{
 "longroom": [
  {
   "id": "flat-ceiling-1733",
   "year": 1733,
   "label": "1733 · flat plaster ceiling",
   "action": "flat-ceiling",
   "height": 15,
   "basis": "measured",
   "source": "https://www.tcd.ie/library/exhibitions/choicebooks/newlibrary.php",
   "note": "The original library had a flat plaster ceiling. Trinity gives an original height of about 15 m; the present barrel-vaulted hall is 14.2 m high."
  },
  {
   "id": "barrel-vault-1861",
   "year": 1861,
   "label": "1861–today · barrel vault",
   "action": "barrel-vault",
   "height": 14.2,
   "basis": "measured",
   "source": "https://www.tcd.ie/library/exhibitions/choicebooks/newlibrary.php",
   "note": "The barrel vault was added in 1859–61. The comparison changes only the ceiling and end-wall height; furnishings and camera position stay fixed."
  }
 ]
}