On the night of the 21st of August 1879 the Virgin Mary flanked by St Joseph and a bishop thought to be St John the Evangelist and an altar with a lamb and cross on it allegedly appeared on the gable wall of the Parish Church for a few hours. Fifteen people witnessed the vision including a child of five (page 60, The Evidence for Visions of the Virgin Mary) and stood watching it for two hours allegedly in torrential rain.
Why the whole village didn’t turn out is a mystery. It is said though that the real figure is about twenty (page 8, The Apparition at Knock).

The testimony that is the most readable and interesting is that of Patrick Hill.  As it appears first in all the lists, it was clearly worked over by publishers to get readers hooked on the story.

Witness Patrick Hill
Hill was allegedly 13 or 14. In fact, believers lie about his age. As he was baptised in 1868 (see page 178, Knock: The Virgin's Apparition..) we may presume that he was born that year. People in those days did not delay baptism. he was 11- far too immature to be taken seriously.

Why Doubt Patrick Hill?
He was certainly guilty of exaggerating. He saw things the others did not see - some did not see the altar he mentioned. His testimony if true would give room for a natural explanation for the apparition. The strange elements are that he mentions the images seeming to go away from anybody that tried to touch them and that they stayed dry. But you would expect that moving away from people if a three dimensional illusion was taking place. If you reach for what you think is a 3-d image and find it is only two dimensional you will get that impression. Also, as the image is an illusion made of light it will not get wet. He does not mention the alleged miracle of the dry gable. He mentions the angels fluttering around the altar who did not seem to have heads. He mentions noticing the sparkles composing the top part of the Virgin's crown. These seem to me to indicate that the rain was interfering with the light source. The angels sound more like an effect caused by a light source in the rain.

"I saw St Joseph to the Blessed Virgin's right hand; his head was bent from the shoulders, forward. He appeared to be paying his respects. I noticed his whiskers; they appeared slightly grey."
"The third figure that stood before me was that of St John the Evangelist".
Compare this to Mary Beirne: "In the figure of St Joseph the head was slightly bent, and inclined towards the Blessed Virgin, as if paying her respect; it represented the saint as somewhat aged, with grey whiskers and grayish hair."
"The third figure appeared to be that of St John the Evangelist."
Either the witnesses had been colluding to get the story straight or they had been asked leading questions to prompt them and confuse their memories so that their story matched better. Or were the priests who wrote down the depositions plagiarising?
A scientist Father Lennon who was neutral towards the visions examined Hill's story and decided that his statement was of little or no value (page 57, The Apparition at Knock).
Lennon had scientific investigation skills which the commission of 1879 did not have thus we should listen to him. Father Lennon examined Hill's claims and dismissed them. His testimony is annulled by this authority.
Hill testified in 1879 that he went to the vision at 8. Not that long after he testified soon in the Weekly News that it was dark then (page 59, The Apparition at Knock). He testified to the Daily Telegraph that he went to the apparition when it was night and dark (page 60, 61, The Apparition at Knock). So it was dark that night at 8. 

His testimony states he stayed with his aunt at Knock. Where was she during the vision?
There was a wall 25 paces from the gable (page 65, The Apparition at Knock). Hill put little John Curry a child on the wall some distance away to look at the apparition. Why did he keep him away from the apparition? This was not natural behaviour. You would take a child close to get her or him blessed. Hill claimed he went close and took Curry with him. The child said he saw the nice figures from the wall meaning he was not near the vision. Why does the child not say that he saw them close up - a child does not focus on the boring information but the more exciting stuff. Seeing the vision close was better than seeing it from a wall.
Was Hill near that near the vision at all? He lied about taking Curry up to it. Hill mentions that when he went to the scene of the vision the people were resting on the wall. "At this time we reached as far as the wall fronting the gable ; there were other people there before me ; some of them were praying, some not ; all were looking at the vision ; they were leaning over the wall or ditch, with their arms resting on the top."
Why were they so far away from the images? You get the impression that the images looked better further off - that would suit the magic lantern theory. He was not telling the truth that the image was detailed when it was looked at close up.
The Hill description of the vision is far too detailed. Nobody's memory is that good. If somebody gave a testimony like that to a policeman two months or more after a crime it would be dismissed as embellished if not fictitious.
Hill said he looked into the book John the Evangelist was holding and could read the letters. Why didn't he write them down? The Catholic psyche associates miracles with messages and there could have been a message in the book.