How did Joseph Henry improve on William Sturgeon’s electromagnet design?

Joseph Henry significantly improved upon the electromagnet design originally developed by William Sturgeon by addressing the issue of electrical insulation.12

While Sturgeon’s design involved wrapping bare copper wire around a U-shaped iron bar, the lack of insulation limited the number of turns he could apply without causing a short circuit. In 1829, Henry refined this by using insulated wire to wrap the iron core. This innovation allowed him to wind hundreds of turns of wire around the core, which dramatically increased the magnetic power of the device. Through this method, Henry successfully created an electromagnet capable of lifting more than one ton of iron, a world record at the time.21