ADDllESS. Ixix 



The ancient Egyptians had a knowledge of Metallurgy, much of which •s\as 

 lost during the years of decline which followed the golden age of their civi- 

 lization. The art of casting bronze over iron was known to the Assyrians, 

 though it has only lately been introduced into modern metallurgy; and 

 patents were granted in 1C09 for processes connected with the manufactui'C 

 of glass which had been practised centuries before*. An inventor in the 

 reign of Tiberius devised a method of producing flexible glass ; but the 

 manufactory of the artist was totally destroyed, we are told, in order to 

 prevent the manufacture of copper, silver, and gold from becoming depre- 

 ciated t- 



Again and again engineers as well as others have made mistakes from not 

 knowing what had been done by those who have gone before them. In the 

 long discussion which took place as to the practicability of making the 

 Suez Canal, an early objection was brought against it that there was a 

 ditFerenco of 32| feet between the level of the Eed Sea and that of the 

 Mediterranean, Laplace at once declared that such could not be the case, 

 for the mean level of the sea was the same on all parts of the globe. 

 Centuries before the time of Laplace the same objection had been raised 

 to a project for joining the waters of these two seas. According to the 

 old Greek and Eoman historians, it was a fear of flooding Egypt with the 

 waters of the Eed Sea that made Darius, and in later times again Ptolemy, 

 hesitate to open the canal between Suez and the Nile J. Yet this canal 

 was made, and was in use some centuries before the time of Darius. 



Strabo § tells us that the same objection, that the adjoining seas were of 

 ditFerent levels, was made by his engineers to Demetrius ||, who wished to 

 cut a canal through the Isthmus of Corinth some two thousand years ago. 

 But Strabo ^ dismisses at once this idea of a diff'erence of level, agreeing 

 with Archimedes that the force of gravity spreads the sea equally over the 

 earth. 



When knowledge in its higher branches was confined to a few, those who 

 possessed it were often called upon to perform many and various services for 

 the communities to which they belonged ; and we find mathematicians and 

 astronomers, painters and sculptors, and priests called upon to perform the 

 duties which now pertain to the profession of the architect and the engineer. 

 And as soon as civilization had advanced so far as to admit of the accumula- 

 tion of wealth and power, then kings and rulers sought to add to their glory 

 while living by the erection of magnificent dwelling-places, and to provide 

 for their aggrandizement after death by the construction of costly tombs and 



* Layard's 'Nineveh and Babylon,' p. 191 ; Bectraan's 'History of Inventions,' vol. ii. 



p. 85. 



t Pliny, Nat. Hist. bk. sxxvi. cap. 66. | Ibid. bk. vi. cap. 33. 



§ Strabo, cap. iii. § 11. || Demetrius I., King of Macedonia, died 283 r.c, 



^ Strabo, cap. iii. § 12. 



