Which inventor used a revolving cutting tool to mill a slot in a lock in 1780?

The correct answer is Henery Maudslay, who is recognized for his significant contributions to the development of machine tools in the early 19th century. One of his notable innovations was the use of a revolving cutting tool to mill slots and other features in locks. This advancement was crucial as it allowed for greater precision and efficiency in manufacturing, which was essential for the production of complex mechanical components.

Maudslay's work laid the foundation for modern machining processes, influencing the design of subsequent tools and machinery. His ability to produce components with consistent dimensions marked a departure from the traditional methods of handcrafting, which were more variable and time-consuming.

The contributions of other inventors mentioned in the options focus on different areas of technology and engineering, but they do not specifically relate to the invention of the milling process as applied by Maudslay for locks at that time. Their work came later or focused on different technological innovations altogether.