68 Messrs. T. L. Brimton and J. Fayrer on the [Jan. 22, 



so often alleged, that the power o fogs to deaden sound is well known, 

 the disjunctive not is to be inserted before the predicate. 



The real enemy to the transmission of sound through the atmosphere 

 has, I think, been clearly revealed by the foregoing inquiry. That enemy 

 has been proved to be not rain, nor hail, nor haze, nor fog, nor snow 

 not water in fact in either a liquid or a solid form, but water in 

 a vaporous form, mingled with air so as to render it acoustically turbid 

 and flocculent. This acoustic turbidity often occurs on days of surprising 

 optical transparency. Any system of measures, therefore, founded on 

 the assumption that the optic and acoustic transparency of the atmosphere 

 go hand in hand must prove delusive. 



There is but one solution of this difficulty : it is to make the source of 

 sound so powerful as to be able to endure loss by partial reflection, and 

 still retain a sufficient residue for transmission. Of all the instruments 

 hitherto examined by us the syren comes nearest to the fulfilment of this 

 condition ; and its establishment upon our coasts will, in my opinion, 

 prove an incalculable boon to the mariner. 



An account of the observations made during the recent fog will be in- 

 cluded in the paper shortly to be presented to the Society. These 

 observations .add the force of demonstration to others recorded in 

 the paper, that fogs possess no such power of stifling sound as that 

 hitherto ascribed to them. Indeed the melting away of fog on De- 

 cember 13th was accompanied by an acoustic darkening of the atmo- 

 sphere, so great that, at a point midway between the eastern end of the 

 Serpentine, where a whistle was sounded, and the bridge, the sound pos- 

 sessed less than one fourth of the intensity which it possessed on the day 

 of densest fog. 



Thus, I think, has been removed the last of a congeries of errors which 

 for more than a century and a half have been associated with the trans- 

 mission of sound by the atmosphere. 



January 22, 1874. 



JOSEPH DALTON HOOKER, C.B., President, in the Chair. 

 The following Paper was read : 



I. "On the Nature and Physiological Action of the Poison of 

 Naja tripudians and other Indian Venomous Snakes."- 

 Part II. By T. LAUDER BRUNTON, M.D., Sc.D., M.R.C.P., 

 and J. FAYRER, C.S.I., M.D., F.R.C.P. Lond., F.R.S.E., Sur- 

 geon-Major Bengal Army. Communicated by Prof. HUXLEY, 

 Sec.R.S. Received November 8, 1873. 



The effects of the poison of Naja tripudians are probably the same as 

 those of OpldopJiagus daps, Bungarus, Hydrophidae, and other poisonous 



