Bench Degree·REFRIGERATIONchapter
On the Cover
How the cover of every Bench Degree volume is chosen. One question, and it is not who got there first or who is famous. If we could bring anyone back to teach you this subject, who would you actually want at the bench? That is the whole test. It picks people who did the work with their hands, who checked things themselves, and who would be worth standing next to. Every one of them actually lived, which is why a cover portrait in this series is either a real document or openly a drawing, and never a photograph of something that did not happen.
Willis Haviland Carrier, photographed around 1920, at about forty-four.
He is on this cover for a specific reason, and it is not that he invented air conditioning. Several people built cooling machines before him, and Chapter 3 is largely about how wrong most of them were.
Carrier is here because in 1911 he stood up in front of the American Society of Mechanical Engineers and read out a paper called Rational Psychrometric Formulae, and then let everybody have it. He had worked out the relationship between air temperature, moisture and the dew point, put it in equations, and turned it into a chart any engineer could read. He did not keep it.
That chart is Chapter 14 of this book. It is also the chart still taped inside service van doors, and the reason a technician with a sling psychrometer and a pencil can work out in ninety seconds what would otherwise take a laboratory. A great deal of what follows in these pages exists because one man published his working instead of hoarding it.
He also named the field. The company he founded in 1915 is still called Carrier, which is why the word is on equipment nameplates in every country on earth, and why the name on this cover may already be familiar to anyone who has opened a rooftop unit.
The curves drawn faintly behind him are his: the saturation line and the relative humidity family of the psychrometric chart, plotted from the same numbers as the figure in Chapter 14.
About the photograph. It is a real one. Carrier Corporation’s own archive, published in the 1920s and in the public domain in the United States. It has been converted to greyscale, levelled, and faded at the edges so it sits on a black page. Nothing in it was generated, retouched or invented, and no part of his face has been altered.
This matters to us more than it might seem. Every man who will appear on the cover of a Bench Degree volume actually lived, actually did the work, and can be misrepresented by a picture he never sat for. So the rule for this series is that a cover portrait is a document or it is openly a drawing, and it is never a photograph of something that did not happen. Where no usable photograph exists, that volume will carry an engraving instead, and will say so here.
The full account of how this book was made, including which parts of it were written with the help of a language model, is on the copyright page and on the back cover, itemised using the five credits published at bookcredits.org.
Bench Degree
Get the degree without the diploma.
Learn the material, not how to pass the exam.