Primary Feathers in Flight. 



157 



The results of the measurements are shown by the accom- 

 panying tables and curves. 



Explanation of Table I V. 



Table IV shows the result of observations on the primaries 

 of a Broad-winged hawk. They were the first made, and while 

 the few measurements must be regarded as only approximate 

 they demonstrate the fact that the feathers were interlocked 

 for some hours previous to the death of this bird, as seen from 



Table V. 



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

 locking, specimen : Sharp-shinned hawk (Accipiter velox), adult $ , shot at 

 2.38 P. M., April 21st, 1904, Paterson, N. J. 





Series 3. 







Series 4. 







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. 



2-51 



*13 



1-85 



2-48 



10 



1-92 



2'57 



19 



1-70 



2-56 



18 



1-80 



3-02 



24 



1-55 



3 45 



67 



1-53 



3-10 



32 



1-50 



4-40 



122 



1-39 



3-19 



41 



1-40 



4-50 



132 



1-16 



4-07 



89 



1-30 



5-15 



157 



1-07 



4-30 



112 



1-0 



5-25 



167 



•98 



4-38 



120 



1-05 



10-45 



487 



•66 



4-42 



124 



1-10 









5-00 



142 



1-10 









5-20 



162 



1-1 









9-00 



382 



•60 









10-40 



522 



•50 









a comparison of the two series of measurements. The time 

 required for the webs of the feathers artificially interlocked to 

 recover (see Series 2) was very short and the notch was not 

 even formed in one-half hour in the case of the third primary. 

 Before the measurements of Series 2 were made the primaries 

 of the left wing were interlocked for five minutes, .but as no 

 notches were formed, the interlocking period was increased to 

 thirty minutes. This bird was shot by a person near me and 

 was handled before I reached it. The primaries were then not 

 interlocked but the notches were very prominent, so their 

 recovery was measured. It was not possible to obtain another 

 specimen of this species of hawk for measurement, 



* Time was lost preparing camera for Series 4. 



