Perhaps you should try some spelling variations:
"optical instrumentss / early works to 1800" » "optical instruments / early works to 1800", "optical instrument / early works to 1800", "opitical instruments / early works to 1800"
"musical instrument / early works to 1800" » "musical instruments / early works to 1800", "optical instruments / early works to 1800"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("musical instrument / early works to 1800") OR ("optical instrumentss / early works to 1800")).
• Removing quotes may allow a broader search: (( musical instrument / early works to 1800 ) or ( optical instrumentss / early works to 1800 )).
• Adding a wildcard symbol may retrieve word variants: (("musical instrument / early works to 1800") or ("optical instrumentss / early works to 1800"))*.