I MUST confess that I was surprised by Mr. R. E. Baynes' communication, in NATURE, vol. xix. p. 33, that the galvanometer I have proposed in NATURE, vol. xviii. p. 707, has already been described. Before writing my article I have searched a good many books and journals relating to the subject without finding an allusion to any such instrument. Since Mr. Baynes drew my attention to “The Elements of Physical Manipulation,” by Prof. Pickering, of the Massachusetts Institute of Technology, U.S., I have procured this book and find that it certainly does contain the theory of a galvanometer like mine, with the coil moving round a horizontal axis. As far as I know, such an instrument has, however, not been practically employed either in. this country or on the Continent before I introduced it, though its want must have been much felt for some time past. This seems to show that Prof. Pickering's description of the instrument has not been brought to the general knowledge of electricians. If, therefore, my article in NATURE, at a time when electric currents of great strength are being so widely introduced into practical working, has contributed to make electricians acquainted with this form of galvanometer, I shall not regret the time I have spent in theoretically and experimentally investigating this subject. Prof. Pickering alludes in his book to the improper dip motions of the needle as a defect in his form of galvanometer; I think I have obviated this by pivoting the axis of the needle at both ends. Since communicating the results obtained with my experimental instrument, more elaborate instruments have been constructed and found very useful in many instances where the ordinary forms of galvanometers would not have answered the purpose.