Lieutenant, United States Coast and Geodetic Survey
(Originally published in The Military Engineer,
Vol. XXIV, No. 135, May-June 1932, pp. 245-249.)
was said, by a certain writer that a particular strip of swampy
jungle land in the tropics was utterly impenetrable. "That is,"
he qualified, "except to the hardiest of explorers, or a civil
engineer!" Without bothering to examine into the sincerity of
this remark, it must be admitted that civil engineers have a
great tradition to uphold - the tradition of success in any
endeavor, however hard.
writer had occasion to recall the foregoing quotation when ordered
by the United States Coast and Geodetic Survey to lay out and
execute second-order triangulation through the interior of Luzon.
What this meant, in effect, was to measure off the miles, meters,
even the millimeters, separating a series of stations which
should be placed in orderly arrangement on the summits of jungle-clad
peaks nearly 10,000 feet high, in the remote interiors of vast
tropical forests, and through the swampy bottom lands of the
great Cagayan Valley. Covering a strip of territory over 200
miles in length, in places 40 miles from side to side, these
stations were to compose a triangulation net reaching from the
Central Valley, at the foot of which lies Manila, through the
little-known lands of northern Luzon to Aparri, on the north,
the seaport of the Cagayan Valley.
nautical charts of the Philippines, like those of all other
well-surveyed countries, are based on a single well-chosen datum.
The three elements of this datum (latitude, longitude, and azimuth)
are made available to all sections of the archipelago by a country-wide
geodetic survey. Throughout large parts of the island group,
with its seven-thousand-odd separate land areas, adjacent islands
are within sight of one another, so that the triangulation nets
used to carry the geodetic datum may span the water areas, and
instrument stations can thus be placed along the shores, within
easy reach of the parties from the survey ships. Only in a few
places are the over-water lengths of lines, or the requirements
as to their directions, so exacting as to require the scaling
of the high peaks far inland on the islands.
Luzon is a large land mass, having almost no off-lying islands.
Triangulation around its coast, therefore, must be almost wholly
upon the mainland. The mountains are high and precipitous, almost
all the way from Manila Bay, around by way of the west, north,
and east coasts, to Casiguran Sound. Coastal triangulation surveys
were made in the early days of the American occupancy, from
Manila to Aparri, but no further progress in such fashion could
be made. The country was so rugged, and in the early days the
natives so hostile, that no great distance inland could be reached,
and the triangulation nets were long in proportion to their
width. They were very weak geometrically in this and other ways.
such work, as far as it went, was adequate for the control of
local charting operations, it failed utterly as a means of carrying
the elements of the datum, accurately, to the great areas of
northern Luzon and the island groups that reach still farther
north toward the Japanese territory of Formosa.
the surveys of these regions came due for completion, it became
necessary to plan means of extending accurate triangulation
northward from the Central Valley - work which should reach
the northernmost of the Philippine group, controlling, along
the way, all the local third-and fourth-order projects upon
which the hydrographic parties base their charting work. Only
in this way could the fundamental plan of a single and strong
datum, basic for all the charts, be followed. The work was essential
to insure that isolated and separate surveys, when brought together,
would join without error, and that all the charts, laid out
in far-flung array to cover all the country, would be consistent
it is impossible to lay out satisfactory figures along the coast
of this rugged island, the interior must naturally be utilized.
Despite whatever obstacles might be encountered in a little-known
land, a well-proportioned network of triangulation figures must
be planned and worked over, spanning the whole distance. A backbone,
a continental main scheme, as it were, would first be erected,
then other links connecting with local coastal areas, especially
on the east coast, could follow. The performance of this first
through link between the Manila area and Luzon's north coast
was the task assigned the writer.
Cordillera Central, domain of the hill tribes, so-called head-hunters,
occupies the western third of the island. It is rugged, and
approaches 10,000 feet in elevation. Along the east coast lies
the Sierra Madre, a range of precipices and virgin jungle, unexplored
and feared. Between lie the broad reaches of the Cagayan Valley
3,000 square miles of rolling hills and rich bottom lands. Sparsely
settled it yields, nevertheless, a great part of the crop of
fine Philippine tobaccos.
this valley lay our route, but first must come the crossing
of the southeast spur of the Cordillera, and the traversing
of the narrow and tortuous valley of the Magat River. These
high mountains are trailless and forbidding, but there is one
road, of sorts, through Balete, the lowest pass. The road, culmination
of years of effort, straggles northward over mountains and through
swamps, the scene of our operations, affording access by truck
to the Cagayan country and Aparri. All plans for transport were
necessarily made dependent upon our natural determination to
make all possible use that we could of this road.
