Benjamin Franklin. 237 



new invented fire-places are applicable to furnaces for 

 almost every use or purpose.' * 



The new ideas in the Smoke- Abatement Exhibition at 

 Kensington, 1881-82, are fewer than at his time in this 

 letter by Mr. Watt, and the knowledge is among few 

 persons. 



We are glad also to bring into the list of our con- 

 tributors an American friend and Englishman, Benjamin 

 Franklin. 



Meteorological Imaginations and Conjectures. By Benjamin 

 Franklin, LL.D.> F.R.S., &c. Communicated by Dr. 

 Percival. Read December 22, 1784. 



' There seems to be a region higher in the air over all 

 countries, where it is always winter, where frost exists con- 

 tinually, since, in the midst of summer on the surface of 

 the earth, ice falls often from above in the form of hail. 



* Hailstones, of the great weight we sometimes find 

 them, did not probably acquire their magnitude before 

 they began to descend. The air, being eight hundred 

 times rarer than water, is unable to support it but in the 

 shape of vapour, a state in which its particles are separ- 

 ated. As soon as they are condensed by the cold of the 

 upper region, so as to form a drop, that drop begins to 

 fall. If it freezes into a grain of ice, that ice descends. 

 In descending, both the drop of water and the grain of ice 

 are augmented by particles of the vapour they pass 

 through in falling, and which they condense by their cold- 

 ness, and attach to themselves. 



1 The specification, which was enrolled on July 9, 1785, is printed in the 

 Mechanical Inventions of James Watt, 1854, vol. iii. pp. 115 to 121. 



