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Boy Builds a Steamboat

LL THE BOYS in Madison, N. J., envy William Webb Davis, Jr. He has built for himself a little steamboat, in which often accompanied by his sweetheart-he rides about on the picturesque Passaic river, visiting interesting points for miles around. The boat is but the latest of young Davis's mechanical achievements. He also has an automobile which he built all by himself, and the boy is only 16 years old. Here is his description of the boat:

"First I made the boat 12 feet long and 3 feet 6 inches beam. The sides are cypress and the bottom is white pine. The bow and stern have water-tight compartments. The paddle-wheels do not come below the bottom of the boat because the Passaic river is very

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shallow in places. The paddle-wheels and paddle boxes are removable, thus making it easy for transportation. The boiler is made of 8-inch wrought-iron pipe. I had a piece two feet long, with a cap on each end, and then drilled holes for the piping. The boiler jacket is made from sheet iron covered with asbestos, which also makes the firebox. The motive power is an upright engine of about one horsepower connected to the paddle shaft by a bicycle chain. I made a small check pump with two half-inch checks and a piece of half-inch brass pipe for the cylinder. The pump not only forces water into the boiler against steam pressure, but also acts as a bilge pump. I am now using wood for fuel, although I made gasoline burners and used them for a while. The boiler is equipped with steam gauge, safety valve, and whistle. The exhaust steam from the engine goes up the stack to make a forced draft. At the end of the boiler is a water glass showing the amount of water in the boiler. The boat may be steered by a person in the bow by means of a lever connected to the rudder with ropes."

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Basin Will Beautify Boston

PANNED by two of America's prettiest and finest bridges, surrounded by splendid parks and driveways, and located in one of the most picturesque parts of picturesque Boston, the proposed Charles River Basin is destined to be one of the handsomest municipal ornamentations in the world. The work is in the hands of a special commission, which will soon advertise for bids with a view of pushing the enterprise to a speedy completion. The basin will be formed by damming the Charles river and dredging the stream. The Congressional resolution authorizing the work provides that the Commonwealth of Massachusetts shall maintain the necessary depth and width of channel for the commerce of the river as fixed by the Secretary of War. The Basin Commission must operate the lock at its own expense, as a free navigable waterway of the United States, subject to such regulations as the Secretary of War may promulgate.

The dam, in deepening the stream, will add greatly to the importance of the waterway. The commission is required to maintain in the basin, from the head of the lock to the channel in the river, a channel 100 feet wide and 18

COURTESY OF THE BOSTON GLOBE.

GENERAL VIEW OF PROPOSED CHARLES RIVER BASIN, BOSTON, MASS.

feet deep at mean low water. Traffic in the basin, however, is to be given up to pleasure craft for the present, as the entire work is for the purpose of affording a place of public amusement and to beautify the city.

The accompanying sketch of the basin is from a large water-color by Walter P. R. Pember, made for the purpose of

the structure is to be opened for traffic next summer. This will be one of the finest and most artistic bridges of the modern world. In a bend of the river beyond, is the present Harvard bridge, resplendent at night with its graceful spans and its scores of lights reflected in the water.

The parkway will be continued from the Charles Bank southward and westward past the Union Boat Clubhouse, and along that part of the river on which the Beacon street mansions abut. All of this section is to be filled in to a width of about 100 feet, and connected with the Back Bay fens near Massachusetts avenue. This splendid boulevard will be planted with shade trees and shrubs, and will probably be connected with the West Boston bridge by a graceful sweep.

Boat landings will be located at frequent intervals on both sides of the basin for the benefit of those who wish to in

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HANDLING SALT BY HAND.

being placed upon the walls of the Massachusetts Building at the St. Louis Exposition. In the foreground appears the proposed dam, which will take the place of the present Craigie bridge, and hold back the waters so as to form the basin beyond. The dam is to be traversed by a wide and beautiful driveway, and will be 100 feet wide on top. The lock, which will be 350 feet long and 40 feet wide, will be a novelty in Boston. On the left or south side of the picture appears the present Charles Bank, which

extends from Leverett street to Cambridge and marks the beginning of the great Charles River improvement work.

