That's a lot of ...

You know all those horses pulling wagons and buggies and coaches through the streets of towns and cities in the nineteenth century? And all those folks riding into town and through town on their horses?

Each horse produced about 40 pounds -- yes, 40 POUNDS -- of manure daily. And they did not wait until they got out of town to let it go, so to speak.

Fortunately, folks did not have to rely on civic-minded neighbors to clean the streets. Stable owners and others collected the manure and sold it to farmers for fertilizer.

Now if only there were some way to capture gasoline fumes and recycle that.