As an antiquarian and author Elias enjoyed an extensive and well-deserved reputation as far afield as America; his works continue to be oft-quoted sources of reference. Facsimile copies of his books The Old Stone Crosses of the Vale of Clwyd, (Bernard Quaritch & Woodall, Minshall & Co., 1886) and Welsh Folk-Lore. A Collection of the Folk-Tales and Legends of North Wales, (Woodall, Oswestry and Wrexham, 1896) were published in the 1990s. The latter work was a revised and enlarged version of his prize essay at the National Eisteddfod, London, in 1887 (in bygone years the Welsh National Eisteddfod was held in several cities outside Wales). His prize consisted of a silver medal and £20.
The Montgomeryshire Collections, of which Elias was for some years joint editor, are collections of antiquary articles published annually by the Powysland Club. Founded in 1867, the Club was a society of antiquarians from in and around Welshpool with a general interest in antiquary and a particular interest in Mid Wales; Elias was a member of its committee. From when he joined in 1871 until his death in 1899, apart from 1890, Elias contributed at least one article a year. Below are listed some of his articles in that publication. In 1874 the Powysland Museum now in Welshpool - was built to display some of the interesting articles belonging to several members of the Club.
- Archaic Words, Phrases, &c, in Montgomeryshire; in eight parts. Vols. iv-ix.
- Children's Rhymes on New Year's morn. Vol. xi, 155-8.
- Weather Signs in Montgomeryshire. Vol. xii, 357, xiii.
- Folk-lore, Superstitions, &c. Vols. xv, xvi, xvii, xxix, xxx & xxxi.
- Itinerant Tradesmen, that have passed or are passing away in this century. Vol. xxi.
- The Place where the first Welsh Testament was translated. Vol. xxii.
- Churchyard Walls. Vol. xxiii.
- Parich Terriers, Parson's Pay. Vol. xxv.
- The Holy Wells of North Wales. Vol. xxvii.
- Llanyblodwel Reminiscences. Vol. xxviii.
- Offa's Dyke. Vol. xxix. >>