Historical kana usage:How to read
Spellings in Historical kana usage have been unchanged all the time in spite of changes of pronunciation.
Now we are reading those spellings with modern pronunciation.
●ゐ and ゑ,those are obsolete in Modern kana usage,are commonplace in Historical kana usage.
ゐ is to be read with い, and ゑ is to be read with え.
こゑ→こえ（声） and so on.
（Katakana of ゐ is ヰ, and that of ゑ is ヱ.）
●を can be used not only as a particle but also in other kinds of words.
を is to be read with お .
をばさん→おばさん and so on.
●ぢ and づ are used more often.
ぢ is to be read with じ, and づ is to be read with ず.
まづ→まず（先ず） and so on.
●Some kana are read with different sounds instead of their original sounds under a certain condition. These phenomena are called Tenko(Change of call).
は,ひ,ふ,へ,ほ located in any place other than the top of a word are to be read with わ,い,う,え,お.
おほい→おおい（多い） and so on.
Such sequences of kana as あう,あふ,かう,かふ,さう,さふ,・・・ are to be read in the same way as おう,こう,そう,・・・.
散らう→散ろう and so on.
ざふきん→雑巾 and so on.
All the verbs such as 会ふ,買ふ,慕ふ,嫌ふ are exceptions.They are read with あう,かう,したう,きらう in Modern Standard Japanese.
But in case of Ancient writings,they are generally read in the same way as おう,こう,しとう,きろう according to the principle.
Such as きう,きふ,しう,しふ,ちう,ちふ,・・・ are to be read with きゅう,しゅう,ちゅう,・・・.
美しう→美しゅう and so on.
じふじ→十時 and so on.
Such as けう,けふ,せう,せふ,てう,てふ,・・・ are to be read in the same way as きょう,しょう,ちょう,・・・.
でせう→でしょう and so on.
てふ→蝶 and so on.
●There are some other kinds of Tenko in Sound reading of kanji, in addittion.
Such as きやう,しやう,ちやう,・・・ are to be read in the same way as きょう,しょう,ちょう,・・・.
ちやうちやう→町長 and so on.
くわ,ぐわ are to be read with か,が.
ゆくわい→愉快 and so on.
●Small letters are generally not used in Historical kana usage.
Large つ,や,ゆ,よ of Sokuon and Yoon are read in the same way as small っ,ゃ,ゅ,ょ.
ちやんと→ちゃんと and so on.
●In case of Ancient writings,the following rule is to be added.
む of an auxiliary verb is to be read with ん.
まかりなむずる→まかりなんずる and so on.
Further regulations (in Japanese)