514 Scientific Intelligence. 
which so em reflections of the sound-wave took place. In the 
same way, at sea the heat of the sun produced copious evaporation 
and the de in rising would mix — with the air, which 
would reflect the sound like the columns of hot air 
hus appears that on a perfectly calm day a stratum of air 
three miles thick is capable of stifling both the cee a and fog 
sounds. All the observations point to the mixture of air and aque- 
ous Vapor as the cause which could fill the air ete an acoustic 
cloud on a day of the most perfect optical transparency. If this 
explanation is correct, the sound cut off by the vapor should be 
rooney Pea is producing an echo, a result fully verified by observa- 
ore marked effects were obtained with a Brown’. 
seus ages The morning of October 8th was remarkably clear » 
afternoon it clouded up, rained and hailed with almost tropical vio- 
lence. In the midst of this furious squall both born and syren 
were heard, and when the shower — thus lessening the lo- 
cal pattering, the sounds so increased that at 74 miles they were 
more audible than before the shower at ai miles. This observa- 
is utterly opposed to the statement of Durham and others, regard- 
ing the ee influence of falling rain on sound. 
On 10th, during a dense fog, some experiments were made in 
London ‘68 a similar nature. unds were then heard at double 
the distance, as sek ree as on Dec, 13th, when the fog was re- 
prom by a slight haz 
n 
aced an electric ball in a padded box, with a single opening in 
it. At the other end was a funnel with a sensitive flame opposite 
its small end. When the box contained air only, at each stroke of 
the bell the flame responded, so that its length was greatly less- 
ened and emitted a musical roar when the bell sounded ve wR 
When now the gases were admitted, the sound was comp ‘ely cut 
off by reflection from the interposed _— so that {> flame 
remained perfectly tranquil.— Nature, ix, 251, 
12. Reflection of Sound by me.—Mr. Gace G tia recent 
performed some experiments of the division of sou <j by a 
flame or heated gas into a reflected and transu. rt 10n. 
A vibrating bell contained in a padded box was di ed so as to 
propagate a sound-wave through a tin tube, and its — rendered 
manifest by its causing a sensitive flame, ‘placed a t a distance in 
tion of an ignited coal-gas flame, issuing from an ordin 
wing t urner, was allowed to stream — across the en¢ of the 
d-wave i ortion of tht sound- 
nas limiting st'rfaces 
wave issuing from the latter was reflected at t 
of the heated layer; and-a part being transmitted nace? ieee 
now — nec tae to slightly agitate the sensitive flam 
2 erg owas neers ee os st: 
