Ipad 1 and pdf files via Camera Adapter

I have recently been handed down an Ipad 1 and want to view pdf files from an external storage device. (i.e usd stick or usb hdd)

Would I be able to use a camera adapter and if so most of the ones I have seen (Ebay) state for Ipad2>.

Or if there is another way anybody can suggest doing this I would be most gratefull.

Orty