l8iS.| 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



151 



buildings, excepting a rumour which I heard from our consul at Trieste, 

 that there was something very curious recently discovered in the ancient 

 buildings at Athens. 



These peculiarities, which were then pointed out to me, were the convexity 

 of the stylobate on the four sides of the building, and the inclination of the 

 columns towards the centre of the building ; that is to S2y, on the east front 

 the axes of the columns incline in a westerly direction, and those of the 

 west front easterly. Those on the north and south flanks, south and north 

 respectively. It follows that the angle columns share the two inclinations; 

 for instance, the north-east angle column inclines in a direction south-west. 



This fact has been ascertained some time; it is given with considerable 

 accuracy in that part of the supplement to Stuart which was supplied by 

 Mr. Jenkins. The exact amount, owing to the slight displacements which 

 the building has suffered, is only to be obtained by a diligent survey of tbe 

 whole building. 



The observation of the convexity of the lines of the steps is more recent. 

 I believe that one of our countrymen, Mr. John Pennythorne, was the first 

 who paid any discriminating attention to these lines. I use this phrase as 

 they cannot but have in some measure influenced our earliest investigation, 

 as no one could ever have cast his eye along any portion of the upper mem- 

 bers without being sensible of them. The lower lines of the building were, 

 as I understand, quite encumbered with rubbish until the excavatious of the 

 last few years. Any measures obtained by boring must have been vitiated, 

 and they have doubtless given many a diligent measurer a vast deal of trou- 

 ble, and many have been the dimensions which have stood at dismal variance 

 with themselves, and been cast aside without being really to blame. 



Mr. Pennythorne was the first to see in these an original intention and 

 meaning ; he however kept his knowledge to himself, and the world first 

 heard of it through the communication of MM. Hofer and Schawbert, German 

 architects, to the Bauzeitimg, in the year 1838. 



I was very much struck, as all who have seen the Greek buildings must he, 

 by the perfection of the workmanship, and I took such levels and dimensions 

 as I could with the instruments I had with me, for the purpose of ascertaining 

 the amount and nature of these adjustments. And I arrived at a suflicient 

 degree of exactness to assure myself that it was well worth while to go 

 deeper into the matter. I, however, (in 1846), was not able to pursue the 

 subject any further, and I returned to England in the autumn of that year, 

 and had the pleasure of reading a paper to this Institute on the observations. 



They attracted more sensation than I had any right to expect, and I re- 

 ceived a proposal from the Society of Dilettanti, that if I were willing to go 

 out to Athens, for the purpose of taking more accurate observations, they 

 would assist ray operations with a sum of money. This proposal I willingly 

 accepted, and provided myself with the necessary implements, and induced 

 a young architect (son of Mr. E. Wilson, of Lincoln, the well-know archaeo- 

 logist) to accompany me, and we arrived at Athens towards the end of 

 October last year. I was also so fortunate as to fall in company with Mr. 

 Meyer, associate. 



The first thing which we attempted was the measurement of the base 

 line, namely, the length and breadth of the building. This was done with 

 steel tubular measures, compared at the time of measurement with the 

 thermometer, from which also long deal rods were graduated for the mea- 

 surement of the heights, and for general purposes. The steel rods were 

 carefully compared by Mr. Simms, both before and after my return, with his 

 standard, and 1 gave the results as delivered at Athens. They are still sub- 

 ject to a very minute correction, but not worth troubling you with at 

 present. 



.\s soon as the weather allowed, and the requisite permission obtained 

 from the local authorities, I proceeded to hoist a scaffolding at the east-end, 

 of which I made an entire circuit, beginning with the three columns which 

 are standing on the north side, and ending with the south-east angle column. 



In tliis examination we plumbed every column, measured every stone of 

 the architrave, the capital, and upper and lower stones of each column, 

 in every direction ; took careful measurements of all the cracks which have 

 in any way modified the original form, and obtained levels of all the lines of 

 the entablature at fixed points; and finally examined the entasis of five dif- 

 ferent columns, taking several sections of each. 



We then migrated to the west-end, where I contented myself with making 

 an exact examination only of the two angular columns, which position en- 

 abled me to obtain the levels of the upper members of the western part. 

 I also took all such measurements in the western parts as my examination of 

 the eastern part had pointed out to me as necessary to arrive at the exact 

 original state. I then proceeded to examine the upper members of the 

 posticum, and the arrangement of the tympanum, which has some pecu- 

 liarities worth notice connected with the support of the statues. Then the 

 roofing, the ceiling, and lastly, the original painting, engaged our attention. 



This work in the upper part of the building was naturally very much ex- 

 posed to wind, &c. It often happened that while it was impossible to do 

 any accurate work on the scaffolding, we might be employed profitably 

 below. But frequently it was altogether out of the question to go up to the 

 Acropolis at all. The pavement was of course levelled in every part and 

 several times over, until the whole system worked perfectly together, and I 

 could satisfy myself that I had got the exact curve in every instance, or at 

 least within one or two thousandths. We also took such measures as suf- 

 ficed for the accurate position and proportions of the cella, with the ar- 

 rangement of columns within it. This sums up our proceedings at the 



Parthenon, which occupied nearly five months. The Propylaa O'cupieu a 

 considerable share of aitentiun, and I searched the temple of Theseus to find 

 how far it was analogous to the Parthenon. 



