14.7 pounds of 15 pounds per square inch is on the

per square inch; this is usually considered other side, the force tending to move

as being 15 pounds. the piston is 100 — 15 (= 85) pounds per square inch. The result would be the Steam Engine With Condenser same if 85 pounds were the intensity of Steam is a vapor of water. A cubic pressure on one side and zero on the foot of water will make about 1,700 cubic other.

feet of steam at atmospheric pressure. This shows that the power of an engine From this we can see that when steam is can be increased by increasing the steam condensed, its volume is decreased. With pressure or by decreasing the back pres- a decrease in volume comes a decrease (188)

(Rights of Publication Reserved by Author)

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in pressure. Hence by condensing the rectangle A B C D of Fig. 4. Although exhaust steam, the pressure is reduced steam is admitted at 100 pounds per until it is almost nothing. In fact it is square inch, the average net pressure in often reduced 1212 to 13 pounds. To this case is only 70 pounds. thus reduce the pressure, the exhaust N ow let the exhaust steam enter the steam is conducted to a condenser; that condenser. The back pressure will now is, the cylinder is placed in communica- be about 12 pounds below atmospheric tion with a vessel cooled by water which pressure (see Fig. 5). The actual reenters in the form of spray (see Fig. 2). duction in back pressure will then be 14 This cooling draws the exhaust steam pounds; and the power developed will be from the cylinder, and, by condensing it, represented by the rectangle B C E F, if reduces the resistance, as already stated. FE is drawn below the atmospheric line Gain by Condensing

to the same scale as BC is above.

Now, if the power developed while Let us determine, if we can, the gain in

non-condensing is represented by the expower due to condensing the exhaust.

pression, Suppose the indicator card from a noncondensing engine is represented by the

70 X Length of Card, diagram (Fig. 3) on the blackboard. It

and that developed while condensing is is evident from the foregoing, that the

84 X Length of Card, then entire card is above the atmospheric line. the increase is evidently The scale of pressures is laid off as

14 X Length of Cand, and shown.

the gain per cent is In a previous Chalk Talk, we learned

14 x Length of Card_1 that the area of an indicator card is pro

70 X Length of Cardo portional to the power developed, and The gain in power does not indicate also that this area is equal to its length the gain in economy, although it is often multiplied by a height representing the economical to use a condenser. The relamean effective pressure. Therefore, the tive cost of the fuel and cooling water is work done may be represented by the the important factor.

Length of Card=5=20%

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