New Bridges Around Washington Some of the Enduring and Artistic Engineering Constructions Supplementing Nature's Handiwork at Beauty Spots in the Vicinity of the National Capital D By GUY ELLIOTT MITCHELL URING the last ten years, Congress has been fairly liberal in its appropriations for the improvement of the outlying districts of the national capital, and the Army engineers have taken much pride in devising plans for enduring and artistic engineering work. Rock Creek Park Rock Creek, a small stream which for years was the dividing line between Washington and Georgetown, is a watercourse possessing great natural wild beauty in the seven or eight miles from its debouchure into the Potomac back to where it is a placid stream traversing farm and meadow lands. Considerable of a torrent in the flood season, it has cut its way through the comparatively high outlying hills and heights north and west of Washington. Appropriations aggregating some million and a-half dollars were made by Congress to purchase 2,000 acres including the Creek, for the establishment of a national zoological garden, and, adjoining it on the north, a national park, known as Rock Creek Park. While the primal beauty of this region has, perhaps, not been enhanced by the building of perfect driveways and many bridle paths and the construction of handsome bridges, these works have made it possible for the country lover to visit and see this section, heretofore the haunt only of a great variety of birds and wood and water animals. The earlier history of the District of Columbia bird and animal life shows. Rock Creek to have been an exceptional breeding place. Over 500 species of birds have been observed within ten miles of the national Capitol building, and 100 have been known to breed within this limit. Many of these have retired from the scene since the opening of the Park; but in the early mornings of spring, Rock' Creek is still alive with dozens of species of feathered songsters. The Extension of Washington The City of Washington itself is rapidly encroaching upon the Park; and while the conservatives vigorously opposed such a large government expenditure in securing this land, the wisdom of Congress is now apparent. Magnificent residence structures now overlook the northwest, the cost of which will be about three quarters of a million dollars. This imposing masonry bridge will be from one of the best designs of the late George S. Morison, assisted by Edward P. Casey, whose work in bridge architecture has attracted considerable notice. The bridge will have five full-center spans of 150 feet each, and two full-center end spans of 82 feet each. The piers of the large arches are 20 feet thick; and those between the large and small arches, 37 feet. These thicknesses were determined partly on the ground of satisfactory construction, STYLISH LITTLE CEMENT AND PEBBLE BRIDGE. Crossing a tributary of Rock Creek in Rock Creek Park, Washington, D. C. Cost, $4,200. Park from the city side, while beyond, land which a few years ago was undivided farms, is now being built up with handsome suburban residences, and the trolley takes people quickly back and forth from the city. One of the most important improvements is the extension of Massachusetts Avenue. This is a government project nearing completion, and costing about $200,000. The Creek flows through a capacious granite tunnel with a 50-foot span covered by a huge embankment 80 feet high, which rises to the grade of the Avenue, enabling it to cross the Rock Creek ravine. Another large bridge project for which the pier foundations are going down, is the extension of Connecticut Avenue for the scheme of work contemplates the simultaneous construction of the large arches and the consecutive building of the short arches. The bridge will be 52 feet in width between the faces; and the total length between abutments, 1,341 feet a quarter of a mile. Above the main arches are a number of full-center spandrel arches having spans of 14 feet each, and supported by transverse spandrel walls 3 feet thick. These arches are open over the 150-foot spans, but closed by face walls at the piers and over the 82-foot arches. The main arches are to be built of 1:2:42 Portland cement concrete; the transverse walls, spandrel arches, and most other parts, of 1:22:6 Portland cement concrete. Alternative proposals will be received for cut-stone and for moulded concrete blocks for parts of the trim and faces. Rustic Ornamentation One of the handsomest rustic ornaments of the Park is a steel, rock, and cement bridge faced with rough, natural boulders, each as large as the body of a big man. This structure justly has the name of being one of the most artistic examples of engineering construction in the country. It has an 80-foot span and a 15-foot rise, and carries a 23-foot roadway. The clear width between the parapets is 23 feet; width over all, 27 feet. This locality of Rock Creek made it desirable to build a boulder bridge, if possible, for æsthetic reasons; but, as only $17,500 was available for construction, it was necessary to adopt some less expensive type, that selected being a Melan concrete-steel arch with a boulder facing, the concrete of the soffit being artificially darkened to harmonize with the faces of the stones. The specifications state that the boulder face of each stone shall project at least two inches beyond the neat lines of the bridge and not more than fifteen inches. The mortar consists of one part Portland cement and two parts sand. Two men were employed to do the entire boulder work, which, while apparently natural, required considerable dressing on the interior faces. Each stone is attached to the top of the adjacent steel girder by a solid steel cramp cemented for at least two inches in a hole in the stone. The outside girders were bound together, just before the concrete was put about them, by means of four 3/4-inch wire ropes. A number of arch stones were made by splitting boulders in two pieces. The bridge was designed under Captain L. H. Beach, Engineer Commissioner of the District of Columbia. The contract was for $14,890, exclusive of steel and royalties, which made the total cost $17,500, the amount of the appropriation. Any