When you look through the bottle with the water
on some things distanced from you, they appear upside-down.
In our examples these things are the words that are standing
upside-down in the bottle. But as far as some letters in the words
have vertical symmetry (as in Figure 1) or horizontal symmetry (see
Figure 2) they remain the same.
In the first example only TAHOMA consists of the letters with vertical
symmetry and that's why it remains the same while SEATTLE doesn't.
In the second example all the letters in the word CODE have horizontal
symmetry, and that's why this word remains the same even standing
upside-down. The word CIPHER does not have all its letters with
horizontal symmetry and thus some of them are "really" upside-down.