IM- PROVEMENTS IN PORTABLE FOG-HORNS OR FOG-SIGNALS
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by Samuel Greenway at the Office of the
Commissioners of Patents on the 14th August 1879. A communication
from abroad by Henry Thomsen, of Lübeck, in the Empire of Germany,
Tinsmith and Brazier.
SAMUEL: GREENWAY, of the Firm of Greenway, Clive, Vale, and Company, of
Birmingham, in the County of Warwick, Merchants and Manufacturers.
"IM-
PROVEMENTS IN PORTABLE FOG-HORNS OR FOG-SIGNALS." [A communication from
abroad by Henry Thomsen, of Lübeck, in the Empire of Germany, Tinsmith and
Brazier.]
The said Invention consists of a portable fog-horn or fog-signal constructed as
herein after described, so that it can be readily and conveniently carried and
worked by one person.
The body of the instrument consists of two light metallic tubes preferably of
about three inches diameter and about two feet long. These tubes are of some-
what different diameter, the smaller one being fixed concentrically within and
separated from the larger one by metallic hoops fixed at intervals between the
said tubes. By this method of construction a blow or accident producing an
indentation in the outer tube does not affect the figure of the inner tube, and
the action of the instrument is not interfered with. To one end of this compound
tube the trumpet shaped tube carrying the vibrating tongue or tongues is
attached by screwing. The other end of the body closed by a cap or cover
which is adapted to the body by a fastening, somewhat resembling a bayonet joint
fastening. The said cap or cover is perforated with a series of holes through
which air can freely pass to the interior of the body. A piston rod passes through
the said cap or cover, and is connected to a light metallic piston in the interior
of the body. The end of the piston rod external to the body is furnished with
a knob or handle by which the piston rod and piston can be worked. The metallic
piston has a cupped packing of leather or india rubber which serves to make the
piston work tightly in its descending stroke, that is, when forcing air through the
vibrating tongue or tongues and trumpet tube, and acts as a valve permitting air
to pass when the piston makes its ascending stroke.
Leather straps attached to the ends of the body of the instrument are connected
by a buckle, by which the length of the compound strap can be adjusted. By this
strap the instrument is suspended to the shoulder of the person using the fog horn
or signal, the body of the instrument being in a nearly horizontal position.

page_text: By working the piston up and down the body by one hand, the instrument being
held steady by the other hand, a series of loud sounds is produced, the nature of
which may be determined by the particular construction of the vibrating tongue or
tongues contained in the bottom of the trumpet tube, and which tongue or tongues
are set into vibration by the currents of air forced through the instrument by the
working of the piston.
The trumpet tube and vibrating tongue or tongues may be removed by
unscrewing the said trumpet tube from the body of the instrument. The un-
screwing of the trumpet tube makes the instrument very portable, and gives ready
access to the vibrating part of the instrument when necessary for repair, or
otherwise.