John Rowland ("John Rowland" )
gurgled happily, sounding much like they were saying:

Well whenever I am using GPS these days [1], I can find my altitude by
reference to my watch and a copy of Reed's Almanac.

Remind me again...how does that work?

Dead easy... Reed's Almanac is a tide table...

I'm not quite sure how it'll tell you whether the transporter that your
boat is on the back of is on the M4 or the A4 underneath it, though...
Oh, wait. If there's a horrible scraping cracking noise, it's the remains
of the top of the mast against the underside of the M4 flyover.