Armed with a pair of wire cutters Bill shows how a common thermostat reveals how good industrial designers keep track of the dimensions of a human being.

Transcript: That thermostat is one of the greatest engineering designs of last cenutry.

I know it seems such a mundane thing, but it features the single most important element of good design: It reflects us!

Look at how perfectly it fits the human hand .... This was no accident. Its a design of genuis from Henry Dreyfuss .....

Dreyfus said he designed anything that could be "ridden , sat upon, looked at, talked into, activated, operated, or in some way used by people." His claim hold up well.

He created sinks, irons, tractors, airliners, typewriters, camera, vacuum cleaners and - my favorite - the flying car. [puts down book] They build a prototype, but it didn't exactly take off.

To make these things fit into the human world he kept very careful tabs on the typical size of person. I borrowed these fascinating charts created by Dreyfuss from a local library. He developed them to guide his design work. He claimed all his success was due to Joe and Josephine.

... a name he gave to these drawings of a man and a woman.

Here he lists the typical sizes of "Three basic human body types":

Ectomorph, Mesmorph and endormorph -- small, medium and large! He lists the typical dimensions of every aspect of each body type, which allowed him to "size" the objects he designed.

If you look here you can even see that he even give the extra dimension needed to accomodate the belly when a large person sits down. [taps belly]

Of more interest for this thermostat is this sheet. It features the typical hand sizes of men, woman, and children. Dreyfuss made measurements of many hands, took averages, and constructed the drawings you see here.

From this he figured out things like this ... the hand grasp. Now, of course, that's exactly the grip used on the thermostat.

That's why it fits so well into our world and became a classic. Honeywell made millions and millions of these round thermostats - you can still buy one at any hardware store. Dreyfuss alos used Joe and Josephine to design another of his most popular designs: This classic telephone.