104 Lt.-C'ol. C. L). Dunifuul on 



move, and tliey even deny them at this time any suppovtino; 

 power whatever. It is their " jieriod of occasional vibration '' 

 or " fluttoring," and their exj)hmation thereof will make a 

 mechanician smile or feel sad, according to his temperament. 

 I have already quoted it from Mobius, and it amounts to the 

 wings trailing in the wind like a loosely flapping flag, thus 

 not only depriving the heavy fish of the so-called support of 

 its miniature aeroplanes, but actually converting them into 

 an active drae. 



And yet, according to tlie theorists, at an extreme suggested 

 speed of 13^ miles an hour, the fi^h still sails ! 



Such an upsetting of one of the best known of nature's 

 laws as all the foregoing implies would be impossible of final 

 acceptance, even if we could not, as many of us can, see the 

 flying-fish flying. 



I studied the "vibration" or flutter periods very carefully 

 this spring when returning from the Gulf of Mexico. Their 

 object and uiethod seemed simple and clear, and to be as 

 Ibllows : — The slowing down from extreme wing-speed into 

 visibility heralds an immediate increased effort of flight, 

 often, if not usually, to enable the fish to sm'mount a wave. 

 The fish is, in fact, pulling itself together for a spurt. Tlie 

 flutter, as was to be ex})ected, is accompanied by a slight fall 

 of the fish of perhaps 2 or 3 inches; but the spurt, at once 

 put on, regains the lost elevation and lifts the fish well over 

 the obstacle. This sudden rise of the fish (the " frequently 

 overtop each wave'' of Mobius) is constantly to be seen, and 

 to many the wings seem still at this time. 



The ditiertnce in the rates of speed of wing-flapping 

 noticeable on diff'erent days is veiy marked. At times, and 

 often for many successive days, it is noticeable tiiat, although 

 the bodies of the fish as they rise from under the steamer's 

 bows are clearly and sharply defined, their supporting wings 

 have a peculiar hazy and blurred look, with a want of defi- 

 nition of outline wliich cannot be accounted lor, for they seem 

 to be still. Then a day will come when the fish, still fleeing 

 in front of the ship, will move iheir wings less rapidly and 

 their motion will become plainl}' visible. There are still 

 many lookers-on who cannot pick it up, but for the rest the 

 aeroplane theory is exploded tor ever, and when next the 

 switter-moving wings are seen with the eye of knowledge the 

 wonder is that there had been any difficulty. Tlie haze and 

 blurr are exactly what should have been looked for under the 

 circumstances. 



We have all of us watched sea-gulls soaring quietly in a 

 certain direction, but obliged to fla[) when they turn away, 



