176 Things not generally Known. 



ants between the two seas ; have proved that the low-water 

 mark of ordinary tides at Suez and Tineh is very nearly on the 

 same levels, the difference being that at Suez it is rather more 

 than one inch lower. Leonard Homer; Proceedings of the Royal 

 Society, 1855. 



THE DEPTH OF THE MEDITERRANEAN. 



Soundings made in the Mediterranean suffice to indicate 

 depths equal to the average height of the mountains girding 

 round this great basin ; and, if one particular experiment may 

 be credited, reaching even to 15,000 feet an equivalent to the 

 elevation of the highest Alps. This sounding was made about 

 ninety miles east of Malta. Between Cyprus and Egypt, 6000 

 feet of line had been let down without reaching the bottom. 

 Other deep soundings have been made in other places with 

 similar results. In the lines of sea between Egypt and the 

 Archipelago, it is stated that one sounding made by the Tar- 

 tarus between Alexandria and Rhodes reached bottom at the 

 depth of 9900 feet ; another, between Alexandria and Candia, 

 gave a depth of 300 feet beyond this. These single soundings, 

 indeed, whether of ocean or sea, are always open to the cer- 

 tainty that greater as well as lesser depths must exist, to which 

 no line has ever been sunk ; a case coming under that general 

 law of probabilities so largely applicable in every part of physics. 

 In the Mediterranean especially, which has so many aspects of 

 a sunken basin, there may be abysses of depth here and there 

 which no plummet is ever destined to reach. Edinburgh Ile- 



COLOUR OF THE RED SEA. 



M. Ehrenberg, while navigating the Red Sea, observed that 

 the red colour of its waters was owing to enormous quantities 

 of a new animal, which has received the name of oscillatoria 

 rubescenSj and which seems to be the same with what Haller 

 has described as a purple conferva swimming in water ; yet Dr. 

 Bonar, in his work entitled The Desert of Sinai, records : 



Blue I have called the sea ; yet not strictly so, save in the far dis- 

 tance. It is neither a red nor a Hue sea, but emphatically i>-reen, yes, 

 green, of the most brilliant kind I ever saw. This is produced by the 

 immense tracts of shallow water, with yellow sand beneath, which always 

 gives this green to the sea, even in the absence of verdure on the shore 

 or sea-weeds beneath. The blue of the sky and the yellow of the sands 

 meeting and intermingling in the water, form the green of the sea ; the 

 water being the medium in which the mixing or fusing of the colours 

 takes place. 



WHAT IS SEA-MILK ? 



The phenomena with this name and that of " Squid" are 

 occasioned by the presence of phosphorescent animalcules. They 



