RATHERNON, a parish, in the barony of CONNELL, county of KILDARE, and province of LEINSTER, 5? miles (N. E.) from Kildare, containing 1010 inhabitants. This parish comprises 3437 statute acres, as applotted under the tithe act : it is situated on the bog of Allen, by which it and the parish of Kilmaogue are entirely insulated, forming what is called the isle of Allen ; its chief feature is the hill of Allen. On its northern border are the ruins of Ballyteigue castle. Limestone is found under the greater part of this tract, but thc hill of Allen is wholly composed of trap : at the northern extremity of the hill, about a quarter of a mile distant, is a slight eminence called the Leap of Allen, composed of red sandstone conglomerate, arranged in beds varying in thickness. The greenstone of the hill, combined with greenstone porphyry, appears all round the base, on the sides and on the summit, in protuberant masses without any stratification. It is a rectory and vicarage, in the diocese of Kildare, forming part of the union of Kilmaogue : the tithes amount to #118. 4. In the R. C. divisions it is part of the union or district of Allen and Miltown. There are ruins of the old church.