Dictionary of National Biography, 1885-1900/Pennethorne, John
PENNETHORNE, JOHN (1808–1888), architect and mathematician, son of Thomas Pennethorne and younger brother of Sir James Pennethorne [q. v.], was born at Worcester on 4 Jan. 1808. At an early age he entered the office of John Nash [q. v.] in London, and became the favourite pupil of his master. In 1830 he began a five years' tour of professional study in Europe and Egypt, visiting Paris, Milan, Florence, Venice, Rome, Athens, and Thebes. On his first visit to Athens in 1832 he observed the curvature of the horizontal lines of the Parthenon, and other deviations from recognised rules. While spending the winter of 1833 at Thebes he made careful studies of the mouldings and coloured decorations of the temples and tombs, and particularly of the curved lines of the great temple at Medinet Haboo. Returning to Athens in 1834, he renewed his study of the Parthenon, taking wax moulds of the mouldings and ornaments. He returned to England in 1835, but in 1837 he again visited Athens to make more complete observations and measurements of the curved lines and the inclination of the columns of the Parthenon. He finally came to the conclusion that there was no foundation in fact for the universally received notion that the system of design in Greek architecture was absolutely rectilinear. This discovery was first publicly noticed in 1838 by Joseph Hoffer in C. F. L. Förster's ‘Allgemeine Bauzeitung,’ 1838, vol. iii. p. 249, plates ccxxxvii–ix; but Hoffer quoted measurements of the Parthenon, which had been made subsequent to Pennethorne's investigations by Schaubert, a Prussian investigator. Schaubert arrived at the same conclusions as Pennethorne, and anticipated Pennethorne's publication of his results.
In 1844 Pennethorne published, for private circulation, a pamphlet of sixty-four pages, ‘The Elements and Mathematical Principles of the Greek Architects and Artists, recovered by an Analysis and Study of the remaining works of Architecture designed and erected in the age of Pericles,’ in which he showed how passages in Plato, Aristotle, and Vitruvius, hitherto obscure, were explained and illustrated by his discoveries in Athens. He set forth a theory of ‘optical corrections.’ The Greek architects, he showed, changed the first figure of their design into one which should produce to the eye an apparent symmetry and accuracy of outline, or, in the words of Plato, ‘the artists, bidding farewell to truth, change the real symmetry, and accommodate to images such commensurations as are only apparently beautiful.’
His discoveries were in 1846 pursued by Mr. F. C. Penrose, who, in 1851, published his ‘Investigations of the Principles of Athenian Architecture.’ The elaborate and exact measurements here given supplied Pennethorne with materials to fully work out his theory of optical corrections. Long-continued ill-health interrupted his studies, but in 1878 he published, in a noble folio volume, ‘The Geometry and Optics of Ancient Architecture, illustrated by examples from Thebes, Athens, and Rome,’ London and Edinburgh, 1878, with fifty-six plates in line and colour, and numerous woodcuts. Pennethorne sets forth in minute detail his theory of the manner in which the actual proportions of the original design were adapted to the optical conditions of correct perspective.
In February 1879 he contributed, to the ‘Transactions of the Royal Institute of British Architects,’ 1878–9, a paper on ‘The Connection between Ancient Art and the Ancient Geometry, as illustrated by Works of the Age of Pericles.’ Here he again explained how the Greek architects, having first designed a building so that geometrically its proportions were harmonious, afterwards corrected those dimensions with reference to the visual angle under which it would be seen, and by these methods of work produced a building which optically displayed the same harmony of proportion as characterised the merely geometrical projection.
Pennethorne died at his residence, Hamstead, Yarmouth, Isle of Wight, on 20 Jan. 1888.
[F. C. Penrose in the Times, 25 Jan. 1888; Breton's Athènes décrite et dessinée, Paris, 1868, p. 92; Dictionary of Architecture, vol. vi. ‘Optical Corrections.’]