Coast and Geodetic Survey (Retired)
12934 Desert Glen Drive
Sun City West, AZ 85375-4825
Tables to Mechanical Calculators
the beginning of the American geodetic experience, no mechanical
calculators were available and the computations were made using
a variety of tables including logarithms, augmented by the individual
computer's arithmetic abilities. Despite of what today would
be considered the most extreme of primitive computational means,
the work got done.
method of least squares was introduced in 1847 or 1848 and as
early as 1868, adjustments were carried out involving closures
in length, azimuth, latitude and longitude, a formidable task
even in later years.
estimates determined directly from least-squares adjustments
were not routinely computed until the mid 1960's because of
the additional effort involved and other approaches were taken
to come up with acceptable substitutes. Charles A. Schott in
the Superintendents's Report for 1865, p. 192, explains the
problem and the rationale for its solution as follows: The strict
application of the method of least-squares in connection with
the computation of probable errors of the adjusted parts of
a triangulation becomes, in our case, impractical from its laborious
nature, and a shorter method must be sought and followed, which,
while it is a sufficient approximation of the truth, yet furnishes
us with all desirable data to judge the accuracy of our results.
The approximations took several forms depending on the element
(length, azimuth or position) for which the accuracy estimate
was desired. Most evolved from the specific condition equation
for the element and all included the probable error of the angle
(or direction) derived from the adjustment. That for the length
eventually became the strength of figure formula, long used
to evaluate the strength of triangulation and in determining
the need for additional base lines.
Makes It Less Work
1878, Myrick H. Doolittle made a combination of improvements
to Gauss' method for solving normal equations that continued
in general use for more than 80 years. European geodetic circles
insisted on dubbing the method as Gauss-Doolittle and so it
remains today. However, in 1924 when F. R. Cholesky, a European
(France), modified Doolittle's procedure, this method is identified
as Cholesky or Cholesky-Rubin. T. Rubin, another European (Sweden),
apparently discovered the same approach as Cholesky, but two
and cumbersome mechanical calculators appeared later in the
19th century and despite their awkwardness reduced the task
of making multiplications and divisions, the major chore in
computations. Later improvements, including small electric motors
resulted in further reductions to the computational effort and
made feasible the simultaneous solution of several hundred normal
From the South - Why ?
1850 to the adoption of NAD83 in 1986, azimuths in geodetic
surveys were reckoned from the south, clockwise, rather than
from the more logical origin, north, used by land surveyors.
Walter D. Lambert in a short 1946 article and some notes compiled
in 1954 gave several explanations, any of which could suffice
as a good reason for the practice.
his 1954 notes he reports that in Hassler's 1817 work and after
1832, there was no uniformity, sometimes azimuths were reckoned
from the north and on other occasions from the south, and furthermore
in either direction, without any specific notation whether east
or west. The remainder of the notes conclude from various writings
of French geodesists of the 1800-40 period that they preferred
to measure azimuths from the south around to west and according
to him so did their American colleagues.
1946 article provides probably the best rationale for the practice.
Lambert noted that Charles A. Schott was a German trained geodesist
and while not a student of Karl Friedrich Gauss (1777-1855)
he was well aware that Gauss followed the general practice of
azimuths from the south, clockwise, in his Hanoverian triangulation.
And, further, that Schott joined the Computing Division shortly
before 1850, was highly regarded from the beginning and it was
very likely he was responsible for the bureau adopting the practice.
After 1986, azimuths are measured clockwise from north.
1879 the first national datum was established and identified
as the New England datum. Station PRINCIPIO in Maryland, about
midway between Maine and Georgia, the extent of the contiguous
triangulation was selected as the initial point with its position
and azimuth to TURKEY POINT determined from all available astronomic
data, i.e. 56 determinations of latitude, 7 of longitude and
72 for azimuth.
its position was transferred to station MEADES RANCH in Kansas
and the azimuth to WALDO by computation through the triangulation.
