194 PROCEEDINGS OF THE AMERICAN ACADEMY 



Mr. G. p. Bond stated that he had found that the horizon- 

 tality of the axis of the Great Equatorial at Cambridge is sub- 

 ject to a regular disturbance, its position going through a 

 succession of changes almost uniform every year. This he 

 ascribed to the unequal action of temperature upon the two 

 supporting pillars. The western pier rises from March to 

 September, and is depressed during the remainder of the year. 

 Mr. Bond exhibited a diagram, showing by a series of curves 

 the rate of elevation and depression through different months, 

 for the past five years. The amount of departure from a 

 horizontal position is ^ of an inch in all. 



Mr. Bond also said that he had been making some investi- 

 gations to ascertain whether the attraction of the moon has 

 any effect on the motion of a pendulum, and consequently 

 upon the rate of a clock. He had found this last to be 

 changed to the amount of j^jg of a second daily. At the 

 equator the moon's attraction changes the weight of a body 

 only Yooocoo of the whole ; yet this force is sufficient to produce 

 the vast phenomena of the tides. 



Four Iiuiidred and fiftcentli meeting. 



May 29, 1855. — Annual Meeting. 



The President in the chair. 



The Treasurer presented his report for the year, which was 

 certified by the Auditing Committee. 



The Committee on the Library reported, and their report 

 was accepted. 



Professor Agassiz referred to the allusion in the Report to 

 the Smithsonian Institution, and expressed in strong language 

 his sense of the indebtedness of the scientific world to that 

 Institution for its enlightened efforts to diffuse knowledge, 

 particularly as a medium of exchange of publications. In 

 conclusion, he moved that the thanks of the Academy be pre- 

 sented to the Smithsonian Institution, for its efficient agency 

 in effecting for the Academy its exchanges with foreign 



