Report on Terrestrial Magnetism. 329 



of magnetical observatories. This is a subject on which it will 

 be most proper to enter fully when their establishment has been 

 determined upon ; and we would recommend that then the Com- 

 mittee should be appointed to investigate the subject, and that 

 this Committee should report to the Council of the Royal So- 

 ciety what instruments they consider it would be most advisable 

 to adopt at all the stations, and, at the same time, give in an 

 estimate of the expense that must be incurred for one complete 

 set of such instruments. We may, however, in the mean time, 

 offer a remark on one apparatus referred to by M. de Humbolclt, 

 that of M. Gauss. However well we may consider this appara- 

 tus to be adapted for the determination of the course of the re- 

 gular diurnal variation, yet we apprehend that the great weight 

 of the needles employed would prevent their recording the sud- 

 den and extraordinary changes in the direction of the magnetic 

 forces, which are, probably, due to atmospheric changes. Ano- 

 ther, and we conceive a very serious objection to this apparatus 

 is, that bars of the magnitude employed must have an influence 

 so widely extended, that there would be great risk of the inter- 

 ference of one of these heavy needles with the direction of an- 

 other, especially in places where the horizontal directive force is 

 greatly diminished, unless the rooms for observation were placed 

 at inconvenient distances from each other. 



By referring to M. de Humboldfs letter, it will be seen that 

 the plan of observation so comprehensively conceived by him, 

 has been most powerfully and liberally patronized by the Govern- 

 ments offFrance, of Prussia, of Hanover, of Denmark, and of 

 Russia : Indeed, it is quite manifest that a plan so extensive in 

 its nature must be far beyond the means of individuals, and even 

 of scientific societies unaided by the governments under which 

 they flourish. To suppose, even without the example thus held 

 out, that the Government of this, the first maritime and com- 

 mercial nation of the globe, should hesitate to patronize an un- 

 dertaking, which, independently of the accessions it must bring 

 to science, is intimately connected with navigation, would imply 

 that our Government is not alive either to the interests or to 

 the scientific character of the country, and would show that we 

 had little attended to the history, even in our times, of scientific 

 research, which has been so liberally promoted by the Govern- 



