The sun., 1902-03-09
STEAMER


whistle at the signal station on shore he
would have a wireless signal sent so that
any steamers within the zone of the Hertz
ian waves would receive the signal and by
counting the seconds elapsing until the
sound of the foghorn reached them the
distance of the steamer from the signalling
station could be determined.
But TO determine the most Important
point, namely. the exact direction from
which the sound proceeds las IL is we'll
known fact that IL is almost impossible
to locate by hearing the direction Of sound
during fog), Mr.. Kelway has recourse 20
the simple geometrioal problem Of con-
structing a triangle Say, for illustration
the first signal which is received indicates
that the steamer in question is ten miles
in an unknown direction from the signal
ling station. Mr.. Kelway then would have
the steamer proceed three miles or some
ot her arbitrary distance, and get another
signal, which would be, say, nine miles.
The result would be triangle with a base
of three miles, one side of ten miles and
the other side Of nine miles. To get the
signal stations direction is then an easy
mathematical problem. Mr.. Kelway con-
tends that there is no eNigenoy that his
scheme cannot meet. II the distance
at the first point be ten miles, and when
the vessel is run three miles the second
signal taken gives distance Of seven
miles, the signal station must be directly
ahead.
But TO construct triangles and figure
angles takes time, Mr.. Kelway has
turned his attention toward simplifying
the calculations, and with that end in view
he has invented telemeter which de-
hn
maticaly This teemeter is a combi-
nation of three two-foot rules. divided
into inches. representing miles, and these
inches subdivided into tenths, representing
cable lengths. II is 80 arranged that
any well-conditoned triangle may he
formed.
One of the rules serves as a base and
is always held in direction coincident
vii IN the ships course. The other two are
as sides Of the triangles One of the sides
is fixed by a screw az the zero point of ths
base, but can be pointed in any direction.
The other side has a sliding device which
enables the operator to set il at any place
on the base he may desire, as well As in
any direction. Attached TO this last side
is a protractor, which indicate. not only the
angle al which the side sets. but also the
compass points. Thus the operator getting
his first signal at ten-mile distance. steams
on three miles and gets nine-mile dis
tance Then all he has 10 do is to set his
movable side Of the teemeter at 3 on the
base figures, arrange the two sides SO that
the first side crosses the second side at
and tie second side crosses the first at 10.
while the angle thus formed is immediately
shown on tine protraCtor
To determine accurately he time elaps-
ing between the receipt of the wireless
signal and the foghorn signal Mr.. Kewav
has invented stop-watCh, This watch is
timed 10 ffths Cf seconds and il 30 arranged
that when il is stopped the distance the
sound has proceeded is shown on the dial
Thus no time is lost in computation.
This watch has had successful trial
in South Africa in getting he range Of Boer
batteries In some of The cases the range
was determined accurately at the first try.
while In others IL was gagged within fifteen
feet Mr.. koiway points out that by N-
watch the element Of error, instead Of lcirs
/ 100 fee, second or more when ordinary
watches are used, Is 10y his invention ie-
duccd To POO feet at the maximum
Mr. Kcwavs telemeter was originally
invented as n range and distance finder
and a. such has been used with corsidcra-
BILE SllCtP~~ ny captains u wv anu "
steamer.
Mr. Kclway. speaking Of nis f"g signal
ling device, says tha, in placer whore thoro
are 40 fog whistles submarine bell sigma
may be substituted, and the only difference
in the calculations is thai sound through
the water travels approximately Tour
times ~ quickly as through the air
His scheme admits o." savs, ~ eN'rn-
sivc developments. and hy H. U," he a,-e''s
that ciitrance 30 n haThor during 'h'cN
weather would be very sdi" and easy, a.
10 his mind Il would ho 81 sImr'" matter
TO regulate the force ~ 'nc l!'nl'an waNo-
So that vessel might come into tho y"n"
Of certain stations much as IL comes In'
line with range lights and ~" like nov,
and by tho prlicati.n of li~ watch and
teleme,er the position - the ship could no
with dcsIaich and accuracy.