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



If only some boulder could be found whose whole story was known, 

 whose hieroglyphic strias could be entirely interpreted! 



It has occurred to me that on man}^ of these points we may be 

 able to gain some facts of value through a special study of at least 

 one huge block of hewn granite, whose known but vast antiquity 

 renders it, to some degree, comparable with a natural boulder, while 

 its record of varying experiences of natural and artificial agencies 

 of destruction is quite definitely known. A recent re-awakening of 

 public interest in the Egyptian Obelisk, now in Central Park, New 

 York, and of anxiety as to its permanent preservation, led to the 

 appointment, in 1890, by the Board of Commissioners of the Public 

 Parks, of two successive Committees of Experts to consider these 

 subjects. Service on these committees gave me the opportunity of 

 commencing a series of experiments, whose continuance, at inter- 

 vals, during the last three years, has }■ ielded the results presented 

 in this paper. 



Moreover, the Nile valley, as well as the streets and squares of 

 European capitals, is strewn with similar Egyptian boulders, of huge 

 size and of the same homogeneous granite, which have long lain in 

 definite positions, exposed to known agencies of geological change, 

 during periods coeval with the establishment of ancient dynasties, 

 often yet plainly recorded upon their faces. For at least the partial 

 elucidation of our problem, we are fortunate to possess, in this 

 peculiar class of historical monuments, a happily arranged series of 

 trial-boulders of approximately known age and tests. 



The history of the Obelisk is naturally divided into four periods, 

 corresponding to the four sites it has occupied: Syene (Sun-t or 

 Assouan), where it was quarried; An (On or Hcliopolis), where it 

 stood erect for about 1050 years, and then perhaps lay prostrate for 

 513 years longer; Alexandria, where it stood for 1893 years; and 

 New York, where it has fought with the elements for over 12 years, 

 since its re-erection, January 22, 1881. 



I. Syene. 



At this point, 560 miles north of Cairo, the great range of the 

 Libyan Mountains, called the Gebel Silsilih, "Mountain of the 

 Chain," is crossed by the Nile through a narrow gorge. Above, 

 its obstruction of the waters of the river, with a chain, as it were, 

 of rocky ledges, forms the famous First Cataract. In these moun- 



