224 
MR. LUBBOCK ON THE METEOROLOGICAL OBSERVATIONS 
Obs" 5 at Somerset 
House. 
Obs n 
at the Paris Observatory. 
9 A.M. 
3 P.M. 
9 A.M. 
12. 
3 P.M. 
9 P.M. 
January .... 
+ .006 
+ .005 
+ .085 
+ .067 
+ .072 
+ .069 
February . . 
+ .064 
+ .070 
+ .071 
+ .070 
+ .065 
+ .063 
March .... 
-.004 
-.009 
-.006 
— 004 
-.007 
-.005 
April 
— 044 
— .143 
—.044 
-.047 
-.053 
— 042 
May 
+ .002 
— .025 
-.044 
-.043 
— .047 
-.046 
June 
+ .006 
— .031 
+ .037 
+ .040 
+ .040 
+ .064 
July 
— .017 
-.022 
+ .008 
+ .004 
+ .009 
+ .008 
August 
-.005 
— .001 
+ .018 
+ .016 
+ .014 
+ .013 
September . . 
-.039 
-.048 
+ .016 
+ .014 
+ .015 
+ .019 
October .... 
+ .117 
+ .116 
-.063 
-.060 
— 062 
— .056 
November . . 
+ .036 
+ .025 
— .021 
— .015 
-.012 
-.011 
December . . 
—.006 
+ .005 
-.047 
— .042 
-.035 
-.039 
Mean .... 
29-861 
29-840 
29-778 
29-767 
29.748 
29-762 
Thus the mean height of the barometer at 9 a.m. for January is 29.861 + .006 = 29.867. 
It may be remarked, that according to this Table, the annual variations appear 
to be independent of the diurnal variations. The Paris observations present 
much greater regularity than those made here, which results perhaps from their 
greater number. In order to determine the diurnal variations of the baro- 
meter, it is necessary that the observations should be repeated much more fre- 
quently in the course of the day than is done here at present. The mean 
height of the barometer here at 9 in the morning is greater by .02 1 inch (or 
about xotli of an inch), than at 3 in the afternoon ; and so regular is this diurnal 
variation, that considering the mean of each month separately for the years 
182/, 1828, 1829, and 1830, there are only two cases in which the mean height 
is greater at 3 in the afternoon than at 9 in the morning. The corresponding 
difference at Paris is .030 inch # . 
In order to determine the fluctuations of the barometer due to the moon, 
it would have been desirable to possess many more observations ; but, unfor- 
tunately, previous to 1827, the observations of the barometer at Somerset 
House seem not to have been made at stated times of the day, a condition which 
appears to me absolutely necessary, in order that meteorological observations 
* There is a very interesting paper on the annual and diurnal variations of the barometer, by 
M. Carlixi, in the 20th volume of the Memorie della Societa Italiana. Fasc. lmo. (Memorie di 
Matematica.) 
