95 FIGURE OF THE EARTH. 



b^rs. With these elements, and with the data to be found in 

 the work of M. Svanberg, we have by the western series of 

 v triangles 5840",196 and 5840", 138 by the eastern. So that 

 the mean calculated arc is 1° 37' 20", 167, while the arc ob- 

 served was 1° 37' 1$',56G. The difference then is 0',6 for 

 the total arc, and 0',37 for the mean degree, or 5,86 toises 

 excess in the linear extent. One can never depend upon 

 quantities so small as this, so that the agreement between the 

 results of computation and actual observation, proves not only 

 the skill of the observers arid the accuracy of which their in- 

 struments admit ; but also that the elliptic elements employed 

 in the calculation are a sufficiently near approximation to the 

 truth to be deserving of confidence, 

 and also In the 8th volume of the Asiatic Researches, published by 



tures on the " ^ e Society at Calcutta, are contained the details of another 

 meridian taken measurement performed in 1802, by Major William Lamb^ 

 Ma^or William. * onm Bengal, on the Coromandel coast. In this undertaking, 

 Lambton; which was executed with great skill and attention, Major 

 Lambton employed Bengal lights as signals, chains for the 

 linear measures, and a theodolite, and a zenith-sector made by 

 Ramsden. The base measured was 6667,740 fathoms reduced 

 to the level of the sea, and to the temperature of 62° Fahren- 

 heit ; and the stations were so chosen, that four of the sides of 

 the triangles were almost in the same line, and nearly parallel 

 to the meridian at the southern extremity of the arc, so that 

 their sum but little exceeds its whole extent. The lengths of 

 • these arcs in fathoms reduced to the meridian are thus given in 

 the Memoir of Major Lambton. 



AB 20758,13 north latitude of A 1 1? 44' 52' ,59 

 BC 17481,245 



CD 22237,04 north latitude of E 13° 19'4o/<,018 

 DE 35246,43 

 From these data Major Lambton deduces the degree of the 

 meridian to be 60435 fathoms, or 56762,3 toises. By apply- 

 ing to this the same elements as we did to the measurement 

 by Svanberg, we have the entire arc measured equal to 1* 

 34' 55S896 j so that the difference between the results of cal- 

 culation and of the observations is only 0'',532 for the whole arc, 

 or 0'',337 for the mean degree. The elliptic hypothesis and 

 observation agree more correctly in this instance, for the diffe- 



jence 



