36 SIXTH REPORT — 1836. 



eluded by giving the leading conclusions which he conceives himself 

 justified in deducing from his researches. They are as follows : 



1 . That the law so much insisted upon in modern times by Hay- 

 crapt, Marcet, and De La Rive, and others, that the simple gases have 

 under equal volumes the same specific heat, is not the law of nature. 



2. That the more limited proposition enunciated by Dulong, that 

 tlie simple gases have under a given volume the same specific heat, 

 does not appear true in a single instance, and is altogether at variance 

 with his (Dr. A.'s) result for hydrogen. 



3. That the numbers at which he (Dr. A.) has arrived, correspond 

 tolerably well with those of De la Roche and Berard except in the 

 case of hydros'en. 



4. That there does not appear to be any simple relation between the 

 specific heats of the gases and their specific gravities or atomic 

 weights, and that philosophers in searching for such are probably 

 pursuing a chimsera. 



A paper on the above subject by Dr. Apjohn will shortly appear in 

 the Transactions of the Royal Irish Academy. 



On the ImpermeaUlity of Water to Radiant Heat. By the Rev. B. 

 Powell, F.R.S. 



On the Vibration of Bells. By R. Addams. 



On an Improved Ear-trumpet. By Chaeles J. B. Williams, 

 M.D., F.R.S. . &c. 

 Having lately had occasion to examine the ear-trumpets in common 

 use. Dr. W. found them all more or less faulty, especially in that they 

 produce confusing noises, like the roaring in large shells, which render 

 indistinct the articulate sounds which they are intended to convey. On 

 further examination, these disturbing noises were found to consist in : 



1. An exaggeration of all the foreign sounds which may happen to 

 accompany the voice, such as the rustling of clothes, reverberations in 

 the room, the rolling of carriages out of doors, &c. This defect is ma- 

 nifestly as inseparable from all insti-uments which augment sound, as 

 an inefficiency to render distinct an object in a mist is from telescopes. 



2. A sound dependent on the longitudinal ^dbrations proper to the 

 column of air contained in the tube. This sound is the note of the 

 instrument as a tube closed at one end, and is therefore deep according 

 to its length and the narrowness of its open end. 



3. A sound more or less tinkhng or metallic in character, resulting 

 from the transverse vibrations which repeated reflections of sound gene- 

 rate within hollow bodies, and which constitutes the tinkling note 

 produced in the interior of bottles, bladders, and other hollow objects. 

 This sound exists especially in those instruments in which sound is 

 concentrated by repeated reflection from curvilinear surfaces. 



I 



