tar problem - HELP!!

[lad]

I did something really dumb today.  I hope someone out there can help.

I careated a tar archive of a directory on a 1/2" tape drive on a Sun 3/180. 
I used the command :

	% tar cvbf 100 /dev/rmt8 /usr13

to create the archive.

I newfs'ed the fs and went to restore the fs again.  I cd'd to /usr13 and then 
typed:

        % tar cvbf 100 /dev/rmt8 

again. Before I could stop myself I hit RETURN and then I realized what I did.

The question: Is there any way to recover those files from that tape?  The
second tar command should only have initialized the first few blocks of
the tape.  I know my files are on the rest of it.  

If someone knows what to do, please call me at the number below.  I will
pay your LD charges!  Anything anyone can do to help will be appreciated.