346 CAPTAIN SABINE'S LETTER. 



portion of the polar and equatorial diameters by 

 its combination with an arc near the equator, 

 is equivalent to one of 9° in the mean latitude 

 of France, and of 7° in the mean latitude of 

 Britain ; its value, therefore, in the ultimate de- 

 termination, may be estimated by the known im- 

 portance which is attached to the national arcs of 

 Great Britain and France. It may be further 

 noticed, that it is equivalent to an arc in Lapland, 

 of nearly six times the extent of the arc measured 

 by the French Academicians ; the importance of 

 which at this day is such, in the view of the first 

 geometrician of the age, that M. Laplace has 

 recently proposed, that a fresh commission should 

 be sent to re-determine the latitudes of the extre- 

 mities. 



The expediency, then, of undertaking such a 

 measurement at Spitzbergen, is principally to be 

 considered in reference to the natural difficul- 

 ties which may impede its execution. And on 

 this point, having myself actually resided some 

 weeks on shore at Spitzbergen, having conducted 

 operations of a similar nature, having personal 

 knowledge of the general character of the country 

 to be traversed, the difficulties it presents to per- 

 sons carrying astronomical instruments, and the 

 modes and facilities of overcoming those difficul- 

 ties, and having made observations of much deli- 