On the right or north side of the picture, is shown that part of the Cambridge River Park, known as the "Front." It is pierced at its easterly end by the Lechmere, and, further along, by the Broad canal. Extending across the center of the basin is shown the magnificent new West Boston bridge, joining Boston and Cambridge. Work on this bridge is now rapidly progressing, and

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to harden and cake when piled away any length of time, and some of the cellars where it is stored contain beds of it twenty feet high and so hard that but little impression can be made upon them even with the pick or axe.

For this reason a somewhat curious device has been brought into use to loosen the material so that it can readily be secured. This is a large boring tool or auger which is operated by compressed air. As the photographs show,

by the power method as two dozen men by using picks and shovels.

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Great African Bridge

ICTORIA FALLS in Rhodesia, twice the width and more than double the height of the farfamed Niagara, are to be spanned by an enormous bridge to form a link in the Cape-to-Cairo Railway. The bridge will be 600 feet high, with a span of 500 feet, which would be high enough to permit nearly two of America's tallest skyscrapers to rest under it. The falls are on the Zambesi river, and were discovered by Livingstone in 1855, during his African explorations. Plans for the great bridge have already been prepared in London, and work is to begin without delay.

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PROPOSED BRIDGE ACROSS ZAMBESI RIVER AT VICTORIA FALLS, ON ROUTE OF CAPE-TO-CAIRO RAILWAY.

the auger is mounted on a wheeled truck which is guided by handles projecting from the rear of the framework. The rear end of the auger revolves in a socket fitted into the framework, while the air is admitted to the socket from the hose which supplies it. When operated, the boring tool is pushed against the mass. of salt, and the auger is set in motion; and in a minute or two-so rapidly does the tool work-a hole about five inches in diameter is made in the formation the entire length of the auger. Then another hole is drilled parallel with the first, and another, until the pile has been undermined, so to speak, when its contents can easily be broken out. The advantage of this method is seen when it is stated that two men can get out as much salt

LAUNCHING SUBMARINE "PIKE."

ment and built for a speed of eight knots an hour. Their cost is $170,000 each.

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CHALK
TALKS

by CARL S. DOW.

Number Eight-Capacity of Pumps

IN FINDING the capacity of a direct-acting pump, the water-end only need be considered. The steam

end is taken into account when the calculation involves the pressure against which the pump is to force the water. The size of the steam-end of a pump determines the pressure of the water issuing from the water-end, but has nothing to do with the amount of water delivered.

In the direct-acting pump, the water cylinder fills with water when the piston moves. Thus, when the piston is moving toward the right, the water follows it, filling more or less completely the right-hand end. On the return stroke, the piston forces this water out of the cylinder. Thus we see that the volume of water pumped per stroke is equal to the volume of the cylinder; or, to be more exact, the volume swept by the piston. This is also called the "piston displacement."

Calculation

The finding of the cylindrical volume of the piston displacement is no different from the finding of the volume of any right cylinder. Therefore we use the rules of mensuration. The volume of any cylinder is equal to the area of the right section (or piston) multiplied by its length (or stroke). In the first figure. on the blackboard, let D represent the diameter of the pump of the cylinder, and L the distance the piston moves at (200)

each stroke. Let us suppose, for example, that the pump is an 8x10; that is, the water cylinder is 8 inches in diameter, and the stroke is 10 inches in length. From the rules in mensuration, we know that the area of the circle representing the piston is found by multiplying .7854 by the square of the diameter. This would give us for the

area:

.7854 × 64 50.265

To find the volume, we simply multiply this area by the length of stroke, 10. This gives us the volume of the cylinder in cubic inches, since all the dimensions were in inches.

Experiment shows that there are 231 cubic inches in a gallon. Then, to find the capacity of this pump in gallons, we divide the volume in cubic inches by 231, which gives us 2.176 gallons per stroke. To find the capacity per minute, we simply multiply this by the number of strokes per minute.

In the above example, we had two constants-that is, two numbers that would remain the same whatever the dimensions of the pump might be. In the first place we multiplied by .7854. Later we divided by 231. As this calculation must be performed each time, we can do it once for all and obtain a new constant. Thus,

.7854 ÷ 231

(Rights of Publication Reserved by Author)

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