Pollinometers

June 21.

June 21, 2013

Having noticed the pine pollen washed up on the shore of three or four ponds in the woods lately and at Ripple Lake, a dozen rods from the nearest pine, it suggested to me that the air must be full of this fine dust at this season, that it must be carried to great distances, and its presence might be detected remote from pines by examining the edges of bodies of water, where it would be collected to one side by the wind and waves from a large area. The time to examine the ponds this year was, I should say, from the 15th to the 20th of this month.

As chemists detect the presence of ozone in the atmosphere by exposing to it a delicately prepared paper, so the lakes detect for us thus the presence of the pine pollen in the atmosphere. They are our pollinometers.

A large pond will collect the most, and you will find most at the bottom of long deep bays into which the wind blows.

How much of this invisible dust must be floating in the atmosphere, and be inhaled by us at this season!! I do not believe that there is any part of this town on which the pollen of the pine may not fall.

H. D. Thoreau, Journal, June 21, 1860

See June 21, 1850 ("The flowers of the white pine are now in their prime, but I see none of their pollen on the pond."); June 21, 1856 ("Much pine pollen is washed up on the northwest side of the pond. Must it not have come from pines at a distance?"); June 18, 1860 ("I see in the southerly bays of Walden the pine pollen now washed up thickly; only at the bottom of the bays, especially the deep long bay, where it is a couple of rods long by six to twenty-four inches wide and one inch deep; pure sulphur-yellow, and now has no smell. It has come quite across the pond from where the pines stand, full half a mile, probably washed across most of the way."); June 14, 1853 ("The pollen of the pine yellowed the driftwood on the shore and the stems of bushes which stood in the water, and in little flakes extended out some distance on the surface, until at four or five rods in this cove it was suddenly and distinctly bounded by an invisible fence on the surface")