The fubjeéts of thefe Letters, and the Author's method of treating them, fcem to me much adapted to this purpofe. With the a?ifiance of a very moderate apparatus, they might conduét youth of both fexes, with equal delight and emog lument, to avery competent knowledge of natural philofophy: very little pre vions elementary knowledge is necef fary to a profitable perufal of them, and that little may be very eafily acquired.