Various / 2008-06-12 00:00:00

The
frequent stoppages during foggy weather made them sources of danger
instead of aids to navigation. The sound of these trumpets has
deteriorated during the last year or so." Gen. Duane, reporting as to his
experiments in 1881, says: "The Daboll trumpet, operated by a caloric
engine, should only be employed in exceptional cases, such as at stations
where no water can be procured, and where from the proximity of other
signals it may be necessary to vary the nature of the sound." Thus it
would seem that the Daboll trumpet is an exceptionally fine instrument,
producing a sound of great penetration and of sufficient power for
ordinary practical use, but that to be kept going it requires skillful
management and constant care.
_The Siren._--The siren was adapted from the instrument invented by
Cagniard de la Tour, by A. and F. Brown, of the New York City Progress
Works, under the guidance of Prof. Henry, at the instance and for the use
of the United States Lighthouse Establishment, which also adopted it for
use as a fog-signal. The siren of the first class consists of a huge
trumpet, somewhat of the size and shape used by Daboll, with a wide mouth
and a narrow throat, and is sounded by driving compressed air or steam
through a disk placed in its throat. In this disk are twelve radial slits;
back of the fixed disk is a revolving plate, containing as many similar
openings. The plate is rotated 2,400 times each minute, and each
revolution causes the escape and interruption of twelve jets of air or
steam through the openings in the disk and rotating plate.
Read more


Parts: 1 2 3 4 5 6 7 8