The Horse Story that won't go away

Urban myths are tough to beat down. They won't go away. Witness the "United States Railroad Track Gauge and its influence on the Space Program is all based on the width of a Horse's Ass" story. Maybe I am being as overly sensitive, but this story is just flat out WRONG. Even though it is cute and funny, I feel an obligation to set the record straight.

Just for fun, I did a search on Technorati and found this horse story on at least twelve blogs, including redleg07, superelvis, ballistik-brain, antimedia, letslets, forward-humor, macstansbury, and erynfaith. The greatest number of comments showed up on base2wave.

To a blog, they had quoted this story, which first appeared in my e-mail over two years ago. It has been reworded, often with something like "we've always done it this way", or "you can't make this stuff up". Yes you can, because here is the real story. And, please, I am not trying to rain on anyone's humor parade, but as a Railroad Track Construction and Maintenance type-of-guy I am just trying to tell the real story.

Dr. Arnold Kerr has given numerous classes entitled "Railroad Track: Design, Analysis, and Maintenance. He has since retired, but each one of Dr. Kerr's sessions included the real track gauge story, abbreviated here. Standard gauge as defined by the oft-quoted notion that is it based on whatever Roman Legend you choose to believe is actually Five Feet! It is not 4' 8-1/2' as is the case today on U. S. Railroads. How did we get from one to the other? Here is where the British do come into play.

The first "Rail Roads" were constructed with flanges on the rails instead of the wheels. Any farmer or merchant could take his cart onto the "Rail Road" or "Rail Way" and ride in relative bliss. Sometime about 1810, a Mr. Jessup got the wild idea that he could take the flanges off of the rails and onto his wheels. By doing so, he would control all vehicles that used his Right of Way, and could charge a fee for it's use! He constructed his first Railroad in such a way, and maintained a gauge of Five Feet from outside edge of one rail to outside edge of the other.

He placed the wheel flanges on the outside edge. But when he tried to go around a curve, the result was that his carriages would not move. To solve that problem, he moved the flanges to the inside of the wheel and everything worked fine! Trouble was, he had already laid a significant portion of track. What to do?

He simply determined that Gauge should now be measured from inside edge to inside edge! And in order to create a standard for whatever rail would be used, he simply doubled the width of his rail, 1-3/4 inches, and subtracted the total from 5 feet. That came out to exactly 4 feet 8-1/2 inches, the same gauge in use today!

For another account of the inaccuracy of the "Ass" story, go here.

Yes, the real story is still arbitrary. Yes, it is amazing that this particular dimension went around the world as Standard Railway Gauge. But the idea that a horse's ass has anything to do with the Space Shuttle is baseless. We can all blame Mr. Jessup intead.