Of the Palantiri

As the Northern Kingdom of the Dúnedain fell and Gondor's strength waned the palantiri were lost both physically and intellectually. "There remained only the Anor-stone in Minas Tirith and the Orthanc-stone" (p. 403, Unfinished Tales). Two main reasons led to the palantiri passing from knowledge: ignorance and apathy. No one knew what happened to the stone in Minas Ithil (now Minas Morgul) and some suspected that it was destroyed by the defenders before the Ringwraiths captured the tower. However, it seems that it was captured along with the tower and therefore came into the possession of Sauron. "It was for this reason, it may be supposed, that the Anor-stone, about which all the records of the Stewards are silent until the War of the Ring, was kept as a closely-guarded secret, accessible only to the Ruling Stewards and never by them used (it seems) until Denethor II" (p. 403, Unfinished Tales).

In terms of apathy: as Gondor declined so did interest in ancient history. "Gondor after the Kings declined into a 'Middle Age' of fading knowledge, and simpler skills" (p. 403, Unfinished Tales). The Seven Stones of old were generally forgotten by the general public as messages were sent by errand riders or beacons in times of urgent need. In this regard the Orthanc-stone seems to have been disregarded by the Stewards as Gondor's influence in that area declined greatly after the Dark Plague in 1635. During this time Isengard was possession of Gondor  however the tower of Orthanc was long deserted.

Middle-earth timeline: Third Age, circa 2005
Today's reading comes from: Unfinished Tales, pages 403-404