392 DP PETTIGREW ON THE PHYSIOLOGY OF WINGS. 



feathers of parts of the wings so rapid, that only an experienced eye can detect 

 it, all confirm the belief that the living wing has not only the power of directing, 

 controlling, and utilising natural currents, but of creating and utilising artificial 

 ones, which is not less important. But for this power, what would enable the 

 bat and bird to rise and fly in a calm, or steer their course in a gale ? It is 

 erroneous to suppose that anything is left to chance where living organisms are 

 concerned, or that animals endowed with volition and travelling surfaces, should 

 be denied the privilege of controlling the movements of those surfaces quite 

 independently of the medium on or in which they are destined to operate. What 

 would we say of that quadruped or that fish which depended for the major 

 portion of its movements on the ground it trod or the water it navigated % I 

 will never forget the gratification afforded me on one occasion at Carlow 

 (Ireland) by the flight of a pair of magnificent swans. The birds flew towards 

 and past me, and I had my attention directed to their presence by a peculiarly 

 loud whistling noise made by their wings. They flew about fifteen yards from 

 the ground, and as their pinions were urged not much faster than those of the 

 heron,* I had abundant leisure for studying their movements. The sight was 

 very imposing, and as novel as it was grand. I had never seen anything before, 

 and certainly have seen nothing since that could in any way convey a more 

 adequate idea of the prowess and guiding power which a bird may exert. 

 What particularly struck me was the perfect mastery which they seemed to 

 possess over everything. They had their wings and bodies visibly under control, 

 and the air was attacked in a manner and with an energy which left little doubt 

 in my mind that it played quite a subordinate part in the great problem before 

 me. The necks of the birds were stretched out, and their bodies to a great 

 extent rigid. They advanced with a steady stately motion, and swept past with 

 a vigour and force which greatly impressed, and to a certain extent overawed, 

 me at the time.t Their flight was what one could imagine that of a flying 

 machine constructed in accordance with natural laws would be. 



* I have frequently timed the beats of the wings of the common heron (Ardea einerea) at Warren 

 Point (Ireland). In March 1869 I was placed under unusually favourable circumstances for obtain- 

 ing reliable results. I timed one bird high up over a lake for fifty seconds, and found that in that 

 period it made fifty down and fifty up strokes ; i.e., one down and one up stroke per second. I timed 

 another one in a heronry belonging to Major Hall. It was snowing at the time (March 1869), but 

 the birds, notwithstanding the inclemency of the weather and the early time of the year, were actively 

 engaged in hatching, and required to be driven from their nests on the top of the larch trees by knock- 

 ing against the trunks thereof with large sticks. One unusually anxious mother refused to leave the 

 immediate neighbourhood of the tree containing her tender charge, and circled round and round it 

 right overhead. I timed this bird for ten seconds, and found that she made ten down and ten up 

 strokes ; i.e., one down and one up stroke per second precisely as before. I have therefore no hesitation 

 in affirming that the heron, in ordinary flight, makes exactly sixty down and sixty up strokes per 

 minute. The heron, however, like all other birds when pursued or agitated, has the power of greatly 

 augmenting the number of its beats. 



+ The above observation was made at Carlow on the Barrow in October 1867, and the account of 

 it is abstracted from mv note-book. 



