"Jerkwater town" explained

I encountered the term "jerkwater town" recently, and wondered about the genesis of the phrase.  It turned out to be much more interesting than I had anticipated.  I found a thorough explanation at Wordmall.  First there is a traditional - but wrong - explanation:

The term goes back to railroading. Steam engines were nothing more than boilers on wheels, where water was heated to the boiling point in order to get steam power. In larger towns, water towers were available for the trains to use. In jerkwater towns, they were not.

A jerkwater train was a branch-line train. It received its name from the fact that these trains were smaller than the main-line trains, so water had to be replenished far more often. The crews would have to stop at a river or stream and “jerk” water (draw it) from the source and carry it in buckets to the train.

There then follow some citations and discussion and the revelation that this traditional explanation is quite incorrect.  The term does derive from the railroading era, but has nothing to do with drawing water by hand.  Quite the opposite:

" . . . Ramsbottom troughs, or 'jerk-water' system for filling the tenders while the train is in motion . . . " (from The Elements of Railroading, Charles Paine, 1885).

An excellent find.  So now we turn to the website of the Ann Arbor Model Railroad Club for an explanation of how that was done:

Kinnear, located two miles east of Dexter, was the site of Michigan's first railroad track water pans, which were built in 1901. The pans were situated between the rails and heated during cold weather. Steam locomotives scooped up the water as they moved over the pans. The Kinnear pans and telegraph station were named after Wilson S. Kinnear, chief engineer of the Detroit River railroad tunnel.

[In the embedded image at the top] a westbound Michigan Central passenger train takes up water while traveling 60 miles per hour at the Kinnear track pans in 1907.

Final details from Wikipedia:

A scoop is fitted to the underside of the locomotive's tender (or the locomotive itself in the case of tank locomotives) in such a way that it can be raised or lowered, by a screw mechanism or a compressed air mechanism. The scoop feeds into a vertical pipe that discharges into the water tank... Venting on the tender needed to be free to allow a high release of expelled air from the tank...

Taking water at speed results in considerable spray behind the scoop; this risks drenching passengers in the leading vehicles, and in Great Britain it was customary for the guard or other traincrew to warn passengers in the first coach to keep the windows closed. In one incident on the LMS railway in Britain, two streamlined trains with "Coronation" class locomotives happened to pass each other at a water trough when one of the trains was taking on water. The other train suffered broken windows due to lumps of tender coal scattered by the spray and the complaints from drenched passengers caused the management to retimetable the trains to ensure this could not happen again...

Track pans normally took a while to fill up after being used, so they could not be used immediately by a close-following train. They were also expensive to maintain, generally requiring a pumping station, a lot of plumbing, and an employee or two to maintain... 

Fascinating.  You learn something every day.