A rose-breasted grosbeak, invisible (but I can see him), is warbling not far off. He has taken the tanager’s tune--which is the robin’s as well--and smoothed it and smoothed it, and sweetened it and sweetened it, till it is smoother than oil and sweeter than honey. I admire it for what it is, a miracle of mellifluency; if you call it perfect, I can only acquiesce; but I cannot say that it stirs or kindles me. Perhaps I haven’t a sweet ear. And hark! the wood thrush gives voice: only a few strains, but enough to show him still present. Now I am free to trudge along up the railroad track, pondering as I go upon the old question why railway sleepers are always too far apart for one step and not far enough for two. At short intervals I pause at the sound of a mourning warbler’s brief song, pretty in itself, and noticeable for its trick of a rolled _r_. Some of the birds add a concluding measure of quick notes, like _wit, wit, wit_. It is long since I have seen so many at once. In truth, I have never seen so many except on one occasion, on the side of Mount Washington. That was ten years ago. One a year, on the average, shows itself to me during the spring passage--none in autumn. Well I remember my first one. Twenty years have elapsed since that late May morning, but I could go to the very spot, I think, though I have not been near it for more than half that time. A good thing it is that we can still enjoy the good things of past years, or of what we call past years. And a good thing is a railroad, though the sleepers be spaced on purpose for a foot-passenger’s discomfort. Without this one, over which at this early date no trains are running, I should hardly be traversing these miles of rough mountain country on a day of tropical sultriness. The clear line of the track gives me not only passage and a breeze, but an opening into the sky, and at least twice as many bird sights and bird sounds as the unbroken forest would furnish.[10] I drink at the section men’s well--an ice-cold spring inclosed in a bottomless barrel--cross the brook which, gloriously alive and beautiful, comes dashing over its boulders down the White-cross Ravine, fifty feet below me as I guess, and stop in the burning on the other side to listen for woodpeckers and brown creepers. The latter are strangely rare hereabout, and this seems an ideal spot in which to look for them. So I cannot help thinking as I see from how many of the trunks--burned to death and left standing--the bark has warped in long, loose flakes, as if to provide nesting sites for a whole colony of creepers. But the birds are not here; or, if they are, they do not mean that an inquisitive stranger shall know it. An olive-sided flycatcher calls, rather far off, making me suspicious for an instant of a red crossbill, and a white-throated sparrow whistles out of the gulch below me; but I listen in vain for the quick _tseep_ which would put an eighty-seventh name into my vacation catalogue.