Perhaps they've invented an instrument that tells what you think about.

M. Gobley has invented an instrument which he calls an areometer, to detect this fraud.

Paul Kotlarewsky, of St. Petersburg, has invented an instrument for measuring or ascertaining the velocity of water and air currents.

He has since busied himself with the study of airplanes and wireless, and has invented an instrument for transmitting sound by light.

In order to be able to measure the amount of this action, he invented an instrument which he called a voltameter, or a volta-electrometer.