Viii CONTENTS. 



18. Journal of the Acadenfl^, of Natural Sciences of Phila- 



delphia, - - - - - - 414 



19, 20, 21. New monthly Journal, called The Friend of Man- 



kind — Proposed exchanges by the Franklin Society of 

 Providence — Destruction of Life by explosions of Steam 

 Boilers, ------ 415 



22, 23. Encyclopedia Americana — Ohio Canals, - - 416 



24. Journal of Law, _ - - - - 417 



25. Alum in Mica Slate, - - - - - 418 

 Addition to Prof. Johnson's piece on steam, - - 418 

 Postcript— Gen. Van Rensselaer's Note, - - - 419 



ERRATUM. 

 No. 1, Vol. XX, p. 153, line 9 from top, for stones read stars. 



