IN reference to the question of “Harmonic Echoes,” allow me to suggest to those who may have the opportunity of observation, how desirable it is that these echo-tones should be investigated in a manner to determine whether they are truly harmonic or not. There would be no difficulty in testing the sounds given in response to the notes of a closed organ-pipe and an open one, or the notes of representative musical instruments, clarionet and flute. It might be found that the echo at Bedgebury Park would give the octave always, irrespective of the particular instrument provoking it; or, on the other hand, that it refused to answer to a closed pipe, or gave only the twelfth, its proper reply. We should then know whether the echo-tone was that of the harmonic or a new fragmental tone consequent on the breaking up of the wave of the fundamental or ground-tone, by “breakers ahead.”