user: Question: What is the boiler pressure for the Hesperus model?
Columns: ['Name', 'Number', 'Builder', 'Date built', 'Wheel arrangement', 'Driving wheels', 'Cylinders', 'Boiler pressure', 'Notes']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Selsey', '2', 'Peckett and Sons', '1897', '2-4-2 T', '2ft 9in', '10" x 15"', '140 psi', 'New']
SQL:

assistant: SELECT "Boiler pressure" FROM "Table" WHERE "Name" = 'Hesperus';