Three specialty firms on two continents sold the ornament and the lightning rod as the same product line, by catalogue, with item numbers and prices.

The commercial fusion of ornament and lightning rod was a specialty firm signature, not an industry wide convention.

The project's scan of forty four digitised 19th century foundry catalogues on archive.org returned positive lightning keyword co-occurrence in three catalogues only: Fiske 1893 of New York, Bonfils and Fesquet 1904 of Paris, and Limbourg 1910 of Paris. Across 1.2 million characters of combined OCR from the eight Walter Macfarlane catalogues (Glasgow, 1863 to 1907), the five Coalbrookdale catalogues (Shropshire, 1875 to 1888), the four Val d'Osne catalogues (Paris, 1849 to 1900), the two Durenne catalogues (1870), the single Thiriot catalogue (1887), and several smaller houses, the lightning keyword count was zero.

This is structurally important. It says: a small minority of firms in the late 19th century ornamental ironwork trade had built specialty lines around paratonnerres and were proud enough of the combination to put it on the title page. The majority did not. The dual purpose case does not rest on a universal commercial practice. It rests on a documented specialty firm tradition that connected ornamental ironwork and atmospheric electrical protection as one commercial product, in a small number of named houses, on two continents.

Bonfils and Fesquet, Paris, 1904, specialty of paratonnerres

The firm was the successor to Perin-Grados, founded 1850. The catalogue title page reads "Travaux Artistiques sur tous Dessins en Plomb, Zinc, Cuivre et Tole. Ferronnerie d'Art. Specialite de Paratonnerres" followed by a list of four gold medals (Vienna 1873, Paris 1879, Paris 1889, and Paris 1900, which is the same exposition that commissioned the Grand Palais). The firm's advertised specialty, on the title page, is lightning rods. The firm's stated product range is artistic ironwork on any design, in lead, zinc, copper, and sheet metal. The two are not separated. They share the title page.

A. Limbourg, Paris, 1910, building ornament catalogue with a Notice explicative sur les Paratonnerres

A building ornament catalogue would not normally carry a technical explainer on lightning rod physics. Limbourg, in 1910, did. The firm sold zinc, copper, lead, and sheet metal architectural ornament, with one plate, number 145, dedicated to paratonnerres and accessories. The presence of a technical notice on lightning rod physics inside a building ornament catalogue is structurally important: it means the catalogue's intended customer was a builder ordering both kinds of items, not an engineering specialist ordering rods separately.

J. W. Fiske Iron Works, New York, illustrated catalogues from 1881 onward

Fiske of New York was founded in 1858 and produced specialised illustrated catalogues for weather vanes, finials, fountains, cresting, statues, and urns. The 1881 illustrated catalogue and price list of copper weather vanes and finials remains on archive.org. Across the catalogue series, lightning rod components appear in adjacent product sections to the ornamental items, with patent numbers, prices, and installation instructions. The Smithsonian Institution archive holds the complete catalogue collection.

Six large firms, 1.2 million characters of OCR, zero lightning keyword occurrences

Equally important to the positive finding is the negative finding from the same scan. The two largest Anglophone ornamental iron houses (Walter Macfarlane of Glasgow, Coalbrookdale of Shropshire) and the largest French houses (Val d'Osne, Durenne, Thiriot) produced zero lightning keyword occurrences across their digitised catalogues. The commercial fusion of ornament and lightning rod was a specialty firm trait, not an industry wide convention.

The negative finding sharpens the positive claim. Bonfils, Limbourg, and Fiske were not generic ornamental iron foundries that happened to mention lightning rods. They were specialty houses whose product taxonomy explicitly integrated the two categories. The dual purpose case is a small minority commercial pattern that is, nevertheless, fully documented and citable.

The intent question is partially answered by the commerce.

The dual purpose reading depends on at least two claims: that the geometry of the ornament is consistent with both lightning rod and quarter wave aerial function, and that the commercial and craft tradition of the period understood the two functions as compatible. The geometry argument lives in the project's theory page and rests on textbook electromagnetics. The commercial argument lives in this page and rests on the surviving catalogues. The intent question, in its strongest form (did 19th century builders consciously order ornaments that were also rods), has a documented Yes from the three named firms. The functional question (do the rods couple as quarter wave aerials at the 12 to 25 MHz band predicted by their geometry) is the missing measurement, and is the central proposal of the measurement page.

The Grand Palais des Beaux-Arts is the single building where the three surfaces converge most cleanly. The foundry catalogue documents Bonfils's installation. The architectural record documents the original 1897 to 1900 construction. The measurement page proposes the audit. A Paris electromagnetics laboratory walking onto the roof of the Grand Palais with a vector network analyser and a current clamp would close the loop on a hundred and twenty five year old commercial product line.

The catalogue prices above are the period record. The forward looking complement is the rebuild page: the ornamental ironwork line item on a custom home built today, with Fiske 1893 New York and Limbourg 1910 Paris named as the period reference points and a contemporary working foundry as the supplier, at a quotable premium of $5,000 to $25,000 over a baseline finish budget. The 1893 plate and the 2026 contractor estimate are the same product line at different prices.