SIR WILLIAM SIEMENS, h\K.S. 383 



horizontally upon the upper surface of the bathometer upon a 

 regularly divided scale, which horizontal tube is connected at one 

 .-ml with the uppermost chamber of the bathometer above the 

 mercury, while the other end remains open to the atmosphere. 

 The space above the mercury in the upper chamber is filled by 

 preference with oil, which terminates in the horizontal spiral glass 

 tube at a point which will vary with the total attractive influence 

 of the earth, and thus furnish a means of reading the instrument. 

 The electric contact arrangement described in the paper is thus 

 rendered unnecessary, and the reading of the instrument much 

 simplified. 



Since presenting my paper on the bathometer to the Royal 

 Society in February last, I have continued my endeavours to pro- 

 duce an instrument in such a form as to be practically in- 

 dependent of the disturbing influences to which reference is made 

 in my paper, and of a construction so simplified as to render the 

 instrument available for practical uses. 



It is my intention to present before long a supplementary paper 

 to the Royal Society describing the improved instrument, and 

 giving an account of the further trials which I have had the 

 opportunity of making, for the purpose of verifying the indications 

 of the instrument by actual sounding. 



The first set of observations was made by Mr. Alexander 

 Siemens, on board the steamship " Faraday," in American waters 

 of a depth not exceeding 100 fathoms, when the readings were 

 found to accord closely with the results of sounding. Besides 

 this, several trials of the instrument have been made : one under 

 my immediate superintendence in crossing lately from New York 

 to Liverpool, on board the steam-ship " Bothnia," Capt. M'Mickan 

 (who rendered me every facility) ; another on board H.M. steam-ship 

 " Fawn," between Southampton and Gibraltar ; while another has 

 been made, at the instance of Dr. Higgs, with a modified form of 

 apparatus, on board a sailing-ship in its passage from Southamp- 

 ton to Rio Janeiro. The results of the observations on board the 

 u Fawn " were unsatisfactory, owing to a mechanical defect in the 

 apparatus, whereas the others confirmed generally the results given 

 in my paper confirming also the observation there referred to, that 

 differences of latitude do not seem to exercise the full amount of 



