A CLOCK is a five-letter instrument for measuring time. An altimeter is a nine-letter instrument for measuring altitude. A caliper is a seven-letter instrument for measuring the distance between two points. A BAROMETER is a nine-letter instrument for measuring atmospheric pressure. A galvanometer is a twelve-letter instrument for measuring electric current. A seismograph is an eleven-letter instrument for measuring seismic activity. A sextant is a seven-letter instrument for measuring angular distances. A thermometer is an eleven-letter instrument for measuring temperature. An ANEMOMETER is a ten-letter instrument for measuring wind speed.