34-8 Account of the nem Magnetical Observatory at Gottingcn. 



distances ; a fact which had indeed been noticed before in 

 cases of very great irregularities in connexion with auroras 

 boreales. It is therefore to be expected that, as the participa- 

 tion in these preconcerted observations with this both conve- 

 nient and exact apparatus increases (for which there are al- 

 ready the best prospects), we shall obtain very remarkable and 

 comprehensive solutions of these very singular and till now 

 inexplicable phaenomena. 



Similar observations have frequently been made here at other 

 times also, from which sometimes very striking anomalies have 

 resulted. Thus, for instance, on the 14-th January, in the even- 

 ing between 8 and 9 o'clock, the declination decreased, within a 

 quarter of an hour, by 13 minutes, with the greatest regularity, 

 and then gradually returned to its former position. Such ob- 

 servations, however, can produce no further results, since, 

 without a preconcerted arrangement, corresponding observa- 

 tions are very seldom to be expected. 



From time to time also the experiments relative to the deter- 

 mination of the absolute intensity of terrestrial magnetism will 

 be repeated at the observatory ; but as they require various 

 preparations to perform them with the greatest exactness, the 

 first could not be made till the month of July. Three de- 

 terminations with different bars gave the following results : 



July 17th 1-7743 



20th..., 1-7740 



21st 1-7761 



as the value of the horizontal power by which, as in the earlier 

 determinations with smaller bars, the second of time, the mil- 

 limetre, and the milligramme form the foundation as units. 



The new apparatus in the magnetical observatory has also 

 been adapted for making electro-magnetic observations and 

 measurements, in a similar manner as in the astronomical obser- 

 vatory. The suspended magnetic rod is surrounded by a mul- 

 tiplier consisting of 200 circumvolutions, the construction of 

 which permitted the use of uncovered wire : the length of the 

 wire is 11 00 feet. With the help of a very simply constructed 

 commutator, the observer may, without taking his eye from 

 the telescope, reverse the direction of, or entirely interrupt, 

 the galvanic current. 



Nor can we omit mentioning on this occasion an apparatus 

 on a grand and hitherto unique scale, connected with the ap- 

 paratuses just described, and which we owe to our Professor 

 Weber. This gentleman had during the last year conducted 

 a double line of wires from the cabinet of natural philosophy 

 over the houses of the town to the astronomical observatory. 

 These are now continued to the magnetical observatory, thus 