The Clarke spheroid of 1866 was selected as the computational
surface for the datum in 1880, replacing the Bessel spheroid
of 1841 used after 1843. Prior to 1843, there is some evidence
that the Walbeck 1819 spheroid was employed.
datum was renamed the U.S. Standard datum in 1901 and in 1913
the North American datum (NAD) as Canada and Mexico adopted
the system. In 1927 an adjustment of the first-order triangulation
of the U.S., Canada and Mexico began and was completed about
1931. The end result was the North American datum of 1927 (NAD27).
was not a simultaneous solution because it was simply economically
impractical to do so with the available computing equipment.
Nonetheless, it was the largest geodetic computation effort
to that time. More importantly, the resulting datum was the
first to be oriented by Laplace azimuths strategically spaced
throughout the triangulation. The azimuth to WALDO in the datum
definition was changed by about 5" due to the inclusion of a
Laplace azimuth at the nearby SALINA base line. Its inclusion
in the NAD27 definition was only for completeness purposes since
the datum is actually oriented by 175 Laplace azimuths held
fixed in the adjustment as noted previously.
1909, John F. Hayford using data only from the U.S. triangulation
determined new dimensions for the figure of the earth, appropriately
named the Hayford spheroid. The International Geodetic and Geophysical
Union adopted the parameters in 1924 as the basis for the International
Ellipsoid of Reference and it is presently used in several countries.
he had perfected the strength of figure formula used in deciding
where base lines are required in the triangulation. The original
concept was developed and used in the U.S. Lake Survey and later
improved by William H. Burger (C&GS). Hayford also was the
co-author with Thomas W. Wright, formerly of the Lake Survey,
of the widely used text Adjustment of Observations. He served
with the C&GS for 20 years and was Chief of the Computing
Division and Inspector of Geodetic Work for about 10 years.
National Accuracy Standards
1921 a committee decided that the C&GS nomenclature for
accuracies of geodetic surveys of Primary, Secondary and Tertiary
would henceforth be identified as Precise, Primary and Secondary.
Looking back over more than 70 years it appears now to have
been a political decision, probably some agency objecting to
the tertiary classification for their work. As usual with such
edicts, it created nothing but confusion.
in 1925, the Federal Board of Surveys and Maps adopted the now
familiar standards of Firstorder, Second-order and Third-order
accompanied by the also familiar 1:25,000, 1:10,000 and 1:5,000
length and position closures, that were reaffirmed in 1933 and
remained in place until 1957.
Replaces Triangulation 1917-1927
1900 the C&GS had observed about 5,150 miles of first-order
triangulation and the USLS about 1,650 miles. Between 1900 and
1925 about 13,000 miles of the same class triangulation was
measured in the western half of the country including the 1,460
mile 49th Parallel arc straddling the U.S.-Canada border from
the Lake of the Woods, MN and the Pacific Ocean observed jointly
with the Geodetic Survey of Canada (GSofC).
to the high cost of building wooden towers, little or no triangulation
was observed from 1900-27 in the eastern part of the country.
First-order traverse was substituted because routes could be
selected along railroads, with the measurements facilitated
by utilizing the rails to support the tapes throughout and then
projecting the distances to the stations offset from the tracks.
Between 1917 and 1927 some 3,300 miles of traverse were observed
in 13 states, all east of the 98th Meridian arc except for about
100 miles in South Dakota.
the development of the Bilby tower in 1926, survey methods for
the eastern half of the country reverted to triangulation and
between 1927 and 1931 about 9,000 miles of first-order work
was accomplished. Among the major pieces of work completed after
1900 were the 98th Meridian arc, 1,720 miles in length observed
1897-1907; 49th Parallel arc, mentioned previously, about 1,460
miles long measured in 1924 and the last of the great triangulations,
the Atlantic coast arc, perhaps 1,600 miles in length from Providence,
RI to Key West, FL completed in 1932.
the adjustment that created NAD27, all the first-order triangulation
and about 100 miles of first-order traverse for a total of 15,050
miles were included in the western half computation. For the
eastern half adjustment only the triangulation west of the Eastern
Oblique arc amounting to 11,850 miles was used including USLS
(1,650 miles) and GSofC (630miles) work, but none of the first-order
traverses. Other omissions were: International Boundary Commission
(IBC)-GSofC triangulation observed before 1920 from Lake Superior
westward to Namakan Lake (about 200 miles) because the connection
to the 98th Meridian arc was a first-order traverse measured
on the frozen Rainy River in Minnesota and a 200 mile section
of the Mississippi River arc from St. Louis northward completed
in 1931, possibly because the records were not yet received.
