Uhase.] ±-±\J [Feb. 7, 



It is often much cooler at Charleston, Key West, and elsewhere at the 

 South than it is at Baltimore or New York in these cases of excessive heat. 

 And a whole month, as well as a shorter period may exhibit such com- 

 paratively cool weather at the points from which it might be inferred that 

 the heat would be transferred to us. In fact, at Charleston and Savan- 

 nah, the intense heat of the last summer at New York and the North were 

 unknown ! — a mean of 85° at the North being reduced there to a mean of 

 81£° only. 



5. These more striking non-periodic extremes, both of heat and cold, 

 appear to be instituted at the districts where they are felt, by or through 

 some superior and extraneous agency, the elements of which are at 

 present extremely difficult of determination. 



I beg for the present merely to submit these propositions, as being indi- 

 cated only, not proved, although much time and observation have been 

 given by me to the consideration of the subject. I shall beg also to sub- 

 mit at an early day, the numerical elements of the investigation as so far 

 conducted . 



OSCILLATORY FORCES IN THE SOLAR SYSTEM. 

 By Pliny Earle Chase, Professor of Physics in Haverford 



College. 

 (Read before the American Philosophical Society, February 7th, 1873.) 

 All material motion seems to be determined by tendencies to equilibrium 

 between elastic, or centrifugal, and attractive, or centripetal forces. It 

 may, therefore, be presumed that every molecular motion can be so con- 

 nected by simple equations, with solar force, as to furnish an almost 

 endless variety of methods for estimating the Sun's mass and distance. 



The solar radiating forces (luminiferous, caloriferous, etc.), are sup- 

 posed to move with uniform velocities in straight lines. Gravitating 

 motion is uniform only in circular orbits. "We may, therefore, reasonably 

 look for the circular ratio, jr, among the conditions of planetary equil- 

 ibrium. The influence of that ratio in positing alternate planetary 

 orbits, is shown in the following table, each of the theoretical terms being 

 obtained by dividing the preceding term by jr. 



Cardinal Positions in the Solar System. 



Theoretical. Observed. 



Neptune, mean 30.04* 30.04 



Saturn, " 0.56 9.54 



Mars, major axis 3.04 3.05 



Earth, perihelion .97 .98 



Mercury, " .31 .31 



sents the time of fall from the circumference to the centre 



If 7T represents the time of revolution in a circular orbit, "■ ~*~ y 32 