Bureau of Lands, the cadastral survey unit of the local Government,
wanted to make extensive surveys of the Cagayan Valley in order
to open more land to homesteaders. They wanted control points
for the surveys, as well as instruction in the art of extending
geodetic survey work on their own account. These desires were
made the basis of an arrangement whereby the field expenses
were undertaken by the Philippine Government. Six Filipino surveyors
were assigned as students and potential observers. The final
outcome of this arrangement was highly satisfactory to all concerned;
the students nobly did their part and bore their full share
of discouragement, and, later, of triumphant accomplishment.
was known of the country, and nothing of the working conditions
to be met. The first part of the job consisted in finding out.
With a tentative first organization of our resources, the work
of studying the situation and beginning the reconnaissance for
the layout of figures was undertaken.
crossing of the Cordillera was the greatest difficulty. Progress
to the mountain peaks was necessarily over trails of our own
cutting, in a land where trail cutting is a fine art. Often
days were required to reach eminences from which the surrounding
terrain could be examined. The time and effort required for
even the most casual excursion made necessary a nice judgment
in deciding how to see most with the least travel. At last a
layout, geometrically excellent, was adopted, depending only
on a number of choice "if's": "If that ridge, by good
fortune, sags low enough to pass a line of sight from peak to
peak; if that peak is the same one we can see from over
the Isabela country; if we can get there at all with
our instruments." It is a tribute to the luck that persistently
followed us that all these "if's" came out "yes." Various questions
relating to the procurement of cargadores (carriers)
and the selection of routes were left for solution when the
peaks were to be occupied for the actual measurements.
Cagayan Valley presented an easier aspect in many ways. Here
the country is partly open, alternating between the low flood
plains and ranges of grassy hills, intersected in all directions
by deep ravines filled with almost impenetrable vegetation.
These, the foothills of the high mountains farther back on either
side, rise, one range above another, gradually giving way to
the forested slopes of the mighty eminences that rim the valley.
The problem was to make a proper balance against the desire,
the one hand to utilize the lower more accessible open summits,
and, as opposed to this easier country the necessity of placing
the stations far enough back from the river to provide width
and geometrical strength to the layout.
of the stations on this part of the work were selected without
visit, their locations, height and intervisibility being determined
through the use of an alt-azimuth instrument. Only in a few
cases was there grave doubt, and such cases resolved themselves
after visits to the proposed stations.
along the one highway which penetrated the northern part of
Luzon was accomplished by motor-car, this route being a sort
of main stem from which all travel radiated. Expeditions into
the hills were mainly afoot, although in a few places horses
could penetrate short distances. Natives always accompanied
the party as packers and guides. In some places along the river
it was found expedient to travel by launch; this form of transportation
was obtainable in Aparri.
the course of the work two airplane flights were made over the
Sierra Madre, through the courtesy of the Army Air Corps station
in Manila. Aside from making a study of this unknown region
searching for routes of access, and getting the lay of the land
- it was determined that many of the high peaks of the range
are visible alike from the river valley and from the surface
of the Pacific Ocean to the eastward. This assured us that such
peaks which would be located by the use of intersecting cuts
from the main stations in the valley, would be directly available
as control stations for the impending survey of the Pacific
area east of Luzon. One great step was thus made in solving
the difficult problem of how to get geodetic control on the
east and northeast coast of the island. A good tentative layout
for triangulation extensions to that forlorn stretch of coast
was also made available by these flights.
civil engineer, accustomed as he must be to all eventualities
on a job such as this, found a real thrill in the unwonted stopping
of his airplane motor, over wild country an hour's flight from
the nearest possible landing field. The detection of a frozen
fuel pump, and the substitution of an auxiliary hand affair,
were the work of but a few moments for the able pilot, yet there
was a quick vision of a parachute landing in the summits of
200-foot trees in trailless and precipitous jungle land far
from food and shelter, in country containing great pythons and
light and as fast as possible, the whole region was thus studied,
and a tentative plan evolved for the work. The advent of a rainy
season closed up all fieldwork for nearly six months. The country,
during such a time, is torn by cloudburst and gale, being in
the mean track of the feared East Indies hurricanes, or typhoons.
