This book is really more a reference encyclopedia than a textbook.
The author is clearly very knowledgeable about light theory, the history of light, and the different types of lights that are available. I suspect much of the basic information provided on the different construction of various light bulbs will neither be of interest nor much use to most photographers.
However, there are several valuable chapters such as “Light and Shade” and “Controlling Light” that are well worth reading. In addition the sections on hard and soft light, direct and indirect light are very useful.
I feel this is an excellent supplementary text for anyone learning photographic lighting. For schools teaching photography, I’d recommend they include this book in their libraries.