civilized world for its thoroughness and accuracy, and has not been
excelled by the most advanced nations. It has justly been claimed to be
a scientific work, as well as a practical one, for science has guided
those who have conducted it and led them through the fields of their
labors on the only sure basis to produce knowledge. And the great
knowledge that has been acquired by its scientific prosecution, is
beyond comparison with the little that would have resulted had it been
conducted on the less thorough methods of Nautical Surveying that have
been so earnestly advocated. We cannot compute the value of what has
been learned in dollars and cents; that it has saved to the Nation many
times over, all that it has cost, does not admit of a doubt. Its
educational influence has been widespread, extending beyond the seas,
and coming back to us with cheering words of encouragement and praise.
Practical men utilizing the results of the great work in the business
affairs of life, use no stinted phrases in the encomiums they bestow
upon it; Military men compelled to rely upon it in the perils of
warfare, have not found it wanting, and have given only praise for the
great help it was to them; Scientific men, ever watchful of that which
is true, have approved it the world over, and cite it as an example of
the great profit that may come to a people, free to utilize Science in
the conduct of practical work. Our institutions of learning have
adopted its publications in text-books. Our merchants venture millions
of dollars daily on the veracity of its statements, and our mariners
risk their lives on the truthfulness of the Surveys. It has added to
the prosperity of the nation in peace--to her glory in war; and when
history shall record its awards to our people, there will be no page of
the galaxy with more honor than that which bears tribute to the genius
of American Science, in the work of the Coast Survey. From ignorance
most profound we have been raised to knowledge almost perfect; and well
may the commercial communities by their associations and exchanges bear
the testimony to its value that they do, and have done in times past;
as might the whole people for the wise legislation that established the
work, that has defended it, and we may hope will perpetuate it for its
inestimable benefits to them all.
THE SURVEY AND MAP OF MASSACHUSETTS.
BY HENRY GANNETT.
The Geological Survey is engaged in making a map of the United States.
This work was commenced as an adjunct to the geological work, and was
rendered necessary by the fact that, except in limited areas, no maps
of the country on any but the smallest scales were in existence. While
these maps are thus primarily made to aid in the geologic work and in
the delineation of geologic results, they are being made of such a
character as to meet all requirements which topographic maps on their
scales should subserve.
The work is being carried on in various parts of the country and is
being prosecuted on a considerable scale, the annual output being
between 50,000 and 60,000 sq. miles of surveyed area. Commenced in
1882, the work has been extended over more than 300,000 sq. miles at
the present time. Of this work the survey of Massachusetts forms a
part.
In some of its features this survey was an experiment. It was the joint
work of the State and the United States, and, so far as I know, was the
first example of such joint work. In the summer of 1883 the U. S.
Geological Survey commenced topographic work within the State, the
scale adopted being very nearly 2 miles to an inch. Only a beginning
was made during the season, and in the following winter the Governor of
the State recommended to the legislature that if practicable advantage
be taken of the opportunity, and an arrangement for coöperation be made
between the State and the Geological Survey, by which a map upon a
larger scale and with a greater degree of detail might be obtained as a
result of this survey. Accordingly, after some correspondence with the
Director of the U. S. Geological Survey, the legislature authorized the
appointment of a commission, with power to make an arrangement with the
Director of the Geological Survey looking toward the result above
indicated, and appropriated $40,000, being half the estimated cost of
the survey upon the larger scale, $10,000 of which was to be available
the first year and $15,000 in each of the two subsequent years. The
following is the text of the bill, which is in many respects a model
legislative document:
COMMONWEALTH OF MASSACHUSETTS.
_Resolve_ to Provide for a Topographical Survey and Map of the
Commonwealth. (Chapter 72, 1884.)
_Resolved_, That the governor, with the advice and consent of the
council, be and is hereby authorized to appoint a Commission to consist
of three citizens of the Commonwealth, qualified by education and
experience in topographical science, to confer with the director or
representative of the United States Geological Survey, and to accept
its coöperation with this Commonwealth in the preparation and
completion of a contour topographical survey and map of this
Commonwealth hereby authorized to be made. Said Commission shall serve
without pay, but all their necessary expenses shall be approved by the
governor and council, and paid out of the treasury. This Commission
shall have power to arrange with the Director or representative of the
United States Geological Survey concerning this survey and map, its
scale, method, execution, form and all details of the work in behalf of
the Commonwealth, and may accept or reject the plans of the work
presented by the United States Geological Survey. Said Commission may
expend in the prosecution of this work a sum equal to that which shall
be expended therein by the United States Geological Survey, but not
exceeding ten thousand dollars, during the year ending on the first day
of June, eighteen hundred and eighty-five, and not to exceed the sum of
fifteen thousand dollars in any one year thereafter, and the total cost
to the Commonwealth of the survey shall not exceed forty thousand
dollars.
