(The following is in response to a question asked by A.T. over in the Hill Name forum) The 670 c hill that we may refer to as 'Moel Derfyn' situated at SH 665 481 has been surveyed, but only in a rudimentary way. Firstly by Dewi Jones who measured it as 15.3 metres of reascent. I then looked at it and came up with a total of 14.475 metres of reascent. We then both went back to have a look and surveyed it together as having 47 ft of reascent. Ideally 'Moel Derfyn' and 'Y Cyrniau' both need an accurate survey (the margin of error associated with the surveying method Dewi and (following in his footsteps) I used is about + / - 2ft - 3ft). I believe these two hills are amongst the 240 odd currently in the in-tray.