Note 32 — Chapter IV · CONTEMPORARY DOCUMENTS.

[This rather obscure passage refers to the call-key or communicator fixed to the side of the instruments, and which as the inventor explains in his Prospectus (see p. 87), to be intended, like the call-bell or communicator of modern telephones, as a means of sending signals to the speaker, and which, as the Prospectus says, can also be used—as any call-bell can—for telegraphing words by a pre-arranged code of signals.]—S. P. T.