ENGINEERING STUDIES PART I American Stone Arches By CHARLES EVAN FOWLER, M. Am. Soc. C. E. "Whoever thinks a Faultless piece to see, Thinks what ne’er was, nor is, nor e’er shall be.” * * * * * * * * * "Content if hence th’ unlearn’d their wants may view, The learn’d reflect on what before they knew.” —Pope. FIRST EDITION. NEW YORK. THE ENGINEERING NEWS PUBLISHING CO. 1899. ERRATA. Page II—line 29, for ‘crown’ read ‘spring.’ Page 13—line 35, correct span is ‘150 feet.’ w mfc _ / ENGINEERING STUDIES PART I American Stone Arches By CHARLES EVAN FOWLER, M. Am. Soc. C. E. 'Whoever thinks a Faultless piece to see, Thinks what ne’er was, nor is, nor e’er shall be.” ********* "Content if hence th’ unlearn’d their wants may view, The learn’d reflect on what before they knew.” — Pope. FIRST EDITION. NEW YORK. THE ENGINEERING NEWS PUBLISHING CO. 1899. Copyright, 18!)!*, by CHARLES EVAN FOWLER. THE WISSAHICKON ARCH, PHILADELPHIA. ► T HE bridge in Fairmount Park, Philadelphia, over Wissahickon Creek is a very handsome structure, having been built from the design of General Russell Thayer, chief engineer of The Fairmount Park Commission, at a cost of $27,743, including the removal of the old bridge. The arch is on a skew of 69 degrees 26 minutes, which is taken up by arch rings, four feet wide each. The span of each ring is 106 feet 6 inches, the clear span of the arch 105 feet and the rise 11 feet. The spring of the arch is about six feet above the surface, at which point the arch ring has a depth of 4 feet 6 inches, while the depth of keystone is 3 feet. The roadway 25 feet in width and the two sidewalks of 5 feet width each are paved with asphalt. The stone of which the arch was built was quarried about one-half mile ^e site and is a dark colored gneiss. The stone work is quarry-faced a one-inch chisel draft at each joint, thus making a two-inch joint. This gives a very fine appearance to the work. |w depth at the center is relieved by the solid parapet, which le coping, post and caps, and which is supported on a cop- F/Aveli proportioned modillions. "symmetry of the design is unfortunately spoiled by the character fie bank at the left end, which is the more to be regretted as the right Rebutment is a most suitable and elegant arrangement. THE CABIN JOHN BRIDGE AND AQUEDUCT, NEAR WASHINGTON, 4 THE WHEELING, W. VA., STONE ARCH, o MEMORIAL RRIDOE AND ARCH, HARTFORD. CONN 6 THE EAST BRIDGE, ELYRIA, OHIO. THE WEST BRIDGE, ELYRIA, OHIO. 8 SCHENLEY PARK ARCH. PITTSBURG. 9 li'iGH BRIDGE, CROTON AQUEDUCT, NEW YORK. 10 WISSAHICKON ARCH, PAIRMOUNT PARK, PHILADELPHIA. ENGINEERING STUDIES. INTRODUCTION. This collection of photographic views of Engineering Works should be found valuable alike to the practicing engineer and to the student. Short descriptions and criticisms are appended to point out the good and the bad features of the designs, with the view of bettering the character of future engineering structures. A stone arch is very often regarded as a work of art so aesthetic, that it' cannot be injured in appearance by care¬ less detailing. Never was there a greater mistake than this, nor one more frequently made. The intention is to bring out a number of parts forming a series which will include, in addition to stone arches, Bridge Approaches of Masonry, Bridge Towers and Portals, Notable Bridge Piers, Tunnel Portals and other engineering works of like character. There will be six parts devoted to stone arches of several countries, and six or more parts devoted to miscellaneous structures. AMERICAN STONE ARCHES. THE CABIN JOHN ARCH. T HE largest stone arch ever built was the one constructed over the river Adda at Trezzo, by order of the Duke of Milan, about the year 1380. It had a span of 251 feet at low water, but it was destroyed in 1427, and now only about 24 feet of the arch ring, near each haunch, re¬ mains. The largest one in existence at the present time, is the Cabin John bridge and aqueduct over Rock Creek, at Washington, D. C. It was de¬ signed by Gen. M. C. Meigs, and has a span of 220 feet, a rise of 57 feet, while the roadway of 20 feet width is 101 feet above the stream. The arch ring is of granite, six feet deep at the crown and four feet at the cen¬ ter; the spandrels are of sandstone, laid partially with radial joints. The splendid architectural effect is due to the proportions and to the relief af¬ forded by the projecting courses at the roadway, which gives a cornice-like effect in entire harmony with the whole design. This can best be expressed by quoting from what Fergusson has to say in his “History of Architecture,” regarding the efforts of the engineer at architectural effects. “If this is all that can be done with bridges, (their decoration with inap¬ propriate details) it is far better that they should be left, like most of those recently built, to tell their own tale without any ornament whatever. A long series of tall arches is so beautiful an object in itself that it is difficult to injure it; but occasionally a slight moulding at the impost, a bold accen¬ tuation of the arch, and bold marking of the roadwav render those beauti¬ ful which otherwise may only be useful in appearance.” 