the Combustion of Gases in Tubes. 475 



In the first experiments I made use of a tapering brass jet 



}01 mches long, and having a superior orifice about 1th of In 



glassTub'^TheT thJ'^-^'^''"^ ^^ *^^ ^'"^^"^^ «-^ ^^ 



f to be seen W, Tf^'f ^r^''^^ ^'^'^'< ^^« «« ^^^ifest 

 as to be seen by several hundred people at once. 



1 placed a syrene within a few feet of the singino-.flame and 



the £n \ 1 ^^ ^"""^ 'y^'^"^ approached perfect unison, 

 JntP Tk ! ''''^' •1^'"P'^» ^^P ^"'l ^«^^ ^'tbin the tube. The 



rogSfeetTeeTr^^- '^' ^^^^^ -t.f ^nallf ^S^^^a^ 



obs^er^edTvlr^ch^ffT'^/^'S*'^' J^^^P'^^ ^^ *^^ A^^^e, 

 oDserved by M. Schaffgotsch, is the optical expression of thp 



beas which occur at each side of the perfect unisoi the beats 

 could be heard in exact accordance with the shorten .^.o-^i 

 lengthening of the flame. Beyond the region of theleTefts in 

 both directions, the sound of the syrene piSduced no v sibTe mo 

 tion of the flame. What is true of the syrene is true of the voTce' 

 mile repeating and varying these experiments I once had , 

 of^t^Tb^hrflam^^ ^"' ^^ ''''''^' °^^ -- '"he'not 



Ts^obta-n^f '^' ^^ ''^'^-^ ''^ -P— ^ t^e sa^e iSSt" 

 I placed the syrene near the flame, as before. The latter w., 

 burning tranqmlly within its tube. Ascending giilaHv fZ 

 ounro? t."''" '^ '^' -strument, at the mL^ if whe'n the 

 sound of the syrene reached the pitch of the tube which sur 

 rounded the gas flame, the latter suddenly stretched Sf and 



srered^fsrnr'^^'^^"^""^^^^^^^^^^^^^^ 



be obtained with ease and certainty. If thT voice hVfl. "" 



little higher or lower than the note due trthe tube nn'''T,* 

 effect is produced upon the flame- the ni ch of fl ""'"'^^^ 



lie within the regioi? of the audfble beats^ '^' ''''' '"'^^' 



By varying the length of the tube we vary the r^nto n..« 1 ^ 

 and the voice must be modified accordingfy^ ' P'"^"*^^^^ 



That the shaking of the flame, to which 1 have already referr.^ 



wd,og the f„..t ,„ a, .o^h.ow,tsl4r„rt„f\l„''rtl• 



