Although largely absent from modern accounts of the Industrial Revolution, watches were the first mass produced consumer durable, and were Adam Smith's pre-eminent example of technological progress. In fact, Smith makes the notable claim that watch prices may have fallen by up to 95 per cent...

We study how environmental regulation in the form of a cap on aggregate emissions from a fossil fuel (e.g., coal) interacts with the arrival of a clean substitute (e.g., solar energy). The cost of the substitute is assumed to decrease with cumulative use because of learning-by-doing. We show...