The entrance to the factory was concealed by placing two short railway sleepers on either side of the hole and on top of these sleepers a notch was cut out. A timber box was then made with two groves on top which would fit into the notches cut out of the sleepers allowing it to swing like an axle. When someone was entering the factory a box could be lifted up and a stick put under it to support it and when leaving the factory the stick was taken out and the box came down into the hole. The entrance was then covered so that it could not be seen.

While the dug out was being prepared, Ned Fitzgerald was gathering all the equipment that was needed and these were put into the dugout. We are not sure exactly what equipment was in the factory or where it was all placed. There was a barrel lined with firebricks which were set in marla (a soft putty like substance). There was a hole of approx 4 square inches cut in the bottom of the barrel for the purpose if tapping to get out the molten metal. Firebricks were placed against the hole and a further hole was made through these blocks of approx 2 inches into the center of the barrel. This furnace was standing about 2 feet from ground level. Over the furnace a hole was cut in the roof of the factory into which was placed a foot long earthenware pipe which went up through the ditch to leave fumes out of the furnace.

This is a sample of the notes that were written by Ned Fitzgerald. It is very difficult to read and it has not been rewritten in legible writing.


Ned Fitzgerald was an engineer in UCC. While in his final year, he approached Martin Correy to offer his services in the struggle for independence. He was sent to the bomb factory in Blossomgrove. Having seen this operation he found that it was not being run efficiently. he made recommendations for change but they were ignored. He then decided to set up a new factory in Knockraha East. In setting up the factory, it was important to keep it secret. It was decided that the dug out would be 35 feet long by 8 feet wide. it was dug 9 feet deep. Horses were used to draw away the earth into a furze-brake so that people passing wouldnt see it. Hundreds of tons of earth had to be removed. At the top of the dug out a shoulder was cut into the ground 3 feet deep around the top of the whole. This was used to place the beams in and to support the roof. Railway sleepers were used that were found on a local farm where they were used to cross over drains. These sleepers were put side by side to support the roof and 2 feet of earth was put on top along with a sod of grass so it wouldnt be noticed. A hole was then dug to make an entrance. This was sloped into the factory and was big enough for a man to pass. Steps were made from the hole down to the floor of the factory.

Over the past couple of days I have been doing some research on Knockraha and in particular the bomb factory and Sing Sing prison. The bomb factory seems to be a more interesting site as it is no longer visible. I visited the site on Saturday and there is no indication that there was ever anything there.

There are very few artifacts that still survive. The trough was half full of sand and the casting would have fallen into it and left to cool. 

This is the only drawing that exists of any of the equipment that was in the bomb factory.