Last, but not least, we ascended tbe temple of Jupiter Olympus, from 

 which we obtained various measurements and drawings. 



Tbe measurements of the breadth of the temple on the upper step, at the 

 east and west ends, I found to he respectively 101'341 and 101-3C1, — 

 north and south, 228-141 and 228'154 respectively. Tliis exceedingly 

 small difterence in measures which were certainly intended to be equal, 

 pomis out the limit of error, which can be attributed solely to inaccuracy 

 of measurement in other dimensions, namely, about 1 in 5,000. I may 

 just observe that I found my wooden measures, notwithstanding they hail 

 been previously saturated in oil, subject to a fluctuation in various states of 

 the atmosphere rather greater than this amount. So that, bad the eastern 

 front of the Parthenon been set out with deal rods on a dry day, and the 

 western on a moist day, we should have had as great a difference between 

 them as actually exists. 



It follows that all quantities which tend to proportionality must be looked 

 at with great suspicion, in which varieties exist sensibly greater than this 

 small admissible error. 



The breadth of tbe temple of Theseus is 45-011, and its length is 104-23. 

 The former is almost exactly in proportion of ^ths of the breadth of the 

 Parthenon : this, I think, was intended. 



But a difficulty occurs if we attempt to proportion the front with the 

 flank on the upper step. It has been suggested to try the equilateral 

 triangle. That, however, notwithstanding its being near enough tbe mark 

 to suggest the trial, leaves the quantity = -282 unaccounted for at tbe end ; 

 and, besides, I do not find that in the Parthenon there are any affinities 

 whatever to that figure. 



I very much prefer to descend from the upper step, and try the propor- 

 tions on the second. By this addition, the flank becomes 106-63, and the 

 front 47-41. 



We now obtain a proportion 9 to 4, differing from exactitude by so small 

 a quantity as to be fairly admissible. 



It is somewhat remarkable that the quantity 1-066 is found frequently in 

 the measures of the Erectheum. 



The proportion of solids to voids is 4522 to 1000, nearly as 9 to 2. 



I have now stated the principal larger proportions : I will state a few 

 others, which are the more important secondary ones. A very happy 

 artifice is the walls of the pronaos and posticum being thicker than th* 

 cella walls. 



The height of the columns of the Parthenon is exactly iVj length of 

 temple on upper step, the breadth of the abacus of six of the eastern 

 columns is exactly -jij breadth of temple; they are not all equal, but I have 

 given the dimensions of those at the eastern end, which always gives the 

 key to the main proportions. 



In the temple of Theseus, the column is exactly Jj^jth of length of temple 

 on the lower step, and the abacus -[Ijtb of the breadth on the upper step. 

 In both, this memlier appears to be the unit of measure for all the details. 



The whole building is most accurately proportioned in every part, and I 

 think it not unlikely that it will be possible to find a standard which shall 

 express every dimension without any incommensurable fractions. 



I now proceed to that part of the subject which is more particularly the 

 object of the present paper, namely, the optical corrections. I shall first 

 state the case as I found it, and lastly, say a few words on the probable 

 origin and intention of these subtleties, which prevail, more or less, in 

 almost all the Greek temples — in all, indeed, that I have examined, with the 

 exception of (he temple of Bassce, on the borders of Arcadia, wnere I 

 could not find satisfactory indication of either convexity of pavement, or 

 inclination of the columns, or even entasis. 



The pavement of the Parthenon is bounded by four curved lines, viz., 

 the edges of the upper step on tbe four sides of the building. The four 

 angles of this curved surface are not precisely level, the south-west angle is 

 about -16 above the north-east and south-east angles. 1 think that this is 

 simply owing to the lines of the earlier temple, which were also curved, being 

 made use of as far as they would go, and by being produced in one direction 

 only, and remaining fixed at the south-west angle. The line so produced 

 would naturally fall below the fixed point. This is the case on tbe west 

 front, south and north sides. The extreme points of the upper step of the 

 east front are exceedingly near level. The result of a number of observa- 

 tions gives only a diflference of -002, or ^ feet, a quantity which we need 

 not stop to discuss. 



If these two points be joined by a straight line, the curve which forms 

 the edge of the step will be found under the middle columns to rise to a 

 height of -214 above it. If the uniform curve had been preserved, it would 

 have been -218 in the middle, which is about :^ breadth of front; and the 

 curvature is so regular on the northern half of this front, where the steps 

 rise immediatelyfrom the solid unbroken rock, and consequently no settle- 

 ment can have taken place, that of four points measured at the centres of 

 each column, three agree exactly with a circular arc: the fourth difi'ers only 

 by -003. The curvature is so very slight that it might be any regular con- 

 tinuous curve ; for instance, in so small an arc no appreciable difterence 

 could be shown between the arc of a circle or that of an ellipse or parabola, 

 and I think that the work was set out by means of the latter figure, which 

 might be done very easily ; whereas, I need scarcely point out the difficulty, 



