The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1892-09-03
TkIANGULAT1ON OF THE STRAITS.
Description Of the Work Being Carried
on by Capt. Gilbert and Assistants.

on by Capt. Gilbert and Assistants.
PoRr CRESCENT, Sept 2.-Isnecial. 1.-The trail
has been completed to the Summit of Striped
peak, the mountain just east eli this place, and
the most conspicuous elevation Immediately
adjoining the straits. Captain J. J. Gilbert, of
the United States coast survey, has an assistant
stationed on the summit whIle ne has been
making observation from Duneeness lighthouse
and from Discovery island. the coast survey
steamer Gedney is conveying HIM to the differ
ent points he desires to touch. The assistant on
Striped peak at this place is provided with q
heliotrope, and begins his work Just before sun
rise each morning. The view frpm the noun
tain is grand. as it rises abruptly from the
straits. Every indentation of the coast is visi.
BILE from Dungeness to Cape Flattery. Victoria
and Vancouver islandsare spread out before the
observer like one great map. while the straits
present an interesting scene, with numerous
vessels OF every kind.
The local assistants at the principal stations
occupied in the work Of the United States coast
and geodetic survey are technically termed
heliotropers, or operators OF the heliotrope, the
simple but wonderful kstie tnatrament which
reflects the rays Of the sun so shat they can be
used in conveying signals at long distances.
Tho word heliOtropo is pOpularly associated
with the floral kingdom, but the activity OF the
surveying corps il familiariziug the public with
its scientific meaning. 1t ia a;mirror of small
size which reflects the rays OF the sun toward a
distant observer who is watching with hand
telescope. A code Of signals 10 used, long and
short flashes taking the place OF dots and dashes
In the telegraph code. The intervals between
the flashes are produced by the observer inter-
cepting the rays OF the sun by holding his hat
or some similar object In front OF the heliotrope
1t is apparent that there is no limit to the ex.
tent to which the code OF signals by the hello
trope could be carried.
The work of triangulation now being con.
Quoted by Captain Gilbert and the steamer Ged-
ney is part of a similar system which scientists
have carried from the Atlantic to the Pacific
During this summer party of specialists have
been making observations froa1 some OF the
highest mountains in California, greatly ex-
tending the lines of the triangies previously
used. In this work. as in Captain Gilbert's on
the straits here, heliotropes are used in making
signals. One line is nearly l40 M les in length.
The great transcontinental arc Of the parallel
stretches from the Atlantic TO tha Pacific along
the 39th degree Of latitude, striking the Pacific
at Point Arena Northward and southwark the
great arc of the meridian stretches from San
Diego to the Straits OF Juan de FGca.
The accuracy of the measurements in the tri-
anguiaton is something remarkeble 1T as.
serted that the probable error in direction be-
tween the Atlantic aud Pacific oceans is less
than five feet.
Signals by the helio.rope have been seen 1872
miles, thrown by mirror eight inches square
Signals thirty five miles distant are very daz-
ventures OF the observers veFg noteworthy.
as they scale mountains over l0zs}0) feet high
The work on the straits here is 0ot so hazard
Gus, but is difficult and aborious st times owing
10 the dense underground surrounding MANY of
the points OF observation.