Say What?

So, just how do you pronounce the river Thames? If you said it the way it looks, it'd be "TH-ames". Then I always kind of thought it was said without the "H", like "tames". Then last night I hear CNN saying it like it was pronounced without the "H" and with an "E" instead of an "A", so it sounded like "Tems". The River Tems? This is said so far away from the way it's spelled, it's ridiculous! What's the point of the H and the A if you're going to completely ignore them? So, just to be sure, I Googled it, and guess what - CNN actually got something right for a change. It's pronounced "temz" with a soft "E". Who knew? So, has it always been like this, or this another word like "Harassment", where media types suddenly out of nowhere started pronouncing it "hare-iss-mint"? Stop butchering the English language people, and say it the way it's spelled, or spell it the way you want it to sound, but pick one already! ....There, end rant...