As an instance of the violence of such storms, the Cagayan River,
midway of its course sometimes rises 30 and even 40 feet within
the space of a night's time, flooding great areas of its valley.
Such a storm destroys practically all crops. The native planters
contemplate the loss of at least one of three years' efforts.
time was spent perfecting our organization and outfitting a
field party to undertake observing work. Six units took the
field the following dry season each in charge of a Filipino
assistant, and occupied the assigned stations. Camping there,
each of these parties operated heliotrope and electric signaling
apparatus for the benefit of the observing unit. Work started,
when all was in readiness, with the writer as observer.
frail-appearing but resolute Model-T truck began wending its
way up and down the muddy lane that threaded the Cagayan Valley,
carrying its regular overload of men and equipment. In many
a case the services of the plodding water-buffalo or carabao,
were required to move it from seemingly bottomless quagmires,
but somehow it always got there. It clung precariously to the
ribbon of trail that skirted cliff-like mountain sides steaming
mightily with the strain of it, and it forded rushing streams
hopping gaily from boulder to boulder. It disturbed the slumber
of torpid iguanas along the roadside, and sent many a band of
rollicking monkeys into wild flight.
the truck reached a town or outlying barrio that lay nearest
the station to be visited, there was always a band of gaping
natives to watch the unloading of instruments and camping gear,
and to offer the services of two-wheeled bull carts or, more
often, carabao sledges, under whose jolting mercies the trip
into the wilds would begin. The sledges could travel over unbelievably
rough country. Nothing but dense forest really stopped them.
At times it seemed to be preferable to pack the equipment on
the backs of the carabaos or the ridiculously small native horses.
The theodolites and other delicate instruments were always carried
on the backs of trusted Cargadores, and when animals could go
no further, everything was so handled.
twenty or more dialects were available in the mouth of the linguistic
surveyor-assistants. Whatever babel prevailed in a remote barrio
up under the brow of the mountain some one of them could always
address the head man, expressing our need for labor, which was
always forthcoming. The men assigned by the village ruler dropped
all personal matters for the prospect of earning 30 to 40 cents
a day apiece, and came, dressed in cotton undershirts, drawers,
and wide-brimmed woven hats, ready for their trip into the forest.
They welcomed this excuse to make a holiday, and anticipated
a return laden with rattan and other prized forest products.
There would always be certain strong ones, proud of the great
loads they could carry, who would jeer at the others, thus spurring
men subsisted principally upon rice, using a little dried or
fermented fish, or native fruits, as seasoning. When working
they ate without stint, and, for the longer trips, the packs
consisted more of rice than anything else. Indeed, it was frequently
the case that a man could carry little more than the rice he
would consume during his absence from home, making it necessary
to hire as many as thirty or forty carriers, with elaborate
plans for regular trains of supply to follow. At mealtime each
man filled, with rice and water, a section of bamboo, 4 or 5
inches in diameter, and 18 inches long. The contents of this,
boiled over a small fire, set him eager for two or three hours
of packing his load through hip-deep swamp mud, or up sixty-degree
mountain slopes. At night, a few strokes of the ever-present
bolo would provide the sticks and palm leaves which suddenly
and mysteriously would form themselves into quite adequate sleeping
men engaged far in the back country were usually expected to
act as guides, although their limited intelligence often made
it difficult for them to understand where we wanted to go. They
were most peaceable, Christianized Filipinos - illiterate farmers
who worked more or less diligently on their lands, and who made
excellent laborers when needed. In the surrounding mountain
lands lived a variety of pagan races. The negritos of the Sierra
Madre ... roam the forest in search of wild pig and deer, which
they shoot unerringly with bow and poisoned arrow. They wear
nothing but the gee string, or breech clout. Timid and diffident,
they were of little use to the party, except through their expert
knowledge of woodcraft. As guides or packers they were useless
extensive mountain lands west and south of the valley harbor
the various tribes of the so-called head hunters, robust and
picturesque savages, who have hardly risen above their ancient
traditions of warfare. They still believe the gods of the harvest
will be propitiated by offerings consisting of the severed heads
of enemy tribesmen. They are of various races and characteristics,
but are uniformly fond of bright color in their dress and personal
ornaments, and are all of proud and disdainful mien. They wear
the gee string, eat dog meat whenever possible, and hunt with
spear and head-axe. Centuries of rice culture on the steep mountain
slopes of their home land have seen the construction, by these
people, of thousands of miles of stone retaining walls, holding
in place almost endless levels of terraced rice paddies. This
system of terraces must be ranked with the foremost engineering
feats of the world. These pagans, forced by the local government,
have done extensive work in the building of graded trails through
certain of the more accessible areas of the mountains, yet they
persist, almost unanimously, in making their way direct toward
their objective, over thousands of feet of rise and fall, rather
than utilize the excellent trails laid out through their country.
