ABC of the Steel Square and Its Uses

This is a 19th-century masterclass in one tool that could do the work of modern calculators. The steel square was the carpenter's compass, their protractor, their slide rule, all rolled into a single piece of hardened steel. Hodgson writes for builders who measured twice and cut once, who understood that geometry was not abstract math but the difference between a roof that held and one that collapsed. The book is divided into three sections: types of squares and their uses, roof framing and rafter calculations, and a practical Q&A for problems builders actually faced on the job. What makes this book endure is its revelation that traditional carpentry was applied mathematics, a craft built on understanding angles and proportions with nothing but an L-shaped piece of metal. For modern woodworkers, this is a direct line to the craft's pre-electric roots. For anyone curious about how things were built before smartphones, it is a fascinating artifact of ingenuity. Read this to understand what hands could do when the mind had to do all the heavy lifting.