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Historic American Engineering Record
Panther Hollow Bridge
HAER No. PA-489

Pennsylvania Historic Bridges Recording Project - II
Spanning Panther Hollow at Panther Hollow Rd.
Allegheny County

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HAER No. PA-489
(Page 6)

proportional spending for such work: more than half of the Bureau of Parks' $527,000 budget for Schenley Park in 1896 focused on constructing the three bridges.(19) In 1896, the Bureau of Parks budgeted nearly $117,000 toward the cost of erecting the Panther Hollow structure and about $166,000 for the two other bridges.(20) In total, the city paid $167,700 for the structure, just $200 more than the contract price.(21)

Designers and Contractors

The Department of Public Works originated plans for the Panther Hollow Bridge, but the individual designer's identity is unclear. Project drawings include two aspects particularly relevant to studying technological history at the turn of the century: graphical calculations and a subtle aesthetic philosophical statement about the relationship of technology, humans, and nature.

An erection diagram for the structure prepared by Schultz Bridge & Iron Works shows the structure supported by falsework and the resulting member forces, and would be familiar to modern engineers.(22) A third element of the drawing presents structural analyses in a graphical format used until the mid-twentieth century but since discarded from engineering training. The scale in "strains" shows the forces on members, with a scale of 200,000 pounds to the inch drawn below for converting the zigzagging lines between panel points into force results.(23)

The project proposal drawing reveals further insights into the context of the bridge's construction. The proposal shows the elevation and a cross section of the steel and stone arch spans, with simple dimensions of span, height of the springing line, rise, and roadway and sidewalk widths.(24) An architectural sensibility permeates the drawing, from the shadow lines in the delineation of the stone arch to the roadway supports, which are shown lighter than in the as-built structure.

19. "Start To Build Park Bridges," Pittsburg Post, 6 July 1896; Pittsburgh, Annual Report... 1896, 334, 336.
The date for the bridge's dedication is often reported as being that of the first two panther sculptures, which occurred in early July 1897. Although the contractor expected the ceremony to be held 1 August, no mention of the event was found in local newspapers during that month.

20. Pittsburgh, Annual Report... 1896, 36.

21. "The Panther Hollow Bridge, Pittsburg, Pa.," Engineering Record 38, No. 1 (4 June 1898): 5; and City of Pittsburgh, Annual Reports of the Executive Departments of the City of Pittsburgh for the Year Ending January 31, 1912, vol. 1 (Pittsburgh: Pittsburgh Publishing Co., 1912), Table 3. Table 3 is an invaluable reference that lists all city-owned bridge, dimensions, contractors, contract prices, and dates of construction as of 1912. Dates occasionally differ by one year from those of known completion, possibly because of a difference in the date of payment and completion. Some data about early bridges at those sites is also included.

22. City of Pittsburgh, Engineer's Office, "Erection Diagram, Sheet No. 12" Drawing No. F-2795, n.d.

23. Justin M. Spivey, HAER engineer, personal conversation, July 1998.

24. City of Pittsburgh, Engineer's Office, "Project for Proposed Crossing of Panther Hollow," Drawing No. F-2776. n.d.

HAER No. PA-489
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The details of greenery in urns on the approaches, light posts with triple globes, and suggested lion sculptures on either end contrast with the relatively sparse structural details. Although a four-ribbed arch supporting the roadway was indeed built, the original proposal for one stringer between each pair of ribs and cables for diagonal bracing differed from the as-built
structure. The final structure included two stringers between ribs, stronger trussing under the roadway, and bars instead of cables for bracing.(25)

Curiously, a small figure of a man with hat and walking stick appears beneath the bridge, drawn nearly in proportion to actual human size. Traditional Chinese paintings emphasize the magnificence of nature by depicting the humans, cattle, or farmhouses as insignificant intrusions on a landscape of precipitous mountains. Using the same style, the bridge's rendition produces an ironic effect. The bridge elevation unites Homo sapiens and Homo faber, with the built world magnifying instead of diminishing human presence. The drawing subtly refers to faith in human ability to improve upon nature, echoing the Park Department's work in grading and reshaping the slopes of Schenley Park.(26)

