You would also need the catalog that was used to apply the adjustments to those photos. The catalog could be copied to the external drive as well.
Thank you Jim. I think I'm getting closer to a cure but I'm not there yet. It seems the catalog is on the hard drive as you indicate it needs to be. The means by which I'm coming to this conclusion is that when I book LR on the MacBkAir
(which is where the catalog was initially created) without having the external hard drive connected, the message I get is that the catalog could not be found and references the location (not found) to be the external drive. Yet, when that drive is connected to the IMAC and I boot LR the photos come up but with out the edits, ratings etc. My key word list that was also created on the MacBkAir does show up on the IMAC.
I'm overlooking something that's probably obvious but I'm not very intuitive at the outset when learning new software to the first 12 hours of use is excruciating. Suggestions welcome.