34 ° Don J. Rodriguez’s Observations on the 
the total arc, and o' 7 , 3 7 for the mean degree, or 5,8 6 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 and 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. 
In the 8th volume of the Asiatic Researches, published by 
the Society at Calcutta, are contained the details of another 
measurement performed in 1802, by Major William Lamb- 
ton in Bengal, on the Coromandel coast. In this undertaking, 
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° 
Fahrenheit ; 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 tire 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 17481,243 
CD 22237,04 north latitude of E 13 0 19' 49", 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 
