Hinxtava Mountains, $93 
and most accurate calculation.* If then we can resort to a method of 
calculation, so true as to have regard to the deviation of the figure of the 
~ earth from the sphere, yet equally convenient and expeditious as though 
we had considered it to be a plane, we shall I conceive be justified in 
adopting it even though it may seem like affecting a degree of accuracy, of 
which the operations of such a survey are not susceptible. When there 
are two methods equally mtelligible and equally short, one of which is 
but an approximation and: the other strictly accurate, there can be but 
one opinion as to which should be chosen. In the one we cut off every 
source of error but that of observation, and if we can do this without a 
greater expence of time, it would seem like courting error to choose the other. 
But those who have attempted these operatious know how much will al- 
| ways ‘attach itself to. the work in the field, and how unnecessary it is to 
increase it by additions from other sources. The calculations of this sur- 
vey have therefore all been made on the supposition of the earth’s being 
an ellipsoid, and it is to be explained here what the nature is of the for- 
mulze on which they have been conducted. 
3. Tue first step is to determine the dirsensions of the earth and the 
degree of ellipticity, and this has. been done by means of Colonel Lais- 
ron’s formule, given in the [2th Volume of the Asiatic Researches. The 
Data which have been adopted are those generally allowed to be the most 
unexceptionable, as they, are the latest measurements, viz. the French 
— ——] 
' * “On peur toujours concevoir un ellipsoide, tangent a chaque point dela surface terrestres 
** and sur lequel les mesures Geodesiques, les longitudes et les latitudes, a partir dupoint de contin. 
s° sence dans unepetite etendue seraient les: mémes qu’a cette surface.’ La Peace. Mec. Cevesre, 
VOL. XIV. AN 
