330 
POPULAR SCIENCE REVIEW. 
in the Chemical News ” (May). It has been devised by M. Le Roux. It 
is an instrument by which one may vary almost instantaneously the nature 
of the light illuminating the slit of a collimator. The rays emergent from 
a prism are received on a moveable mirror, and the simple ray required is 
sent in the proper direction. The prism and mirror, with two collimators 
in the positions of the incident and emergent rays, are fixed on an articu- 
lated parallelogram composed of two lozenge-shaped frames. 
The Solar Cyclones . — In the Comptes Rendus ” for May 14th, some 
matter appears which relates to the above. M. Respighi, in a letter, asserts 
the excellence of his telespectroscope (called in question by P. Secchi). The 
chromosphere may appear, as P. Secchi says, more elevated where the spots 
are by a simple effect of perspective, the surrounding faculse being projected 
on each other ; but having carefully watched the progress of the spots in 
periods of quiet especially, he (M. Respighi) had often observed depressions 
at the spot, the red layer being almost interrupted. He also urges that the 
rarity of reversal of spectral lines in the nuclei is a proof of the small thick- 
ness of the chromosphere there ; if it were as thick and as largely mixed 
with luminous jets as neighbouring parts, one should be constantly seeing a 
reversal of the lines. The reversal when observed is doubtless due to the 
projection of an intense jet or protuberance on the spot. M. Faye remarks 
on the complexity of the spot phenomena; including faculse, jets emanating 
from them, depression at spot axis, the spot itself, and the solar rotation 
causing it, all in mutual dependence. 
A Novel Sensitive Flame is described by Mr. G. J. Warner, F.C.S., in the 
^‘Chemical News,” May 9th. It seems' to be obtained from a peculiar gas- 
burner devised by Mr. Wallace, of which he gives the following account : — 
It consists of a hemispherical chamber, into which the gas is introduced 
through a cone fixed horizontally at a tangent, the position of the jet with 
regard to the cone being so adjusted that the quantity of air injected by the 
velocity of the gas at all ordinary pressures is always the proportion re- 
quired for its perfect combustion. The upper part of the interior of the 
chamber is lined with wire gauze, and from it issue one or more tubes, at 
which the gas is burned. The burner which he has used had only one tube. 
At ordinary pressures the flame is of the colour of a Bunsen burner, but 
with a central cone, clearly defined, of pure green, whether it be turned 
high or low. But if the gas be reduced below the ordinary pressure on the 
main, the flame becomes white-tipped, and there is no longer perfect com- 
bustion, as in a defective Bunsen. It is then found that the flame is sensi- 
tive to sound, to all sound in fact, but to high notes particularly. He con- 
siders this a curious fact, as he believes it has been generally supposed that 
a high pressure is necessary to produce such a flame. The first effect of the 
sound is to elevate the flame several inches, after which, if the sound be 
prolonged, it shrinks down, producing the same perfect combustion as at 
ordinary pressures, and this continues as long as the sound. It would 
appear, therefore, that the gas at a very low velocity does not carry with it 
sufficient air, and that the effect of the sonorous vibration is to increase the 
velocity of the gas so long as the vibration continues ; so that by sound, by 
the rattling of a bunch of keys at a distance, we can bring the flame from a 
state of imperfect ” to one of “ perfect ” combustion. Of course the burner 
