The coffin gate along Blackstone Shaft Vein seems to have been inaccessible since before c1850 (except for its tail area, which reputedly could be entered in the 1950s). It ends in Nestus Mine on Spar Holes Vein. There was only a trickle of water from it – will probably back up into the main sough to the aquarium.

Another coffin gate level with thermal water is the sough along Jackdaw Vein. This was described in Cyril Maddocks’ papers, and a copy exists in Nellie Kirkham’s papers. It was near the bandstand by the Jubilee Bridge in the Lovers Walks:

"Take the first path up the rocky slope past the bandstand. So far up turn off into the wood about 10 yds. and look for a depression (look for 2 or 3 elm trees from one root), in the depression you will find two loosely gobbed up gates. Take the right hand one and you will come to a 4 ft. drop, proceed on for about 200 yds. and you will notice on the right hand side an old type miner’s pick. Take a ladder with you and you can get right through to ‘Bullistree Mine’, Cromford. On the way through notice the roof a classical example of the ‘Old Mans’ architecture arches, like horse’s ribs [i.e. sweeping pick marks]. Also notice the stalactites, lovely curtains of them."

The sough tail is in the riverbank at the south end of the vein, the course of which is more or less as shown on the barmaster’s plans. Nobody seems to have found a way in since before WW2.
The founder shaft on Jackdaw Vein is at the north extremity of Lover’s Walks (north of the paths) in an area of rough and steeply sloping ground. I have looked for it several times but could find no trace.