One could claim that the history of the efforts to measure the Parthenon began with the visit paid to Athens by the humanist Cyriacus of Ancona at the time of the rule of Duke Nerio II of the Acciajuoli family. In a letter dated March 29, 1447 Cyriacus provides an elaborate account of his exploration of the monuments of the Acropolis,1 but his statements about the diameter of the columns of the peripteros, the width of the peristylar corridors and the length of the architrave beams are of little value.
The first significant effort to measure the Parthenon was that of the English mathematician Francis Vernon, assisted by Giles Eastcourt. In July 1675 the two had arrived at Athens together with the French archaeologist Jacob Spon and the English botanist George Wheeler, but these had continued for Constantinople. During his two months of stay in Athens, Vernon succeeded in visiting the Parthenon three times and in taking some measurements of it, in spite of the Turkish soldiers to whom his measuring appeared a particularly suspicious and threatening activity. Although Vernon and Eastcourt succeeded in leaving Athens without being shot at, they soon met with a tragic end: Eastcourt died in the Peloponnese and Vernon was murdered in Persia.
Nothing was left of the notes of Vernon, except for a brief excerpt that he sent in the form of a letter to the Philosophical Transactions.2 In this letter he provides some dimensions expressed in English feet, adding the qualification: These measures you can rely on as exact to 1/2 of foot. He reports that the peripteros has a length of 230 feet (70.10 m.), and that the cella, or body of the temple measures 168 x 71 feet (51.20 x 21.64 m), subjoining: I have taken all the dimensions within, with those of the pronaos and the Porticos; but they are too long for a letter.
As to the length of the peripteros, which Vernon calls the Portico, it can be observed that about a century later with a much more leisurely testing, Stuart and Revett obtained the result of 227 feet 7/20 inches, the correct figure being a trifle less than 228 feet 4 inches.
The report about the width of the cella is excellent, being close to the correct one of 21,733 mm. But there is an excess of about 9 feet 7 inches in the calculation of the length of the cella; probably Vernon included in the length the semi-circular apse that was added at the eastern front of the cella when the temple was converted into a Christian church. Vernon provided also the information that the columns of the peripteros have a circumference of 19 ½ English feet, that is, 5.944 m., against a correct figure of 6.053 m., which is about 4 English inches more.
Soon after Vernon had written the mentioned letter from Smyrna, Spon and Wheeler came back to Athens, where they remained from January 27 to February 14, 1676. An account of this visit was published independently by Spon in French and by Wheeler in English.
According to Spon the peripteros measures 218 ¾ x 98 ½ pieds de roi (70.815 x 31.997 m.)3 Wheeler reports instead a dimension of 217 ¼ x 98 ½ pieds, the first figure being the equivalent of 70.733 m. The measurements of length are in excess by 1.3 and 1.2 m., whereas the measurement of the width is in excess by about 1.1 m. Spon also reports that the circumference of the columns near the foot is 17 ½ pieds (5.685 m.). It can be concluded that Vernon proved more successful in the art of measuring.
Because the explosion completely changed the appearance of the Temple, it is expedient to pay close attention to the reports of Vernon, Spon and Wheeler, no matter how sketchy they may be. Those who have seen the temple after the explosion have been led to concentrate their attention on the peripteros, neglecting the cella. Vernon on the contrary focused his attention on the Cella or Body of the Temple. Spon too saw the peripteros, which he calls the Portico, as an addition to the temple, which he identified with the cella. Spon stressed the point, neglected by later investigators, that the cella is divided into two parts, of which the western is half as long as the eastern: qui tient presque le tiers de toute la fabrique.
Spon attacked the problem that has been ever since the major concern of all investigators, namely, to ascertain the dimension for which the Temple was called hekatompedos. He properly identified the temple in the narrow sense of the term with the eastern two thirds of the cella. he measured the internal length of this room and found it to be 90 pieds (29.236 m.), which by accident or by deliberate design was an excellent measurement.
In the middle of the eighteenth century the Englishmen James Stuart and Nicholas Revett, who had spent many years in Italy as artists, organized an expedition to Greece. In Italy they had absorbed the spirit of the architectural school of Palladio, a neo-classicism with great stress on mathematical proportions. From 1751 to 1753 they were in Athens where at great personal risk, because of the political conditions under Turkish rule, they measured the Parthenon and other buildings of the ancient city.
When the first volume of their report appeared in print in 1762,4 it was greeted as a great event in the history of scholarship, because it seemed as if their tests of the Parthenon had finally solved the problem of the Attic foot and, hence, that of the Roman foot. They found that the Parthenon, measured on the stylobate, is 1213.7 x 2731.05 English inches. Since there are texts that refer to the Parthenon as hekatompedos neos, one-hundred-foot temple, they concluded that the width of the Parthenon had been calculated as 100 of the Attic feet mentioned by Pliny.5 Dividing the width of the Parthenon by 100, they inferred that the Attic foot was 12.137 English inches, being 25/24 of a Roman foot of 11.651 inches. This result was considered most impressive, since there was general agreement among scholars that the Roman foot was most close to 11.650 English inches. The results of Stuart and Revett were so much in agreement with what was expected, that nobody at the time questioned the precision of their measurements.
