ADDRESS. Xliii 



to announce one of the results. After consideration of the singular appear- 

 ances observed in the eclipse of 1842, it was determined by the Committee 

 to recommend (among other things) that observing stations should be se- 

 lected, if possible, in triplets : the three stations of each triplet having rela- 

 tion to the north boundary, the centre, and the south boundary of the shadow. 

 The Russian Government has fully adopted this suggestion ; and has actually 

 equipped six triplets, including in all eighteen stations, with observers and 

 instruments for the observation of the eclipse. Russian officers in the Sea 

 of Azov and the Black Sea will also observe it. Since the issue of the Sug- 

 gestions, the observations made last year on an eclipse visible at Honolulu 

 in the Sandwich Islands have been received ; and they make us, if possible, 

 still more desirous that the spirit of the Suggestions should be complied 

 with, as far as possible. There is only one subject of regret connected with 

 this remarkable eclipse, — namely, that it will deprive us of the assistance of 

 several astronomers who would undoubtedly have joined this meeting but 

 for the necessity of being ready, at definite points, for the observation of the 

 phsenomena. 



Among subjects related in some measure to astronomy, I may first allude 

 to M. Foucault's experiment on the rotation of the plane of a simple pen- 

 dulum's vibration ; an experiment which has excited very great attention 

 both in France and in England, as visibly proving, if proof were necessary, 

 the rotation of the earth. It is certain that M. Foucault's theory is correct, 

 but it is also certain that careful adjustments, or measures of defect of ad- 

 justment, are necessary to justify the deduction of any valid inference. For 

 want of these, the experiment has sometimes failed. The Council of the 

 Association have long regretted the very great delay which has occurred in 

 the publication of the geodetic results of our great National Survey ; and 

 they were prepared some time since to represent strongly to the Government 

 the expediency of taking immediate steps for completing the few calculations 

 which yet remained to be made, and for publishing the whole in a form 

 which should be available for discussions of the figure of the earth. On 

 communicating with the Royal Society they learned that that body had made 

 an urgent recommendation to the same tenor, and that in consequence 

 Government had consented to place on the Estimates a sum of money ex- 

 pressly for the purpose of completing and publishing the scientific portions 

 of the survey. I have received official information that this work is now in 

 active progress ; and I cannot but remark on it as a striking instance of how 

 much may be sometimes effected for the purposes of science by simply com- 

 pleting what i^ nearly complete. The great Swedish and Russian Arc of 

 Meridian, from the North Cape to the Danube, is so far advanced that its 

 completion is expected in the present year. 