The work to the east of the Eastern Oblique arc, including the
entire Atlantic coast arc and other triangulation in parts of
Virginia, North and South Carolina, Georgia and Florida was
left out because traverses were involved.
1950 it was evident that NAD27 had many problems caused by large
loops in the west and an insufficient number of base lines and
Laplace azimuths. Estimates made then suggested that half again
as much of the 26,900 miles of triangulation included in the
computation and twice as many base lines (112 included) and
Laplace azimuths (175 included) would be needed.
1940, this amount of new work was largely available, made possible
by civil works' funds allotted to aid the unemployed, but no
one in 1927 foresaw this happening. Hindsight, of course is
always better than foresight.
surveys, the in-field planning and selection of locations for
triangulation stations were always part of geodetic operations
in the U.S. However, it didn't become a separate and distinct
function until the 1880's when multiple observing parties began
to come on the scene. Up to then, there was only an occasional
need to plan more than a few figures ahead and this could easily
be done by the units as work progressed.
strength of triangulation depends solely on well-shaped triangles
and sufficient redundant observations to verify the acceptability
of the angle measurements. The latter was the basis for adopting
the specification, during Bache's time, that all triangulation
was to consist of braced-quadrilaterals and/or central point
High is Enough ?
these basic criteria often required towers for intervisibility
and deciding on their heights was a problem within itself. Prior
to Bilby towers, the cost and time needed to erect wooden signals
was a major factor for making an additional effort to assure
that a minimum height would suffice. Profiling lines by various
means, including the determination of elevations from vertical
angles and estimated distances, and by barometric observations
were common solutions to the problem at all times. The effect
of the earth's curvature and refraction often had to be worked
into the equation, as well. For examples: On a 10 mile line,
absolute flat terrain, 15 ft. towers at each end, or 58 ft.
at one end, would be required for minimum clearance; and for
a 20 mile line, same situation, 58 ft. at each end, or 230 ft.
at one end.
were two schools of thought, however, on how extensive the profiling
effort should take. One side contended that regardless of the
effort, blocked lines would happen, and the usual solutions,
raising the heights of towers or adding another station would
be less costly overall. Others thought otherwise. And many who
traveled some distance to reach the station site, only to find
a line not visible, would agree with the latter.
base line sites and planning the base expansion net to the triangulation
was another responsibility. Depending on the length of the base
that could be accommodated by the location, the connecting figure
had to be very carefully chosen, so as to minimize the number
of observed angles involved in the expansion of the distance,
and that they would be the strongest possible. Prior to the
availability of EDMI, the ratio of triangulation lines and bases
was about 3:1 on the average, albeit some approached 10:1.
unlike triangulation and trilateration, has no strength of figure
per se, and the general instructions were to select points about
equally spaced and in a straight a line as possible. More frequent
astronomic azimuths and positions, than required for triangulation,
were observed to help control sway in the survey.
addition to selecting the station sites, lines to be observed
and height of towers required, the reconnaissance engineer was
responsible for preparing a sketch showing that information,
ties to established control and marks of other agencies, and
topographic features such as landmarks that might serve as intersection
stations. Also, prepare descriptions on how to reach the proposed
station sites, recovery notes for old stations,indicate types
of marks to be set at each station, setup contacts with public
officials and property owners and specify any arrangements made
with the owners in regard to crop damage, etc.
Makeup and Can Do Spirit
parties generally consisted of a Chief of Party (Assistant prior
to about 1910), one or two assistants, and the necessary vehicles
and equipment, usually an absolute minimum. As a case in point.
