B. TERRESTRIAL PHYSICS AND METEOROLOGY. 87 



narrow orifice up to the region of the clouds under the form 

 of a column, surrounded by vapors condensed by cooling, and 

 spreading as they ascend. Fourth, on the contrary, I sub- 

 mit that the common origin of all these phenomena is found 

 in the upper currents, whose power and directions are clear- 

 ly shown to our eyes by the clouds, and not in the lower 

 strata, where an almost perfect calm continually reigns. 

 Not, of course, that a calm reigns at the precise spot where 

 the waterspout exists at any moment, but all about it. 

 Upon this capital point, so easy to demonstrate, so frequent- 

 ly denied by observers, and which lends so much to the so- 

 lution, all the witnesses are agreed. This does not prevent 

 the aspiration theorists from placing violent currents, like 

 immovable layers, around the heart of this perfect calm, 

 which the waterspout or the tornado does not disturb for an 

 instant in its rapid course. Never have we seen iu science 

 a similar disregard of facts; a strange indiiference which is 

 explained, only by the influence of a very ancient and very 

 extended prejudice, whose history I have traced in the An- 

 nuaire for 1875, and which has caused meteorologists to re- 

 place facts by theories upon the stability or instability of at- 

 mospheric equilibrium. 6 J3^ LXXX., 660. 



THE EFFECT OF MOVEMENT OF THE AIK ON THE BAROMETEE. 



M. Faye having stated in his defense of the law of 

 storms that the barometer does not measure the weight of 

 the atmosphere above us, but that its indications are to be 

 interpreted by dynamical and not statical principles, this 

 idea has been made by Montigny the subject of a commu- 

 nication to the Belgian Academy, on the difterent pressures 

 exerted by the air upon the barometer, according as it is in 

 movement or quiet, and upon the estimation by means of 

 the barometer of altitudes in balloon ascensions. Montigny 

 has communicated some five or six memoirs on the relation 

 between the height of the barometer and the pressure of the 

 wind. Among them is a series of interesting determinations 

 of the height of a point in the cathedral of Anvers, by means 

 of barometric observations taken under very varied influ- 

 ences as regards the direction and velocity of the wind. 

 These observations had especially as their object to show 

 that the law of diminution of pressure is not the same when 



