Year: 1879

very ingenious application of electricity to the
purposes OF navigation has recently been effected by
Mr.. Henry A. Severn, of Herne Hill, who has sue
ceeded in producing mariners compass which
enables the captain officer in charge to hear. by
the ringing of bell. when :he vessel il out of the
ordered In the construction Of this compass
Mr.. Severn has svaed himself Of the constant posi-
of the card and the varying position of the
ship for the purpose of making and breaking
metallic contact. which causes electric bell to be
sounded and thus to the that the ves-
sci is of her The whole of the apparatus is
contained IN a small box which is easily carried
about aud intended. a rule. to be placed in tho
captains cabin. over the card two index hands,
which be adjusted to any angle allowing OF
greater less deviation In steering to either the
port or starboard side. Assuming the captain. on
quitting the deck. TO have gwen instructions to
steer the ship on certain course he sets the index
hands to a certain angle, allowing the stcersman
gwen latitude for deviation either to port star
board OF that course. Instead OF having to be
stantly watching the compass as at present, to
that his orders carried out the captain Leaves the
instrument 10 tell him by it's silence II they aro and
by it's sounds IL they not obeyed. Should the
ship be steered OF her beyond tho limit al
lowed either side an electric alarm bell rings In
Simultaneously, and, moreover. continues ringing
until the right course Ia resumed. The index hands
be raised away from the card. when the bell be-
comes disconnected and the compass DO used
like an ordinary one. The means whereby this use-
ful result il attained may be thus briefly stated.


DESCRIPTION OF THE COMPASS.


Tho metal point on which the card is hung is in
sulated from the compass bowl and to II In attached
y wire from one pole of small battery. About an
inch above the card. placed parallel to its surface
and attached to its metal centre (which is insulated
from the needle) is of metal reaching nearly
the edge of the card. This is therefore, in me-
talc communication with the wire from the battery
already referred to- Tho glass lid OF the compass has
n short brass rod working within n tube passing
through It, These severally attached to two brass
mlled heads above the glass lid and to
the two movable index hands beneath the
glass. These arc in metallic contact with
the brasswork of the compass. and this with
the other pole of the battery Beneath the outer
tremities of the index hands suspended two
pieces of platinum wire about thrce-q quarters of
inch long, These hands can, by means of the two
milled heads. be moved round to any position over
any point of the card Hence they admit of being
placed either side and equally distant or other
wise from the end OF the metal arm on the card IL
will thus be seen that whenever the platinum wires
in contact with the metal arm on the card
the circuit is completed. The electric bell being
placed In the circuit sounds whenever such con-
tact takes place. The boil is disconnected by SIM
ply raising the mlcd hoad up half inch
through sliding tube. and the compass then be-
comes in all respects ordinary one. Two bells OF
different tone can be used. and thus the instrument
will indicate TO the captain whether the deviation In
steering u 70 port Or starboard. The arrangement