Jacquerod and Perrot have found that quartz-glass is freely permeable to helium below a red-heat (Comet.
Test.; Perrot and Chipiez, Hist.
Perrot and C. Chipiez, Histoire de fart Bans l'antiquite, v.
In 1585 Lord Deputy Sir John Perrot undertook the shiring of Ulster (excluding the counties Antrim and Down, which had already taken shape); and his work, though of little immediate effect owing to the rising of Hugh O'Neill, served as a basis for the division of the territory at the plantation of Ulster in the reign of James I.
Fermanagh was formed into a county on the shiring of Ulster in 1585 by Sir John Perrot, and was included in the well-known scheme of colonization of James I., the Plantation of Ulster.