It is likely that other adventurous people descended the cave at times over the following years, but they have left no record. The next significant exploration took place on 3rd May 1760 when the cave was descended by three colliers from Kingswood. They were accompanied by Alexander Catcott, at whose instigation this exploration took place. He went down the first few feet, and recorded the colliers' findings in his Fossil Journal, now in the Bristol Reference Library (Catcott, A. 1757-[1767?]). These are quoted here in full:
May 3rd 1760
John Rathbone, Abraham Stout, William Bryant, three coalminers from Kingswood, descended Pen Park Hole;- about 10 fathom below the surface they came to a cavity the entrance of which was about 20ft wide and about 7 feet high, the inside about 20ft wide and 10 feet high towards the mouth of the entrance for some way; in other parts lower and narrower and in some places so narrow and low as hardly room left to crawl in at, the whole summing in about 40 yards, and the passage Eastward about 10 fathom.
Lower in the hole they came to another Cavity wch appear'd to be about 30 feet wide and 30 feet high, and runs in westward for about 30 yards, but towards the further end grows narrower and lower. About 14 fathom lower they came to the edge of the water in the bottom, the whole length of the slope from the surface of the Earth to the surface of the water being as they said exactly 34 fathoms. They plumbed the water with a line, & say it was a full fathom deep, lying on one side of the bottom, they computed the water to be about 30 yards long and 12 yards over, and beyond the water which there was no way to cross, there appeared a roundish hole in the rock about 9 or 10 feet above the surface of the water, of about 7 or 8 foot diameter at the entrance, into which they threw some Stones, they think 20 yards horizontally; the inside of this great Cavern they say represents the appearance of a large glasshouse. They tasted the water, which they said was very clear & sweet.
The descent into this hole about 12 ft below the surface appears to be about 10 yds long and one and a half over and seems for the most part declining to the North East, so that from a small opening about 20ft below the surface where I went I could see them go down and come up the greatest part of the way and see them walk about some parts of the bottom and near the side of the Water; the water they say has been near about 2 fathoms deeper in the hole, which they judge from the mud left there, some of which they brought me up of about the consistency of new made hard sope. They say that they could not find the least appearance of oar in any part of this Cavern below the place where I was; that there was not the least sign of its having been worked below, nor did they believe it ever had, as the greatest part of the Caverns on top and sides was covered with pointed spare.
This statement, by miners, agrees with the present author's conclusions, given above, that prior to this date at least, the cave had not been worked by miners. It is doubtful that this journal was seen by either Tratman (1963) or Rudder (1779) who had they known of it would have been unlikely to have reached their conclusions about early mining at this site. There is nothing in the written record to show that the cave had been mined before this time. Hunt (1978) mentions Sturmy's descent and Collins' description, but nothing else and as long-time Keeper of Mining Records he is likely to have seen any other extant material.
A few years later came the most well known event to happen at the cave, the death of the Reverend Thomas Newnam, on 17th March 1775. Newnam fell to his death whilst trying to plumb the main shaft, when the branch of a tree to which he was holding broke. As might be expected, this event re-kindled a great deal of interest in the site and led to several further descents being undertaken. Notable amongst this group of explorers were Robert Tucker, whose assistant found the Rev. Newnam's body; William White, a local land surveyor who made several visits and subsequently drew up the second survey of the cave and George Catcott, brother of the aforementioned Alexander Catcott, who made several descents, accompanying White and who subsequently wrote an account of these events, quoting also the descriptions of Sturmy and Collins and including a version of White's survey (Catcott, G.S. 1792).
Samuel Rudder, writing in 1779, stated that his information on mining within the cave came from a Mr. Harmer. There is in the Bristol Reference Library a manuscript, B10158 which contains handwritten copies of Catcott's and White's descriptions, draft copies of White's survey and an expanded version of the material in Rudder's book, written in the first person. The hand is neither Catcott's nor White's and is therefore likely to have been written by the said Mr. Harmer and to be the material that Rudder used. It shows that most of the evidence for early mining at this site remains purely hearsay and could easily be applied to other nearby sites, the lead mines on the south side of Coombe hill, for example. The direct quotes about the state of this cave are seen to have come from miners investigating the eastern branch of the cave, unsuccessfully, for ore in about 1769. Their statements do not agree with the evidence to be seen within the cave and as they were attempting to negotiate terms for work at the cave with Mr. Harmer, can be regarded as unreliable. This is the first recorded occasion, however, when miners are known to have searched the cave for ore, albeit unsuccessfully. This account only indicates work in the eastern branch, the present entrance passage. This is confirmed by a passage in White's account, in the same manuscript, which shows that the route through to this part from the main chamber was difficult to locate and to pass. The account of the miners' work also indicates that there is a further eastward running passage from somewhere near the first chamber whose entrance was stopped up by them, and is now lost.