Things not generally Known. 



embouchure of that river. It was about 126 feet deep. Its spe- 

 cific gravity was = 1 '0204, and the specific gravity of the sea- 

 water = 1-0262. This appears to be the greatest distance from 

 land at which river-water has been detected on the surface of 

 the ocean. It was estimated to be moving at the rate of three 

 miles an hour, and had been turned aside by an ocean- current. 

 " It is not a little curious to reflect," says Sir Henry de la Beche, 

 " that the agitation and resistance of its particles should be suf- 

 ficient to keep finely comminuted solid matter mechanically 

 suspended, so that it would not be disposed freely to part with 

 it except at its junction with the sea-water over which it flows, 

 and where, from friction, it is sufficiently retarded. " 



THE THAMES AND ITS SALT-WATER BED. 



The Thames below Woolwich, in place of flowing upon a 

 solid bottom, really flows upon the liquid bottom formed by 

 the water of the sea. At the flow of the tide, the fresh water 

 is raised, as it were, in a single mass by the salt water which 

 flows in, and which ascends the bed of the river, while the fresh 

 water continues to flow towards the sea. Mr. Stevenson, in 

 Jameson's Journal. 



FRESH SPRINGS IN THE MIDDLE OF THE OCEAN. 



On the southern coast of the island of Cuba, at a few miles 

 from land, Springs of Fresh Water gush from the bed of the 

 Ocean, probably under the influence of hydrostatic pressure, and 

 rise through the midst of the salt water. They issue forth with 

 such force that boats are cautious in approaching this locality, 

 which has an ill repute on account of the high cross sea thus 

 caused. Trading vessels sometimes visit these springs to take 

 in a supply of fresh water, which is thus obtained in the open 

 sea. The greater the depth from which the water is taken, 

 the fresher it is found to be. 



" THE BLACK WATERS." 



In the upper portion of the basin of the Orinoco and its 

 tributaries, Nature has several times repeated the enigmatical 

 phenomenon of the so-called " Black Waters." The Atabapo, 

 whose banks are adorned with Carolinias and arborescent Me- 

 lastomas, is a river of a coffee-brown colour. In the shade of 

 the palm-groves this colour seems about to pass into ink-black. 

 When placed in transparent vessels, the water appears of a golden 

 yellow. The image of the Southern Constellation is reflected 

 with wonderful clearness in these black streams. When their 

 waters flow gently, they afford to the observer, when taking 

 astronomical observations with reflecting instruments, a most 

 excellent artificial horizon. These waters probably owe their 



