Vernier scale Vernier acuity Training a straw man Commentary

Pierre Vernier metrology

Vernier scale

• Pierre Vernier added a secondary scale
• to the moving part of a caliper,
• where each division on the moving scale
• is a constant fraction of divisions on the fixed scale.
• When divisions of the moving or “vernier” scale
• are nine tenths of the divisions on the fixed scale,
• then where the vernier scale aligns with the fixed scale
• gives you tenths to be added to mark preceding the zero.

Vernier acuity

• If humans had a superpower
• it might be in detecting alignment of lines
• more accurately than the optical ability of the eye.
• We can detect differences of alignment
• smaller than the size of the receptors of our retinae.
• This hyperacuity gets better with training
• but worsens with age and changes of attention
• and may not be the same from eye to eye.

Training a straw man

• Some people don’t like to think
• we need to be trained; instead,
• we are shown how, or we are taught.
• We don’t try to herd cats;
• we don’t put zebras to the saddle.
• We train dogs, not ourselves.
• Why don’t we admit, as the most
• domesticated animal on the planet,
• we are more like dogs than cats?