322 TRIGONOMETRICAL SURVEYS. 



coast on the east, and descending again to the level of the 

 sea on the Malabar coast, a distance of more than 360 miles, 

 the sum of all the ascents differed from the sum of the de- 

 scents only by eight feet and a half. 



From the triangles thus carried across the peninsula, a 

 correct measure of its breadth was obtained, and one con- 

 siderably different from what had previously been supposed. 

 The distance from Madras to the opposite coast was found 

 to be nearly 360 miles, instead of 400 miles as given in the 

 best maps before the time of the survey. 



The great extent of the triangulation now required a 

 second base to be measured in the interior of the country. 

 This was accordingly done near Bangalore, about 170 miles 

 west from Madras, not far from the position of the first base. 

 The work was performed with great accuracy by Lieutenant 

 Warren of the 33d regiment. It was connected with the 

 Madras base by the intermediate triangles, and by these its 

 length was computed. The result differed only about three 

 and a half inches from what it was found by the actual 

 measurement, — a remarkable proof of its accuracy, con- 

 sidering that the two bases were 170 miles distant. Such 

 a near coincidence must produce great confidence in the 

 skill of the observers and the excellence of the instruments 

 they employed. The length of the second base, reduced to 

 the temperature of 62° and to the level of the sea, was 



39.793.7 fathoms, or 7.536 miles. The latitudes were de- 

 termined by the zenith sector with every precaution at both 

 stations ; the same stars were observed at both many times, 

 and a mean of the results taken. From the observations 

 it was found that a degree of the meridian in lat. 12° 55' 

 10", is 60,498 fathoms. 



The next thing attempted was the measurement of a de- 

 gree perpendicular to the meridian in the above latitude, 

 which is that of Savendroog, near Bangalore ; but here an 

 uncertainty similar to that in the former case was found 

 in the result. This, indeed, was inseparable from the nature 

 of the thiiicp to be done. The degree was found to be 



60.747.8 fathoms. Colonel Lambton remarks that, suppos- 

 ing the ratio of the earth's diameter to be 1 to 1.003125, the 

 meridional degree 60,498 fathoms gives 60,858 fathoms for 

 the perpendicular degree, which differs by 110 fathoms from 

 what is found by measurement ; hence we must infer either 



