Intelligence and Miscellaneous Articles, 397 



Astronomers, also, will find in this new determination of the velo- 

 city of light an important confirmation of the value of the sun's 

 parallax 8"*86, which is obtained by comparing this number with 

 the constant of the aberration. It is the value which M. Le Ter- 

 rier has found again by three series of observations relative to the 

 motions of the planets, particularly Mars and Venus. The import- 

 ance, then, for astronomy, of the precise determination of the ve- 

 locity of light cannot be too much insisted on. 



In conclusion, I think I am right in affirming, as M. Fizeau an- 

 nounced immediately after his first researches, that the same expe- 

 riments could, without much more difficulty, be repeated, under 

 favourable atmospheric and topographical conditions, with stations 

 from 20 to 30 kilometres apart. Then, with the aid of a special 

 geodesic operation, I doubt not that we could obtain a determination 

 of the velocity of light approximate within less than a thousandth 

 part. I have the greatest desire to attempt this experiment, and 

 should deem it a great honour if the Academy would receive the 

 project favourably. It is desirable, for the honour of French 

 science, that those grand labours commenced by Ecemer at the Ob- 

 servatory of Paris, simplified and continued by French savants, 

 should be completed in France with all the precision which com- 

 ports with their importance in the light of physics and astronomy. 

 — Comptes Rendus de V Academic des Sciences, vol. lxxvi. pp. 338-342. 



NEW EXPERIMENTS ON SINGING FLAMES. BY FR. KASTNER. 



If two flames of suitable size be introduced into a glass tube 

 and both placed at two thirds of the length of the tube from its 

 lower end, they will vibrate in unison. The production of the 

 phenomenon continues as long as the flames are kept separate ; 

 but the sound ceases as soon as the two are put in contact. 



I took a glass tube 55 centims. in length, 41 millims. in exterior 

 diameter, and 2*5 millims. in thickness. Two separate flames, 

 produced by the combustion of hydrogen gas issuing from burners 

 of suitable construction, placed at 183 millims. from the base gave 

 the sound of fa natural. 



As soon as, with the aid of very simple mechanism, the flames 

 are brought together, the sound is suddenly interrupted. If w r e 

 vary the position of the flames in the tube, leaving them still 

 separate, above the third part of the length the sound diminishes 

 as far as the middle of the tube, beyond which all sound ceases ; 

 below the same point, on the contrary, the sound augments as far 

 as the quarter length of the tube. If at this place the flames are 

 brought together, the sound does not cease immediately, as the 

 two flames can continue to vibrate as a single one. 



The interference of singing flames is only produced under 

 special conditions. It is of importance that the length of the 

 tubes be in accordance with the number of the flames ; the height 

 of the flame exerts only si limited action upon the phenomenon, 

 while the form of the burners plays an important part. 



