Q: I have two books (Vols 1 and 2) called In Darkest Africa by Henry M Stanley and published by Sampson Low and Co. They have many illustrations. What are they worth?

A: This sounds as if it is the first edition of this book, published in 1890, and written by the same Stanley who found the famous Dr Livingstone. This was a popular book in its day and while copies are not that rare, nice-condition examples are sought-after and the set of two would be worth about £100 if in good order.