156 Trowbridge — Interlocking of Emarginate 



hours formed notches only about one-half as deep as those 

 found when the hawks were killed. 



As previously stated, the records of the widths of the 

 notches were made by the impression of the points of a pair 

 of dividers, the actual measuring being done in the laboratory 

 afterwards. In this way each measurement was little influ- 

 enced by the preceding. This naturally resulted in experi- 

 mental variations, but it seemed to be the best method to 

 employ and the measurements give approximate curves of the 

 rate of recovery of the web of the feathers in each case, which 

 was all that was desired. If the measurement had been mostly 

 confined to the second, third, etc., primaries instead of the less 

 elastic first primaries, more nearly perfect curves would have 

 been obtained, as shown by curves 14, 15 and 16. 



Table IV. 



Recovery of the webs of three primary feathers of a Broad- winged hawk 

 (Buteo latissimus) shot at 10.30 a.m., April 13th, 1904, atPaterson, N. J. 



Series 1. 

 Notches found in the primaries of the right wing a few minutes after the 

 bird was shot. 



Time after First primary Second primary Third primary 



fall of bird. width of notch, width of notch. width of notch. 



Minutes. mm. mm. mm. 







10 (approx.) 1-1 2-0 1-7 



20 0-8 .. 1-7 



30 0-3 1-0 1-3 



40 0-3 0-2 0-8 



60 0-3 0-0 0-0 



Series 2. 



Primaries of left wing artificially interlocked for 30 minutes with strong 

 pressure within one-half hour after death of bird. 



Time after First primary Second primary Third primary 



unlocking. width of notch. width of notch. width of notch. 



Minutes. mm. mm. mm. 



2-1 0'4 



5 1-0 0-0 



The reason for making sixteen series of measurements was 

 to include every possible condition and to obliterate the effect 

 of experimental errors in the conclusions drawn. The results 

 all point to the fact that wherever notches were found the 

 primaries must have been interlocked for two or more hours. 

 Deep notches are almost always present in primaries that are 

 found interlocked, and, moreover, in almost all of the primaries 

 that are emarginate that are not found interlocked, showing 

 that the latter were unlocked when the birds were shot and 

 fell to the ground. 



