ON MAGNETICAL AND METEOROLOGICAL OBSERVATIONS. 11 



Airy contending for the inadequacy of Gauss's formula, and proposing a 

 different method, and Dr. Lloyd for its practical sufficiency. The subject 

 must be considered as still under discussion, and the necessary revisal of the 

 instructions for the new period will either cause both methods to be practised, 

 or otherwise bring the point to a satisfactory issue. Opportunity will also be 

 afforded for attention to many other valuable practical suggestions which 

 have been offered as the result of experience already gained ; such as Mr. 

 Lamont's correction for change of magnetism in the deflecting bar in the 

 same class of experiments, when in the meridian, and when perpendicular to 

 it ; as also Dr. Lloyd's determination of the ratio of the distances of the de- 

 flecting bar which shall give the smallest possible error in the resulting in- 

 tensity corresponding to a given force of deflection, and his suggestion re- 

 specting the employment of the bifilar suspension for the purpose of magni- 

 fying small declination-changes, whether such changes require to be mea- 

 sured for ascertaining the temperature correction of a deflecting magnet, or 

 simply for their own sake, at stations near the equator where they are habitu- 

 ally very small. 



No expense beyond a charge of 10/. 8s. lOd. for observatory registers sup- 

 plied to Mr. Boguslawski for the new period of three years, has been incurred, 

 but your Committee pray a continuance of the remainder of their grant to 

 meet such demands as may arise. 



Signed on the part of the Committee, J. F. W. Herschel. 



Annual Report of Professor Von Boguslawski, addressed to Colonel Sabine. 

 " My dear Sir, " Breslau, June 18, 1842. 



" I have received with great pleasure, although much retarded, your es- 

 teemed communications of May 19th, 1841, and January 11th, 1842, as well 

 as the highly interesting inclosures, but am still in expectation of the arrival 

 of the required forms, as also of the new books for observations of this year, 

 from 2 to 2 minutes. They will however arrive in time, because for this year 

 past, extraordinary obstacles to the labours of the observatory have taken 

 place, which however have now been happily removed. The only assistant 

 who was associated with me was suffering under a complaint of the chest, 

 which rendered him incapable of continued work. The labours thereby fallen 

 to my share were increased by the death of Dr. Scholtz, Professor of Mathe- 

 matics, part of whose lectures I was obliged to take upon me until his place 

 was supplied again. 



" Not without much exertion I have taken care, that all the magnetic term 

 observations were made complete, and that everything was prepared to proceed 

 presently to the absolute observations under more favourable circumstances, 

 as also not to omit observations of perturbations out of terms. 



" During the vacancies of the Easter holydays I have caused to be made for 

 that purpose, not without difficulty, a deep blind (niche) within the old thick 

 and strong wall of the tower, in order to get thereby sufficient room for ob- 

 servations of deviations of the declination needle also in the westerly direction. 

 I place much confidence in the new assistant, who is to arrive by the 1st 

 July, and live in hope that my request for a second assistant will be acceded 

 to, so that the magnetic observations will be continued with redoubled zeal, 

 and more time can then be given to the forming of the abstracts and registers 

 for you. 



" I beg to request of you the favour of communicating this to the Council of 

 the British Association, and to present to them at the same time my most 

 sincere and hearty thanks for the honour conferred upon me for naming me 

 a corresponding member." 



