Table: rail_solanocounty_history
Columns: city
1860
1870
1880
1890
1900
1910
1920

Question: What is the 1880 figure when 1860 is N/A and 1910 is 494?
SQL: SELECT "1880" FROM rail_solanocounty_history WHERE "1860" = 'n/a' AND "1910" = 494