TWO RHYMING RIDDLES

1)
I'm a word of letters four,
Myself, a fastener, and one thing more.
This one thing is clear to see,
When people are nervous, they bite me.
Behead me and find a second trick,
I'm now another word for sick.

2)
I never move - not fast or slow,
And yet around the world I go;
I can't be seen, or heard, or felt,
And yet some frame me as a belt.
I have no beginning, I have no end,
Between the south and north I wend.`

Answers:

1. NAIL
2. EQUATOR