late19th century antique american industrial mahogany wood spirit or bubble level fabricated by the stanley rule & level co., new britain, ct. retains the original ground glass vials incompletely filled with alcohol (leaving a bubble). original yellow brass corner bindings dovetailed into the wood. the top plate contains lightly incised manufacturer markings identifying the maker. the spirit level was invented by melchisedech thevenot, an amateur scientist and patron of many scientists and mathematicians. he was wealthy and well-connected, later becoming the royal librarian to king louis xiv of france. thevenot invented the instrument some time before february 2, 1661. within a year of this date the inventor circulated details of his invention to others, including robert hooke in london and vincenzo viviani in florence. it is occasionally argued that these bubble levels did not come into widespread use until the beginning of the eighteenth century, the earliest surviving examples being from that time, but adrien auzout had recommended that the académie royale des sciences take "levels of the thevenot type" on its expedition to madagascar in 1666. it is very likely that these levels were in use in france and elsewhere long before the turn of the century.