Reference is made in Dick Stephen's article on the CNC conversion of a Sieg X3 milling machine to the use of a Centreing Microscope, he goes on to supply a couple of references.
I know it's a bit cheeky but I wondered of some kind person could supply me with scans of either/both of the following articles?
Model Engineer Vol 183 Issue 4103 Page 389 Optical Alignment for Machine Tools
Model Engineers Workshop Issue 98 2004 May/June Page 44 Simple Prismatic Centre Finding Microscope