The farmer and mechanic., 1915-04-13

=. or annn SCcohu duration estimated |
dl Zo,ooO,0OO candlepower. Althouqb
On account Of the curyatura of r.
eartn, the light itself cannot he eaan
more tnan two miles its beam has
oeen reported to have been observed
III the SKY at distance of seven nau-
1lcai miles. This light consists of =
~: ave ienSe, with an electric arc
nsht source. The lens is seven feet
Tour inches in diameter and there ara
TWO OF them, back to back with the
arc hght In between, SO thai tho
hSnI Is conVerged into two diametric-
aiiy opposite beams. each of $1,000
900 candlepower. These lenses are
mounted on a mercury float SO that
they revolve with the least amounI ~
friction and power
Inc tallest light tower in this coun-
Try, 2Oo feet high, is the Cape Hat
teras lighthouse, North Carolina. II
| mas spiral painting Of red and
| "h.te To furnish d distinctive dan
| mark to mariners. A light must be
| ABOUT zoo feet above the water to be
| seen from the deck Of vessel twenty
nautical miles distant; beyond that
distance the curvature Of the earth
| would prevent light at this elevation
being seen.
The oldest existing lighthouses in
| the United States. both built in 1864,
are at Sandy Hook, New Jersey and
l
the Sandy Hook tower are seven feet
thick at the base and it is $50 feet in
height.
There are in use a large number
Tor acetylene gas-lighted beacons
supplied by tanks of gas of sufficient
capacity to maintain a quick flashing
light for five months without atten-
ton. These are visited by lighthouse
tenders and replenished. In other
acetylene lights the gas is generated
from carbide at the stations or il
the buoy. Oil gas under compression
is also extensively used for lighted
buoys, having first been employed 70,
this purpose in 1873. Some of tn.
acetylene beacons are provided with
. matically cutting off the gas suppl,
, during the time the sun shines.
There is a flashing beacon o.
Richardson Rock, a Wave-swept rock
west Of the Santa Barbara islands
California, which, without attention
. will flash its warnings every thre
!. seconds for seven months, or over s,
00O.000 flashes, before it requires All
! | other charge of gas.
: There are ninety-five lights o
+ Alaskan waters, and this number
I due to the facility with which flasl
S ing gas lights, unattended, may y
= established in that region, where
d would be difficult and expensive
maintain keepers.
e Submarine bells were first regular
d 1y employed as fog signals in tt
3 United States in 1906. The bell
s suspended in the water from a ligl
q vessel to a depth of twenty-five
ID thirty feet, and is operated by con
l. pressed air, or the bell is mounted {
iy;n nd nrx Z
he by electric power transmitted fro
Il the shore through a cable. or it
or suspended from a buoy and actuatt
t. by the motion Of the sea. whit
e moves valve and winds sprin
Sound from submarine bells is tran
mitted through the water more ur
ia fOrInly and effectively than it
o. through the air from aerial sign:
es However, the efficient use Of the su
ne marine bell requires that vessels
Dy equipped with suitable receiving q
en paratus attached to the hull on ea'
ed bow and telephonically connect
as with the wheel house. By comparil
a the loudn ness on the two sides the {
ed rection Of the signal may be obtai
A ed Submarine bells have frequent
of been heard through the water
"a | distances Of fiftee miles and more.
" Light vessels are placed in loo
" tons off the coast where 1t would
impractlCable or neeOIeSSly expense
,is to build n lighthouse, and they usu:
ng ly mark the approach to port
iii bay or the outer limit Of an offlyi
oii danger They are equipped with po
" erful and distinctive lights and
. signals Life on lightship is SON
th what dreary, but not without exci
nt- ment, and the men are allowed lib
60 al shore leave.
I'VE The pay Of ishtkeepers is sm
III ana tne NE IL io'ey. 49, l,i0le N
an willing to take large risks in dol
oh their duty and also helping those
taa distress. There are many cases
;ch faithful service and bravery. I
hurricane Of September, 1905. did
tho rious damage TO lighthouse prOpe
ow along the Gun coast, anu O nui'l =
the OF nFeS were los. d. '2e',Iu
oil at horn lSidhu 'Sii'