164 Scientific Intelligence. 
and is provided with a catch to keep it just within the conical open- 
ing. ‘The mouth tube may consist of two pieces, one sliding into the 
other, so as to be readily adjusted to any convenient length. The 
Jamp should be covered, when in action, with a hood having two 
openings, one in front for the admission of the blowpipe, and the 
other opposite for the exit of the jet of flame. The air may be 
forced out of the bladder mechanically, by surrounding it with a 
course net of twine, and hanging a weight to the bottom of it. This 
blowpipe unites great simplicity to cheapness and facility of adjust- 
ment.— Bull. d@’ Encour. Sep. 1828. 
7. Linear unit.—If the earth should ever be struck by a comet, 
its axis of rotation and its form would indubitably be changed, and 
from that time the measure of the pendulum or the are of the me- 
ridian could no longer be resorted to, for the recovery of the metre. 
This speculative question having been one day debated in Paris in a 
‘company of scientific gentlemen, Sir Humphrey Davy proposed a 
seale, which, in his opinion, might be resorted to or rediscovered after 
the greatest changes in the form of the globe: this linear unit would 
be the diameter of a capillary tube of glass, in which the ascent of 
the water would be exactly equal to that same diameter. _ In reflect- 
ing on the various difficulties of the experiment, (observes the editor,) 
I suggested, in turn, the measure of the length of luminous undula- 
tions in a vacuum, as a method which would lead more certainly to 
the object proposed. Although these two projects are very old, and 
the means of observing them had been prepared, they have been 
hitherto attended with no results, and indeed it is no cause of regret, 
as there is no probability that they would be attended with any real 
utility—Ann. de Chim. et de Phys. Fev. 1829. 
8. Smoke Disperser of M. Millet. (Bull. Soc. Enc.)—A report 
upon this apparatus, made by M. Derosne, speaks favorably of its 
powers. The apparatus is simple, consisting of a kind of tub, pierc- 
ed with @ great number of holes, having the burs outwards. It has 
-been taken into practice by many persons. In order to prove its 
‘efficacy, one of them was fixed on the top of the funnel pipe of a 