In 1911, Jasper Bilby and one assistant ran the reconnaissance
for the 104th Meridian arc from Colorado Springs, CO, to the
Canadian border, about 720 miles, in a little over 3 months,
selecting sites for 74 primary stations, 23 supplementals and
2 base lines. His equipment was 3 mules, 1 wagon, 1 riding saddle,
necessary tools for repairing the outfit, 1 tent, cots and bedding
for 2 persons, and a few cooking utensils. He also had a 4-inch
surveyor's transit, a prismatic azimuth compass, a field telescope,
binoculars, a set of drawing instruments and all available maps.
later years, trucks were substituted for the mules and wagon,
and living conditions were different and usually better, but
all else, including the work itself, remained substantially
the same. GPS changed all this and reconnaissance surveys are
considerably simpler today, no intervisibilities required for
example, yet geometry and other factors are no less important
formal reconnaissance was usually made in leveling. Bench mark
setters selected the locations and set the marks, at intervals
as called for by the project instructions, sometime prior to
(C&GS) following names, for events after 1920, indicates
they were commission corps officers at the time.
- Hawaii - Philippines
1940 first-order triangulation on NAD27 had been extended to
Skagway in southeast Alaska and earlier in the century first-order
surveys from Shelikof Strait to Cook Inlet to Anchorage and
on to Fairbanks were completed on an independent datum. Lower-order
surveys computed on several independent datums covered much
of the coastal areas including the Aleutians. In 1943 Skagway
and Fairbanks were connected by first-order triangulation bringing
NAD27 to the main land mass, albeit it would be more than a
decade before all of Alaska was on a single datum.
1900-40 geodetic surveys, mostly second-order triangulation,
were established in the Philippines, Hawaiian Islands, Puerto
Rico-Virgin Islands and the Panama Canal Zone with positions
based on datums specifically developed for each region. Surveys
of the islands west of Hawaiian chain, including Midway were
based on local astronomic datums. Surveys on Midway Island were
completed late in November, 1941 and personnel were en route
by C&GS ship to Pearl Harbor on December 7, 1941. Their
arrival was delayed due to running zigzag courses under radio
silence causing a fear for several days that they had been lost
in the first actions of the war.
of the work in Puerto Rico and the Hawaiian Islands was upgraded
in the 1960-80 period. During the same time frame, new surveys
were carried out on Guam, American Samoa and for the Defense
Department, on Kwajalein in the Marshalls.
Philippines presented a unique situation because of the agreement
that 50 years after the war ended in 1898, the islands were
to become an independent nation. The role of the C&GS was
therefore an advisory one to the Insular Government and to this
end about 1906 a processing office, including computations and
map making functions was set up in Manila. All the geodetic
records were held there and only the lists of adjusted geographic
positions were furnished the Washington office.
of the geodetic work, primarily second-order triangulation,
as noted earlier, including the connection to the British surveys
on Borneo, was completed when the war began in 1941. An extremely
difficult task to accomplish because of the tropical jungle,
mountainous terrain and occasionally hostile natives.
processing office was taken over by the Japanese early in 1942
and destroyed in 1944 during the retaking of the islands, with
a loss of most of the geodetic records. George D. Cowie (C&GS),
in charge of the office was killed in the bombing of the city
on Christmas Eve, 1941, and several C&GS employees and a
few families were imprisoned by the Japanese for the duration.
One prisoner, Joseph W. Stirni (C&GS) was killed in 1945
when a ship taking him to Japan was torpedoed. Two others, Clarence
F. Maynard, a civilian mathematician and George E. Morris (C&GS)
were captured on Bataan, survived the Bataan Death March and
imprisonment in Korea. Maynard returned to the Philippines after
the war, remaining until all C&GS personnel were recalled
in 1950. On his return, he was Chief, NY Computing Office for
the 1906 San Francisco earthquake, a selected scheme of triangulation
from Monterey to Fort Ross involving primary, secondary and
tertiary stations and a detached net of tertiary points at Point
Arena were reobserved to determine the amount of crustal motion.
This was the first time in the U.S. that triangulation was reobserved
for this purpose. Displacements were computed for all points
in the disturbed area resulting from the 1906 event and where
possible for stations effected by an earthquake in 1868 also.
