392 Hutchins — Radiant Energy of Standard Candle. 



A fact which may be of much significance, is that, the Pots- 

 dam or Lower Cambrian sandstone of Southern Dutchess 

 County lies unconformably on the second or granulitic member 

 of the pre- Cambrian formation, and it is upon the same second 

 member that the basal beds of the Manhattan Group rest. 

 No unconf or m ability has yet been found between the Manhat- 

 tan Group and the underlying pre-Cambrian beds, and it is 

 chiefly this lack of positive evidence that leaves the writer in 

 doubt as to the geological equivalence of the former. Of 

 equal significance, however, is the lack of unconf ormability 

 between the Lower Silurian strata of Peekskill Hollow, Tomp- 

 kins Cove, and Verplank's Point, which are but partially 

 metamorphosed, and the metamorphic beds of the Manhattan 

 Group which adjoins them. 



The crystalline limestones of the Manhattan Group are, as. 

 already stated, highly magnesian and in this respect they cor- 

 respond in composition to the Calciferous limestones of New 

 Jersey which according to Professor Geo. H. Cook (Geology 

 of New Jersey 1868) contain from seventeen to twenty per 

 cent of magnesia. 



In this abstract it has not been possible to give in detail the 

 evidence upon which the writer's conclusions are based. A 

 complete discussion of the evidence must therefore be reserved 

 for future publication. 



Art. XLIX. — The Radiant Energy of the Standard Candle / 

 Mass of Meteors ; by C. C. Hutchins. 



The following investigation was undertaken with the pri- 

 mary object of finding, if possible, more trustworthy data for 

 determining the mass of shooting stars ; but a reliable deter- 

 mination of the radiation of the standard candle cannot fail to 

 be of value for other purposes. 



The apparatus employed in making the measurements was 

 my thermograph,* the constant of which was found in the 

 two following ways. 



First method. — A copper Leslie cube, holding about 3 kilos, 

 of water, was placed behind an opening of 16 sq. cm. in a wooden 

 screen, which opening was closed by a movable shutter, by 

 opening which the thermograph, one meter distant, could be 

 exposed to the radiation from the cube. 



The following quantities were then determined : dimensions 

 of cube ; weight of water contained in cube ; water equiva- 

 lent of cube ; mean of the galvanometer deflections taken dur- 



* Proc. American Academy, 1889. 



