[Illustration: Fig. 3]

[Illustration: Fig. 4]

It would appear, then, that M. Van Rysselberghe has made an advance of
very extraordinary merit in devising these combinations. We have seen
in recent years how duplex telegraphy superseded single working, only
to be in turn superseded by the quadruplex system. Multiplex
telegraphy of various kinds has been actively pursued, but chiefly on
the other side of the Atlantic rather than in this country, where our
fast-speed automatic system has proved quite adequate hitherto.
Whether we shall see the adoption in the United Kingdom of Van
Rysselberghe's system is, however, by no means certain. The essence of
it consists in retarding the telegraphic signals to a degree quite
incompatible with the fast-speed automatic transmission of telegraphic
messages in which our Post Office system excels. We are not likely to
spoil our telegraphic system for the sake of simultaneous telephony,
unless there is something to be gained of much greater advantage than
as yet appears.--_Nature._

* * * * *




THE ELECTRIC MARIGRAPH.


For registering the height of the tide at every instant, hydrographic