1. Condition: The overall condition of the set, including the bindings, covers, pages, and illustrations, plays a significant role in determining its value. A set in excellent condition with minimal wear and tear will be more valuable than one with significant damage.
2. Completeness: A complete set of the 9th edition typically consists of 25 volumes, including the index volume. The value of the set decreases if any volumes are missing or incomplete.
3. Edition and Printing: The first printing of the 9th edition is generally more valuable than subsequent printings. Check for the printing date and edition information to determine its rarity.
4. Binding: The type of binding can also impact the value of the set. Sets with original leather bindings or other special bindings may be more valuable than those with cloth or later replacement bindings.
5. Provenance: If the set has a known history of ownership or provenance, such as being from a notable library or collection, it can add to its value.
Based on these factors, the value of a complete set of the 9th edition Encyclopedia Britannica 1878 can range from a few hundred dollars to several thousand dollars. To get a more accurate estimate of the value, it's recommended to consult with a rare book dealer or an expert in antique books and collectibles. They can assess the condition, completeness, and other relevant factors to provide a more accurate valuation.