Er bod y Rhufeiniaid yn gwybod amdanynt, ni chafodd pwysigrwydd y ffynhonnau ym Mhrydain eu gwireddu'n llawn tan ddiwedd y bedwaredd ganrif ar bymtheg pan ddaeth y rheilffordd i'r dref. Agorwyd yr orsaf reilffordd yn Llandrindod yn 1865, er ychydig iawn arall oedd yn y dref y bryd hynny. Yn 1870 ymlaen y dechreuodd y dref dyfu, pan ddechreuodd letya'r niferoedd cynyddol o ymwelwyr -- ond nid oedd pob un yn chwilio am iachâd, gan fod yna ddigonedd o bethau eraill i'w gwneud am adloniant.

Serch hynny, roedd yna amrywiol fathau o ddwr ar gael i'r rheini oedd yn ymweld â'r dref er lles eu hiechyd.

Roedd yna ffynhonnau sylffwr ar gael yng Ngwesty'r Hen Dy Pwmp ac ym Mharc y Creigiau, a ddarganfuwyd gyntaf yn 1867.

"So great was the quantity of sulphuretted hydrogen gas given off, that it rose in a quick succession of bubbles to the surface of the water, and upon applying a lighted match to them they exploded with a slight blue flame, somewhat to the consternation of the workmen employed, who, from this fact, concluded that the source of the spring was from a region not usually mentioned in polite society."

General Observations on Sulphuretted Waters.

Both these springs are probably produced by the action of water upon the metallic suphurets. These absorb oxygen from the water and part with sulphur, and this unites with the hydrogen of the water to form sulphuretted hydrogen gas, which remains in solution.
Their Medicinal Qualities, a stimulent, diuretic, and alterative. It is found of service in cutaneous and uterine diseases, in chronic rheumatism and gout, and great benefit is often derived in chronic bronchitis and asthmatic affections. This is also the case with a sluggish liver, and with the disorders of the stomach dependent thereon. It should be used both internally and externally in the form of baths, and should be taken in doses of not more than a tumblerful three, four and five times a day.