in Thoreau’s Journal:
Since July 30th, inclusive, we have had perfect dog-days without interruption. The earth has suddenly [become] invested with a thick musty mist. The sky has become a mere fungus. A thick blue musty veil of mist is drawn before the sun. The sun has not been visible, except for a moment or two once or twice a day, all this time, nor the stars by night. Moisture reigns. You cannot dry a napkin at the window, nor press flowers without their mildewing. You imbibe so much moisture from the atmosphere that you are not so thirsty, nor is bathing so grateful as a week ago. The burning heat is tempered, but as you lose sight of the sky and imbibe the musty, misty air, you exist as a vegetable, a fungus. Unfortunate those who have not got their hay. I see them wading in overflowed meadows and pitching the black and mouldy swaths about in vain that they may dry. In the meanwhile, vegetation is becoming rank, vines of all kinds are rampant. Squashes and melons are said to grow a foot in a night. But weeds grow as fast. The corn unrolls. Berries abound and attain their full size. Once or twice in the day there is an imperfect gleam of yellow sunlight for a moment through some thinner part of the veil, reminding us that we have not seen the sun so long, but no blue sky is revealed. The earth is completely invested with cloud-like wreaths of vapor (yet fear no rain and need no veil), beneath which flies buzz hollowly and torment, and mosquitoes hum and sting as if they were born of such an air. The drooping spirits of mosquitoes revive, and they whet their stings anew. Legions of buzzing flies blacken the furniture. (For a week at least have heard that snapping sound under pads.) We have a dense fog every night, which lifts itself but a short distance during the day. At sundown I see it curling up from the river and meadows. However, I love this moisture in its season. I believe it is good to breathe, wholesome as a vapor bath. Toadstools shoot up in the yards and paths.