THE EARTH. 



85 



sandy plain at bottom, extending for several 

 hundred miles, without an intervening object. 

 But in others, particularly in the Red Sea, 

 it is very different : the whole bottom of this 

 extensive hed of waters is, literally speaking, 

 a forest of sub-marine plants, and corals form- 

 ed by insects for their habitation, sometimes 

 branching out to a great extent. Here are 

 seen the madrepores, the sponges, mosses, sea- 

 mushrooms, and other marine productions, 

 covering every part of the bottom ; so that 

 some have even supposed the sea to have 

 taken its name from the colour of its plants 

 below. However, these plants are by no 

 means peculiar to this sea, as they are found 

 in great quantities in the Persian gulf, along 

 the coast of Africa, and those of Provence 

 and Catalonia. 



The bottom of many parts of the sea near 

 America presents a very different, though a 

 very beautiful appearance. This is covered 

 with vegetables, which make it look as green 

 as a meadow, and beneath are seen thousands 

 of turtles, and other sea-animals, feeding 

 thereon. 



In order to extend our knowledge of the 

 sea to greater depths, recourse has been had 

 to the plummet ; which is generally made of 

 a lump of lead of about forty pounds weight, 

 fastened to a cord." This, however, only an- 

 swers in moderate depths; for when a deep 

 sea is to be sounded, the matter of which the 

 cord is composed, being lighter than the 

 water, floats upon it, and when let down to a 

 considerable depth, its length so increases 

 its surface, that it is often sufficient to prevent 

 the lead from sinking; so that this may be 

 the reason why some parts of the sea are said 

 to have no bottom. 



In general, we learn from the plummet, that 

 the bottom of the sea is tolerably even where 

 it has been examined ; and that the farther 

 from the shore, the sea is in general the 

 deeper. Notwithstanding, in the midst of 

 a great and unfathomable ocean, we often 

 find an island raising its head, and singly 

 braving its fury. Such islands may be con- 

 sidered as the mountains of the deep ; and, 

 could we for a moment imagine the waters 

 of the ocean removed, or dried away, we 



Boyle, vol. ii. p 5. 



should probably find the inequalities of its 

 bed resembling those that are found at land. 

 Here extensive plains ; there valleys ; and, in 

 many places, mountains of amazing height. 

 M. Buache has actually given us a map of that 

 part of its bottom, which lies between Africa 

 and America, taken from the several sound- 

 ings of mariners : in it we find the same un- 

 even surface that we do upon land, the same 

 eminences,and the same depressions. In such 

 an imaginary prospect, however, there would 

 be this difference, that as the tops of land- 

 mountains appear the most barren and rocky, 

 the tops of sea-mountains would be found the 

 most verdant and fruitful. 



The plummet, which thus gives us some idea 

 of the inequalities of the bottom,leaves us total- 

 ly in the dark as to every other particular; 

 recourse, therefore, has been had to divers : 

 these, either being bred up in this dangerous 

 way of life, and accustomed to remain some 

 time under water without breathing, or assist- 

 ed by means of a diving-bell, have been able 

 to return some confused and uncertain ac- 

 counts of the places below. In the great diving- 

 bell improved by Dr. Halley, which was large 

 enough to contain five men, and was sup- 

 plied with fresh air by buckets, that alternate- 

 ly rose and fell, they descended fifty fathom. 

 In this huge machine, which was let down- 

 from the mast of the ship, the doctor himself 

 went down to the bottom, where, when the 

 sea was clear, and especially when the sun 

 shone, he could see perfectly well to write or 

 read, and much more to take up any thing 

 that was underneath : at other times, when 

 the water was troubled and thick, it was as 

 dark as night below, so that he was obliged 

 to keep a candle lighted at the bottom. But 

 there is one thing very remarkable ; that the 

 water, which from above was usually seen of 

 a green colour, when looked at from below, 

 appeared to him of a very different one, cast- 

 ing a redness upon one of his hands, like that 

 of damask roses b a proof of the sea's taking 

 its colour not from any thing floating in it, but 

 from the different reflexion* of the rays of 

 light. Upon the whole, the accounts we have 

 received from the bottom, by this contrivance, 

 are but few. We learn from it, and from 



b Newton's Optics, p. 56. 



X* 



