52 



LEWIS : 



shown by Figure i. At this hour the rings were so bright 

 that to look at them with the naked eye was blinding — it was 

 quite impossible to study them carefully without the aid of 

 smoked or colored glass. 



The temperature as registered by the standard thermometer 

 at the office of the Superintendent of the Media Division, 

 Pennsylvania Railroad, was 68° Fahrenheit, but at 12 o'clock 

 noon the temperature had fallen several degrees and the halos 

 had almost entirely disappeared, owing to the slowly accumu- 

 lating clouds of an approaching rain storm. Between 12.30 

 and 1. 00 P. M. a heavy, cold rain began falling. Rain or snow 

 may always be expected following the display of a halo, but 

 usually several hours will elapse before precipitation occurs. 

 The general weather conditions during the month of May, up 

 to and including the 20th, were very unseasonable, being unus- 

 ually cold and wet. The forenoon of the 20th was, however, 

 apparently cloudless until about 11.30 A. M., although a pro- 

 nounced haze pervaded the atmosphere from early in the 

 morning. The following statement, furnished by Mr. Bliss, 

 of the local United States Weather Bureau at Philadelphia, 

 sets forth the actual weather conditions existing for a period 

 of four days from May i6th to May 21st. The table was 

 prepared as an item of additional interest, and supplies data 

 that are believed as having considerable and direct bearing on 

 the causes attending the display of the halos. 



TABLE SHOWING WEATHER CONDITIONS 



