178 ANNUAL OF SCIENTIFIC DISCOVERY. 



a porous cell. The iron in the sulphuric acid acted as the positi\ e 

 element, and the other as a negative. A constant and quite an 

 intense current is obtained l)y this arrangement. Another novel 

 battery, termed an " electric buoy,'' is now being experimented 

 upon at Cherbourg. It consists of a zinc plate and a cylinder of 

 carbon, attached to a cross-piece of wood, having sea-water as an 

 exciting liquid. Still another variety is that of M. Miergue, of 

 Bonfarik, consisting of a cylindrical cell of porous carbon, con- 

 taining nitric acid, and an exterior cylinder of amalgamated zinc 

 in a cell full of water. 



New Galvanic Exciting Liquid. — M. Delamier, in a communica- 

 tion to the Acadeni}' of Science, states that the following mixture 

 forms an exciting liquid for galvanic batteries of great energy and 

 economy, disengaging no deleterious fumes or gas. Dissolve 

 20 parts by weiglit of proto-sulphate of iron in 36 parts of water. 

 Then stir in 7 parts of a solution of sulphuric acid (equal parts) ; 

 then in the same manner add 1 part of diluted nitric acid (equal 

 parts) . 



TRANSMISSION OF SOUND. 



From the observations of M. Flammarion, as taken in a bal- 

 loon, it appears that sounds produced on the surface of the earth 

 are transmitted upward to great heights. The whistle of a loco- 

 motive is heard 3,000 metres high ; the noise of a train of cars, 

 2,500; the barking of dogs and the report of a musket, 1,800; 

 the sounds of a town (including the crowing of the cock and the 

 ringing of bells) often 1,600; the beating of a drum and the 

 tones of an orchestra, 1,400; tlie rumbling of carriages on a pave- 

 ment, 1,200; a loud human voice, and, in a very still night, the 

 rushing of a river, 1,000; the croaking of frogs 900; and the 

 chirp of the cricket 800 metres. This is not true of sounds pro- 

 ceeding from above downward; for while he could hear a voice 

 speaking 500 metres below, his own voice could not be clearly dis- 

 tinguished more than 100 metres below. On one occasion, when 

 the balloon was 900 metres high, was heard a piece of music, ex- 

 ecuted very nearly beneath, as distinct and perfect as if only a few 

 metres distant ; the parts could be clearly distinguished even at a 

 height of 1,400 metres; this observation was repeated 5 times, 

 and he noticed the permanence of the intensity of all the tones, 

 which were transmitted with the same quickness and reproduced 

 the music at this height in perfection. The clouds did not oppose 

 any obstacle to the transmission of sound. — Comptes Rendus^ 

 July, 1868. 



VELOCITY OF SOUND IN TUBES. 



M. Kundt has established that the velocity of the propagation 

 of sound diminishes with the diameter of the tube, — the diminu- 

 tion, however, only becoming sensible at a diameter equal to one- 

 fourth of the length of the wave of sound or note yielded. Above 

 this diameter, and in larger tubes, the velocity remains the same. 



