﻿HuTTON.— C« the Flight of the Albatros. 347 



MISCELLANEOUS.— (Co;i«. /row ^j. 164). 



Aet. T:XlY.r~On the Sailing Flight of the Albatros; aRephj to Mr. J. S. Webb. 

 By Captain F. W. Hutton, F.G.S.* 



[Head lefore the AucMand Institute, I3th June, 1870.] 



In the second volume of tlie Transactions of the ZsTew Zealand Institute, 

 p. 233, there appears a criticism by Mr. J. S. Webb, on a paper of mine, 

 published in the " Phil. Mag." for August, 1869, on the flight of the Albatros, 

 in which he says that T have not been happy in the mathematical treatment 

 of the subject, having made a mistake at the outset of my calculations, and 

 that the higher velocities that he derives from my data upset the conclusions 

 that I have drawn. I am, therefore, almost compelled, in self defence, to 

 criticise a little his criticism. 



Before commencing, however, I ought perhaps to inform those who have 

 not read my paper, that the object I had in view in that part of it to which 

 Mr. "Webb has taken exception, was to show as clearly and as simply as 

 possible, that if an albatros started with a certain velocity it could, by slightly 

 altering the angle at which it was flying, continue to support itself in the air 

 without using its wings until its velocity had been reduced below a certain 

 point, and I, therefore, pointed out the two main principles on which this 

 depended, and omitted many minor points which would have to be considered 

 if fully discussing the case. Any person who reads my paper will see that 

 these calculations make no pretensions to accuracy, for the data on which they 

 are founded are merely rough approximations. They are simply used as an 

 illustration, and rough demonstration, of a previously propounded theory 

 (see " Ibis," July, 1864) ; for, in order to ^jroi7e the theory, both the resistance 

 of the air to the bird and the velocities at which it sails must be obtained by 

 observation and experiment, and they must then be shown by calculation to 

 be not inconsistent with one another when connected according to the theory. 



I will here, also, take the opportunity of explaining to those who notice 

 discrepancies in my two papei'S, that after I had read the first to the Auckland 

 Institute I received from England a copy of Dr. Pettigrew's paper on the 

 flight of birds, and in the second paper (published in the "Phil. Mag.") I used 

 his observations on the angle which the Avings of a bird make with its body, 

 as giving probably a more accurate result than taking the wings and body to 

 be in the same plane, as in my first paper ; and not unnecessarily to comjoli- 



* See previous Articles, Vol. II. , p. 227, and 233. 



