ON MAGNETICAL AND METEOROLOGICAL OBSERVATIONS. 14.5 



Expedition passed several months), and the North American group collected 

 in the Toronto volume, as well as the European group collected in the 

 ' Resultate ' of MM. Gauss and Weber. 



So much is yet prospective in regard to publication, that comparatively 

 little can be at present ventured in regard to conclusions. The only portion 

 of the observations which is yet before the public, viz. observations on days 

 of unusual magnetic disturbance 1840, 1841, does however afford some con- 

 clusions which may be taken as an earnest of the fuller harvest. The most 

 important of these is the fact, shown in the preface of that volume, of the 

 universality of the disturbances of the higher order. The establishment of 

 so important a general law, on evidence which may be considered to have 

 placed it beyond a question, is a happy augury of what may be expected 

 from a combined system of observation, of which it is the first fruits. 



Further, it was shown from the observations in that volume, that though 

 these great disturbances are universal in their occurrence, yet their magni- 

 tude is clearly modified by season and by other local causes ; so that for 

 example, while the northern and southern hemisphere participate in every 

 great disturbance, the influence of summer in the one and winter in the other 

 is clearly traceable. 



There are also facts stated in regard to the periodical march of the mag- 

 netic elements at Toronto and Hobarton, valuable in themselves, but yet more 

 so in the evidence they afford of the exact determinations which will be every- 

 where accomplished in this branch of the phaenomena. 



Another conclusion has also been drawn in regard to the great disturbances, 

 Avhich will have a more full development in the Toronto volume. It has been 

 shown that the effects, as manifested by the movement of the magnetic instru- 

 ments at all places of observation, of a disturbance taking place in all parts of 

 the earth at the same time, were not the same, — thus limiting the distance 

 of the superimposed force which produces disturbances coinstant in respect to 

 time, but differing in respect to direction and intensity, at stations remote from 

 each other. The mode of computing the direction and amount of the super- 

 imposed disturbing force from the observations at a single station is also 

 stated. 



In the Toronto volume, the term observations of the three American ob- 

 sei'vatories for the three years ending in December 1842, all showing the 

 closest harmony with each other, are compared with those at Prague, taken 

 as a type of the European group : the comparison exhibits frequent unequi- 

 vocal evidence of connexion in many of the larger irregular movements. In 

 such case the simultaneous movements in Europe and America take place 

 sometimes in the same direction, as by a force operating upon both conti- 

 nents from the same quarter ; and sometimes the European and American 

 movements are in opposite directions, as by a force operating intermediately 

 between the two continents. It is obvious that, if the observations were m- 

 stantaneous as well as simultaneous, the locality of the disturbing force might 

 be immediately deducible. Without, however, going further into anticipation 

 of what may hereafter be concluded from observations not yet before the pu- 

 blic, there is ground, in what is already known concerning them, for expressing 

 the hope that important conclusions will be drawn in respect to the locality 

 of the disturbing causes, especially when the observations made with the most 

 recent magnetometers, constructed to exhibit instantaneous effects, shall come 

 to be considered. In our present ignorance of the nature of the causes of 

 these phaenomena, we are surely advancing in the proper, legitimate and phi- 

 losophical mode of ascending to them by this careful study of their effects. 



In meteorology, a system of careful observation with compared instru- 

 1844. L 