The first drawing was probably prepared by a consulting architect or engineer with artistic training. The Department of Public Works received credit on other drawings, with the signatures of Director Bigelow and an engineer named Paul Brighton also sporadically present, but the creator of the initial proposal is unnamed. H. B. Rust, engineer in charge of the Bureau of Parks, may have been involved with the design over and above his duties as engineer. Historians Carl W. Condit and Donald C. Jackson cite Rust in their descriptions of the Panther Hollow Bridge, and this has encouraged a common belief that Rust himself designed the bridge. However, no information available through the City of Pittsburgh's Department of Engineering and Construction files makes any connection between Rust and the design. Henry Grattan Tyrrell noted that Rust directed construction of a later Schenley Park bridge, completed in 1897 for $240,000. That bridge was "quite similar" to the Schenley Park Bridge over Panther Hollow completed the year before: the 1897 structure also was a 360'-0" three-hinged steel arch over steep terrain, was 620'-0" long overall and 80'-0" wide, and had 50'-0" stone arches on each side.(27)

25. City of Pittsburgh, Engineer's Office, "Proposed Crossing"; and City of Pittsburgh, Engineer's Office, "Floor System," Drawing No. F-2783, n.d.

26. For excellent discussions of these concepts in a technological context, see David E. Nye, The Technological Sublime (Cambridge, Mass.: MIT Press, 1994); and George Basalla, The Evolution of Technology (New York: Cambridge Univ. Press, 1988). Compare the drawing to photos of Panther Hollow from 1908 - one showing a distant view of a panther sculpture and men working in ravine below; another showing sub-grade of bridle path on north side of bridge - in the City Photographer's Collection, Archives of Industrial Society, Hillman Library, University of Pittsburgh, Pittsburgh, Pa.

27. Carl W. Condit, American Building Art: The Nineteenth Century (New York: Oxford Univ. Press, 1960), 192-93; Donald C. Jackson, Great American Bridges and Dams (Washington, D.C.: Preservation Press, 1988), 151;
and Henry Grattan Tyrrell, History of Bridge Engineering (Chicago, 1911), 333-34.

HAER No. PA-489
(Page 8)

Different contractors erected the bridges, however: Drake and Stratton constructed the later structure, whereas Schultz Bridge & Iron Works built the first bridge over Panther Hollow.(28)

Schultz Bridge & Iron Works operated from about 1890 until 1900 at nearby McKee's Rocks, and has appeared in some publications as Schultz Bridge & Iron Company. The company had its roots in a firm founded around 1850 by C. J. Schultz, which began providing iron components for wood bridges but became the nation's first manufacturer of steel bridge materials.(29) Schultz Bridge & Iron Works was active in Pittsburgh bridge construction from 1896 to 1901, building structures at South Twentieth-Second Street in 1896, at South Highland Avenue over Pennsylvania Railroad tracks in 1898, at South Main Street over Saw Mill Run in 1900, and another three-hinged steel arch, the Forbes Street Bridge over Nine-Mile Run 1901.(30) Albert L. Schultz, son of the company's founder, supervised engineering for Schultz Bridge & Iron Works' contract at Panther Hollow. After studying in Berlin at the Royal Polytechnic lnstitute and returning to Pittsburgh, the younger Schultz worked briefly with the Iron City Bridge Company, then became president of the Schultz Bridge & Iron Works. Upon the formation of the American Bridge Company in 1900, he "was one of the first to merge his company into the present combination," eventually becoming director of the Operating Department for American Bridge. He contributed to the city's short-lived experiment with cable railways in the 1890s but was chiefly known for his involvement with bridge projects in the Pittsburg area.

