Are you a member of MOLES as well?
I havn't been to Ruskin in quite some time, last time I went, I went with some people I knew to look at the Slate Section. Very good museum, I didn't really look at much save the C old man slate heritage stuff.
Have you tried Threlkeld?-, though They're not really an archive, just a fake lead mine & old quarry
Kein geneis kanaf - Cain gnais canaf
Byt vndyd mwyhaf - byth onddyth moyav
Lliaws a bwyllaf - Líows o boylav
Ac a bryderaf - ac o boryddarav
Kyfarchaf y veird byt - covarcav yr vairth
Pryt nam dyweid - poryth na'm dowaith
Py gynheil y byt - Pa gonail y byth
Na syrch yn eissywyt - na soroc yn eishoyth
Neur byt bei syrchei - nour byth bai sorochai