TRIANGLES CARRIED ACROSS THE PENINSULA. 321 



miles, between the stations of Carangooly and Camaghur, 

 nearly due east and west of one another. To determine 

 the length of this degree, very correct measures of the angles 

 which that line made with the meridians at its extremities 

 were necessary. In fact, the angles were observed with the 

 greatest care ; but from the nearness of the intersection of 

 the meridional arc and perpendicular arc to the equator, the 

 result is less to be relied on than the measure of the merid- 

 ional degree. The degree perpendicular to the meridian of 

 Carangooly was found to be 61,061 fathoms.* By com- 

 paring this with the meridional degree. Colonel Lambton 

 found that the earth's compression at the poles should be 

 reckoned 1-210. This, however, we know to be too much ; 

 but if we diminish the perpendicular degree by 200 fathoms 

 and make it 60,861, as a writer in the Phil. Trans. 1812 

 contends that it ought to be because of an error in Colonel 

 Lambton' s calculations, then the compression will come out 

 1-330, which is probably near the truth. 



The measurements which we have hitherto described 

 were made in the year 1803. In 1806 the series of trian- 

 gles was carried quite across the peninsula to the Malabar 

 coast, which they intersected at Mangalore on the north and 

 Tellicherry on the south. They passed over the Ghauts, — 

 so celebrated both in the natural and civil history of Hindos- 

 tan. Two of the stations, Soobramanee and Taddianda- 

 mole in the Western Ghauts, not far from the coast, were, 

 the former 5583 feet, and the latter 5682 feet above the 

 level of the sea. The heights of the stations were all de- 

 termined from the distances and observed angles of eleva- 

 tion ; and it is no small proof of their accuracy, that after 

 ascending the chain of the Ghauts from the Coromandel 



* The reader should know thai the earih is not an exact sphere, but a 

 solid, formed by an ellipse, turning round its lesser axis ; so that a me- 

 ridian is not a circle, but an ellipse, the curvature of which gradually 

 diminishes from ihe equator to the poles. It is a consequence of this 

 figure that the degrees of latitude gradually increase from the equator 

 to thi poles ; and the inequality of the degrees in dilferent latitudes de- 

 pends on the inequality of the axes in such a way that the one is de- 

 ducible from the other ; that is, if we know the proportion wliich the one 

 axis bears to the other, we can find the proportion w hich the lengths of 

 degrees in any two parallels, 5^ and 10* for example, have to each other, 

 and the contrarj-. The deviation of the figure of the earth from a per- 

 fect sphere is called its compression, and it is measured by the fractional 

 part that the difference of the two axes is of the greater. 