28. "Decks Cleared by Councils," Pittsburg Post, 3 July 1896. This article also mentioned that a Pittsburgh councilman was a member of Drake and Stratton, which won the bid for the 1897 bridge. Drake and Stratton's experience included masonry and foundation work for the third Sixth Street Bridge, designed by Theodore Cooper and completed in 1892; see W. G. Wilkins, "The Reconstruction of the Sixth Street Bridge at Pittsburg, Pa.," Proceedings of the Engineers' Society of Western Pennsylvania 11 (1895): 150-51, 161-62; and "The New Sixth Street Bridge, Pittsburgh, Pa.," Railroad Gazette (28 July 1893): 560.

29. Victor C. Darnell, A Directory of American Bridge-Building Companies, 1840-1900, Occasional Publication No. 4 (Washington, D.C.: Society for Industrial Archaeology, 1984), 59. Although Darnell calls the variant "erroneous," the City of Pittsburgh Engineer's Office shop drawings for the Panther Hollow bridge bear the name "Schultz Bridge & Iron Co."

30. Pittsburgh, Annual Reports of Executive Departments.

31. Lewis R. Hamersly, Who's Who in Pennsylvania, listed. (New York: L. R. Hamersly Co., 1904), 661.

HAER No. PA-489
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Steel Arches

The Panther Hollow Bridge's main span is a three-hinged, spandrel-braced steel arch 360'-0" long, rising 45'-0" from the spring line (for a total height of about 1 l5'-0" from the ground to the bottom chord at mid-span). In spandrel-braced arches, an upper chord supports the floor beams, upon which a deck rides. The arch ribs forming the lower chord may be constructed with a variety of sections: I-beams, HH-beams plate or box girders, or hollow tubes. Webbing, commonly a system of diagonals, joins the upper chord with the curved lower chord, or rib. The entire frame is denoted as the arch. Because of their resemblance to truss construction, spandrel-braced arches with open webbing are particularly well suited for metal arch designs, according to a 1931 treatise on arch construction by Conde B. McCullough and Edward S. Thayer.(32) An article in Engineering Record revealed that the Panther Hollow bridge's engineer designed the parabolic lower chord to support itself, merely accepting uniformly distributed loads through vertical and diagonal web members. Only for "special" (i.e., concentrated) loads would the web members exhibit truss action.(33)

Steel arches may be either fixed or hinged, but among the latter most have two or three hinges rather than one. Three-hinged arches are statically determinate, unlike the other types, meaning that an exact structural analysis is easily accomplished. The three-hinged design also eliminates secondary stress caused by temperature changes, shifting in supports, and other causes. As statically determinate structures, three-hinged metal arches make better subjects for close calculations, which can reduce the cost of materials, noted McCullough and Thayer.(34) This appealed to engineers who, in the wake of the Eads Bridge's success in St. Louis, wished to exchange trusses for more attractive arches. According to Condit, the Panther Hollow bridge's design perfectly fit the environment and specifications of the ravine. The bridge matched its location's requirements for retaining a clear view of the surroundings and selecting the most elegant type possible:

In the rich quality of its simple, fine-textured masonry elements, in the lightness and purity of the arch, and in the sweeping curve of the parabola, with its 8:1 proportions, Panther Hollow Bridge satisfies these requirements as fully as it is possible to do so. It represents the culmination of thirty years of progressive development in the arch, and there are few structures of its kind that can match it.(35)

32. Conde B. McCullough and Edward S. Thayer, Elastic Arch Bridges (New York: John Wiley & Sons, Inc., 1931), 17-18.

33. Engineering Record, "Panther Hollow Bridge," 4.

34. McCullough, Elastic Arch Bridges, 18-19.

35. Condit, American Building Art, 192-93.

HAER No. PA-489
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In addition to the 360'-0" steel arch span, stone abutments at either end, each pierced by two 28'-0" arch spans, extend the Panther Hollow bridge to its total length of 620-0". Masonry plans for the approaches specified a main abutment pier of rough coursed stonework. Twenty-seven voussoirs, anchored by the number 14 keystone, form each of the closed-spandrel arches. Because of a projecting belt course, passages through the arches measure only 26'-9" from wall to wall, with a l0'-0" high column between the pair.(36)

