On the quietest day, even after a thorough sweeping and dusting of the library, you are able to write your name plainly on the film of dust that lies on the polished table. Take a book from the open shelves, and blow into the trough of its top. This is always dusty. Where does the dust come from? This is the house-keeper's riddle.
The answer is not a hard one. I look out of my window on a street which is famous as the road Washington took on his retreat from White Plains to Trenton. It has always been the main thoroughfare between New York and Philadelphia, and now is the route that automobiles follow. A constant procession of vehicles passes my house, and to-day each one approaches in a cloud of dust. The air is gray with suspended particles of dirt. The wind carries the successive clouds, and they roll up against the houses like breakers on the beach. Windows and doors are loose enough to let dust sift in. When a door opens, the cloud enters and lights on rugs and carpets and curtains. Any ledge collects its share of dust. The beating of carpets and rugs disturbs the accumulated dust of many months.
In this lonely Arizona desert the wind drifts the sand into dunes, just as it does on the toe of Cape Cod
The Grand Canyon of the Colorado shows on a magnificent scale the work of water in cutting away rock walls
The wind sweeps the ploughed field, and takes all the dust it can carry. It blows the finest top soil from our gardens into the street. It blows soil from other fields and gardens into ours, so the level of our land is not noticeably lowered. The wind strips the high land and drops its burden on lower levels. This is one of the big jobs the water has to do, and the wind is a valuable helper. To tear down the mountains and fill in the valleys is the great work of the two partners, wind and water.
Dead, still air holds the finest dust, without letting it fall. The buoyancy of the particles overcomes their weight. We see them in a sunbeam, like shining points of precious metal, and watch them. A light breeze picks up bits of soil and litter, from the smallest up to a certain size and weight. If the velocity of the wind increases, its carrying power increases. It is able to carry bits that are larger and heavier. The following table is exact and interesting:
| Velocity in Miles per Hour | Pressure in Pounds per Sq. Ft. | |
| Light breeze | 14 | 1 |
| Strong breeze | 42 | 9 |
| Strong gale | 70 | 25 |
| Hurricane | 84 | 36 |