Re: Why do people says the rotation of Earth causes tiolets to spin differently

People say this because it is largely true. I can assure you as a Southern 
Hemisphere dweller that the vortex which forms when a symmetrical bath is drained  
consistently rotates clockwise in this part of the world. And when I was living 
in England my curiosity led me to explore the question there. The effect was much 
stronger (latitude 52 deg N as against 38 deg S), and was anti-clockwise. And 
even if you set up a clockwise vortex with a swirl of the hand, it would slow and 
stop over the course of 20 to 30 seconds, and a new anti-clockwise vortex would 
then form. I have tested several different bathtubs in each country!

You are right when you say that this effect is not an extremely strong one, and 
that in many cases other issues of shape or flow might mask the coriolis effect 
as it refers to drainage of small water bodies. But bathtubs are traditionally 
made with twofold mirror symmetry, and if stationary water is allowed to flow out 
by simply pulling the plug, the coriolis force is the determining factor in what 
is observed.

It is a mistake to think that the Earth's rotation can only cause "slow" coriolis 
effects. Once again I can assure you that tornadoes and willy-willies (= dust 
devils??) that form around here rotate clockwise at quite large speeds, unlike 
those in the USA. Although the earth's angular velocity of rotation is very small 
-- 1 revolution per day -- the actual velocity of rotation is quite significant 
--1700 kilometres per hour!

I do not know about the flow of water from a hogwash; I suspect that the 
agitation of the hog would mask any other effects.