May 7, 1869.] ^^-^ [Cliase. 



nolds, said Appendix consisting of a sub-report on the Carices 

 of the Expedition made by the late Dr. Dewey. On motion, 

 the Memoir (with its five plates) was referred to a Committee 

 consisting of Mr. Dnrand, Mr. James, and Dr. Euschenberger. 



Mr. Eothwell, Engineer of Mines, exhibited through the 

 Secretary a published copy of his new map of the eastern end 

 of the first Anthracite Coal Basin, with cross sections, showing 

 the excessive plication of the synclinal. (See Plate 2, fig. 2.) 



Mr. Chase communicated by permission of Mr. Pierce, Di- 

 rector of the U. S. Coast Survey, the more recent results of 

 his investigations into the rain gauge curves. 



The observations which were examined, and the method of treatment, 

 were described in my discussion of the tidal rain-fall of Philadelphia, 

 {ante, vol. x., pp. 523-7). 



The frequent tendency to triple maxima and minima, which I have at- 

 tributed to lunar influence on the daily barometric spheroid, — the estab- 

 lishments, both of temperature, and of position with reference to great 

 bodies of water, — the different relations of precipitation to atmospheric 

 pressure at different seasons of the year, — the influence of the moon and of 

 each of the principal planets on temperature, winds, cloudiness, and both 

 frequency and amount of rain-fall, — the probability that the influences upon 

 temperatnre are due to the induced aerial currents and not to radiation, 

 (a South wind raising, and a North wind depressing the thermometer), — the 

 secular variation, which appears to depend principally upon the combined 

 action of the Moon and Jupiter, — are all clearly indicated by the normal 

 curves. 



Most of the curves show a great similarity at the opposite equinoxes, 

 and a great contrast at the opposite solstices, both at Greenwich and at 

 Philadelphia. But in the total rain-fall at diff"erent solar hours, the equi- 

 noctial and solstitial contrast is modified by a synchronous divergence at 

 the two stations, the Philadelphia curves differing greatly at the equinox- 

 es and being nearly alike at the solstices. This peculiarity may be owing 

 to the fact that the prevailing winds at Greenwich are from the ocean, 

 while those at Philadelphia are from the land, so that an atmosphere sat- 

 urated with moisture is normal at the former station, abnormal at the 

 latter. 



The planetary curves are so strongly marked that it seems impossible 

 to account for them by any action analogous to the Moon' s ditt'erential at- 

 traction. They may perhaps be satisfactorily explained by the moment 

 of inertia, and the constantly and often rapidly varying distance of the 

 centre of gravity of the earth and distui'bing planet. 



Dr. Brinton communicated the information which he had 

 obtained respecting the valuable Arawak MSS. Grrammar and 



A. P. S. — VOL. XI — O 



