1 St. Basil's fourth century Homily on the first Psalm has been interpreted as a reference to metal strings:
Τῆ χιθάρᾳ μέν ϒὰρ χαὶ τῆ λύρᾳ χάτωϴϵν δ χαλχὸϛ ὑπηχεῖ προϛ τὸ πληχτρον...
Nam Citharæ ac lyræ æs ex inferiori parte sonitum edit ad plectrum...
For the brass wires of the cithara and the lyre sound from below against the plectrum...
Basil's original Greek, and contemporary Latin translation by Rufinus of Aquilea, from Patrologia Graeca vol.29 p.214; English translation from Oliver Strunk, Source Readings in Music History, 1950, p. 66
If correct this may be the earliest surviving evidence for such
strings. However, current Classical (Greek) scholarship finds no
evidence for the use of any string material besides gut (Marth Maas
and Jane McIntosh Snyder, Stringed Instruments of Ancient Greece,
1989, pps. 178–179).
There is no evidence of the use of gut strings in Gaelic areas at any time for either their stringed crot or tiompáin. Writing at the end of the twelfth century, Norman cleric Geraldus Cambrensis uses the Latin term aeneis to describe Irish cithera strings, which parallels the Gaelic use of uma to define Irish music strings, as both terms have been interpreted as brass/bronze.
Beginning in the sixteenth century English writers used brass and occasionally bronze in their accounts, and the detailed studies of Talbot and Bunting use brass exclusively. Unfortunately, as late as 1755, a dictionary definition of bronze included brass so there is no assurance that any author in any language actually knew or cared to distinguish the precise copper alloy(s). The English translations in our appendix mirror this indifference, as do contemporary scientists, who tend to use the term "brass" for a zinc-rich copper alloy and "bronze" for all other copper alloys, whether tin is present or not.
The principal published study of music wire to date is that of Martha Goodway and Jay Scott Odell (The Metallurgy of 17- and 18th-Century Music Wire, 1987), and to our knowledge every surviving copper-based music wire dating back to the eighteenth century that has been analysed is brass (copper/zinc), with the exception of four lengths of wire excavated at Castle Sween in Argyll, Scotland that Graeme Lawson in a private email correspondence describes as tin-bronze: no zinc. Its postulation as music wire is supported by the find of a harp tuning peg at the same excavation, yet its musical use remains suspect.
2 Despite late sixteenth and seventeenth century evidence for chromatic tunings of large clairseachs possessing forty or more strings (See Vincenzo Galilei, Dialogo Della Musica Antica Et Moderna, 1581 and Michael Praetorius, Syntagma Musicum Vol. 2, 1619), later information from Bunting and others allows the conclusion that this abberation of chromaticism was short lived and that diatonic tuning was and continued to be the tradition's standard.
3 The name for two consecutive strings, approximately one-third of the way up the gamut from the longest and lowest pitched strings, that were tuned to the same tenor G pitch. Bunting used two spellings: caomhluighe (lying together) and comh luighe (equally stretched). The RIA Dictionary lists two meanings of comluige; one is act of swearing jointly, making a pact, and the second is act of lying, sleeping together, which the RIA associates with the word coiblige (cohabitation, wedlock, copulation). [For an explanation connecting these meanings to harpstrings, see Ann and Charlie Heymann, Cláirseach: The Lore of the Irish Harp, Éire-Ireland XXVI #3, Fall 1991, pps. 82-95.] The latter word, with the spelling coblaigib, appears in ninth century or earlier glosses on the lines is crot cen cheis, is cell cen abbaid (a crot without cheis , [is like] a church without an abbot) in the seventh century Amra Coluim-cille. Crot is a stringed instrument that sometime before the eleventh century (and possibly long before) was a triangular framed harp with most if not all of the characteristics of the later cláirseach.
4 The first three items listed are found in Gaelic poetry and oral tradition recorded by scribes of the seventh through the eighteenth centuries, and corroborated by Edward Bunting at the 1792 Belfast Harp Festival. Both Bunting and wear marks on the instruments themselves affirm the left shoulder orientation.
5 Stringing with metal does not necessarily dictate higher tension. Metal strings of sufficiently thin guages can display similar tensions to gut strings of the same lengths, but the clairseach's reinforced pillar and heavy frame prove that its tensions were substantially higher than those seen on gut and horsehair strung harps.
