You who knew him well, and know how his mother's heart and mine were
wrapped up in him, will understand how great is our affliction. He was
attacked with a bad form of scarlet fever on Thursday night, and on
Saturday night effusion on the brain set in suddenly and carried him off
in a couple of hours. Jessie was taken ill on Friday, but has had the
disease quite lightly, and is doing well. The baby has escaped. So end
many hopes and plans--sadly enough, and yet not altogether bitterly. For
as the little fellow was our greatest joy so is the recollection of him
an enduring consolation. It is a heavy payment, but I would buy the four
years of him again at the same price. My wife bears up bravely.

I have read your proofs at intervals, and you must not suppose they have
troubled me. On the contrary they were at times the only things I could
attend to. I agree in the spirit of the whole perfectly. On some matters
of detail I had doubts which I am not at present clear-headed enough to
think out.

The only thing I object to in toto is the illustration which I have
marked at page 24. It is physically impossible that a bird's air-cells
should be DISTENDED with air during flight, unless the structure of the
parts is in reality different from anything which anatomists at present
know. Blowing into the trachea is not to the point. A bird cannot blow
into its own trachea, and it has no mechanism for performing a
corresponding action.

A bird's chest is essentially a pair of bellows in which the sternum
during rest and the back during flight act as movable wall. The air
cells may all be represented as soft-walled bags opening freely into the
bellows--there being, so far as anatomists yet know, no valves or
corresponding contrivances anywhere except at the glottis, which