⁴Lhwyd, Edward. "Several Observations Relating to the Antiquities and Natural History of Ireland, Made by Mr. Edw. Lhwyd, in His Travels Thro' That Kingdom. In a Letter to Dr. Tancred Robinson, Fellow of the College of Physicians and Royal Society." Philosophical Transactions (1683-1775) 27 (1710-1712): 503-06.
Some 70 years later Thomas Pownell described his difficulty in entering Newgrange, with its cairn partially collapsed into the entrance of the passage: "Four of the side stones, beginning from the fifth on the right hand, or eastern side, stand now leaning over to the opposite side; so that here the passage is scarce permeable. We made our way by creeping on our hands and knees till we came to this part. Here we were forced to turn upon our sides, and edge ourselves on with one elbow and one foot. After we had passed this strait, we were enabled to stand; and by degrees, as we advanced farther..." (Pownall, Thomas. "A Description of the Sepulchral Monuments at Newgrange." Archaeologia (1773): 2, 236-75.)