﻿350 Transactions — Miscellaneous. 



a round sliot, not, liowever, because a round sliot is a projectile, for an Alba- 

 tros when sailing is a true projectile also, but because the initial velocities are 

 so very different. Instead, therefore, of the round shot formula I will take 

 the one given by Mr. "Webb. 



E=i Q v2 sin3 LA. 

 and take the body of the Albati'os to be a cone of 20°. We shall then haA'e 

 R=0-0006 sin3 10° A v2 

 = 0-000003 A v2 

 which is very nearly that which I calculated would allow an Albatros to sail 

 for half an hour, and is just half way between the resistances calculated in 

 ray first and second papers ; and, therefore, if this formula may be relied upon, 

 all the difficulties of my theory disappear, for, although something would 

 have to be added for the resistance to the wings, something would also have to 

 be deducted for the tapering away of the hinder parts of the bii'd, which is 

 known to decrease the resistance considerably. At page 234, line 6, Mr. Webb 

 I'emarks, " I do not know whether the merit of the demonstration belongs to him 

 (Captain Hutton), he appears to claim it." I may, therefore, I hope, without 

 being considered egotistical, be allowed to make a few remarks on the subject. 

 In 1864, when I first took iip the question, the prevailing opinions about it 

 were various and confused, as pointed out by me in the previous paper that I 

 read to the Auckland Institute. Even those authors who had seen that sailing 

 flight must be due to previous momentum (such as Darwin in his account of 

 the flight of the Condor), had no clear ideas of how the two wei^e connected, 

 and thought that probably the momentum was kept up, or increased, by the 

 bird occasionally closing its wings and falling rapidly for some distance. I 

 was, I believe, the first, in March, 1865, to enunciate the theojy that it was 

 by slightly increasing the angle of flight that a bird was enabled to sail, and 

 my paper published in the "Phil. Mag." for August, 1869, was, I believe, the 

 first attemjot made to treat the subject mathematically, and to show, not only 

 the mechanical principles on which it depended, but also that the resistance of 

 the air was no insuperable objection to my theory. This is all I claim, and I 

 do not know that any one has ever disputed either the truth of the theory, or 

 my priority in enunciating it. A German named Prechtl, and a Frenchman 

 named, I think, Maret, have both written books on the flight of bii-ds, but 

 they are rare and but little known, and I have not seen either of them, nor do 

 I know the dates of their publication, and it is possible that I may have been 

 forestalled by one or other of them. 



