NATURAL HISTORY NOTES 
235 
This principle is understood by torpedo and submarine ship inventors, and no 
doubt by those who have to do with modern airships (formerly styled balloons), 
which are now being built of a rational shape. I hardly think any bird could 
sink in absolutely still water : he would have to use wings or feet to get down. 
The larger birds, and notably the albatross, going against a strong wind hardly 
move a muscle, they set their sails and rudder and hold them steady, and can 
raise or sink themselves by slight movement. The stiffer the gale the more 
quickly they do it. Look and see. So the bird that moves in the denser medium, 
water, “ without apparent muscular effort ” must, so it seems to me, do likewise. 
Let us remember that in running water the upper layers go much faster than the 
lower ones, which are retarded by friction, the pace very quickly decreasing, till 
stillness, or backwater over certain surfaces, is soon attained. Also remember 
that with wind the same rule holds good, but in a lesser degree, for the friction is 
less. There are water eddies where man would be sucked down never to rise again. 
Is it to be supposed that birds who live at least half their time under water in 
pursuit of food do not avail themselves of eddies, currents and backwaters to 
assist them, the same as other birds seek help by drifting with the wind or holding 
themselves so that they be borne up against it ? To this any young sailor can 
reply. Set your sails properly according to the current ; you can go up or down, 
rise or sink, as you please. Of course in some currents navigation is impossible. 
I have never seen a bird keep himself upright and at rest in perfectly still 
water, as seems to be suggested. To do this one would suppose he must hold a 
stone in his feet, a not very difficult performance. Eagles carry great weights in 
their claws. 
As regards the movements of the dabchick at Zurich, mentioned at p. 215, 
I wish to say that I could only observe him going down-stream. I think that 
going up-stream he would use his wings. Whereas a wild duck will fly up- 
stream under water after his prey, he will drop down-stream in more easy fashion, 
as the driver of an engine will shut off steam going down hill. A wounded 
bird will go down-stream, under water, if strong enough to maintain himself so. 
Your spaniel will be looking for him down-stream. 
We have yet a great deal to learn regarding the movements of birds in air and 
in water. And it follows, from what I have said above, that the time will come 
when airships will go up wind without the exercise of propulsive force. 
Ivy Bridge , South Devon , Giles A. Daubeny. 
October 5, 1903. 
63. Eider Duck. — That eider ducks will often become extraordinarily tame 
while nesting is well known, and I have met with Light-keepers who have told me 
how they have lifted sitting birds from their nests so that visitors might see the 
eggs and then replaced the birds, which have continued to sit as if nothing 
unusual had occurred. When nesting on heathery hillsides above the lochs, 
however, the eiders are much more shy, and I heard of a very curious habit, which 
I give in the hope that someone will either refute or affirm it. A crofter told me 
he had found a donter duck (eider) sitting on four eggs, which he wished to take. 
It was not, however, convenient for him to do so then, and when he returned two 
days later he found that the old bird and eggs had vanished. After a search he 
rediscovered her and the eggs about a hundred yards away down the hillside. 
He further told me that he once came upon an eider in the act of trundling one 
of her eggs down hill with her beak, but immediately the bird found she was 
discovered she deliberately broke the egg and left it. My informant next told 
me that he had found another nest only two days previously, and I expressed a 
desire to see it. He kindly took me to the spot, and there remained nothing but 
a quantity of down ! There were no egg-shells to prove that the birds were 
hatched and no young birds on the loch below (the young are taken to the water 
almost as soon as they leave the shell), but instead, there was a trail of down 
distinctly traceable for a considerable distance over the short, scrubby heather. 
Search as we would, however, we could not discover the bird sitting elsewhere. 
The incident lends some colour to the story the man told me. Can anyone 
confirm it ? 
Bideford , North Devon, A. J. R. Roberts. 
September 14, 1 903. 
