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ON MAGNETICAL AND METEOROLOGICAL OBSERVATIONS. 17 
twenty-four (perhaps in future thirty-five) elements of the ‘ Erdmagne- 
tismus-Theorie.’ ; 
1 believe that as far as this object is concerned considerable reductions may 
be made in the above very comprehensive system. 
It appears to-me necessary for the permanent problem,— 
1st. To preserve all the observatories at remote stations out of Europe; 
2nd. To repeat regularly (every month) all absolute measurements at all 
these observatories. 
I consider it unnecessary for this object to continue,— 
Ist. The term observations, which may perhaps in future be confined to 
European stations ; 
gnd. The two-hourly daily observations, which may perhaps be reduced to 
eight-hourly. 
In short, it seems to me that, supposing we have really been so successful 
that nothing but the permanent problem remains, we may so far simplify our 
system that one well-instructed and practised observer at each observatory 
will suffice and will need no assistants. Such a limited system of observation 
must be constantly continued without interruption, if the history of terrestrial 
magnetism is to be no mere fragmentary work ; and if the magnetic maps 
based upon it are to possess that precision and conformity to system which 
would make them so useful in praxis. 
II. In regard to the indirect results which the systematic prosecution of 
magnetic observations may have had in exciting and furthering other scien- 
tific efforts, such effects are already unmistakeably recognizable, but they re- 
quire time for their further development before their whole extent and full 
importance can be seen. In Germany, for example, there existed hitherto 
mere collections of physical instruments without arrangements for their use ; 
there were no physical laboratories and observatories: these, which are be- 
come indispensable to the progress of science, are now beginning to arise, and 
for this the arrangements made for magnetic observations afford a solid and 
secure point d’appui, as I can testify from my own experience. Further, 
_ since magnetic observations have received their recent improvement and com- 
pleteness, we have begun in several places in Germany to subject galvanic 
observations to analogous principles, and have introduced for them also abso- 
lute measure ; but for all these researches magnetic observations afford neces- 
sary elements which must be regarded as data. Magnetic observations are 
therefore not only necessary for terrestrial magnetism, but are besides now 
become an important element for many other physical investigations. There 
is at our universities a growing recognition of the importance, both for science 
and for practical life, of forming exact observers of nature. Hitherto astro- 
nomy alone has afforded a very partial opportunity for the formation of fine 
observers, of which few could avail themselves. Experience has shown that 
magnetic observatories may serve as excellent training-schools in this respect. 
III. In regard to instruments, it appears to me that if the results obtained 
shall be found to correspond to the expectations of the Magnetic Committee, 
there will be no ground for alteration; and even if these expectations shall 
have been occasionally disappointed, I should yet be persuaded that (except 
in regard to vertical variations) the cause would be found to be not in the 
instruments, but in the unskilful handling of particular observers, and that 
a change of instruments would be likely to do more harm than good, as every 
new instrument requires a new skilful mode of handling. In every point of 
view it seems to me advisable to retain the present instruments without ma- 
terial alteration. But I should think it very desirable to take more frequent 
opportunities of sending magnetic bars, whose time of vibration (and correc- 
845. c 
