What is a fuse composed of compressed cylindrical blocks with a hole in the center called?

The correct term for a fuse composed of compressed cylindrical blocks with a hole in the center is indeed the boric acid fuse. This type of fuse is specifically designed to provide a reliable method of protecting electrical circuits from overloads. The compressed cylindrical structure allows for enhanced current-carrying capacity and depends on the melting point of the materials used, in this case, boric acid, which is effective in dissipating heat during operation.

Boric acid fuses are notable because they can effectively interrupt electrical currents and are less prone to moisture-related issues compared to some other fuse types. Their design helps facilitate both melting and quick disconnection of the circuit when an overload occurs.

On the other hand, the other fuse types listed do not share the same characteristics. Copper fuses generally utilize pure copper to conduct electricity and are not constructed as described in the question. Glass fuses have a glass casing providing visibility for checking the fuse status but do not have the specified structure of compressed blocks. Lead fuses may have specific applications in older electrical systems but do not match the characteristic design of the fuse in the question. Thus, the unique structure and function of the boric acid fuse make it the correct choice.