Two years ago we decided to follow Spring north. First we welcomed as usual the spring migrants and the spring flowers in April and May. When the sky-pilgrims had passed on, and the lush growth of summer began to show, we traveled northwards to the top of Mount Pocono, the highest mountain of our state, and found Spring waiting for us there. The apple blossoms were just coming out and the woods were sweet with trailing arbutus. There we found the nests of the yellow-bellied and alder fly-catchers, solitary vireos, and black-throated blue and Canada and Blackburnian warblers. As once more Summer followed hard on our heels, we took passage and traveled to a lonely camp in northern Canada. The second day of our trip we overtook Spring again, and were traveling through amethyst masses of rhodora and woods white with the shad-blow. At last the apple orchards were not yet in flower, and for the third time that year we found ourselves among the cherry blossoms. We never stopped until we reached a lonely bay far to the north. The sun was westering well down the sky when at last we crowded into a creaking buckboard for a ten-mile drive. The air was full of strange bird-songs. From the fields came a little song that began like a feeble song sparrow and ended in a buzz. It was the Savannah sparrow, which I had seen every year in migration, but had never before heard sing. At the first bend in the road we came to a bit of marshland so full of unknown bird-notes that we stopped to explore. From the edge of the sphagnum bog came a loud explosive song--"Chip, chip, chippy, chippy, chippy, chippy!" The singer was a greenish-colored bird, light underneath, with a white line through the eye, and looked much like a red-eyed vireo except that it had a warbler beak, the which it opened to a surprising width as it sang. It was none other than the Tennessee warbler, so rare a bird in my part of the world that even to see one in migration was then an event. Here it was one of the commonest birds of that whole region. Then I stalked a strange vireo-song, something like the monotonous notes of the red-eyed vireo, but softer and with a different cadence. I finally found the singer in a little thicket, and studied it for some ten minutes not six feet away. For the first time in my life I had seen and heard the smallest and rarest of all the six vireos, the Philadelphia, so named because it is never by any chance found in Philadelphia. Its tininess and the pale yellow upper breast shading into white were noticeable field-marks. To me it seemed a tame, dear, beautiful little bird.