210 REPORT— -1842. 



however, are the large ones of the German makers. In regard to the cor- 

 rection for temperature of the horizontal-force instrument, I arrived at no 

 satisfactory result by the ordinary method of obtaining it. This winter an 

 approximation to the correction has been obtained by allowing the observa- 

 tory to cool down on Sunday. If we had had a second set of instruments 

 for comparison these results would have been unexceptionable ; as it is, the 

 method of vibrating a declinometer bar and of observing a portable vertical- 

 force instrument for comparison, led to no satisfactory result. Had the winter 

 been of its usual severity so as to give us a result every week, this comparison 

 would have been of less consequence. 



"Having ascertained by the observations in 1840 and 1841 nearly the 

 hours of maximum and minimum of the magnetic phenomena, I have during 

 the present year caused observations to be made within those limits as fre- 

 quently as on term-days. As these observations occupy, with moderate 

 intervals, the whole twenty-four hours, I hope to be able to render a better 

 account of disturbances than heretofore. This makes me more than ever 

 anxious to keep up the observatory during the present year. The regular 

 bi-hourly observations form a part of this series. 



" You have doubtless a report from the observatory at Harvard, and know 

 how zealously they are at work. Mr. Gilliss, of the navy, keeps up his ob- 

 servations of the declination and vertical force at the observatory at Wash- 

 ington city. 



" In reference to our knowledge of the magnetic elements in different parts 

 of the United States, the work goes bravely on. Prof. Loomis has contri- 

 buted within the year a large quota in his observations of dip, chiefly in 

 Ohio, Indiana, Illinois and Missouri. Mr. Nicolet has observed in the same 

 region, and has added a few observations of horizontal intensity to those of 

 the dip. You will see an account of these results in the Proceedings of the 

 American Philosophical Society, and at a later day in their Transactions. 

 Dr. Locke has also made his contribution, which you will find in Silliman's 

 Journal. I completed last summer a systematic survey of Pennsylvania com- 

 menced the year before, and hope to be able to calculate the observations du- 

 ring the coming vacation. The observations were for declination, dip, and hori- 

 zontal intensity at the chief stations, and for dip and total intensity by Lloyd's 

 method, at the subsidiary points. By observations made at the same station 

 with different instruments, it appears that we now have several dipping circles 

 which may be relied on to furnish accordant results, and they are in hands 

 which will not let any opportunity pass of using them. The visit of Lieut. 

 Lefroy will doubtless stimulate us to further exertion by showing an example 

 of activity near. 



" The Association have now a great work before them in drawing out of 

 the results at the magnetic and meteorological observatories the interesting 

 laws which they must furnish. Wishing you and your co-labourers all 

 success, "I remain, very truly yours, 



" Lieut.- Colonel Sabine" " A. D. Bache." 



Report of the Committee for the Translation and Publication of Foreign 

 Scientific Memoirs. 



Since the list meeting of the British Association the Committee have obtain- 

 ed and published in the ninth Number of Taylor's " Foreign Scientific Me- 

 moirs," translations of the two following works, viz. Gauss, ' General Propo- 

 sitions relating to Attractive and Repulsive Forces, acting in the inverse ratio 



