How to resume a partially-downloaded file using wget
Answer:
Use the -c flag, e.g.
# wget -c ftp://sunsite.doc.ic.ac.uk/ls-lR.Z
If there is a file named ls-lR.Z in the current directory, Wget will assume that it is the first portion of the remote file, and will ask the server to continue the retrieval from an offset equal to the length of the local file.
Reference: http://www.gnu.org/software/wget/manual/wget.html