1922-24, the primary triangulation from Lake Tahoe to San Francisco
to Santa Barbara and eastward to southern California was reobserved
for the same purpose. Extensions were reobserved in 1924-25
northward to Point Arena, east to Carson Sink, NV and to western
Arizona as further verification of stability of the terminal
special point of interest arose from a discussion of the computations.
Arthur L. Day, Director of the Carnegie Institution's Geophysical
Laboratory wrote to Bowie and Walter F. Reynolds, Chief Section
of Triangulation, in 1931 supporting a suggestion made by a
reviewer of the results, Harry O. Wood in 1930 that circular
errors, representing the precision of the observations be determined
in the adjustment and shown on the sketches with the movement
vectors. The request has to be among the first anywhere for
such information. Both nicely sidestepped the issue knowing
full well determining such estimates was impractical at the
time, especially so because the C&GS used the method of
condition equations for their adjustments and that method was
the least amenable to providing such data. In fact no method
could readily do the job then. It wasn't until about 40 years
later that circular errors and error ellipses were routinely
crustal movement resurveys included the 1929 Newport Beach to
Riverside arc, CA following the Long Beach 1933 earthquake with
little movement indicated. Also, during the 1930's several lines
were releveled in San Francisco, San Jose, Los Angeles and vicinity,
San Diego area and the Imperial Valley, CA, with all showing
some displacements. One or two arcs and a number of level lines
in California and other parts of the country were observed specifically
for future crustal motion studies.
1922-23, the most accurate invar taped base line ever, with
a precision of 0.2ppm one sigma, was measured near Pasadena,
CA. The sole purpose for the 20.9 mile base line was to provide
Albert A. Michelson with the best possible distance between
points on Mount Wilson and San Antonio Peak used in his experiments
to determine the speed of light.
assure the least loss of accuracy in projecting the measured
distance to the line between the two points, the base was measured
parallel to that line and to its approximate length. Astronomic
positions were determined to correct the angles for the deflection
of the vertical. The work was carried out under the direction
of Clement L. Garner (C&GS), later to succeed William Bowie
as Chief, Geodesy Division.
and the C&GS were interested in Michelson's experiments
in the hope that means could be found to measure distances using
light. It was not to be. The experiments were not totally successful
and the Great Depression began, leaving Erik Bergstrand to develop
the equipment 25 years later, in Sweden.
1938 AMSTERDAM Avenue base line in New York City presented a
similar problem, but here the stations were atop high buildings.
It was necessary first to project the base vertically to temporary
points offset from the stations and then a lateral shift to
the station marks.
1903-08 a first-order triangulation network encompassing greater
New York City was observed; Cincinnati did the same on their
own in 1912-13 with Hugh C. Mitchell, on assignment from the
C&GS in charge and in the mid 1920's, combined first-order
triangulation and traverse systems were established for Rochester,
NY and Atlanta, GA. These were the forerunners of the numerous
State-wide, county and urban nets observed later in the century.
Prior to 1940, several cities developed networks on their own
or with private sector assistance. As a case in point, first-order
control surveys and associated topographic mapping for a number
of municipalities were accomplished by the R.H.Randall Co. of
Toledo, OH between 1920-34.
plane coordinate systems, most at ground level, were setup for
these early urban surveys. After the advent of the State coordinate
system,only the Cleveland Regional Geodetic Survey (CRGS) adopted
a tangent plane ground level grid.
- UTM and Oscar S. Adams
1933-34, Oscar S. Adams ably assisted by Charles N. Claire developed
the State Plane Coordinate System (SPCS) at the request of George
F. Syme a North Carolina Highway engineer. Syme died shortly
after the North Carolina system was developed being succeeded
by O.B. Bestor to carry on the cause. Bestor was in charge of
the State local control project established in 1933, later identified
as the North Carolina Geodetic Survey. Most State and the few
county projects involved in this program also were so named.
