570 GREEK HORIZONTAL rURVEP IN MAISON CARREE AT NIMES. 



have arisen from maccnracy of workraaushii) in the rartheiion." To 

 quote his oavu words a^ain: "In the measurement of modern or even 

 Roman bnihiings an attempt to obtain the original measurements of con- 

 siderable distances to the thousandth i)art of a foot would be fallacious, 

 but in a building of the best Greek workmanship it can be done satis- 

 factorily if proper care be taken to selec^t such measurements as have 

 been least exposed to the action of the weather, for, owing to the j^erfect 

 jointing of the stones, the errors occasioned by any small shifts, which 

 may have arisen from earthquakes or the violence of human agency, 

 can be corrected most satisfactorily." To illustrate the refinement of 

 masonry jointing he mentions the observation of Stuart that the stones 

 of the steps under the columns of the Parthenon have actually grown 

 together. "On breaking off ])arts of two stones at the joint he found 

 them as firmly united as though they had never been separate." This 

 is explained as due to molecular attraction of two surfaces ground 

 together to a very smooth finish, on the principal which explains why 

 two panes of glass may adhere to one another. For an account of the 

 methods by which this wonderfully fine fitting and jointing were 

 obtained, the Avork I am quoting must be consulted. 



II. 



Although the ultimate topic of this ])aper is the discovery of Greek 

 horizontal curves in the Maison Carree at iSTimes, which I nmde in 

 LSOl, I have considered it necessary not only to include an account 

 of the existence of the Greek curves themselves, but also a rather 

 exj^licit mention of all the irregularities connected with them; not only 

 because incommensurate intercolumnar spacings and leaning faces and 

 members are included in my observations at Nimes, but also because 

 the existence of the Greek horizontal curves is one of a series of facts 

 whose startling significance and importance can not be wholly grasped 

 until all of them are made known. This point again reacts on the 

 importance of all observations which tend to supplement or accent cer- 

 tain explanations of any one set of these phenomena as against some 

 certain other explanation. It will i^resently appear that my discovery 

 at JSTimes has the result of agitating the still undetermined purpose or 

 I>ui'i>oses of the Crreek optical refinements in masonry, and that it tends 

 to minimize the importance of the explanations offered by Penrose in 

 favor of those which have been offei*ed by certain other students. It 

 also, as we shall see, throws a strong side light on the probable Egyp- 

 tian origin of the Greek curves, and thereby again tends to throw new 

 light on their j)urpose on account of certain peculiar features of the 

 Egyptain examples. 



We will, therefore, draw nearer to my ultimate aim by degrees, and 

 bj^ considering in the next place the history of the discovery of the 

 Greek horizontal curves, whose confirmation and detailed demonstra- 

 tion it was the great mission of Penrose to accouq)lish. 



