58 RECORDS 



rapidly through the woods and flying in a strong wind. The 

 important functions of interlocking appear to be : (i) To make 

 more rigid the outer portion of the wing, that part of the aero- 

 plane formed by the primaries, and (2) to produce a curve of 

 the wing which enables the bird to have a better control of its 

 swift flight through the air than the unlocked condition would 

 permit. The end of the bird's wing when the primaries are in- 

 terlocked becomes shaped somewhat like the blade of a pro- 

 peller screw. The interlocking also would keep the primaries 

 extended without muscular exertion on the part of the bird. 



Considerable discussion was aroused by Mr. Trowbridge's 

 paper. Dr. Jonathan Dwight, Jr., presented a series of argu- 

 ments against the theory of the speaker, to the effect, in brief, 

 that in the absence of a proper controlling musculature, any 

 such interlocking as that described could be brought about only 

 by accident ; that habitual interlocking would bring about, fur- 

 thermore, conspicuous wearing of the vane in the areas of con- 

 tact, a phenomenon not observed in emarginate primaries ; and 

 that he concluded from his extensive studies upon feathers and 

 feather structure, that habitual interlocking did not take place. 

 Mr. Frank Chapman, with a series of fine lantern slides of 

 birds in actual flight, demonstrated that in some soaring birds, 

 at least, which possess emarginate primaries these feathers are 

 certainly spread and not interlocked. Mr. Chapman agreed 

 with Dr. Dwight that the facts tend to support Allen's theory 

 of the origin of emargination, namely that aerial friction wears 

 down the web ; and that no such function is to be attributed to 

 emarginate primaries such as that ascribed by Mr. Trowbridge. 

 Prolonged discussion followed, participated in by Mr. Trow- 

 bridge, Dr. Dwight, Mr. Chapman, Professor Dean, Professor 

 Crampton and others. Henry E. Crampton, 



Secretary. 



SPECIAL BUSINESS MEETING. 



April 24, 1902. 



The Academy was called to order at 8:1 5 P. M., by President 

 Cattell. Professor Richard E. Dodge was elected Recording 

 Secretary, pro tcvi. 



