sightsman

from The Century Dictionary.

• noun One who points out the sights or objects of interest of a place; a local guide.
• noun One who reads music readily at sight.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Mus.), rare One who reads or performs music readily at first sight.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun dated, music A sight-reader.