Possible Liniar Inffjience vpon the Vplocify of the Wi)/(1 at Ki inhpt-lpi/. 
295 
diminishing in magnitude and falling progressively earlier, counting from 
greatest north declination, than the pressure crests. In general the 
velocity is two miles a day above the mean when the moon is coming south, 
and two miles a day below the mean for the rest of the time. If there be a 
tidal connection between the pressure and the velocity of the air during tlie 
tropical month, it cannot be a very direct one. 
Luke Howard devoted a good part of his time to an attempt to connect 
the moon's motions with changes of atmospheric pressure. By dividing the 
days of the year, for twenty-seven years, into periods of about seven days 
each, 
" the middle day of each week corresponding (1) with the moon's 
position coming north from the equator ; (2) with her position in fall 
north declination; (3) with her position returning to south over tlie 
equator; (4) with her full south declination," 
lie obtained the following averages by means of a " clock barometer " : 
N. 29-782 inches 
Equator 29777 
S. 29-774 „ 
Equator 29792 
Howard's interpretation of these numbers was that— 
" the barometric mean in our climate (England) is depressed (on 
an average of years) by the moon's position in south declination. . . . 
We have here, I think, evidence of a great tidal wave or swell in 
the atmosphere, caused by the moon's attraction, preceding her in 
her approach to us, and following slowly as she departs form these 
latitudes." * 
* Papers on Meteorology, 1854. 
