jpk -

The "fleafart*Angstrom" has passed into colloquial speech as a euphemism for "a very small torque;" but appears to have originated with a friend at a lab where I worked about 50 years ago to describe the maximum unbalance torque permissible for a mechanical gyro with an x million gram cm^2/sec gyroscopic moment in order to achieve a maximum drift (error) rate of 0.(several zeros)1 MERU (milli-earth-rate-units). I don't know that "one fleafart" was ever calibrated in the original units, but it's a fairly small force.

Hope that clarifies it.

John