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ARTICLE XXVII. 
Results of the Magnetic Observations in Munich during the 
period of three years, 1840, 1841, 1842. By Dr. J. Lamonr*. 
(From the Transactions of the Royal Bavarian Academy of Sciences. } 
A PORTION of the period of three years during which, ac- 
‘cording to the original design, the two-hourly magnetic obser- 
yations were to be continued, was consumed in Munich, as well 
as in most other places, in the construction and establishment 
of the observatory. Early in August 1840 all the preliminary 
_ arrangements were completed, and the regular observations were 
: commenced ; but subsequent experiments showed, that in order 
to obtain correct determinations, conditions and precautions, 
_ previously unrecognised by any one, were requisite. In conse- 
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quence of this circumstance the declination results previous to 
July 1841, and the intensity results previous to November of 
the same year, must be regarded as undeserving of confidence, 
and have therefore been omitted in the following account, with 
the exception of the mean declination, in which the errors of the 
single results may probably have compensated each other. 
Diurnal Movement of the Declination. 
The first of the following tables shows the diurnal movement 
of the declination as given by the monthly means. On a closer 
inspection, however, we may perceive that this march is consi- 
derably disfigured by the influence of the days of disturbance ; 
and Table II. has therefore been formed for the purpose of ex- 
hibiting the same monthly means, with the omission in the cal- 
culation of the days of disturbance. Even after this has been 
done the corresponding months of 1841 and 1842 present con- 
siderable differences, so that, even setting aside disturbances, 
thirty days appear: insufficient to eliminate the irregularities, 
and to afford a correct representation of the regular diurnal 
movement; and it is probable that the combination of the re- 
sults of several years will be required for this purpose. In the 
meantime I have attempted to reduce the irregularities by taking 
* Communicated by Lieut.-Colonel Sabine. 
