Machinamenta in Old English

Reading a little about the etymology in Lord of the Rings, I came across the word that they used in Old English to translate the Latin word "machinamenta." It was Orþanc, and that p/b shaped letter (called thorn) is pronounced 'th.' This meaning of ingenious devices and siege engines was the reason Tolkein picked the name Orthanc for the tower of Saruman (whose name similarly means 'cunning mind.')