LONGITUDE AND TIME-RECKONING, 139 



As far as practicable, the interests of all nations should be con- 

 sulted in its choice, and the principle should be recognized, that the 

 first meridian should be determined in accordance with the views of 

 the greatest possible number. 



Although the general acceptance of a common meridian for reckon- 

 ing longitude has long been desired, unanimity has in no way been 

 attained. 



The meridians passing through the following points are more or 

 less in use at the present time, viz. : Cadiz, Christiania, Copenhagen , 

 Ferro, Greenwich, Lisbon, Naples, Paris, Pulkova, Rio de Janeiro, 

 Stockholm, and Washington. 



Several other meridians have at different times been used, or pro- 

 posed to be used, for the computation of longitude. Ptolemy, to 

 whom we are indebted, along with Marinus, for introducing the terms 

 'longitude' and 'latitude,' drew the first meridian through the Insulse 

 Fortunatse, or Canary Islands, as the western limit of the earth's 

 boundaries of his time; the exact position is not known with 

 certainty. 



According to Malte Brun, Louis XIII. of France, in order to 

 render the manner of expressing longitude in French geography uni- 

 form, ordered, by an express declaration, that the first meridian should 

 be placed in the Isle of Ferro, the most western of the Canaries. 

 Delisle, one of the first who endeavoured to give precision to geo- 

 graphical determinations, fixed the longitude of Paris 20 degrees east 

 of that meridian. When, by more rigorous observations, it was known 

 that the difference of longitude between Paris and the principal town 

 of the Isle of Ferro was 20° 5' 50", it was necessary to advance the 

 first meridian 5' 50" to the east of that point, so that it is now a circle 

 of mere convention, which passes through no remarkable point. 



Geographers at one time established the first meridian at the 

 island of St. Nicholas, near Cape Verd; others at the isle of St. 

 James. Gerard Mercator, who lived in the sixteenth century, 

 selected the meridian passing through the Island del Corvo, one of 

 the Azores, on account, it is said, of the magnetic needle pointing 

 due north at that time. It was not then known that the needle 

 itself was subject to variations. The Dutch placed their first 

 meridian at the Peak of Teneriffe. The Spaniards have chosen 

 Cadiz. The British formerly used Cape Lizard, but subsequently 

 selected Greenwich Observatory, near London. The Russians, Pul- 



