PHILOSOPHICAL SOCIETY OP WASHINGTON. 3t 



ice, but that their being found frozen up at the mouth of a river 

 did not necessarily indicate glaciation. 



Mr. Meigs called attention to the fact that the tusks were 

 found under water, and that the animals may have floated down 

 in water, instead of having been carried by ice. 



Mr. Henry also made a second communication 



ON FOG signals AND ABNORMAL CONDITIONS OP SOUND, 



in which he spoke of the great attention which the Light House 

 Board of the United States had given to fog signals, and men- 

 tioned the steam-whistle, the trumpet, and the syren, and an 

 instrument for estimating the intensity and penetrating power 

 of sound, and the experiments which had been made with them ; 

 in reference to recent instances of several cases of abnormal 

 phenomena of sound. 



{This paper forms part of the Reports of the U. S. Light House Board.) 



85th Meeting. March 21, 18t5. 



The President in the Chair. 

 Thirty-two members and visitors present. 

 Mr. E. B. Elliott read a paper on 



CALENDAR FORMULA, 



explaining more particularly and illustrating, by examples, the 

 following expressions : — 



k -\- m -\- d — 1n = w, in which 

 ^ := y -j- I -j- 4 — c, for the years of old style, 

 k =y -{-{ -\- Q — 2r " " new style. 



In these, k, the year number, is, in general, after rejecting the 

 sevens, the number of the day of the week for a common year of 

 the preceding December 30, for a leap year of the preceding De- 

 cember 31, but for the first two months of a leap year must be 

 diminished by 1 ; in, the month number, is the day of the week 

 on which the first day of the month falls in a common year, 

 which opens on the first day of the week, and is unchangeable; 

 i. e., the number will be for 