In pursuance of this resolution Gov. Robinson appointed the following
gentlemen as commissioners on the part of the State: Gen. Francis A.
Walker, President of the Massachusetts Institute of Technology, Mr.
Henry L. Whiting, Assistant U. S. Coast and Geodetic Survey and Prof.
N. S. Shaler of Harvard College. The Director of the Geological Survey,
upon being notified of this action, laid before the commissioners a
proposition for a joint survey in the following terms:
1. It is proposed to make a topographic map of the State of
Massachusetts, the expense of which shall be borne conjointly by the
Geological Survey and the State of Massachusetts.
2. The Borden triangulation and the Coast and Geodetic Survey
triangulation will be utilized as far as possible, and additional
triangulation will be made to such extent as may be necessary.
3. The topographic work of the Coast and Geodetic Survey will be
utilized as far as it extends.
4. The survey will be executed in a manner sufficiently elaborate to
construct a topographic map on a scale of 1:62,500.
5. The topographic reliefs will be represented by contour lines with
vertical intervals varying from ten to fifty feet, as such intervals
are adapted to local topography.
6. As sheets are completed from time to time copies of the same will be
transmitted to the commission.
7. When the work is completed and engraved for the Geological Survey,
the Commission, or other State authorities, may have, at the expense of
the State, transfers from the copper plates, thus saving the State the
cost of final engraving.
8. The survey will be prosecuted at the expense of the Geological
Survey for the months of July, August and September. During the last
half of the month of September the Commission shall examine the work
executed up to that time, and if the results, methods and rates of
expenditure are satisfactory to the Commission, the expenses of the
work for the month of October shall be borne by the State of
Massachusetts, for the month of November by the Geological Survey, and
the work thereafter shall continue to be paid alternately by months, by
the Geological Survey, and the State of Massachusetts severally. But as
the larger expense incident to the beginning of the work is imposed on
the Geological Survey, at the close of the work the State of
Massachusetts shall pay such additional amount as may be necessary to
equalize the expenditures; provided that the total expenditure of the
State of Massachusetts shall not exceed forty thousand dollars
($40,000); and if the completion of the survey of the State of
Massachusetts and the preparation of the necessary maps on the plan
adopted by the survey shall exceed in amount eighty thousand dollars
($80,000), then such excess shall be wholly paid by the Geological
Survey.
The commissioners suggested some minor amendments to this proposition,
which were accepted, and under these provisions work was commenced and
carried forward continuously to its completion. The field work of the
state was finished with the close of the season last fall, and the
drawing of the maps is now substantially done. The work was done in the
field with such accuracy and such degree of detail as to warrant the
publication of the map upon a scale of one inch to a mile, or, what is
practically the same thing, 1:62,500. The relief of the surface is
represented by the contour lines, or lines of equal elevation above
sea, traced at vertical intervals of 20 feet. These contour lines,
which are becoming a common feature of modern maps, add an additional
element. They express quantitatively the third dimension of the
country, viz: the elevation. An inspection of such a map not only shows
the horizontal location of points, but their vertical location as well.
It gives the elevations of all parts of the country represented, above
the sea.
