78 THE HISTORY OF SCIENCE 



would be afforded, gentlemen, by frequent visits to 

 your famous Venetian Dockyard (jar senate), espe- 

 cially that part where mechanics are in demand ; 

 seeing that there every sort of instrument and ma- 

 chine is put to use by numbers of workmen, among 

 whom, taught both by tradition and their own ob- 

 servation, there must be some very skillful and also 

 able to talk." The view of the shipbuilders, that a 

 large galley before being set afloat is in greater dan- 

 ger of breaking under its own weight than a small 

 galley, is the starting-point of this most important 

 of Galileo's contributions to science. 



Vesalius (1514-1564) had in his work on the 

 structure of the human body (De Humani Corporis 

 Fabrica, 1543) shaken the authority of Galen's 

 anatomy ; it remained for Harvey on the basis of 

 the new anatomy to improve upon the Greek physi- 

 cian's experimental physiology. Harvey professed to 

 learn and teach anatomy, not from books, but from 

 dissections, not from the dogmas of the philosophers, 

 but from the fabric of nature. 



There have come down to us notes of his lectures 

 on anatomy delivered first in 1616. A brief extract 

 will show that even at that date he had already for- 

 mulated a theory of the circulation of the blood : 



"Wf 1 By the structure of the heart it appears 

 that the blood is continually transfused through the 

 lungs to the aorta as by the two clacks of a water- 

 ram for raising water. 



" It is shown by ligature that there is continuous 

 motion of the blood from arteries to veins. 



1 This is Harvey's monogram, which he used in his notes to 

 mark any original observation. 