The steel arch span springs from bridge seats 20'-0" thick and 70'-0" wide. Four box-section arch ribs rise from shoes on each seat to the l0"-diameter center hinge pin.(37) The shoes measure 5'-3" wide, 5'-1-3/4" high, and 4'-3" deep, with a 10"-diameter pin hole centered 3'-0" from the abutment side. The 6"-wide bearing surface was constructed out of laminated plates
gusseted vertically into the angle of the shoe.

Vertical and diagonal web members, mostly built-up box sections, connect the arch ribs to the deck, forming twenty truss panels each 18'-0" wide. five-inch-diameter pins occur at each panel point, according to truss details prepared by Schultz Bridge & Iron Works.(39) An erection diagram for Panther Hollow Bridge showed falsework in four places. Following this plan, workers constructed wooden trestle bents under panel points Ll through L3, L5 through L7, L13 through L15, and L17 through L19, to support the arch during erection(40)

The arch trusses are spaced 13-6" on center, which accommodates a 39-0"-wide roadway flanked by two cantilevered sidewalks each l0'-6" wide. Channel sections form crossed diagonal bracing in each panel between the arch ribs, as well as in transverse planes between vertical struts. The box-section upper chords occur at the same level as the roadway stringers, which are supported by 2'-10-1/2"-deep trussed floor beams running transversely. Cantilever brackets of similar trussed construction extend outward to support the sidewalks. Two 15"-deep I-beam stringers occur between each pair of ribs, and one l2"-deep l-beam stringer rims down the middle of each sidewalk, supporting Carnegie corrugated sheeting. The sidewalk received a 1-1/2" asphalt topping on concrete fill, separated by a 10"-high curb from the roadway, which was topped by a 2" asphalt layer on concrete fill.(41)

36. City of Pittsburgh, Engineer's Office, "Masonry Plan," Drawing No. F-2775, n.d.

37. City of Pittsburgh, Engineer's Office, Drawing No. F-2788, n.d.

38. City of Pittsburgh, Engineer's Office, "Shoe and Stringer Details" Drawing No. F-2792, n.d.

39. City of Pittsburgh, Engineer's Office, "Truss Details A-B-C, Sheet No. 1," Drawing No. F-2784, 28 Jan. 1896.

40. Pittsburgh, "Erection Diagram." Compare this drawing to City of Pittsburgh, Engineer's Office, Drawing No. F-27828 Jan 1896.

41. Pittsburgh, "Floor System."

HAER No. PA-489
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Decorative Features

Originally, a built-up hollow metal cornice combining angular and grooved faces supported an elaborate 3'-7"-high, wrought-iron hand railing. Separated by hexagonal paneled newel posts with scrolled and faceted caps, the railing design resembled interlocking paisley shapes with additional scrolled detailing. Over the abutments, stone balustrades interspersed with triple-globe light standards continue to pedestals for the famous panthers sculpted by Giuseppe Moretti, a locally prominent artist.(42)

During Independence Day celebrations at the bridge in 1897, city officials unveiled two of the panthers that soon became as much of an identifying symbol for the bridge as its elegant steel arch. Moretti's panthers were cast in bronze at the Gorham Manufacturing Company in Providence, Rhode Island. Each statue, with its 4'-6" x 6'-4" base, weighed 1050 to 1200 pounds. Two more of the muscled metallic creatures eventually completed a foursome guarding each corner of the bridge. The statues were said to be in tribute not to only the panthers for whom the hollow was named, but also in honor of Pittsburgh's colonial founders, who conquered a forbidding environment in establishing the western Pennsylvania city.(43)

