36 THE HISTORY OF SCIENCE 



aqueducts, public buildings, organization of the 

 State and the army, the formulation of legal proce- 

 dure, the enactment and codification of laws, were 

 necessary to secure and maintain the Empire. The 

 use in building construction of a knowledge of the 

 right-angled triangle as well as other matters known 

 to the Egyptians and Babylonians, and Archimedes' 

 method of determining specific gravity were of pecul- 

 iar interest to the practical Romans. 



Julius Caesar, 102-44 B.C., instituted a reform of 

 the calendar. This was very much needed, as the 

 Romans were eighty-five days out of their reckoning, 

 and the date for the spring equinox, instead of com- 

 ing at the proper time, was falling in the middle of 

 winter. An Alexandrian astronomer (Sosigenes) as- 

 sisted in establishing the new (Julian) calendar. The 

 principle followed was based on ancient Egyptian 

 practice. Among the 365 days of the year was to 

 be inserted, or intercalated, every fourth year an 

 extra day. This the Romans did by giving to two 

 days in leap-year the same name ; thus the sixth day 

 before the first of March was repeated, and leap- 

 year was known as a bissextile year. Caesar, trained 

 himself in the Greek learning and known to his con- 

 temporaries as a writer on mathematics and astron- 

 omy, also planned a survey of the Empire, which was 

 finally carried into execution by Augustus. 



There is evidence that the need of technically 

 trained men became more and more pressing as the 

 Empire developed. At first there were no special 

 teachers or schools. Later we find mention of teach- 

 ers of architecture and mechanics. Then the State 

 came to provide classrooms for technical instruction 



