290 PROFESSOR RIGAUD, ON THE RELATIVE QUANTITIES 



county of England, " having cut a six sheet map in pieces for that 

 purpose *." He used " nice scales " but he did not consider that he 

 arrived at more than a certain approximation, which however he 

 chiefly attributed to the imperfection of the maps on which he had 

 to work. The projection, likewise, that was used for them, obliged 

 him to reduce all the parts to the same mean size of the acre, and 

 consequently the experiment best known for the purpose, and described 

 by Dr Long in his Astronomy f, possessed in this respect a decided 

 advantage. He says that by " weighing thus the papers of Mr Senex's 

 globe of 16 inches diameter, the weight of the paper whei'eon the 

 sea was represented was 349 grains, that of the land Ig'l grains : 

 so the surface of the sea is almost three times as great as that 

 of the land hitherto discovered. I omitted," he adds, "weighing the 

 parts contained within the polar circles, because it is not known to 

 any degree of exactness how much of them is land and how much 

 is sea." Mr Vince refers to this passage \, and observes, that " the 

 conclusion would be more accurate, if the land were cut out from 

 the sea before the paper was put upon the globe ;" and he gives his 

 opinion that "after all our modern discoveries, this method would pro- 

 bably give the proportion of land to water, to a considerable degree of 

 accuracy." Senex died in December 1740, and Dr Long published the 

 first volume of his work (which contains the passage just quoted) in 

 1742 : they may, therefore, be considered as contemporaries ; and no dif- 

 ficulty can be well imagined to interfere with the plates being obtained 

 before they had been used. But Mr Vince prints the word "before" in 

 Italics, Avhich seems to indicate that he alludes to some tradition which 

 was credited in his time. Under such circumstances, however, the ex- 

 periment must have been worth absolutely nothing. The varnish must 

 have been broken off unequally, and the greatest care could not have 

 been sufficient for taking off the paper without some of it remaining in 

 adhesion to the substance of which the globe was formed, or other 

 portions bringing off some of that substance with them. We have, 



* See a Collection for the Improvement of Husbandry and Trade, by John Houghton, 

 F.R..S. Nos. 25, 26. 



+ Article .580. J Astronomy, 4to. Vol. ii. p. 112, 



