164 Study of the New York Obelisk as a Decayed Boulder. 



ing, within the pores of a stone, is so well knov/n, that it needs no 

 discussion here. 



It is therefore evident that, for the protection of the Obelisk from 

 this fierce attack, it was only necessary to insure the complete ex- 

 clusion of moisture. 



Any process, however, in which waterproofing material is applied 

 in solution, even to a theoretically dry stone, must be imperfect 

 per se. On the evaporation of the solvent, which constitutes the 

 chief volume of the solution, the outer pores of the stone, empty to 

 a slight depth, are in large part simply lined instead of filled with 

 the protective residue. Nor can this deficiency be supplied by fur- 

 ther applications of the solution, in successive coats: for already 

 many of the pores have been sealed to further permeation, and the 

 result must be a merely superficial cellular coat. On the other 

 hand, practically, in any large solid mass of stone or masonry ex- 

 posed to the weather in our climate, the pores are already occupied, 

 and permanently, almost to the surface, by water, even in the 

 hottest and driest weather. This forbids the satisfactory penetra- 

 tion of a waterproofing solution to any material depth. 



The process theoretically called for by the decaying Obelisk, in 

 1885, was one by which the pores of the granite should be first 

 emptied of moisture to the depth of at least two inches, by some 

 gently applied but long continued absorbent, such as dry air or 

 gentle heat: and by which, secondly, the empty pores should be 

 completely saturated to that depth with a liquid preservative, of 

 melting-point above the mean temperature of the stone, strongly 

 adherent, permanent under weathering, and solidifying with slightest 

 possible contraction. These conditions were, I think, fortunately 

 approached by the process then applied, and will be still more closely 

 approximated by the modified process, recommended by the two 

 Committees, for the special retreatment of the decayed spots upon 

 the Obelisk. 



As an additional means of protection to the injured surface, I 

 have elsewhere' suggested the propriety of restoring the ancient 

 gilded cap to the apex of the pyramidion, regilding the remainder 

 of the surface of the pyramidion below the cap, and regilding the 

 hieroglyphic intaglios on the four vertical faces of the Obelisk. 

 Aside from the appropriateness of this restoration from the archseo- 



^ The Misfortunes of an Obelisk, 128. 



