Chap. 4.] the Ocean. 475 



wring it a little till it will not drip, when hung up to 

 dry; weigh it in this wet ftate, then dry it either in 

 the fun or at the fire, and, when it is perfectly dry, 

 weigh it again. The excefs of the weight of the wet- 

 ted cloth above its original weight, is the weight of 

 the fea water imbibed by the cloth j and the excefs of 

 the weight of the cloth, after being dried, above its 

 original weight, is the weight of the fait retained by 

 the cloth; and by comparing this weight with the 

 weight of the fea water imbibed by the cloth, we ob- 

 tain the proportion of fait contained in that fpecies of 

 fea water. 



Whoever undertakes to afcertain the quantity of 

 fait, contained in fea water, either by this or any other 

 method, would do well to obferve the flate of the 

 weather preceding the time when the fea water is taken 

 out of the fea, for the quantity of fait contained in the 

 water near the furface may be influenced both by the 

 antecedent moifture and the antecedent heat of the 

 atmofphere V 



Whether the fea is falter or not at different depths 

 has not yet been afcertained ; but that its temperature 

 varies confiderably in proportion to the depth v/e have 

 decifive proof. 



' With refpe6b to the temperature,' fays bifhop 

 Watfon, c of the fea at different depths, it Teems rea- 

 fonable enough to fuppofe, that in fummer time it will 

 be hotter at the furface than at any confiderable depth 

 below it, and that in winter it will be colder. Suppofe 

 a ciftern, twelve feet in depth, to be filled with fpring 

 water of 48 degrees warmth, to the height of eleven 

 feet; then, if we fill up the ciftern to its top, by gently 

 pouring water heated to 100 degrees upon the furface 



* Watfon's Chemical Efiays, vol. ii. p. nd. 



Of 



