Thank you very much for this information. I have also discovered that Hildebrand Ramsden was a Fellow of the Royal Microscopical Society and Vice president (possibly President) of The Quekett Microscopical Club - so it is hardly surprising that a first edition of the most famous book on the subject should be found in his library. The Quekett still exists http://www.nhm.ac.uk/hosted_sites/quekett/index.htmlhttp://www.nhm.ac.uk/hosted_sites/quekett/index.html and I have written to the Secretary. If any further interesting information emerges, I will post it here.
Maybe it will prove to be just a delightful coincidence that Hildebrand and his brother combine the names of the two key pioneers of British microscopy.