Just to make clear I didn't invent this particular wheel:

In our Archives section you can find History Lesson II, which is about a book by Tony Betts called "Across The Board". It came out 60 years ago, in 1956, there's a good chance Miff knew Al (The Brain) Windeman), famous speed handicapper of the day, who was responsible for the following quote (page 303).

"...you need a track variant, and that differs from race to race. The composition of the soil and the moisture it contains affects a track's speed. I check the sprinkler wagon all afternoon, because I know the speed varies with each drink. Tracks near the seashore may change speed with the tides".

There's more, check out the Archives. The book was republished a few years ago, you should be able to find it.