Starting to read classic literary texts, mainly in Aozora Bunko, I am encountering symbols like /″\, /\, ――, ○○ (above a word) or ```````` (above a word), which I don't know what they mean.
For example, in this work by Kasai Zenzō (葛西善藏)
https://www.aozora.gr.jp/cards/000984/files/1097_22274.html
it can immediately be seen the repeated use of /″\,/\and ――.
ありがたくしみ/″\と眺めやつた
此の朝つく/″\と身に沁みて考へられた
僕にはもと/\掠奪りやくだつの心はないんだ
一応――三四日しておせいはまた下宿に逃げて来たのだ――で彼女の言ひ分も確めたいと思ひ
In the same work, we can find this sentence
下宿の女中さんなどは無論寝てゐたんだが、電話に出て、読売からだと取次いでくれた。
in which, the word 読売 has a ○ above each kanji, that is, a ○ above 読 and another ○ above 売 .
On the other hand, for example, in the work Botchan (坊っちゃん) by Natsume Sōseki (夏目漱石)
https://www.aozora.gr.jp/cards/000148/files/752_14964.html
in this sentence
おくれんかな、もしは生温るい言葉だ。
each of the kana in おくれんかな、もし has a ` above.
My question is: what do all these symbols mean? Are they something common in the Japanese language used in most classic literary texts (and therefore, if I read these texts through a physical format, printed in a book, I will also find them) or do they only appear in Aozora Bunko texts for any particular reason?
If these symbols (and other ones that may be and I don't know them) are known in Japanese under a certain name, I would also like to know it, so that I can read more about the matter.
Thanks a lot in advance for your help!