The harper and tradition-bearer, Arthur O’Neil, wrote in a letter around 1800, “My harp has thirty-six strings of four kinds of wire, increasing in strength from treble to bass”.

We can follow Arthur O’Neil, and use an easily memorised string chart for any harp, using four different gauges of wire. All you need to know is what are the top and bottom notes of your harp, and how the low bass strings are tuned (with or without short-octave gaps). If you don’t know that, get in touch and we can work it out!

This is my recommended string chart for any full-size old Irish wire-strung harp:

The strings above treble g′ are 0.48mm
yellow brass
or 0.48mm
soft iron
The octave above
na comhluighe /
sisters g is 0.6mm yellow brass
The octave below
na comhluighe /
sisters g is 0.75mm yellow brass
The lowest bass strings, below bass G are
yellow brass

We also have instructions from two other tradition-bearers; Patrick Murney in the 1880s recommended using a thinner gauge for the very highest octave, so using 5 gauges in total on his 36 string harp. And Patrick Byrne in about 1840 also used two different gauges for the lowest 8 strings, so using 6 gauges in total. I am still working on these systems. I think it depends a bit on the design of your harp.

I have made detailed stringcharts available for certain standard models of harps. These are free to download:
Hollybrook harp stringchart (2018)
Downhill harp string chart (2018)
NMI Carolan harp stringchart (2019)
Kildare harp stringchart (2020)
Clonalis Carolan harp stringchart (2020)
Castle Otway harp stringchart (2020)

If you want to read more about my thinking, and the rationale for stringing and setting up an old Irish harp in this way, you can read about this in two of my scholarly papers:
Simon Chadwick, ‘Stringing’, as part of the HHSI Hollybrook harp survey, HHSI 2021 (PDF download)
Simon Chadwick, ‘Provenance and recording of an eighteenth-century harp’, The Galpin Society Journal 73, March 2020, pages 103–5.
I have also written about speculative ideas for stringing and setup of reconstruction medieval harps.

If your harp is not one of the standard models, or you don’t know what the top and bottom note should be, I can do a string length analysis and make a custom stringchart for your harp, based on the measured string lengths. The cost of this is £20.