Moretti also designed a statue of E. M. Bigelow for Schenley Park. Born in Sienna, Italy around 1837, Moretti studied in florence under renowned French sculptor Jean Duprez. Moretti completed works such as "Genesis of Electricity," which was displayed at an exposition in Nashville, Tennessee; large portraits for prominent citizens; and a local sculpture of Cornelius Vanderbilt that received acclaim for its verisimilitude.(44)


By no accident a steel arch was chosen to mesh with the natural topography and sculpted terrain of Schenley Park's Panther Hollow, a deep ravine making access difficult for park visitors. The Panther Hollow bridge's parabolic curves blended with the steep hillsides crossed by the structure, exemplifying the aesthetic concerns intrinsic to the parks movement. As a material, steel combined strength with flexibility, presenting a potent symbol of the new Pittsburgh elite whose growing fortunes derived from steel's versatility as a structural material in the late nineteenth century. The Panther Hollow bridge is a contributing structure to National Register-listed Phipps Conservatory and Schenley Park Historic District, and like them provides a metaphor for the entry of industrial elites into Pittsburgh's cultural inner circle during the late nineteenth century. Instead of merely walking across an existing structure to take command,

42. Pittsburgh, "Floor System," "Masonry Plan," and "Proposed Crossing."

43. "Unveiling of the Panthers." Pittsburg Post, 4 July 1897; see also Marilyn Evert, Discovering Pittsburgh's Sculpture (Pittsburgh: Univ. of Pittsburgh Press, 1983), 190-91. Dates reported by bridge historians vary because local newspapers carried accounts without references to an exact day of the week or date.

44. Pittsburg Post, "Unveiling."

HAER No. PA-489
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civic leaders such as Department of Public Works director Bigelow constructed physical bridges to turn their own vision of the City Beautiful into fact.(45)

Despite subsequent renovations, the Panther Hollow bridge remains historically significant.(46) It was built as part of Pittsburgh's City Beautiful movement and the massive public works program that created the water, sewer, and paved road improvements marking Bigelow's tenure. Schenley Park Bridge over Panther Hollow combines structural elegance with an appropriate use of the locally-produced building material upon which Pittsburgh's late-nineteenth century prominence was based.(47) Along with street cleaning, reconstruction of traction routes, installing utilities for communication and electricity, and building boulevards to enhance the city, Bigelow showed a concern for beautification in the parks that mirrored a growing local movement. The construction of Panther Hollow Bridge continued this assertion of civic authority for public purposes without challenging the city's business interests, imprinting Pittsburgh with a new style of municipal leadership for the next century.

45. A popular local journalist penned satirical poems about Pittsburgh's most prominent citizens. The opening lines of a poem about E. M. Bigelow read: "I am monarch of all I survey; My right there is no one to dispute; From the Hollow de Panther to points far away, I'm lord of the fowl and the brute."

See Arthur G. Burgoyne, All Sorts of Pittsburgers, Sketched in Prose and Verse (Pittsburg: Leader All Sorts Co., 1892), 17. See also Barbara Judd's evaluation of Bigelow's role in the Pittsburg parks movement, "Edward M. Bigelow: Creator of Pittsburgh's Arcadia Parks," Western Pennsylvania Historical Magazine 58, No. 1 (Jan. 1975): 53-67. For a study of the new and old elites in Pittsburgh's iron and steel industries during the nineteenth century, see John Ingham's Making Iron and Steel:; Independent Mills in Pittsburgh, 1820-1920 (Columbus: Ohio State Univ. Press, 1991).

46. The City Photographer's Collection, Archives of Industrial Society, Hillman Library, University of Pittsburgh, contains several photos of construction begun in 1932 on the deck and sidewalks.

47. Hamersly, Who's Who, 54.

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Page created: 15-Feb-2009
Last modified: 15-Feb-2009

HAER Text: Haven Hawley, August 1998; Pennsylvania Historic Bridges Recording Project - II
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