442 
MR. LUKE HOWARD ON THE BAROMETRICAL VARIATION 
Hence it was inferred that the barometrical mean is depressed in these latitudes 
by the moon’s position in south declination : and that which appeared upon the aggre- 
gate of years, was found to hold also in the several nine-years’ averages of which it 
consisted. The depression was stated to be gradual, proceeding through the three 
changes to the south place ; but upon the planet’s quitting her south position to re- 
turn north, a sudden elevation of the mean, effected in a single week of declination, 
indicated the return of the pressure (as far as regarded this influence) to its former 
limit. 
The results of the present examination differ somewhat in the proportions of pres- 
sure shown ; the chief cause being, as I apprehend, the different latitude in which a 
part of the observations took place. In 1828, near the middle of the year, having- 
given up my house on Tottenham-green, I removed the barometer-clock to the Villa, 
Ack worth, Yorkshire, in latitude 53° 39' north, and still on the east side of the island. 
Here I obtained for some time the yearly circle of the variation : but coming subse- 
quently to spend the winter in the south, from my absence joined with other causes, 
the clock for several months in tbe year stood still. I had presented a good baro- 
meter to the Friends’ Institution at Ackworth, where a good meteorological register 
is kept at my instance; and from this the maxima and minima, wantingin the series 
by the clock, have been taken. 
Thus circumstanced, and the instrument standing, from the above date, on con- 
siderably higher ground, and 2° more to the north, the averages from 1824 to 1832 
come out as follows, viz. moon coming north 29-8505 in. ; in north declination 
29-8257 in. ; going south 29-80/6 in. ; in south declination 29-8058 in. Here we 
have still the depression to the place of south declination ; but with a check, amount- 
ing almost to the doing of it away, in the concluding position. Let us, however, see 
further. 
On the solar years, from 1833 to 1841, observed wholly at Ackworth , the averages 
are, — 
Moon coming north 29"71 2/ in. 
Moon in north declination . . . 29 - 6946 in. 
Moon going south 29"6969 in. 
Moon in south declination . . . 297116 in. 
The former variation, presenting a gradual decline of gravity to the moon’s south 
place, is here replaced by one altogether different ; the loss of gravity by the north 
declination continues into the following week, and is restored (very nearly) in the 
fourth week ; the moon yet full south. Had this discrepancy resulted from less per- 
fect observation merely, it ought to have affected each position alike, and to have 
made the calculations useless ; but we have here even more of symmetry than before. 
There must be something then in the more northern latitude, affecting partially the 
mixed average 1824 to 1832, and more completely the northern average 1833 to 1841 ; 
which is commended, with all deference, to the study and consideration of our 
mathematical and astronomical Fellows. 
