Episode #622

January 2, 2021

We all use gauges routinely in our lives.


When driving a car my eyes go regularly to the speedometer, tachometer, temperature and fuel level gauges.

My Prius also had a graphic gauge which showed the apportionment between the electric and gasoline motors. This gauge allowed me to assess the charging level of the battery system.

There are also proximity gauges in my car in the form of rear view mirrors and my own depth of vision.

When a pilot is visually scanning he spends 1 to 2 seconds in 10° increments scanning the sky. He spends 20% of his time on the instruments. The instrument gauges tell him airspeed, altitude, vertical speed, attitude, heading and turn coordination. His eyes warn of hazards in his environment.

The pilot must combine the seven inputs from the Airspeed Indicator (ASI), Altimeter, Vertical Speed Indicator (VSI), Attitude Indicator (AI), Heading indicator (HI), Turn Coordinator (TC) and the 10° graduated compass in his mind’s eye. Combined, these inputs tell the pilot where he is in three dimensional space.

When using graphic gauges to adjust an image i employ an estimator’s approach. When adjusting contrast, for example, i swing the gauge slider widely to the right to the left to the right, etc. My movements shorten as i approach the desired contrast. My eyes are fast enough to see contrast spontaneously so my swinging action can be quite fast as i zero in on the perfect setting.

Most stereo music players have controls and gauges to adjust balance, treble, bass and volume.
On a Mac the system output balance and volume gauges are in Apple menu > System Preferences > Sound > Output.
The Output preference pane includes a right to left balance slider and volume slider (mute to loud).
In the Apple Music app (formerly known as iTunes) volume can be controlled with a gauge in the Music player title bar.

The Music Equalizer is found in the Window menu.

The Equalizer includes a gauge for Preamp volume. There are sliders to adjust the volume of frequencies from 32 hz (lowest bass) to 16 kilohertz (highest treble). These gauges are called faders. They allow the user to adjust the music to what pleases their ear.
The Equalizer includes presets such as Acoustic, Jazz and Rock. These frequency settings are known pleasing balances. The Equalizer allows you to manually set the frequency faders and save them for later listening pleasure.

Clocks, calendars, alarms and timers are gauges that allow us to moderate our projects.

How long have i been on a walk? When is my next appointment? What do i want to accomplish today?
The sun is a gauge in the sky. You can tell if it is night or day at a glance. Face north (most animals, including humans, know north instinctively). If your shadow is directly in front of you, it is noon. The angle of your shadow shows the time of day — a time gauge on the ground.

We even have biological gauges which tell us about our environment. These are sight, hearing, smell, taste, feel and time.
In the stomach, the vagal trunk of the vagus nerve tells us when we are hungry.

Our circadian rhythms are physical, mental and behavioral changes that follow a 24 hour cycle. Circadian rhythms do not have visual gauges. They express themselves in every cell of our bodies. We interpret (gauge) our condition with our nervous system.

There is a gauge on my well pump that tells me what the water pressure is in pounds per square inch. This is a Bourdon tube. A small curved tube inside the gauge straightens out with increased pressure. The end of the tube pulls on a gear, which turns a needle, which points to a pressure gradient on the dial.


Another gauge on my well tank is simpler. It is a float inside the tank connected to a cable.  Outside the tank, connected to the cable, is a red metal junction which slides along a vertical pipe.

If the junction is on the ground, the tank is full. If the junction is near the top of the tank, the tank is empty.

Another kind of pressure gauge is my wrist mounted skydiving altimeter.

The dial of the altimeter is a gauge of how far i am from the ground. Inside the altimeter is a bellows which expands as the air pressure increases. The bellows pulls on a gear, which turns a needle, which points to an altitude gradient on the dial.
i also carry three other altitude gauges with me in free fall. i have an audio altimeter in my helmet which sounds an alarm at various altitudes. It also records my exit altitude, opening altitude and speed in free fall.

There is an altimeter in my Automatic Activation Device (AAD) which deploys my reserve at speeds above 80 MPH at 700 feet above the ground. Click on the picture of an AAD below for the story of how it saved my life.

Finally, i have my eyes which can gauge my distance to the ground.

Gauges are how we interpret the world around us.
Our six senses gauge the gauges.


  1. Luana Langlois January 1, 2021
    • Rick Thues January 1, 2021

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