Mr Siemens' paper on the Bathometer, which we noticed some months ago, is now published in the _Philosophical Transactions_. Objections have been made to the instrument as an indicator of the depth of the sea, because the sea-level is disturbed by the attraction of large masses of land. Mr Siemens answers that he is aware of the objection; that the bathometer is not expected to do more than indicate comparatively small variations in total terrestrial attraction, which the hydrographer or navigator using the instrument will have to interpret according to the circumstances of the case. If the zero-point of the instrument varies with the latitude, or in consequence of special geological causes, we must bear in mind that these causes are of a permanent character, and that when an ocean has been once surveyed by means of the bathometer, the special local conditions become observed facts, and would thus serve to increase the value of the bathometer as an instrument for measuring the depth of the sea without the use of the sounding-line.
At a meeting held at Salem, Massachusetts, a lecture on 'Visible Speech' was delivered by Professor Graham Bell, who, by means of the drum in a human ear cut from a dead subject, has succeeded in producing a phonautograph. The ear is placed in the end of an ordinary speaking-trumpet; on speaking into the trumpet the drum is set in motion; this moves the style; the style traces the effect on a plate of smoked glass; and by means of a camera the curves and lines can be exhibited to a large number of spectators. The five vowels make five different curves; and according to Mr Bell, there is no such thing as a sound or tone pure and simple, but each is a composite of a number of tones; and the wavelets by which these are produced can also be shewn on a screen. Tables of the various symbols have been drawn up, and found useful for educational purposes, as was demonstrated by a young deaf and dumb pupil from the Boston Institution, who interpreted the symbols at sight.
Professor Bell has improved the method devised by his father, formerly of University College, London, for rendering speech visible; and as is well known, membranes have long been used for experiments in acoustics. Some of our readers may remember the experiments of Mr W. H. Barlow, F.R.S., described in his paper 'On the Pneumatic Action which accompanies the Articulation of the Human Voice,' read two years ago at the Royal Society, and published in vol. 22 of their _Proceedings_. And within the past few weeks we learn that the telephone has been so far improved that an account of a public meeting was talked into one end of a wire and was distinctly heard and understood at a distance of eighteen miles.