A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2019 Dec 26, 14:36 -0800
One way you can explore the list is by searching for volumes at hathitrust.org. Enter a number, e.g. 235, in the title search field, and "Hydrographic Office" in the full text etc. search field. You'll get some false positives, but it seems manageable. I had never heard of H.O. 235 before. But now I know (see below)...
I found an index from 1957 from H.O. itself: https://babel.hathitrust.org/cgi/pt?id=mdp.39015092889743&view=1up&seq=3