2nd stanza of "The Star-Spangled Banner":
On the shore, dimly seen through the mists of the deep,
Where the foe's haughty host in dread silence reposes,
What is that which the breeze, o'er the towering steep,
As it fitfully blows, half conceals, half discloses?
Now it catches the gleam of the morning's first beam,
In full glory reflected now shines in the stream:
'Tis the star-spangled banner! Oh long may it wave
O'er the land of the free and the home of the brave!
1' Does "the stream" refer to the flag, or the the deep, or the sunlight?
According to "O'er the ramparts we watched were so gallantly streaming" (in the 1st stanza), it is the flag that is streaming.
According to https://www.american-historama.org/1801-1828-evolution/star-spangled-banner-lyrics.htm (which says "'in full glory' lyrics express the grandeur of the flag and a religious connotation"), "the stream" may be the flag.
According to a popular Chinese translation (https://baike.baidu.com/link?url=HrVBxmNZhYMzkTUmMnE0sgxjYh7nlASirZDS3YITgoxuhlCoem9IsXnARg7wJUhxCzxitxtGSiPgzdyQePopr-43keocngUzjNk41X4mN38qZCS2mkEr0h7mGRJI_buN), "the stream" is translated as "水面" (literally "the surface of the water"). In other words, "the stream" refers to the sea/river in Baltimore.
If "the stream" is the sunlight, see my analysis blew.
2' The lyrics is "in the stream". However, I heard some singers singing "on the stream" (e.g. https://www.bilibili.com/video/BV1rb411r7Ds/?p=2&vd_source=6255052f3ca72cf571c578362d72ede3 where the caption is "on the stream"). What's the difference between "in the stream" and "on the stream"?
3' If the subject of both "reflected" and "shines" is "the gleam of the beam", why isn't the sixth line "In full glory reflected and shining in the stream"?
"Shine" can also be a noun. If "shines" serves as the subject, then what's the predicate? Absolute construction?
If "the stream" is the light, and the flag is the subject of "shines" (which means "to look bright and smooth"), then there should at least be a comma between "in full glory reflected" and "now shines". Therefore, the fifth, sixth, and seventh lines can be rephrased as:
Now it catches the gleam of the morning's first beam, reflected in full glory[,]
Now [it] (i.e. the flag) shines (i.e. appears glossy) in the stream (i.e. sunlight),
It is the star-spangled banner.
related question: Two questions about the 4th verse of "The Star-Spangled Banner"