186 LECTURE XX. 



to the same fundamental principle ; so that the theory of the mechanical 

 powers began at that time to be extremely well understood. The treatises 

 of Hero on pneumatics and on automatons contain many very ingenious 

 inventions, but they are rather calculated for amusement than for utility ; 

 among them is a cupping instrument, which operates nearly in the manner 

 of an air pump. A work of Bito, on warlike machinery, addressed to 

 king Attalus, is included in the same collection. 



Vitruvius was an author of great general knowledge : he lived under 

 one of the earliest of the Caesars, and the greatest part of our information 

 respecting the mechanics of antiquity has been derived from his works. 

 Apollodorus was employed by Trajan, in building a bridge over the 

 Danube, in the year 102 ; he has left a treatise on besieging a town, which 

 is to be found among the Ancient mathematicians. Diophantus, Pappus, 

 and Proclus, were mathematicians of eminence : Diophantus confined him- 

 self in great measure to arithmetic and pure geometry ; but the last book 

 of Pappus's collections is devoted to mechanics, and Proclus wrote a 

 treatise on motion, which is still extant.* The rudiments of algebraical 

 notation and calculation may be found in the works of Diophantus ; but 

 the Arabians appear to have first practised the method of denoting quanti- 

 ties in general by literal characters ; they made, however, no considerable 

 advances, and mathematics in general remained nearly stationary until the 

 time of the revival of letters. 



During the long interval, in which learning and science were involved 

 in the darkness of the middle ages, the arts subservient to the convenience 

 of life were also in great measure neglected. It is evident from many 

 remains of antiquity, that various manufactures had attained in Greece 

 and at Rome, a high degree of perfection ; but the irruptions of the bar- 

 barians were as effectual in suppressing the refinements of civilisation, as 

 in checking the pursuit of literary acquirements : our own country was 

 not the earliest in recovering the arts which had been lost, but it has 

 always received with open arms those who have excelled in them ; 

 and the improvements which have been made, within a few centuries, in 

 the British manufactures, have obtained for them a celebrity unrivalled by 

 those of any other nation. The ancient Britons are supposed to have 

 made, in common with the other Celtic nations, coarse cloths and felts of 

 wool, and perhaps some articles of linen ; their chariots of war, w r hich are 

 mentioned by Caesar, could not have been executed without some skill in 

 the arts of the carpenter and the smith. The Romans introduced a certain 

 degree of civilisation into England, but it appears to have been in a great 

 measure forgotten soon after they left the country. In the seventh cen- 

 tury, several architects and workmen were brought from the continent by 

 Wilfrid and Biscop ; they restored the practice of building with stone, 

 which had been generally superseded by wood, and laid the foundation for 

 other improvements. In the time of king Alfred, the English goldsmiths 

 began to excel, and before the conquest, the woollen manufactures had 

 acquired a considerable degree of perfection. The paper now in use was 

 introduced about the year 1100 ; it was probably imported from the con- 

 * De Motu Disputatio, Basileae, 1531. 