6 In the late 1960's Rev. Chris Warren in Ireland built a copy of the Trinity College harp using a single piece of willow for the soundbox. In an interview with music critic Charles Acton, Warren states I got my wire from Cathal Gannon, what he used for stringing harpsichords. I used the finest gauge to start with and found that this was not satisfactory down in the bass and put in thicker, although it was all right up in the treble... When asked by Acton about this poor sound in the bass, Warren replied: It may be the nature of the instrument, but if you have it [the bass strings] any thicker it will be much too stiff and even as it is, if you look carefully, you can see that the wire is not tight enough for the pitch, because you cannot pull it straight or prevent it being wavy. The tone of the thick wire in the bass is poor and I found that if you pluck these strings hard the tone is wooly whereas if you barely tip them you get a weak tone which makes the bottom of a chord rounding out the harmony and your ear puts it back as a stronger note than in fact it is... (Éire-Ireland VII:4, Winter 1972, p. 124).
7 Use of na comhluighe (two tenor G) strings has been offered as a rationale for lowering treble string stress, implying that they existed as a workaround for a poorly designed harmonic curve. This argument ignores the fact that the harmonic curve would have been designed to accomodate a tuning with na comhluighe. Furthermore, na comhluighe are not located in the range where lowered stresses are necessary. If stresses needed to be lowered in this manner, na comhluighe would have been located among the shortest strings.
8 ...from the 1560's till the invention of overspun strings, twisted wires were used for the lowest ranges [of wire-strung instruments]... (D. Abbott & E. Segerman, Strings in the 16th and 17th Centuries, Galpin Society Journal, May 1974, p. 53).
9 The first evidence for strings with a metal winding is from the 1660's. (E. Segerman, Summary of Historical Use of Strings in About Strings and Stringing, www.nrinstruments.demon.co.uk/About.html ). It is interesting to note that even when available, ...covered strings had not come in at this date  on clavichords. (Michael Thomas, String Gauges of Old Italian Harpsichords, Galpin Society Journal, July 1971, p.77).
10 Phosphorus was first added to tin bronzes as a deoxidizer in the 1850s. (Martha Goodway, private email correspondence).
11 The appendix contains representative Gaelic excerpts that include ór (gold), airgead (silver) and findruine (silver-rich gold). Christopher Page, who has compiled a listing of string materials mentioned in medieval continental literature through the 14th century (Voices and Instruments of the Middle Ages, 1986, pps. 210-242), divides the metal string references into two groups: metal (Latin aeneis, ere and auricalco, Middle French archal, Spanish laton, Middle English latoun and Middle Dutch latoen) and precious metal (Latin argentee and argento, Middle French argent, Spanish plata, Middle English siluer and Middle Dutch siluer). All of the vernacular (non-Latin) mentions of metal strings copy a description of the psaltery in De Proprietatibus Rerum by Bartholomaeus Anglicus, c. 1250, leaving just three non-Gaelic sources for metal string evidence, but all connected to Ireland and the harp: Cambrensis' statement of Irish harps using brass (aeneis) strings, and two Old French romances that borrow significantly from Irish story material. One mentions a harp with silver (argent) strings and the other a harp strung with gold (fin or).
12 Cynthia Cathcart and Ben Zastrow have been focusing on the production of silver music wire and are experimenting with gold.
13 See the appendix.
14 Hammering the metal into sheets, then cutting strips from these sheets that were either twisted, rolled or cold-drawn through a die (a different concept from the later development of drawing) into final form.
15 Because neither the depth of the hammered sheet nor the width of the cut strips could not be precisely controlled.
16 Forcing a heated rod of soft metal through a hole smaller than the rod's diameter.
17 A metal's ductility is defined by its ability to be drawn into wire.
18 There is a higher probability of their use on a student or novice harp or a hybrid design between low- and high-headed. Appearance of frugality was anathema to Gaelic royalty.
19 E. Segerman, Summary of Historical Use of Strings in About Strings and Stringing, www.nrinstruments.demon.co.uk/About.html. Of course his focus was not on Ireland but more generally on western Europe.
20 Modern iron and steel wire differ significantly in makeup from the medieval iron wire, which was almost 100% pure, containing almost no carbon and conspicuously high levels of phosphorus that was not added, but a result of a superior manufacturing process (Goodway & Odell, op. cit., pps. 34-43).
21 The Morphology of the Irish Harp, Galpin Society Journal XVII, February 1964, p. 39.
Ann and Charlie Heymann 2003, 2004