11 54316 THE WHEELING STONE ARCH. T HE Wheeling stone arch bridge is one of the largest stone arches in the United States, having a span of 159 feet. The intrados is the arc of a circle, with a rise of twenty-eight feet. The depth of key¬ stone is 4' 6". Longitudinal arched voids are employed underneath the roadway. The engineers of the work were Hoge & White, the bridge being com¬ pleted in 1893. The large span marks the structure as a notable piece of engineering work, and the detail of the parapet is very pleasing in appear¬ ance, although very simple in design. The coping with the supporting corbels is also very effective. Berea stone was used for most of the work, which amounted to about 9,000 yards, there being 6,000 yards of dimen¬ sion stone. The cost of the bridge was $130,000. The meeting of two straight grades at the center of the span is hardly the best solution possible for giving increased waterway, although plenty of precedent can be found for such an outline. A much more pleasing method would have been to use a parabolic curve for the longitudinal profile of the roadway and coping. Had the offset in the retaining wall been made at the springing of the arch, as a division between the spandrel and retaining walls, it would have been more logical and the effectiveness of the structure as an architectural work much heightened. HARTFORD MEMORIAL BRIDGE AND ARCH. O NE of the handsomest stone arch bridges in the United States is the brownstone structure in Buslinell Park, at Hartford, Conn. Its effectiveness is largely due to the Memorial Arch, over the drive¬ way leading up to the Capitol building. The bridge was constructed originally in 1850, of Portland brownstone, and at a cost of about $15,000. Of the five arches, each having a span of twenty-five feet, the three center ones are semi-circular, while the two end ones are three center, with radii of feet and 14J4 feet. The original width of the bridge was thirty-five feet, but in 1885 it was rebuilt to match the Memorial Arch, and the width increased to forty-one feet extreme, or with a roadway of twenty-eight feet and two sidewalks of four feet each. The widening was accomplished by tearing down the spandrel-walls to the top of the arch rings and supporting the added width by elegant stone brackets, adding much to the beauty of the bridge; while the design was made to harmonize with the Memorial by a parapet railing of elegant design. The remodeling of the bridge cost $11,287, while the cost of the Soldiers’ Memorial was $60,000. This was executed in brownstone and terra cotta, from the designs of Mr. Geo. Keller, a prominent Hartford architect. The two structures, when considered as a whole, form one of the most notable of monumental works. 12 THE ELYRIA ARCHES. HE streams at Elyria, Ohio, have solid rock banks and beds, and the skewbaeks for the eastern and western stone arches are cut in the M. solid rock of the banks. The situations are very picturesque and the falls below the western bridge, forty feet high, add much to the view. The eastern arch is the third largest stone span in the United States and was constructed from the plans of E. C. Kinney in 1886; the span being 15U feet, the rise 24 feet, the width over all 32 feet, while the depth of the arch ring at the springing is 4 feet 6 inches and at the keystone 3 feet 9 inches. In the view of this arch, a beautiful two-span stone bridge on the Lake Shore Railway can be seen in the background. The western arch was designed by E. S. Jackson and E. M. Bunee and was built in 1894. This span is the fifth largest in the United States, having a span of 112 feet, a rise of 19 feet 6 inches, a width across the arch ring of 38 feet, and a width on top of 44 feet. The skewbaeks are from 4 to 8 feet above the bed of the stream, the arch ring having a depth at the keystone of 3 feet 6 inches. Both arches are constructed with first-class rock-faced masonry, the stone being Elyria sandstone, quarried in the vicinity. The width of both arches has been increased by projecting corbel courses and coping, which only serve to intensify the shallow depth at the center. Had separate corbels been sub¬ stituted for the corbel course on the large span, and for the lower corbel course on the small one, giving the effect of dentils, the appearance at the center would have been much improved. A stone parapet would have been a still further improvement in this respect. While having the graceful architectural appearance one would expect in arches of such bold outline, they are nevertheless somewhat severe in design. This effect has been lessened somewhat by the addition of the consoles on the eastern arch, which also afford retreats on the sidewalks. THE SCHENLEY PARK ARCH. HE stone arch bridge recently completed in Schenley Park at Pitts¬ burg is known as the Bellefield Bridge. It was designed by H. B. * Rust, Engineer of Schenley Park, and is one of the most elaborate stone bridges in this country. It has a span of 136 feet 7 inches and a width across the soffit of 82 feet. The roadway is 60 feet in width, while the two sidewalks have a width of ten feet each. The depth of keystone is four feet. The arch is a very bold one, and the general design leaves little to be desired, while the balustrade is a most elegant piece of work. It is, how¬ ever, unfortunate that the abutments and the spandrels were decorated with the paneling, as the apparent size of the arch is very much reduced by these details which have been characterized by Fergusson in a criticism of the Chester bridge as a mistaken application.