H. Briggs, E. Wright, J. Greaves, J. Barrow 49 



brand, and Christopher Wren. Their work now calls for 

 consideration. 



John Greaves (1602-1652), who held also for a time 

 the Savilian Professorship of Astronomy at Oxford, from 

 which position he was dismissed on political grounds in 

 1646, must be considered to be the earfiest scientific metro- 

 logist. He determined with fair accuracy the relation 

 between the Roman and English foot, and also carried out 

 some investigations on Roman weights. One of his suc- 

 cessors at Oxford, Edward Bernard (1638-1697), followed 

 up this work, and published a treatise on ancient weights 

 and measures. 1 



The mathematics of the time, as has already been noted, 

 was under the influence of Descartes, who had invented the 

 method of analytical geometry, in which the position of a 

 point is defined by its distance from two lines at right angles 

 to each other, and which represents a curve in the form of an 

 equation as an algebraic relationship between these distances. 

 When this is done, many problems suggest themselves, 

 such as that of forming the equation to its tangent at any 

 point, or calculating the area bounded by the curve. 

 The solution of such problems led naturally to the concep- 

 tions from which the differential calculus emerged. Isaac 

 Barrow (1630-1677), working along the lines indicated by 

 Fermat and Pascal, succeeded in finding the correct expres- 

 sion for the tangents of a number of curves. A successful 

 lecturer and writer of books, rather than an independent 

 discoverer, he was, nevertheless, an interesting figure in 

 the history of science. The son of a linendraper in London, 

 educated at Charterhouse, he proceeded to study medical 

 subjects as well as literature and astronomy at Cambridge, 

 where he took his degree and obtained a Fellowship at 

 Trinity College. Having been driven out of the University 

 by the persecution of the Independents, he travelled in 

 France and Italy, proceeding thence to Smyrna and Con- 

 stantinople. After spending a year in Turkey, he returned 

 home through Germany and Holland in 1659. In the 

 following year, he was appointed to the Chair of Greek at 



1 See " Report of the Smithsonian Institution, 1890," " The Art 

 of Weighing and Measuring," by William Harkness. 



D 



