26 SEVENTH REPORT—1837. 
seen no later publication containing his own conclusions from 
his observations. The results entered in the table are con- 
sequently computed by myself from the report above no- 
ticed, and are uncorrected for temperature, which is of the 
less importance as the differences of temperature were not 
considerable. It is not stated in the report that the needles 
were re-examined at St. Petersburg at the close of the series; 
but as the two give results very nearly accordant, it is pro- 
bable they underwent little or no loss. At one of the sta- 
tions in the Caucasus no dip was observed ; consequently no 
total intensity can be computed. Some error has obviously 
taken place in regard to the observations at Moscow; the 
times of vibration of both needles as given in the report would 
correspond with a very much higher intensity there than at St. 
Petersburg, which we know from the concordant observations 
of MM. Erman and Hansteen is contrary to fact. M. Han- 
steen, who received the observations direct from M. Kupffer 
at St. Petersburg, has omitted the Moscow results in his notice 
of this series. I have therefore done the same, supposing that 
there is some satisfactory reason for the omission with which 
I am unacquainted. At Stavropol and Taganrog the dips 
employed in the reduction were observed with an inferior ‘in- 
strument, the principal dipping-needle having met with an acci- 
dent. 
Quetelet, 1829-1830.—In 1829 M. Quetelet, Director of the 
Royal Observatory at Brussels, made observations on the hori- 
zontal intensity at several stations in Germany and the Nether- 
lands, with an apparatus similar to M. Hansteen’s and two 
needles ; and in the following year in France, Switzerland, and 
Italy with the same apparatus and four needles. The obser- 
vations of 1829 are contained in a memoir printed in the 6th vol. 
of the Memoires de ? Academie Royale de Bruxelles; those of 
1830 in the Annalen der Physik, vol. xxi. Unfortunately, the 
greater part of the observations of horizontal intensity are un- 
accompanied by observed dips, and the stations are compara- 
tively few at which M. Quetelet either observed the dip himself i 
or has selected dips observed by others, so as to be available 
for our present purpose. There are ten such stations entered 
in the general table. Having vibrated his needles in Paris in 
1830, the values of the intensity are deduced by direct com- 
parison. He has corrected the observations for temperature, 
employing for their reduction the coefficient determined by M. 
Hansteen for his own needle. 
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