1 88 The Migration of Birds 



probably a mile or more. A telescope with a three- 

 inch objective will serve every purpose, and a still, 

 clear night with a full moon is necessary for good 

 results. Focus the instrument upon the moon, the 

 birds, as they pass, appearing quite distinctly against 

 the reflecting planet. With a larger telescope it is 

 possible to detect the species that have well marked 

 and not too rapid wing beats. With a six-inch glass, 

 under favorable conditions, as many as two hundred 

 and eighty birds have been seen within three hours. 

 I have observed the night flight of birds several 

 times from the tower of the East Orange High School. 

 Even an arc light with a good reflector is sufficient 

 to attract the birds under favorable conditions, 

 but with a searchlight good results were obtained. 

 These night watchings have always proved most in- 

 teresting to me and to friends who have been with 

 me at various times, but one of the most interesting 

 evenings I ever spent in the tower was on September 

 23, 1890. The weather conditions were perfect. 

 Shortly after eight o'clock the first bird was seen, 

 although others had been heard almost constantly. 

 In the next half-hour two more birds were seen, but 

 their call notes greatly increased as they hurried past 

 us. The night was only partially clear, and as it 

 advanced a threatening thunderstorm came up at 