— “by exaggerating his details, the bridge has been dwarfed in exactly the same manner as the basilica.’’ * * “It is far better that we should be content with plain, honest, solid but useful erections, than that our buildings should be adorned on the mis¬ taken principles which have hitherto been supposed to constitute the Art of Architecture.” 13 HIGH BRIDGE, CROTON AQUEDUCT. HE most notable stone bridge in the United States, not on account of the size of the spans, but because of its height, chaste design and mon- A umental character, is the structure which carries the Croton Aque¬ duct over the Harlem River at New York City, from the mainland to Manhat¬ tan Island. The erection of the remarkable Washington Bridge, close to it, with its great steel spans, instead of detracting from its appearance as might be expected has only enhanced it. The original intention was to carry the water across the river by a siphon pipe line through a tunnel, and, while the estimated cost was much less than for a high bridge, the uncertainties were so great as to cause its abandonment. The location is a very beautiful one, the south shore being an abrupt bluff of solid gneiss rock, crowned with trees. The requirements of navigation made it necessary to have a clear height of ioo feet above the river, and openings of 80 feet in width. The top of the parapet is 116 feet above high water, while there are eight semicircular arches of 80 feet each over the river, one arch of 50 feet in the Manhattan ap¬ proach and six arches of 50 feet span in the opposite one. The river is 620 feet in width at ordinary high water, the distance up to the springing of the arches being 60 feet, or 95 feet above the lowest foundation. The total length of the bridge is 1,460 feet, and it originally car¬ ried two cast-iron pipes, 3 feet in diameter, to convey the water, their use being with the object of preventing leakage, which would eventually injure the bridge. When it was desired to increase the carrying capacity a third pipe, 7 feet 6 inches in diameter, was added. The structure was designed under John B. Jervis, Chief Engineer of the Croton Aqueduct, and was let at a contract price of $737,755. It occu¬ pied five years in building, being completed in 1842 . The arch ring is finely accentuated, but, unfortunately, the tailing of the ring stones does not match with the courses in the spandrels. The piers, spandrels and parapets have a batter of 1 in 48 , the width across on top of die parapets being 21 feet. The length of the piers is greater than the width of the arches, and counterforts are carried up with good effect. The belt course directly above the voussoirs is in entire harmony with the cor¬ nice above, which is formed by ornamental corbels supporting the coping, thus making a portion of the footways on each side. The footways are protected by iron railings of light design, which, how¬ ever, appear well, owing to the great depth of masonry above the extrados. The difference in the height of the springing of the 50 feet spans and the 80 feet spans is taken care of in a very appropriate manner by the two coping- courses on the piers which are common to both. The water tower of elegant design adds much to the architectural ef¬ fect, which is not much marred by the well-designed stack. While many European structures are more expensive and more elaborate, High Bridge compares favorably with them, and will remain for scores of years, a credit not alone to the engineer who conceived it, but to the City of New York as well. 14 Engineering News BRIDGE BOOKS. GREENE, Prof. CHAS. E., “Structural Mechanics.” Cloth, G x 9 ins.; 271 pp. $3.00 HALL, JOHN L., “Tables of Squares.” Containing the True Square of every foot, inch and one-sixteenth of an inch between one-sixteenth of an inch and 100 ft. Flexible morocco, 3% x 5% ins.; gilt edges. 2.00 JOHNSON, Prof. J. B., “Engineering Contracts and Specifications;” includ¬ ing a Synopsis of the Law of Contracts and Examples of Various En¬ gineering Specifications. New edition, containing additional specifica¬ tions for electric railway work..... 3.00 OSBORN, FRANK C., “Tables of Moments of Inertia and Squares of Radii of Gyrations.” Flexible leather, 4 x 6% ins.; 175 pp. 3.00 WRIGHT, C.H., and WING, Prof. C. B., “Manual of Bridge Drafting.” Flexi¬ ble canvas, 9% x 12 ins.; 214 pp. and 24 pp. tables; 50 pp. plates and 6 full-size blue prints from actual working drawings . 4.00 SPECIFICATIONS. BOUSCAREN, G., “Specifications for Railway Bridges and Viaducts of Iron and Steel.” Paper, 8 x 13 ins.; 9 pp.25 COOPER, THEODORE, “American Railrpad Bridges.” Cloth, 7 X 9% ins.; “Specifications,for Steel Highway Bridges.” (1890.) Paper, 7 x 9% ins.; 25 pp.25 “Specifications for Steel Railroad Bridges.” (1896.) Paper, 7 x 9% Ins.;- FOWLER, CHAS. E., “General Specifications for Steel Roofs and Build¬ ings.” Paper, 6x9 ins.; 12 pp.25 OSBORN GO., “General Specifications for Railway Bridges.” Paper, 8 x 12 ins.; 10 pp....25 “General Specifications for Bridge Substructure.” 8 x 12 ins.; 10 pp.25 "Specifications for Metal Highway Bridge Superstructure.” 8x 12 ins.; 12 pp.....25 STOWE'LL, CHAS. F., and CUNNINGHAM, A. C., “General Specifications for Structural Steel.” Pap6r, 8% x 1314 ins.; 11 pp.25 SWAAB, S. 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