heard distinctly; and so communication was kept up until the cable was
again in working order. Of the two lines used in this case, one extended
from the sea at the end of the island near Hurst Castle, through the
length of the island, and entered the sea again at Rye; while the line on
the mainland ran from Hurst Castle, where it was connected with the sea,
through Southampton to Portsmouth, where it again entered the sea. The
distance between the two terminals at Hurst Castle was about one mile,
while that between the terminals at Portsmouth and Rye amounted to six
miles.--_Science._

* * * * *




PYROMETERS.


The accurate measurement of very high temperatures is a matter of great
importance, especially with regard to metallurgical operations; but it is
also one of great difficulty. Until recent years the only methods
suggested were to measure the expansion of a given fluid or gas, as in the
air pyrometer; or to measure the contraction of a cone of hard, burnt
clay, as in the Wedgwood pyrometer. Neither of these systems was at all
reliable or satisfactory. Lately, however, other principles have been
introduced with considerable success, and the matter is of so much
interest, not only to the practical manufacturer but also to the
physicist, that a sketch of the chief systems now in use will probably be
acceptable. He will thus be enabled to select the instrument best suited
for the particular purpose he may have in view.