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quality in regard to its exactitude. The next in longitude is one 

 at the Cape of Good Hope, done in the first instance by French 

 astronomers of the last century, but extended by the last English 

 astronomer who was at the Cape of Good Hope. Then there is 

 one in Peru, of no great value now, and comparatively a short one. 

 Still I am unwilling to let it go without notice, for this reason. 

 When the question of the figure of the earth was raised theoretically 

 by Sir Isaac Newton, it was disputed; till, of all people in the 

 world, the French took it up, and determined to make a critical 

 observation. They sent out two expeditions of great celebrity, 

 one was to Lapland, and the other went to Peru actually to cross 

 the Equator, and it was a noble combination of enterprise. I 

 should have been unwilling to leave this out of sight at present, 

 although it is not so valuable by any means as these others. These 

 are the principal measures that we have, and upon these depend 

 our estimation of the size of our globe and its shape. When we 

 look at them, they seem hardly sufficient. I should like to see a 

 dozen twice as long, and I have no doubt some of our successors 

 will have an arc measured along the whole of South America, and 

 another along the whole of North America. However, that is not 

 done yet. Taking these as the best materials which we have at 

 present, we find from their agreement that there is no doubt that 

 the earth is very nearly a sphere. In fact, they agree so well — 

 and with another correction, which I shall indicate in a few 

 moments —that they leave no doubt at all in our minds that the 

 earth is essentially a sphere. Everything goes upon that, and 

 everything answers properly. Of course it is a method of 

 measuring the earth, founded, in the first instance, upon few 

 measures, but if our theory were wrong it would soon be found 

 out. But every calculation and every comparison of the theory 

 with observation, has agreed in confirming the notion that, 

 generally speaking, the earth is a sphere. Now to apply this to a 

 numerical measure of the dimensions of the sphere. I mentioned 

 to you that by the use of the zenith sector with its telescope for 

 observation of the stars, we can obtain the curvatures of the earth's 

 surface. Suppose in going from this place in the Isle of Wight 



