Primary Feathers in Flight. 

 Explanation of Table VI and Carves in Fig. 12. 



159 



In Table VI, Series 7, first primary of an osprey was made 

 by calipers and Series 8 by photography and a measuring 

 machine. These series are shown by curves in fig. 12. It 

 should be kept in mind that the purpose of the measurements 

 was to determine the rate of diminution of the width of the 

 notches rather than their exact width. The width of the 

 notches in Series 7 and 8 are not equal, because it was not 

 possible to take the photographs exactly life size. The rates 

 of decrease of 7 and 8 are seen to be the same. 



Tablk VI. 



Eecovery of the web of a first primary feather notched by natural inter- 

 locking. Osprey (Pandion haliaetus carolinensis), shot at 3.45 p. m. , April 

 21, 1904, at Paterson, N. J. First primaries of each wing found deeply 

 notched. 





Series 7. 







Series 8. 







By calipers. 





By photography 







Time after 







Time after 







fall of 



Width of 





fall of 



Width of 



Time. 



bird. 



notch. 



Time. 



bird. 



notch. 



h. m. 



Minutes. 



mm. 



h. m. 



Minutes. 



mm. 



3-49 



4 



3-3 



4-00 



15 



3-22 



4-00 



15 



2-5 



4-08 



23 



2-85 



4-08 



23 



2-4 



4-45 



60 



2-84 



4-30 



51 



2-4 



5-05 



80 



2-76 



4-45 



60 



2-1 



5-20 



95 



2-72 



5-00 



75 



2 "2 



10-45 



420 



1-67 



5-20 



95 



2-1 









9-00 



315 



1-6 









11-45 



480 



1-2 









The primaries of the same bird were then artificially inter- 

 locked. The measurements of the resulting notches are also 

 shown in fig. 12. Series 9 was made two days after the bird 

 was killed, and Series 10 several days after that. 



Explanation of Table VII and Curves in Fig. IS. 



In fig. 13, Series 12, is merely a verification of previous 

 observations, the species being a Sharp-shinned hawk ; and 

 likewise Series 13. 



Series 14 and 15, Table YII, are important since they show 

 the rate of change in the depth of the notch found in the 

 second and fifth primaries of a Sharp-shinned hawk. The 

 webs of these feathers are seen to be more elastic than those 

 of the first primaries and the recovery is more rapid and com- 

 plete. The feather structure of the first primary is very rigid 

 and therefore its web not only requires a long time to recover 



