LIV. A letter from Mr. B. Wilson, F. R. S. and Member of the Royal Academy of Sciences at Upsal, to Mr. Æpinus, Professor of Natural Philosophy in the Imperial Academy of Sciences at St. Petersburg, and Member of the Academies of Berlin, Stockholm, and Erfurth

I have not had the favour of hearing from you since I sent you some experiments upon gems similar to those produced by the tourmalin, which induced me to conclude, that the electric current moves always along the grain thereof. It was the more agreable to communicated these new experiments to you, becuase from the least hints the greatest discoveries have been made; and what may we not expect from that curious observer of nature, who first discovered these extraordinary qualities in the tourmalin, which have since excited the attention of so many philosophers.