Dicul, Irish Monk and teacher at Court of Charlemagne, geographer and author of De Astronomium 814 AD taught by Brother Fidelmus of Fermanagh who went to Egypt to measure Pyramids and Astronomy in Ireland AD 442-1133.

From Google Books:

http://books.google.ie/books?id=0fgIAQAAQBAJ&pg=PT97&lpg=PT97&dq=diciul+geographer&source=bl&ots=6yCaAowXRF&sig=0evntInzpAeCmQsUgOOSSrrwZkU&hl=en&sa=X&ei=HicwVISjEYTd7Qa76oDwAg&ved=0CCMQ6AEwAA#v=onepage&q=diciul%20geographer&f=false