Okay, having read up briefly on what Timeshift does and how it works I find I need to clarify, what do you want to do with this drive precisely?
Do you want to use this drive as your backup drive for storing snapshots?
If that is what you want, you can add a line to /etc/fstab to mount the drive during boot to /timeshift
This requires the drive to be formatted with a Linux compatible file system like ext2 (usually ext4 in practice) It also needs to be connected at boot time.
Alternatively, you can mount it manually to /timestamp using the mount command.
Under Ubuntu, this would be something like;
Code:
sudo mount /dev/sdb1 /timestamp
But take note that this assumes that the drive is /devsdb whereas it might just as easily be /dev/sdc or /dev/sdd etc.
(use blkid to find the device names for connected block devices.)