154 REPORT — 1844. 



with an earnestness commensurate both to its scientific importance and to the 

 large and liberal manner in which that support has been already granted. 



As respects the expenditure of the Committee, the annexed statement will 

 show the amount of their grant expended and the purposes for which the 

 outlay has been incurred. 



Signed on the part of the Committee, 



J. F. W. Herschel. 



Appendix. 

 Letter from Professor Boguslawski to Lieut.-Colonel Sabine. 



" Breslau, 1844, September 18, 139. 



" My dear Sir, — With reference to your letter of the 20th of February, 

 and to the verbal communications lately made to you by Sir Bernhard Hebe- 

 ler, Knt., Consul-General to His Prussian Majestj', I have now the honour to 

 inform you that I shall forward in a few days to Mr. Oswald, our Consul- 

 General at Hamburg, the first part of the magnetic observations made at this 

 place. They will be sent by the mail, being exempt from postage (until twenty 

 pounds Pruss.) as far as Hamburg. I expect you will have arranged with Sir 

 Bernhard the way how to receive the present, as well as the following parts, 

 in the least costly manner ; and you will also please to give your instructions 

 to Mr. Oswald, or communicate them through Sir Bernhai'd. 



" As the first two books of the year 1840 contain only the two terms of 

 August and November, (the monthly terms only having been observed with- 

 out interruption from January 1841 until i)ovr,) I should have liked to send 

 you at least the observations of the year 1841, particularly as not only these, 

 but likewise those of 1842 and even part of 1843, are completely entered, 

 but the drawing of the curves is not yet finished. I have some objection to 

 forward the entered observations without undertaking the projection of the 

 curves, which latter serve as a test and assist in discovering some little errors 

 made in the entries. The two terms of the year 1840 may then be considered 

 as pi-ecursors, and may serve to discover whether all is sufficient for reduc- 

 tion and comparison. 



" In general the observations may be divided in two periods — the first 

 until April term 1841 inclusive, and the second beginning from the May term 

 1841. Until April 1841 inclusive, the old four-pound declination-bar was 

 alone in the magnetic cabinet ; the other two instruments received by your 

 kindness were in the great room of the observatory exposed to many per- 

 manent influences of iron masses in the vicinity, where the observations 

 were made with them on the terms 1840, August and November; and 1841, 

 January, February, Marcli and April. 



"On the May term 1841, all three instruments were united in the magnetic 

 room, the declination magnetometer being then provided with the second bar 

 which belongs to the bifilariura. However, on this term the mutual action of 

 the bars could not yet be done away with, because the declination bar could 

 not at that time have been definitively suspended. But at the June term 

 1841, the same had received a proper regulation, whereupon the mutual ac- 

 tion was neutralised by a fixed bar which was placed immoveably, according 

 to its force, at calculated distances from the other bars. Whether this com- 

 pensation has remained correct 1 wish to examine again at the conclusion of 

 the daily and monthly variation-observations, in order to begin then a series 

 of absolute declination and intensity. The two active bars scarcely change 

 the time of their vibration, and the compensation bar, which is an old bar, 

 seems likewise to be of constant force. 



