Chemical Science* 481 



of (he motion of a particle is equal to the radius of the spherical 

 portion of the fluid suf)poaed to be agitated at the origin of the 

 niotion, divided by the velocity with which the sound is trans- 

 mitted. The first of these qualities is necessarily smaller in 

 water than in air; the second greater: from whence it follows, 

 that the duration of the sound should be much less when trans- 

 mitted by water than when by air. 



A second remark is, that sound is not transmitted from water 

 to air when the direction of the vibrations forms a very small 

 angle with the surface at which the two fluids meet. When the 

 bell 6.56 feet below the surface was struck, the sound could 

 be lieard in the air at the surface of the water at the distance of 

 200 metres (656.17 feet) ; but at a greater distance it diminished 

 rapidly, and at 400 or 500 metres could not be distinguished. 

 If, however, the head were immersed a little way in the water, or 

 a trumpet-formed tube, full of air and closed by a diaphragm, were 

 immersed, so that the diaphragm should be perpendicular to the 

 line extending directly to the bell, then the sound could be 

 heard even at ten or twenty times that distance. 



The agitation of the waves produced no alteration in the 

 velocity, (hiration, or distinctness of the sound under water, 

 when a tube like that just mentioned was used to render them 

 audible. Some of the experiments were made at very stormy 

 periods, but with no observabledifference on these points. — Atnnales 

 de Chimie, xwv'i, 236. iihb^'tvi^i:^ 



.\ 12. lEjctraordinary Experiments on Heat and Stearn, by Mr. Per- 

 kins.— Under tliis title are described in the last number of this 

 Journal, (p. 461,) some results, stated to have been obtained by 

 Mr. Perkins, from an American journal. The details are so cir- 

 cumstantial that we cannot resist the inclination of quoting ano- 

 ther experiment of the same kind from the French journals. 



A generator is said to have cracked when very hot, but no va- 

 pour or water issued out until the temperature was allowed to 

 fall, and then the rush of steam by the aperture formed was tre- 

 mendous. This was supposed to be because the heat repelled the 

 water and vapour to a certain distance from the metal, and, vir- 

 tually, stopped the crack; accordingly, another day, the gene- 

 rator was heated red hot at flie cracked part, and water introduced 

 in the usual w^ay : neither steam nor water came out at the crack 

 during the whole of the day, the generator being at work all the 

 time J but in the evening, on cooling it, the same effects happened 

 as before. 



As some persons still retained doubts, all these, it is said, were 

 removed by the following experiment: a hole, the eighth of an 

 inch in diameter, was made in one of the extremities of one of the 

 tubes of a generator, and an iron tube, three feet long, one inch 

 external and half an inch internal diameter, screwed over it. , The 



