After a wet winter, we are having a dry spring. I had an unusually demanding morning, and I looked forward to a run at the park with the hill. The ground is starting to crack, and I kicked up lots of dust as I ran.

That reminded me of an interesting study I heard about on the radio this week. I wish I could remember the name of the author of the book who was being interviewed so I could give him credit for his work. Someone has gone back and looked at transportation in the decades prior to the mass production of the Model-T Ford. They particularly looked at big cities like New York City. They calculated the number of horses that were in the cities, and the number of tons of manure that those horses produced.

When the weather was wet all that manure ran down into the rivers and streams, polluting the water supply. When the weather was dry, the manure was pounded into dust by the horse's hoofs and the wagon wheels. Manure dust was constantly in the air, blowing into houses through open windows. People breathed it and ate it as it settled on their food. Eating, drinking, and breathing manure brought epidemic disease.

The author contends that the invention of the car brought to a halt a dangerous pollution problem in the cities. Interesting thought.

I was glad that the dust I was breathing was just plain dirt. I sure felt better after the run. You can't hear it too often; Type Os need intense physical exercise.