ILLUSTRATIONS AND ADDITIONS. 



(1) p. 154 — "Across that pacific arm of the sea." 



The Atlantic Ocean, between the parallels of 23° south 

 lat. and 70° north lat., has the form of a furrowed longitudinal 

 valley, in which the advancing and receding angles are oppo- 

 site to each other. I first developed this idea in my work 

 entitled Essai dim Tableau Geologique de VAmerique meri- 

 dionale, which was published in the Journal de Physique, t. 

 liii. p. 61.* From the Canary Isles, especially from 21° 

 north lat., and 23 3 west long., to the north-east coast of South 

 America, the surface of the ocean, is so calm, and the waves 

 so gentle, that an open boat might navigate it in safety. 



(2) p. 155 — "Fresh springs among the Islands of the Antilles." 



On the southern coast of the Island of Cuba, south-west of 

 the harbour of Batabano, in the Gulf of Xagua, at a distance 

 of eight to twelve miles from the shore, springs of fresh water 

 gush from the bed of the ocean, probably from the action of 

 hydrostatic pressure. The jet is propelled with such force 

 that boats use extreme caution in approaching this spot, which 

 is well known for its counter current producing a heavy 

 swell. Trading vessels sailing along the coast, which do 

 not purpose putting into port, sometimes visit these springs, 

 in order to provide themselves, in the midst of the ocean, with 

 a supply of fresh water. The freshness of the water increases 

 with the depth from which it is drawn. River cows {Tri- 

 checus manati), which do not generally inhabit salt water, are 

 frequently killed here. This singular phenomenon (the fresh 

 springs), of which no mention had hitherto been made, was 

 most accurately investigated by my friend, Don Francisco 

 Lemaur, who made a trigonometrical survey of the Bahia de 

 Xagua. I did not myself visit Xagua, but remained in the 

 insular group situated further to the south (the so-called 

 Jar dines del Meg), to make astronomical determinations of 

 their latitude and longitude. 



(3) p. 155 — "Ancient rocky bar?*ier." 



Columbus, whose unwearied spirit of observation was di- 

 * Gilbert's Annalen der Physik, bd. xvi. 1804, s. 394—449. 



