.s'/A' WILLIAM SIEMENS, I'.R.S. 123 



proportion of the motion of the drum will be communicated to the 

 alcohol counter, and this motion is rendered strictly proportionate 

 to the alcohol contained in the liquid, allowance being made in 

 the instrument for the change of volume due to chemical affinity 

 between the two liquids. Several thousand instruments of this 

 description are employed by the Russian Government in control- 

 ling the production of spirits in that empire, whereby a large staff 

 of officials is saved, and a perfectly just and technically unobjec- 

 tionable method is established for levying the excise dues. 



Another instrument, not belonging to any of the classes enume- 

 rated, is one for measuring the depth of the sea without a sound- 

 ing line, which has recently been designed by me, and described 

 in a paper communicated to the Royal Society. Advantage is 

 taken in the construction of this instrument, of certain variations 

 in the total attraction of the earth, which must be attributable to 

 a depth of water intervening between the instrument and the solid 

 constituents of the earth. It can be proved mathematically that 

 the total gravitation of the earth diminishes proportionately with 

 the depth of water, and that if an instrument could be devised to 

 indicate such minute changes in the total attraction upon a scale, 

 the equal divisions on that scale would represent equal units of 

 depth. 



Gravitation is represented in this instrument by a column of 

 mercury resting upon a corrugated diaphragm of thin steel plate, 

 which in its turn is supported by the elastic force of carefully 

 tempered springs representing a force independent of gravitation. 

 Any change in the force of gravitation must affect the position of 

 this diaphragm and the upper level of the mercury, which causes 

 an air-bubble to travel in a convolute horizontal tube of glass 

 placed upon a graduated scale, the divisions of which are made to 

 signify fathoms of depth. Special arrangements were necessary in 

 order to make this instrument parathermal, or independent of 

 change of temperature, as also independent of atmospheric density, 

 which need not be here described. Suffice it to say that the instru- 

 ment, which has been placed on board the S.S. " Faraday " during 

 several of her trips across the Atlantic, has given evidence of a 

 remarkable accordance in its indications with measurements taken 

 by means of Sir William Thomson's excellent pianoforte wire- 

 sounding machine ; and we confidently expect that it will prove 



