OF ARTS AND SCIENCES. 225 



dam, and he had no doubt of the correctness of the explana- 

 tion which had been prepared by a gentleman of great prac- 

 tical judgment. The air confined between the dam and the 

 sheet of water was constantly carried forward with the down- 

 rushing stream, and burst out at short intervals below the sheet 

 of water. At each outbreak of air, there is a strong inward puff 

 at the ends of the dam, accompanied with a waving back of 

 the sheet towards the dam. 



Professor Peirce announced that he had found quite simple 

 forms for the differential coefficients, relatively to the elements 

 of a planet's orbit, of the coefficients of the sine and cosine of 

 the eccentric anomaly in Gauss's formulae for the equatorial 

 rectangular coordinates of the planet. Mr. J. E. Oliver has 

 obtained a very near geometrical demonstration of these 

 results. 



Three hundred and thirtieth meeting. 



May 7, 1850. — Monthly Meeting. 



The President in the chair. 



The Corresponding Secretary read a letter from the Hon. 

 W. M. Meredith, Secretary of the Treasury, acknowledgino- 

 the reception of the report made at the February meeting by 

 a committee of the Academy appointed for that purpose, 

 recommending the establishment of permanent marks to re- 

 cord the present mean sea-level ; and stating that, " the object 

 being deemed important by the Department, and the fitness 

 of its connection with the Coast Survey recognized, author- 

 ity will be given to the Superintendent to cause the neces- 

 sary observations to be made, and the results communicated 

 to the Academy." 



Dr. Pickering offered some further remarks on the Egyptian 

 Astronomical Cycle. 



On motion of Mr. Eliot, the committee formerly appointed 

 to memorialize the Legislature of the Commonwealth, in 



VOL. II. 29 



