[;•].. 
Sciences therein cultivated! Sufficient Motives for 
undertaking Matters of the utmoft Difficulty. 
When I faid above, that an exad Knowledge of the 
Magnitude of a Degree of the Earth in any known 
Meafures of one Country was fufficient for conftru&> 
ing exa& Charts of all other Countries, only having 
a Regard to the different Proportion of the Mea- 
fures $ that is to be underftood upon a Suppofttlon of 
the Earth s being perfectly fpherical : feeing it is well 
known, that in a Sphere the Degrees of all the great 
Circles are every where equal ; and that we likewifc 
know, in a Sphere, the Proportion of the Degrees of 
the fmall Circles to their great Parallels, according to 
their Diftance from them. 
But if the Earth be not perfe&ly fpherical, the Cafe 
is quite alter'd : All the Degrees of the great Circles 
will not be equal to one another ; and thofe of the 
fmall Circles, taken at a certain Diftance from their 
parallel great Circles, will not have the fame Relation 
that the Degrees of the fmall Circles, taken at the 
fame Diftance, would have on a. Sphere. In all this 
there might poffibly arife an infinite Variety, accord- 
ing to the Figure the Earth might have* and as it is 
not yet decided what is the Earth's true Figure, andl 
that there is no better Method of afeertaining it than 
by Obfervations made in fo great an Extent as that of 
RuJJia : For thefe 'Reafons I have advanced, that the 
Perfe&ion of the Geography of Rujfia ftands in need 
of this great Undertakings which, befides the Ufefuk 
nefs of it, will acquire much Honour to the Academy 
of TeUrsbourg \ if that Body can, by means of this 
Work, contribute towards the. deciding the celebrated. 
