Letter 211 is from J.R.R. Tolkien to Rhona Beare answering a series of eleven questions Rhona had asked about his legendarium for a meeting of enthusiasts. Here are the questions and Tolkien's answers, simplified:
1. Q. Why does Sam say O Elbereth Gilthoniel instead of A Elbereth Gilthoniel (first edition)? A. This was an error. The O was an English translation, but since Sam's invocation is in pure Elvish it should be A.
2. What is the meaning of this invocation and of Frodo's words, Aiya Eärendil Elenion Ancalima? A. A Elbereth Gilthoniel means "O Elbereth Starkindler". Aiya Eärendil Elenion Ancalima means "Hail Eärendil, brightest of the stars!" (a referral to a line from Crist).
3. Q. Why is Glorfindel's horse (in the first publication) said to have a 'bridle and bit' when elves ride without any tack? A. This chapter was written early before he considered the elves' way with animals. Glorfindel's horse would have had a headstall instead of a bridle.
4. Q. How could Ar-Pharazôn defeat Sauron when he had the One Ring? A. Ar-Pharazôn defeated Sauron's subjects, not Sauron himself. Sauron's personal 'surrender' was to gain entrance to Númenor to fully corrupt them leading to their downfall.
6. Q. What clothes did the peoples of Middle-Earth wear? A. Tolkien writes that he doesn't know the detail of clothing, but there are general ideas for some of the cultures. The styles for men were very diverse according to different ancestry. The styles in the Bay eux Tapestry fit well with the Rohirrim while the Númenóreans styles resembled the Egyptians.
7. Q. What the winged crown of Gondor like? A. It was tall, like that if Egypt, but the wings were attached and at an angle.
8. Q. What is the meaning of El- in Elven names (like Elrond) and when does it means elf and when does it mean star? Q. The basic element El means star. As the first element in a compound it could mean either star or elf. The translation of some of the elf names are: Elwing (Elf-foam), Elrond (Star cavern, Vault of stars, Star Dome), Elros (ros = Dew/spray), Elrohir (Elf-knight), Elladan (Elf-Númenórean).