Colonel C. H. Birdseye of the USGS, with a strong interest in
Statewide coordinate grids also participated in the several
conferences leading to the decision to honor Syme's request.
first tables for computing Lambert coordinates were developed
for North Carolina and the first tables for the transverse Mercator
grid were for New Jersey. Tables were prepared for all States
early in 1934. For the first time all horizontal control stations
previously defined only by latitudes and longitudes would be
available in easy to use plane coordinates.
had many notable accomplishments prior to this work. For example,
he authored or co-authored 22 Special Publications and Serials
dealing mostly with map projections and adjustments. This group
includes Sp.Pub.no.28 Application of the Theory of Least Squares
to the Adjustment of Triangulation issued first in 1915 which
provides the mathematical basis for adjustments by condition
equations and observation equations on the ellipsoid and still
remains a viable part of the literature.
was actually the father of NAD27 since he gave Bowie's adjustment
proposal life and personally made many of the computations.
Later he was directly involved with the creation of the Universal
Transverse Mercator (UTM) system used by the U.S. Army worldwide,
although his association with the project is not well known.
Adams also collaborated with Bowie in 1918 in developing the
Military Grid System, the forerunner of UTM, dividing the country
into seven zones, 9 of longitude wide, with the polyconic projection
the basis for the grid.
1930's saw a huge increase in funds for public works as part
of the effort to get the country out of the Great Depression
and the C&GS field and office staffs were significantly
increased. At the height of the program more than 1,000 employees
were in the field and as many as 12 observing units, from a
single party were working some nights.
the first time ever a number of second-order arcs were observed
by geodetic parties, bringing grumbles from purists and rightfully
so, the savings in time and effort were very small. In addition
about 23 States and a few counties setup geodetic surveys, under
the overall supervision of the C&GS, with the intent to
establish second-order horizontal and vertical control at the
the earliest stages all States participated and more than 10,000
unemployed surveyors, engineers and technicians were given meaningful
jobs, albeit the pay was less than $20 a week. Most of the 23
geodetic surveys accomplished some work although only a few
made substantial contributions. Among those that did were: Alabama,
Florida, Georgia, Louisiana, Massachusetts, New Jersey, North
Carolina, Oklahoma, South Carolina and Tennessee; among the
counties: Monroe and Westchester in New York and the regional
geodetic survey in Cleveland, OH. Except for Massachusetts and
Westchester county, where first-order triangulation also was
observed, all surveys involved traverses.
the expenditure of the funds had the desired overall economic
effect is still being debated, however there is no doubt the
funds spent were highly beneficial to the geodetic control program
as many thousands of new stations and bench marks were established.
To wit, there were more than 100,000 points of all orders of
accuracy in the horizontal net by 1940.
Leveling, Datums, and Instruments
leveling has always played second fiddle to horizontal surveys.
Perhaps this is so because leveling is perceived as a simple
procedure, although it most certainly is not. Some form of leveling,
mostly trigonometric in nature was always observed in order
to provide elevations needed to reduce base lines and angle
observations to sea level. As a matter of fact, the observations
were often carried out as a separate event using specially constructed
vertical circle only instruments.
work on the Transcontinental arc progressed westward it was
recognized that vertical angle elevations would not be of sufficient
accuracy for the purpose. Accordingly a line of precise levels
following the route of the triangulation was begun in 1878 at
the Chesapeake Bay and reached San Francisco in 1907.
1898, an adjustment was made of the first 25 circuits and a
second in 1903 to include the large amount of new data observed
in the interim. Partial adjustments were carried out in 1907
and 1912 to include the ever increasing work. In 1929 a general
adjustment was made which included 45,000 miles of U.S. first-order
leveling and 20,000 miles of similar accuracy Canadian surveys,
with sea level planes at 26 tidal stations held fixed. The Canadians
had recently published the results of their observations and
didn't accept the combined adjustment values. Difference of
elevations at common bench marks didn't exceed 0.5 ft. The U.S.
data also includes precise leveling observed by the Corps of
Engineers, U.S. Geological Survey and other organizations.
