ON MAGNETICAL AND METEOROLOGICAL OBSERVATIONS. 51 
scribed days of observation, so that much labour has been bestowed in vain. 
As we may assume that the observers are themselves interested in the results 
of their labours, and will willingly supply all the useful service to science in 
their power, we may, I think, leave to themselves what they may do at times 
of disturbance, in addition to the six daily observations, directing them at the 
utmost in some degree as to the intervals at which the readings should be 
taken, and which, with well-established instruments, ought to be as short as 
possible. The chief attention of the observers should be directed to the 
turning points, i.e. to the moment of time when an increase is changed into 
a decrease, and vice versd. If however it be still desired to institute obser- 
vations on prescribed days, it might be done tentatively, ¢.e. by observing on 
such days, in the manner hitherto followed on term days, at those hours when 
disturbances most frequently begin, i.e. from 4 to 10 p.m., completing the 
twenty-four hours of observation only when indications of disturbance are 
perceived. 
As barometric disturbances have the same interest as magnetic ones, al- 
though their range is more limited, it would be desirable on days when they 
occur to take more frequent readings than usual, it may be every hour, and 
oftener near the points of turning, which ought to receive especial attention, 
as the comparison of neighbouring stations of observation may make known 
the direction and velocity of the atmospheric wave. 
In respect to instruments, it appears to me better to retain those already in 
use, unless newly-devised ones offer very important improvement ; because in 
differential observations, which are chiefly in question, the disadvantages at- 
tendant on breaks and on the introduction of a different apparatus, are not 
always compensated by the greater exactness of the new instrument. As far 
as can be done, it will be desirable to lighten the work, and to render it 
more complete by the use of self-registering apparatus. If the barometro- 
thermometro- and hygrometro-graphs sent to England are found to answer, 
their advantage to meteorology will be great, and their use ought to be 
extended. I have made many trials at constructing magnetic autographs on 
the same principle, hut have found the experiment too expensive, and have 
therefore relinquished it, though without being convinced of the impossibility 
of success. In England, where there are such good artists, it might be less 
difficult. 
The earlier the observations and their results are communicated the greater 
will be their interest, and it may often happen that a comparison made while 
the first impression is still fresh on the mind may lead to not unimportant de- 
ductions, which escape when the comparison has to be made with the figures 
merely. Possibly it might be advantageous to publish the observations in 
smaller parts after the manner of a periodical journal,—it might be monthly. 
As the simplification of the system of observation would probably leave 
several observers at liberty, they might perhaps devote the time thus gained 
to the execution of magnetic surveys in adjoining districts. The multiplica- 
tion of such journeys and their results concerning the distribution of terres- 
trial magnetism appears to me to be the step most immediately needed. These 
observations ought to include, besides all the magnetic elements, a notice of 
the geognostic character of the ground, as its connexion with terrestrial mag- 
netism is a point of great importance. 
“IT have now given freely my views respecting this great scientific under- 
taking, and if the Association would think it useful to publish them, either in 
whole or in part, they are entirely at their disposal. 
mt With highest esteem, yours, KREIL. 
ria tt] 
EQ 
