Cirth referred to the runic writing systems in Middle-earth. Cirth (singular certh) means "runes" in Sindarin. Certhas refers to a runic alphabet. The system was an ancient writing of the Elves, and although they were later largely replaced by the Tengwar (which were enhanced and brought by Fëanor), they were adopted by Dwarves because its straight lines were better suited to carving than the curved strokes of the Tengwar.
 Table of the earliest Cirth
- ↑ The original value of this certh wasn’t given by Tolkien, but he mentions that in later Angerthas, it took the value hw after 6 became m (for reasons explained below) while he doesn't give us the early certh for M. We can infer that this was the certh for M judging by both its 'labial' shape, and the symmetrical shape used for nasals, like @, u.
- ↑ this Certh was h when #/% were s and vice versa.
- ↑ This certh will have the value m in later Angerthas, for reasons explained below. Its original value can’t be guessed (maybe the certh for a?), but judging from the “labial” shape, it could be w.
- ↑ 4.0 4.1 The reversal of the stem didn’t had any phonologic significance. These Cirth were interchangeable and used for h or s depending on when g was s or h. This would perhaps apply to these early Cirth as well
- ↑ This Certh will have the value ss in later Angerthas. It must had another unknown value before (maybe the certh for a?).
The known ancient cirth don’t cover all the sounds of Sindarin, since we are missing rh, lh, mh, v, y, œ. Perhaps they were used for the Old Sindarin tongue, and many of the above mentioned sounds indeed didn’t exist in that language. However still frequent sounds w and a are missing. This indicates that some ancient, unknown cirth could have existed, but didn’t make it to the later systems; a fuller table therefore can't be reconstructed.
As for the vowel usage, perhaps the certh for u possibly was used for w (like in early latin orthography). The certh for a can’t be guessed, so maybe this sound was “meant” (like in some Quenya Tengwar Modes). More possibly it was one of the two cirth whose value can’t be determined, or it was one of some other cirth that did not survive till the later Angerthas.
Long vowels were evidently indicated by doubling (cf. the known certh for long o, n, is a simplified form of bb).
During the Chaining of Melkor, the Sindar of Beleriand began developing an alphabet for their language. Its letters were entirely made for carving on wood, stone or metal, hence their angular forms and straight lines. These letters were named cirth (sing. certh).
The assignment of values was unsystematic. The form of a certh was consisted of a stem and a branch. The branch was found usually on the right side of the stem, and sometimes on the left, but with no phonetic significance. Therefore 3 would just be an alternative form of 1.
By the Second Age the cirth were seldomly used. The Noldor of Eregion used cirth as a "matter of lore" mainly for formal writing. It was how the Dwarves of Moria got to know them and preferred them from the tengwar, being intended for carved inscriptions.[note 1] They modifed the system accordngly for their Khuzdul language (cf. Angerthas Moria and Angerthas Erebor).
By the Third Age only some Elves of Sindarin descent wrote in cirth in inscriptions, even though with spelling influence from the tengwar. The Longbeards were of the very few peoples who still knew and used cirth, leading to the misconception that they invented them, and were known as "dwarf-letters" by outsiders.
Many letters have shapes also found in the historical Futhark, but their sound values are only similar in a few of the vowels. Rather, the system of assignment of sound values is much more systematic in the Cirth than in the historical runes (e.g., voiced variants of a voiceless sound are expressed by an additional stroke). A similar system has been proposed for a few historical runes (e.g. p ᛈ and w ᚹ as variants of b ᛒ), but is in any case much more obscure.
The Cirth are not part of the Unicode Standard. However the ConScript Unicode Registry has defined the U+E080–E0FF range of the Unicode "Private Use Area" for Cirth.
 See also
- ↑ J.R.R. Tolkien, The Lord of the Rings, Appendix E
- ↑ J.R.R. Tolkien, Christopher Tolkien (ed.), The Peoples of Middle-earth, "Of Dwarves and Men"