show of authority they would submit to the indignity of acting
as cargadores. At this work the women, the habitual doers
of all manual labor excelled. They were far more useful than
the men who were accustomed to traveling light in their business
of warfare. They could often be made to transport 60-pound loads
up 7,000-foot mountains, all within a day, for which they received
of the assistants was trained as his station was occupied, in
the use of the instruments, with the object of making him an
observer. They were rapid learners, meticulous followers of
instructions, and developed into expert instrument men, but
they were slow to acquire ingenuity and resourcefulness in meeting
with daily obstacles. The chief of party as a consequence, found
it necessary at all times to exercise close supervision over
their work, and he traveled extensively to this end.
of the need of spending his time in this manner, and also because
of the limited opportunities afforded by adverse weather conditions,
it became desirable to turn over the actual observing to the
assistants as soon as possible, thus permitting simultaneous
observations at several stations. By far the larger part of
the entire volume of the observing work was performed by them.
between the various units had to be close. Only in this way
could things be coordinated, supplies and laborers be sent where
needed, and instructions be transmitted. The results of all
observations had to be in the hands of the chief of party before
orders could be given for the transfer of parties from station
to station. The various parties were in communication, during
favorable weather, by heliotroping. The instrument is difficult
to manipulate, as the reflecting mirror must continually be
adjusted for the changing direction of the sun while shading
and unshading the ray of light to form the elements of the telegraph
code. Under insistence, the observers became so expert at this
signaling that they found delight in exchanging bits of Spanish
poetry in leisure moments. The writer traveling from station
to station, or along the way on eminences from which some station
could be "called," kept in close touch with all operations.
weather, even during the so-called "dry" season, was extremely
uncertain. Frequent protracted spells of northeast monsoon brought,
in this region, fine mist which reduced visibility to almost
nothing. Perhaps 15 per cent of the time consisted of sunny
weather. Such times are those chosen, of course, by the farmers
for the burning over of coarse stands of grass on the hills.
This is done to promote the growth of tender new shoots for
the young carabaos. To the heavy natural haze was thus added
the smoke from countless grass fires. The observers waited,
during rain, for the fair days to follow, and when they arrived
they must perforce wait again for the occasional windy day to
clear the atmosphere. The writer waited nine days on one occasion
for observing weather, confined to a little clearing in the
jungle, large enough to contain two tents and a rustic tower.
This had been erected to elevate the instruments and signals
above the level of the surrounding trees. The forest was so
dense that the most expert native trail cutters could back out
in an hour no more than a kilometer of trail barely passable
to an agile man.
atmosphere and a larger proportion of fair weather were found
in the high mountains, but a new hazard, the worst encountered,
was met. The hot air of the tropics rolling up the mountainsides
into coolness of higher elevations, condensed into heavy cloud
mantles which seldom left the summits. Days of waiting would
finally find a few clear moments on a mountain peak, only to
be offset by the fact that other stations were obscured. At
least three stations must be clear to permit of an angle measurement,
and the most dogged kind of patience was worn nearly threadbare
before such an opportunity presented itself. Indeed, what must
be nearly a record of such frustration was experienced as four
observing parties waited, ever on the alert, at four stations
marking a quadrilateral of the network, during a period of almost
two months, in which time the only real work accomplished consisted
of just one completed angle measurement at a single station.
