A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Sean C
Date: 2018 Mar 2, 21:58 -0800
Without seeing it (there is no fig. 1905 in my 2002 ed.), I would say it is probably a blank time diagram. The time digram is used to visualize the relationship between the observer's meridian and various other things, such as the Greenwich meridian and the position of a celestial body. For some people, it helps to clear up any ambiguity about the relationships between them. See attached image.