If their results are converted into French metric units, making the conversion by the value of the foot according to the Imperial standard, the Attic foot (geographic foot in my terminology) is 308.2795 mm.; my estimate is 308.2765 mm. The Roman foot, computed as 24/25 of the Attic foot, is 11.65152 inches, or 295.9484 mm.; my estimate is 294.9454 mm. Their figures are practically identical with mine, within the limit of accuracy that Stuart and Revett aimed at achieving.6
A word of caution, however, is necessary. Stuart explains that he proceeded to the measurement by using a yard-long rule cut by John Bird of London, but does not add any further detail about his procedures of surveying. John Bird was the famous instrument maker who in 1762 at the behest of the Parliamentary committee appointed in 1758 to inquire into the original standards of weights and measures of this kingdom, constructed the yard rule which by the Parliamentary Act of 1824 became the Imperial Standard Yard. All interpreters of Stuart and Revetts report assume that the yards constructed by Bird before 1758 were identical with the one that he constructed in 1762. This may be correct. It may be that Bird, in executing the instructions of the Parliamentary committee foisted on them the standard he had been using earlier.7 If it were necessary, the value of the earlier Bird rulers could be determined, since several important astronomical observatories in Europe, including that of Greenwich, employed through the last century quadrants constructed by Bird before 1758, and these must be still in existence. The settlement of this issue, however, is irrelevant to the problem of the dimensions of the Parthenon, because Stuart and Revetts measuring was imprecise far beyond the differences that existed among the several standards employed before the Act of 1824. For the purpose of our reckonings we may convert Stuart and Revetts figures into metric units by assuming that their yard was equal to the Imperial Standard Yard.
Stuart and Revett concluded that the Parthenon had been calculated by a stylobate of 100 x 225 Attic feet, with a proportion of 4:9. They found that the length was less than ¼ of an inch more than 9/4 of the width, but they ascribed this discrepancy to an imprecision in measurement by the builders. This contention was accepted as correct for about a century and a half, thereby obscuring a basic problem in the study of Greek temples. The conclusion of my analysis is that Greek architects began with round figures for the stylobate, but then proceeded to divide the length into so many intercolumnia which had to be expressed in round figures as well. By adding the intercolumnia they arrived at an actual length of the stylobate that cold be a small fraction of a foot more or less than the figures taken as the starting point. In my opinion the Parthenon was a fraction of a foot larger than 100 x 225 geographic feet.
Through the nineteenth century it was accepted that the Parthenon had been calculated in geographic feet and that it had the width of 100 geographic feet, the feet called Attic by Pliny. But the other dimensions of the Parthenon could not be expressed in round figures by this standard. Hence, there was developed the notion that the details of the Parthenon had not been calculated by using simple multiples of the foot, but by using geometrical constructions or by reckoning by irrational numbers. Since the Parthenon is a monument well known to everybody, and since scholars could not provide an explanation for its dimensions, a similar phenomenon occurred as in the case of the Great Pyramid of Gizah: the dilettantes, some skillful and some not, and the cranks, rushed in offering their explanations. Bizarre theories on the dimensions of the Parthenon continue to appear even today. Not all of these works are worthless, because some contain valuable insights into Greek techniques of measurement, but none has arrived at an acceptable solution for the problem of the Parthenon.
In the light of later surveys, most of the measurements of the Parthenon by Stuart and Revett appear scanty in varying degrees. Most likely they did not taken into account the effect that a hot day has on a brass rule. For instance, they seem to have paid close attention to the dimensions of the columns of the peripteros, for which they report a diameter of the circumscribed circle of 1923.3 mm. and a distance between the opposite faces of the ikosagon of 1899.9 mm., whereas according to my reckoning the figures are 1926.7 and 1902.9 mm. For the dimensions of the stylobate we may compare the results of Stuart and Revett with those of Penrose:
When by the middle of the nineteenth century it was realized that Stuart and Revetts measurements of the stylobate were scanty, scholars split into two factions. One group continued to assume that the front of the Parthenon measured 100 Attic feet and increased accordingly the estimated length of the Attic foot and Roman foot, in spite of the evidence provided by hundreds of other sources, throwing thereby into confusion the study of ancient weights and volumes. Another faction denied that the Parthenon had gotten the name hekatompedos neos because its front measured 100 Attic feet, and presumed that the temple had been reckoned by another standard. Below I will show that actually the front of the Parthenon was intended to be hekatompedos, in the sense of being 100 of the feet called Attic by Pliny, but, for reasons that I will explain, was made a small fraction longer than 100 feet. The rule used by Stuart and Revett appears to have expanded in about the same proportion.