The Astronomical Scrapbook by Joseph Ashbrook:
In the forum Astro Art, Books, Websites & Other Media, there is a topic about this book. I have an old hardback copy of it and decided to check it out again. I came across this section of the book:
Section 46. Lunar studies before the telescope pg. 233
William H. Pickering choose 12 features on the Moon that may be seen with the naked eye. They are listed below in increasing difficulty.
William Pickering's 12 test features on the face of the Moon.
1 Bright surroundings of Copernicus
2 Mare Nectaris
3 Mare Humorum
4 Bright surroundings of Kepler
5 Region of Gassendi
6 Plinius region
7 Mare Vaporum
8 Lubiniezky region
9 Sinus Medii
10 Faint shading near Sacrobosco
11 Dark spot near foot of Montes Apennines
12 Montes Riphaeus
Anyone know for sure what area Pickering was talking about for #10, the "faint shading near Sacrobosco" and for #11, "dark spot near foot of Montes Apennines". He says, "...a dark patch at the edge of Mare Imbrium, just across the Apennine Mountains from Mare Vaporum." Is it the area known as Palus Putredinis? What shading appears near Sacrobosco? What are your thoughts? Any images/sketches of these two "features"?
Thanks for your help,