VOL. XLV.] PHILOSOPHICAL TRANSACTIONS. 525 



Lemma 1. — ^The quantity of water which annually falls in rain, snow, and 

 hail, is very different in different parts of Great Brita-n ; there commonly falling 

 almost double the quantity on the western coasts, that falls on the eastern coasts 

 of that island. 



Lemma 1. — The quantity of rain which falls in Lancashire, during the 4 

 hottest months of the year, viz. May, June, July, and August, does not at a 

 medium amount to more than a third part of the quantity of water which falls in 

 rain, snows, and hail, during the whole year. 



Lemma 3. — The water which ascends in vapours from the sea very greatly ex- 

 . ceeds that which descends thereon in rain and other aqueous meteors : but the 

 quantity of water, which usually exhales from a given part of the ocean in a given 

 time, cannot with any exactness be determined. 



Lemma 4. — The quantity of water which commonly exhales in Great Britain 

 from shallow ponds during the 4 hottest months of the year, greatly exceeds the 

 quantity of rain which commonly falls on the surface of those ponds during the 

 said months. 



From these lemmata, which the author has supported by the observations, 

 not only of himself, but of other learned men, are deduced the following propo- 

 sitions : 



Prop. 1. — In several parts of England large quantities of bay salt may be ex- 

 tracted from sea water during the hottest months of the year, by receiving the 

 salt water into ponds, and suffering its aqueous parts thence to exhale by the heat 

 of the sun, and the operation of the air and winds. 



Prop. 1. — In several parts of England large quantities of bay salt may very 

 commodiously be extracted from sea water, after the same manner that is prac- 

 tised in France, and in other parts of Europe. 



Prop. 3. — Bay-salt may be extracted in England from sea water in larger quan- 

 tities, and with more certainty,' than by the foregoing method, if care be taken 

 to preserve the brine contained in the salt pits from being diluted with rains, and 

 to promote the evaporation of the water by several artificial means, which may 

 easily be put in practice. 



Prop. 4. — In several parts of England large quantities of excellent bay salt may 

 with great ease be made from the natural brine of salt springs, and also from rock, 

 salt dissolved in weak brine or sea water. 



Prop. 5. — Bay salt may be prepared in Englantl by the foregoing methods at 

 a very moderate expence, equal in goodness to the best foreign bay-salt, and in 

 quantity sufficient for the consumption. of all the British dominions. 



Prop. 6. — In several of the British colonies in America, bay-salt might, with 

 little expence and trouble, be prepared from sea water, in quantities sufficient to 



