Two basic types of registers were made.  One type embossed or punched the tape and the other type marked the tape with ink.  The unit shown here is an "inker".  The Gamewell unit shown elsewhere on this site is an "puncher".

A spring motor powers the unit.  It starts when the incoming message begins and is automatically shut off a short period after the end of the message.  The motor pulls the tape through the unit which passes above lever which is operated by the electro-magnets at the right end of the unit.  The lever pushes the tape upwards so that it contacts an ink-coated roller.  A felt wheel above the roller is saturated with ink, and provides a continuous supply of ink to the roller as it turns.

This particular register is configured to record messages simultaneously from two individual telegraph lines, hence the two sets of coils, and two sets of binding posts for the electrical connections.

Registers of this sort were primarily used in landline telegraph service, however, they were also used in early radio telegraph applications.  A sample of the tapes that were produced by a register similar to this one in 1899 during experimental operations by Marconi can be seen here.