200 PLANTS. 



In water, ,t demands our gratitude, that the most 

 necessary liquid is the most abundant and most easily 

 obtained, and has no taste of its own either to offend 

 or satiate ; or to effect the flavor of any thing uni- 

 ted with it. One of most remarkable circumstances 

 in which we discover design in the properties of wa- 

 ter, is the manner in which it is affected by frost It 

 is a provision in the constitution of this most useful 

 element, to preserve it from the sudden effects of bard 

 trosts; that is, in those places where it is of the 

 greatest importance to us, viz. the deeper waters 

 such as wells, rivers, bays, fc c . A short accoum J 

 the matter may be this. Water will not freeze, till it 

 is .cooled down to thirty-two degrees of the common 

 thermometer. But water is heavist when at the 

 temperature of about forty degrees. The conse- 

 quence is plain. When the surface of the water is 

 cooled by a cold wind or a sharp air, to the temper- 

 ature of forty degrees, it does not wait to be cooled 

 down to the freezing point, which is eight dee^rees 

 lower, and to which it would soon be brought if it 

 remained above, exposed to the cold ; but being the 

 heaviest, it immediately sinks, and suffers a wanner 

 portion below to take its place This, also, when 

 reduced to the same temperature of 40, repeats the 

 process ■ and thus the whole quantity must come to 

 the surface and be brought to this particular degree 

 of cold, which is eight degrees above the freezing 

 point, before the circulation will stop. After the 

 whole mass has thus been brought to the heaviest 

 weight which water can acquire, then the surface 



