All plans of the Grianán present a doorway to each passage inside the eastern half of the monument, except two. One can be found in the first known account, given by William Blacker from June 1830. His sketch of the plan shows no entrance to the northern passage and he also writes: “The approach to that gallery or passage, wending northwards, appears to have been from above, there being no signs of an aperture communicating with the area, as in the case of the other passage just mentioned …”(i.e. the southern passage).
The second one was an unexpected find – Colby’s Ordnance Survey. Although on page 218, George Petrie in his description states: “These galleries do not, however, communicate with the gateway, but have entrances from the area at their northern and southern extremities.” These words are accurately reflected in the second plan of the monument itself.
But not in the first and general plan. Although both were drawn by the same man, Lieutenant Robert Kearsley Dawson of the Royal Engineers, who does not show otherwise tendencies towards a lack of attention to detail, a distinct difference can be observed between his two plans, when it comes to an entrance of the northern passage.
Dawson leaves for England in 1831, adding an interesting turn to the sequence of events of the official discovery of the ruin at Greenan Hill, for George Petrie and John O’Donovan do not arrive until the summer of 1834. The latter writing to Thomas Larcom from Moville on July 27th, 1834: “I am very sorry that I missed Petrie as I was most anxious to go with him to see the ruin of Grianan near Aileach, which is in all probability the ruin of the palace of the Kings of the North, and not a Temple of the Sun, as has been stated in the Penny Journal.” But it seems now that the Ordnance Survey was not as oblivious to the existence of the monument as William Blacker suspected. Nevertheless, Robert K. Dawson could not have surveyed and sketched his plans with such accuracy before Blacker’s discovery of the gate “and having directed a clearance to be made” in May of 1830. This places the drawing of the two plans in an unexpected earlier timeframe, in which the ruin was not yet known as Grianán of Aileach, the ‘palace of the Kings of the North’, since that was George Petrie’s interpretation, who arrived four years later.
With Blacker’s account of a missing entrance, despite all his stone clearing, it seems very likely that Dawson’s first and general plan is correct and no error occurred, forgetting the entrance, in his original sketch or in the engraving made by J. Duncan, prior to the publication of the survey in 1837. The miraculous appearance of the doorway in the second plan and the monument itself may be, no doubt well intended, the first modification the Grianán received with many more to follow.
Half a century later this perfectly settled doorway would be disturbed once again and this time it moved position in the shape of Walter Bernard’s plan, sent with his account of the restoration to the Royal Irish Academy, published in 1879.
Many unanswered questions remain about the entrance to the northern passage, left with little to no hope of solution. The monument has been changed too often, although Walter Bernard is forgiven. Not only was his restoration a rescue mission, saving the Grianán from obliteration by the curiosity of 19th century visitors, he also marked the original stonework, an approach, which should have been continued.