1940, about 260,000 miles of first- and second-order leveling
had been observed. The elevation datum was known as the Sea
Level Datum of 1929 (SLD29) until 1973 when the name was changed
to the National Geodetic Vertical Datum of 1929 (NGVD29).
to 1899, geodetic leveling in the U.S. was observed using wye
levels and target rods. Long telescopes were common to such
instruments and critics claimed Americans bought their levels
by the yard. In 1899, the Fischer level designed by Ernst G.
Fischer of the instrument division, a dumpy type and speaking
rods replaced the earlier equipment and were used for almost
70 years with only slight modifications. Invar strips were added
to the rods in 1916.
Whitney - Precisely How High ?
of high mountains are rarely determined by spirit leveling,
most being the result of trigonometric methods, a k a zenith
distance/vertical angle elevations. As a matter of fact, the
highest mountains are seldom occupied for horizontal positioning
either for obvious reasons, clouds and weather conditions among
them. Despite these negative possibilities, in August 1925,
Lansing G. Simmons (C&GS) was sent to Lone Pine, CA to observe
first-order leveling from bench marks on the Owens Valley line
to the summit of Mount Whitney, the highest peak in the then
48 states. The purpose was for crustal motion studies where
future relevelings would give indications whether the mountain
was growing or not. Since it was late in the season, Simmons
decided to level from the summit down, but found the summit
trail from Whitney Portal, about 14 miles west of Lone Pine,
blocked by rock sides and learned furthermore that no horses
had been over the route in several years. He then decided to
horsepack the outfit to Army Pass at an elevation of 11,000
ft. about 10 miles south of Mount Whitney, from where the party
would backpack the equipment to a base camp at 14,000 ft., about
one mile south of the summit.
some of the 8 man party suffering from the altitude, that was
further compounded by living in pup tents, with the only water
from melting snow and the only fire from a gasoline stove, they
were able to complete the leveling from the summit, marked by
a USGS disk set in 1901, to a permanent bench mark near the
base camp in a week's time, a vertical distance of about 500
ft. Bad weather set in with snow, hail, cold and high winds
and there being little chance with September approaching for
better conditions, the camp was backpacked to Lone Pine Lake
near Whitney Portal at an elevation of about 8,400 ft. where
the leveling was picked up again for the 13-14 miles into Lone
years went by without the Forest Service or local people clearing
the trail to Mount Whitney so in June 1928, John H. Brittain
(C&GS) was ordered to Lone Pine to form a party, complete
the first-order leveling from Whitney Portal to the summit and
with authorization to open the trail. He made his first camp
at the 10,400 foot level, opened the trail to 11,500 ft. taking
only one day to do the job and completed the leveling to that
point. From a second base camp at 12,000 ft., leveling was run
to the summit marked by the USGS tablet described earlier by
Simmons. This was a remarkable piece of work. To carry the elevations
over a vertical distance of 6,126 ft. and extremely rough terrain
in 18 days of leveling required determination and esprit de
corps that would rarely be found today.
resurvey has been made to date. Simmons and Brittain went on
to long and distinguished careers in the C&GS. Simmons was
the Chief Geodesist for about 20 years, retiring in 1967 and
Brittain at the time of his retirement in 1961 was Chief, Geodesy
Division. Lansing G. Simmons died in 1986, at age 84.
experience here seems to have discouraged further attempts to
level to the summits of high peaks even when roads are available
such as to Pikes Peak and Mount Evans in Colorado, both over
14,000 ft. However, with increasing interest in replacing conventional
leveling with GPS observations, the tests presently underway
(1994) might consider including first-order leveling to these
and other readily accessible peaks as part of the examinations.
geodetic surveying in the U.S. entered the fifth decade of the
20th century, the first-order triangulation and leveling were
basically complete. Future priorities would be to fill in the
gaps, strengthen and update the networks and carry out new adjustments
of NAD and SLD (NGVD). All would come to pass and much more
in the next 50 years.
brief and informal history of U.S. geodetic surveys covers the
more significant happenings plus a few of the more interesting
incidents in the period 1807-1940. The decades to follow would
be a most dynamic and amazing era as the surveying world would
ever see with new instrumentation, methodology and computers
eventually dominating the scene.