OF ARTS AND SCIENCES: JANUARY 10, 1865. 383 



moon's secular acceleration over and above the late determination. 

 We have seen that the hypothesis of a retardation of the tidal wave 

 by friction of only ten minutes is sufficient, according to Fourier's the- 

 ory, of the loss of heat, and if we suppose the loss to be somewhat 

 greater than this theory requires, it is only necessary to make the hy- 

 pothesis a very little greater. If 6" of the moon's secular accelera- 

 tion is due to tidal action, then the length of the day has increased 

 about -j^g- of a second in the last twenty-five hundred years. If the 

 effect of tidal action is insensible, and the late determination of the 

 moon's secular acceleration from theory be received, then we have no 

 way of accounting for the remaining 6", and besides we cannot allow 

 that the earth's volume has contracted as much as even Fourier's the- 

 ory requires. The main point at which we have arrived is, that tidal 

 action is adequate to account for 6" of secular acceleration upon a very 

 reasonable and probable hypothesis with regard to the magnitude and 

 retardation of the tidal wave by friction, after making due allowance 

 of the effect for counteracting the effect of a probable contraction of 

 the earth's volume, and that we therefore have no just reason to reject 

 the late determination of secular acceleration arising from a change of 

 the eccentricity of the earth's orbit, because it does not cover the whole 

 amount determined from the observations of ancient eclipses. 



Professor Whitney read a paper on the progress of the Geo- 

 logical Survey of California, and presented to the Academy a 

 volume of his report on the Paleontology of that State. 



On the motion of Dr. H. R. Storer a committee was ap- 

 pointed, consisting of Professor Rogers, Dr. A. A. Gould, and 

 Professor Agassiz, to consider what action the Academy should 

 take toward promoting the Geological Survey of California 

 and the adjacent territories. 



Five hundred and forty-fourth Meeting. 



January 10, 1865. — Monthly Meeting. 



The President in the chair. 



The Corresponding Secretary read letters relative to ex- 

 changes ; also a communication from Mr. Otto Struve of the 

 Observatory at Pulkova, announcing the decease of the emi- 

 nent astronomer his father. 



