LelUr from Von Humboldt io haJande. 



55? 



. In the year 1776, accordhig to Cavallo, the inclination of 

 the needle in the undemieniioned latitudes and longitudes 



Since Coiilonib ami Caffini no longer employ themfelves 

 with obferving the declination, I know no place in the earth 

 where the declination has been determined with certainty to 

 ,10", and not ten where it has been determined to \' . What 

 uncertainly (till prevails refpe«fting the real declination of th« 

 needle at Paris ! The ten obfervations which I made at fea, 

 will ferve hereafter to determine whether the inclination 

 fpeedily changes. The longitude and latitude of the places 

 ofoblervalion were always accurately determined, at the time 

 bv means of a Ramfdcn's fextant, divided from 15 to 15 fe- 

 conds; and a Berthoud's chronometer. You will fee by 

 them that the inclination decreafes very rapidly from the 

 latitude of 37°, and that it increafes leis towards the eaft 

 than to the well from the latitode of 37° to 48''. 



It appears to me, that in the higher chain of the calca- 

 reous mountains of this province, not far from the equator, 

 fmall elevations above the level of the fca derange the in- 

 clination nuich more ftrongly than the higher mountains in 

 the Pyrenees and Old Callile. As a proof, I Ihall here 

 give obfervations made at four places which lie pretty nearly 

 m an arch from north to fouth (comprehending 24',) 



Places. 



Height atiovc 



rhe Sea, Paris 



Feet. 



laclinaiion. 



Ccntigr.ide 

 Degrees. 



Old 



Dftircts. 



Vibrations in 



Ten Minutes. 



Cumana 



Zueteppe 



ImpoOibile 



Cumanacoa 



Cocollar 



24 

 ITI 1-2 

 1470- 

 636 



44-20° 



4:^3° 



43-^5 



43 20 

 4^-60 



zr 47' 



3« 50 

 3« 53 



38 20 



229 

 229 



229 



Bordais of ojjinion, as appears by the memorandum drawr; 

 up for the men of fcience wiio accompanied La Peroufe, that 

 the inteuGty of the magnetic power is the fame all over the 

 earth; as he afcribcs tiie fmall variation which he found in 

 it at Cadiz, TeneriH', and Breft, to the imperfcdiou of the 

 compafs. lie refuelled me to verify this circumftance. You 



Z 3 ' here 