is hard to give adequate credit to the patience of the Filipino
assistants who waited during months, their campsites boggy morasses
of mud, while trees, tents, and equipment dripped forever with
the condensation of the clouds which surrounded them with bleak
curtains of obscurity. Patience only, of the most determined
kind, was the answer to this bugbear of obstinate elements.
of horizontal angles were made with Fennel direction theodolites
of about 7 ½-inch diameter circles, using eight positions
of the circle for direct and reversed telescope pointings. All
observed values of a direction were averaged, all values within
4 seconds of the average being retained. Vertical angles were
measured by two sets of double-zenith-distance observations,
from which could be computed the elevations of all stations
within a meter or so. In addition to the necessity of knowing
these elevations in reducing the triangulation position computations
to sea level, a valuable contribution was thus made to any future
topographic surveys of this land. The horizontal angle measurements,
when applied to the triangles of the network, gave triangle
closure errors averaging 2 seconds of arc, thus qualifying the
work under the standards set for second-order triangulation.
In addition to the observations of main-scheme angles, a host
of other objects were sighted upon, notably mountain peaks,
the buildings visible in the river towns, and supplementary
stations throughout the arable lands of the valley, where cadastral
surveys were contemplated.
were hard to see. At night, the powerful electric searchlights
could seldom be seen more than a few miles. Banners or flags
of any description could be seen only over short distances.
The main reliance was on the heliotropes, which would, under
exceptional circumstances, show as faint pin-pricks of light
at distances of 30 or 40 miles, often hovering apparently unsupported
in the haze that completely obscured the distant station hills.
In the highest of the mountains, on the few occasions when clouds
were absent, the atmosphere was far clearer, and large black
banners were sometimes observed upon at distances as great as
matter of food was a difficult one for the chief of party, although
there was no lack of rice to satisfy the palates of the Filipino
personnel. When the inevitable supply of canned goods became
unbearable, resource was necessarily had to the supremely hard
and tough chicken common to the locality, and to certain sorts
of native vegetables with strange names and even stranger flavors.
The only cooks obtainable for such expeditions were Llocano
boys, whose half-hearted efforts were harder to bear than the
work of preparing one's food. Water, except when the rain was
caught direct, had necessarily to be boiled because of the danger
of pollution by the tribesmen in the mountains. The boiling
undoubtedly killed germs, but it didn't remove the slime. Campsites
were generally in dense jungle, and living in them was a continual
fight against the attacks of gnats, leeches, and great mosquitos.
The opportunity to stop a time in the thatched houses of even
the poorest of Filipino farmers was, by comparison, a treat.
days on the trail were spent in plowing, hip deep, through swamp
mud, always with a weather eye out for the lurking semi-savage
water buffalo, or in climbing thousands of feet over the most
precipitous slopes ever seen by the writer, short of rocky cliffs,
through vegetation whose every fiber seemed designed to ensnare
the unwary traveler. This life induced a vigorous state of health
that undoubtedly did much to preserve one from the hovering
agencies of malaria and other scourges.
was made to a factor of luck in the working out of this project.
It did not fail, even at the very end, when there came the day
of reckoning - the day when the final closures were made, and
the ultimate criterion of excellence was applied to the work.
The base lines, measured out on the beaches at the two ends
of the work, agreed with each other in length, as computed through
the triangulation, with an error of only about one part in a
million. Almost no revision or reoccupation of the work had
been made necessary by abnormal triangle closures, nor had any
of the assumptions regarding intervisibilities or identities
of peaks, made during the days of the reconnaissance, been found
wanting. A veritable backbone for survey purposes in northern
Luzon had been erected, with, as offshoots, numbers of fixed
and located peaks in the mountain ranges at the sides of the
valley. Despite the fact that no banners or flags had been used
- that pointings upon these distant peaks had been made upon
whatever aspects had been given by their tree-clad summits --
the computations showed their probable error of position to
be only three or four meters.
valiant little Ford truck chugged wearily into Manila, one day
just two years after the start of the first work, its last gesture
in a great adventure.