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 

 lamp 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 

 coarse 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 arc 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 

 scale, 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 dePhys. 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 a 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 

 stove, and a very close smoky fire made below. By means of a 

 ventilator, an artificial wind was then made to strike directly and 

 powerfully on the smoke disperser for the purpose of driving the 

 current downwards and making the stove smoke ; but neither by this. 



