TRIGONOMETRICAL SURVEY OF INDIA. I95 



If it be conceded that geography is useful — then there is no pure source 

 from which Ave can draw our elements, but this. Let us measure a 

 distance on the earth's surface by the primitive mode of the drying of 

 a wet leaf,* the more modern method of the duration of a smokin"- 

 pipe,t by pacing, by chains, by rods, by perambulators ; we must (do what 

 we will) for geographical purposes reduce the distances so found to degrees, 

 minutes, and seconds, of latitude and longitude. But unless we know how 

 many miles, or feet, or pipes, go to the degree, the mode of comparison is 

 wanting to complete the reductiou. 



If the earth were quite spherical, all degrees of latitude would be 

 equal, and all degrees of longitude would vary as the cosines of the latitude, 

 but that is not the case if it be compressed at the poles, for the length of de- 

 grees of latitude would then increase as we recede from the equator, and the 

 length of degrees of longitude would cease to vary in the above proportion. 



There is a class of people who will reply to this that we have only to 

 look into any elementary book on arithmetic, and there we shall find that 

 sixty-nine and a half British miles make a degree ; — the same gentlemen, 

 amongst whom Mr. Cobbett has occasionally figured, whilst the humour 

 was on him, together with many others as far surpassing him in rank as 

 he does them in intellect, will be ready to declare that pounds, shillings, 

 and pence are the only useful knowledge, and that tare and tret, and 

 bills of parcels, are the fittest boundaries to limit the mathematical educa- 

 tion of Englishmen. We all must recollect M. Voltaire's story of Jean- 

 NOT and Colin. How the young Jeannot suddenly became raised to the 

 peerage from being a peasant, and how tlic father and mollicr of Jeannot 



* A practice common with tlie Hindoos. 



t TIic Dutch boors at Cape ofGooil Hope conimoiilv Citiiiuitc by this method. I .un toiJ 

 the natives of the lulls near Assam do the same. 