Sunday, thousands of stylish equipages cross this small span, their occupants enjoying the wild surrounding scenery, which but a few years ago was the resort of the small boy, willing to tramp miles to enjoy a cool swim in a deep, secluded hole. You cannot go forward without leaving some things behind. Everything should have some use, and we have no use for the thing that hasn't. Of course there are always some men who are not affected by good times. Above all, let us remember that our success in accomplishing anything depends very much upon our not trying to accomplish everything. Wanted-A Waterfall! NOT OT so long ago a waterfall was nothing more than a picturesque feature of the landscape. Its chief purpose was to inspire the rhapsodies of poets, and to furnish artists with subjects. for spectacular paintings. But now comes the science of engineering, and makes a waterfall a valuable commercial asset. All over the world, trained engineers are out looking for waterfalls as prospectors used to look for gold mines. And, if a fall be found within fifty miles of a large city or even farther off-it is likely to pay a larger profit than the richest of Golcondas. For a waterfall is a source of power, and power is a commodity for which the demand is limitless. Few mechanical inventions have produced more spectacular results than those which, by means of the electrical transmission of power, have made available the energy generated by far-off torrents of water. Already it has come to pass that a mountain river, tumbling over a ledge of rocks in some remote, almost inaccessible fastness, has been harnessed to turbine wheels, and forced to furnish light and power to the inhabitants of a city fifty miles away on the seacoast. For months Russian engineers have been searching the country about St. Petersburg for a waterfall which might do the work of the Czar's metropolis. Now they have found it. Up in rocky New England, the mountain rivers and brooks are being made allies of the manufacturing interests of that section. Even in Chicago, located as it is on swampy ground on the shore of Lake Michigan, the building of the great Drainage Canal to the Mississippi has made possible the creation of an immense water-power plant which may well, in the not remote future, furnish light for all the streets of the metropolis, and leave, besides, a surplus to be applied possibly to the running of municipal street-railways. The possibilities of solar motors and tide motors are as yet undeveloped. Meanwhile there is still plenty of wasted water power, which waits only the hand of the skilled engineer to be turned into a source of permanent profit. Don't waste your time looking for a gold mine! Go out and get an option on an undeveloped waterfall! Electricity on the Farm THE 'HE use of electricity on the farm offers inducements of which American farmers seem to be ignorant, but which would transform farm life into an existence of convenience and luxury from one of toil and frequent discomfort. France and Germany seem to realize the advantage of electricity on the farm, and the American agriculturist could gain many valuable ideas by touring the rural districts of those countries. Not only is this force capable of making the farmer's life more enjoyable, but it can be made a source of wonderful economy of labor and consequently a source of wealth. The cost is insignificant compared to the advantages. The American farmer, however, plods along in his easy way, taking it for granted that electricity is only for the convenience of the city. On the contrary, electricity can be made of tenfold more advantage to the farmer than to the urban resident; and he can better afford to enjoy its blessings, because the cost to him would be comparatively insignificant. He can have his own electric plant, whereas the urban resident must depend on the electric monopoly in the city where he dwells, and pay several times over the value for every electric light or other convenience electric power may afford. Frequently the farmer is so situated that the cost of an electric plant would be a minimum. Perhaps there is a waterfall nearby; or, if not, there is probably a swift-flowing stream somewhere on his land, which could readily be made to operate a plant to supply all the electricity needed. Or the necessary water force might be obtained by building a dam in any kind of running stream, and employing a simple water wheel such as can now be purchased at very low cost. Or, again, electric energy can be generated from a windmill and stored away in a storage battery. In fact the windmill offers a magnificent prospect as a source of electrical energy. Some farmers have not been slow to realize this, but most of them have concluded that the windmill can serve no other purpose than to pump water. One farmer near Chicago has everything about his place operated by electricity through the agency of a couple of big windmills. By means of electricity the house and grounds are lighted, and water is pumped for the cattle; electric bells are on all the doors; electric signals connect all the buildings; there is an electric burglar alarm system; a local telephone system reaches to every room in every house; his wife's sewing machine is run by electricity; her laundry iron is heated by the same means; and they have a small electric stove which is used when the power is not required for other duties. But even this enterprising farmer has not applied electricity to perform the most important farm work, as is done in France and Germany. In these countries, motors are adapted for doing all kinds of work-plowing, cultivating, reaping, etc. On smaller farms, tenants combine, making one motor do the work for all by carrying it from place to place as needs require. The saving of labor is so obvious, that, even among the most conservative, the value of the motor is admitted. By burying electrodes in the earth, and then applying electric power, the ground is freed from everything in the nature of crawling and creeping things, solving the problem of dealing with pestiferous insects. A writer says: "Even the farmer need only touch a button if he will avail himself of the results of modern science." |