The map represents all streams of magnitude sufficient to find place on
the scale, and all bodies of water, as lakes, swamps, marshes, etc. In
the matter of culture, in which definition is included all the works of
man, it seemed desirable to represent only such as are of a relatively
permanent nature, and to exclude temporary works, for the very apparent
reason that if temporary works were included, the map would be not only
a constant subject for revision, but even in the interval between the
survey and the publication, the culture might change to a large extent,
and the published map be correspondingly incorrect from the outset. In
searching for a criterion which could be consistently followed in
distinguishing between culture which should and should not be
represented, it was found that by limiting the representation to that
which may be denominated public culture, that is, that which has
relation to communities, as distinguished from individuals, a
consistent line could be drawn. Adopting this criterion, the map
contains all towns, cities, villages, post offices,--in short, all
settlements of any magnitude, all railroads and all roads, with the
exception of such as are merely private ways, all public canals,
tunnels, bridges, ferries and dams. There were excluded under this
ruling isolated houses, private roads, fences and the various kinds of
crops, etc. Forest areas are shown. Subsequently, however, in response
to the urgent wish of the commissioners, the survey consented to locate
the houses upon the maps, although in the engraving these have been
omitted. The omission of all private culture leaves the maps very
simple and easy to interpret. For convenience the field work was done
upon a larger scale than that upon which the maps were to be published,
viz: a scale of 1:30,000, or a little more than double the publication
scale. The map of the state as planned is comprised in 52 atlas sheets,
each of which comprises 15 minutes of latitude by 15 minutes of
longitude and an area of about 225 square miles. These sheets upon the
scale of publication are about 17½ inches by 13 in dimensions. In two
or three cases along the coast it seemed to be in the interest of
economy to vary from this arrangement slightly, in order to avoid the
multiplication of sheets. Many of the sheets upon the borders of the
state project over into other states, and, in cases where the area
lying without the state was small, the survey was extended beyond the
limits of the state, in order to complete the sheets.
Every map is a sketch, which is corrected by the geometric location of
a greater or less number of points. Assuming entire accuracy in the
location of the points, that is, assuming that the errors of location
of the points are not perceptible upon the map, the measure of accuracy
of the map consists in the number of these geometric locations per unit
of surface, per square inch, if you will, of the map. The greater the
number of these locations the greater the accuracy of the map, but
however numerous they may be the map itself is a sketch, the points
located being simply mathematical points. Whatever method be employed
for making these geometric locations, the sketching is substantially
the same everywhere. The methods of making these locations must differ
with the character of the country, as regards the amount and form of
its relief, the prevalence of forests and other circumstances. There
are two general methods of making the geometric locations used in
surveying; one, by triangulation; the other by the measurement of a
single direction and a distance, which is the method employed in
traverse surveying. In practice, the two methods are often combined
with one another. Both methods have been employed in Massachusetts. The
fundamental basis of the work was the triangulation which had been
carried over the state by the U. S. Coast and Geodetic Survey. By this
survey points were located at wide intervals over the state. Besides
this there was executed between 1830 and 1840, at the expense of the
state, a triangulation known as the "Borden Survey." This located a
much larger number of points, but less precisely. The Coast and
Geodetic Survey kindly undertook the adjustment of this triangulation
to an agreement with its own work, and, as many of the lines were
common to the two pieces of work, the locations made by the Borden
Survey were by this adjustment greatly strengthened. Even after this
work was done, however, there remained considerable areas which were
destitute of located points, and it became necessary to supplement it.
This was done in part by the Coast and Geodetic Survey and in part by
the Geological Survey. By these several agencies upwards of 500 points
were made available for the use of the topographers. These are in the
main well distributed, furnishing upon each sheet a sufficiency, while
upon many the number is greatly in excess of the requirements.
The work of location has been done in different parts of the state by
different methods as seemed most applicable to the differing conditions
of relief, forest covering and culture. Throughout most of the western
part of the state the work was done entirely with the plane table,
using the method of intersections as the means of location. Each plane
table sheet comprised one-half of an atlas sheet, cut along a parallel
of latitude. The plane tabler, starting with three or more locations
upon his sheet, furnished by the triangulation, expanded over the sheet
a graphic triangulation, locating thereby a considerable number of
points, before commencing detailed work. This was done as rapidly as
possible consistent with a high degree of precision. The reason for
covering the sheet with the graphic triangulation beforehand lay in the
necessity for locating a considerable number of points before the sheet
had opportunity to become distorted by alternations of moisture and
drying. This done, the plane tabler went on with his usual routine of
work, locating minor points and sketching the topography in contours.
The map was as far as possible completed upon the stations, with the
country in view. Elevations were determined as the work progressed,
with the vertical circle of the alidade, and minor differences of
elevation between points whose height was known were measured by
aneroid barometer.
In this work several different forms of plane table have been employed.
It was commenced with the large heavy movement designed I believe by
the Coast and Geodetic Survey. This, however, was found unnecessarily
heavy and cumbersome, and it was discovered that the requisite degree
of stability could be obtained with much less weight. For this plane
table movement there was soon substituted another form in use in the
Coast and Geodetic Survey, which is very much lighter. This was soon
improved by taking off the slow motion in azimuth, which was found to
be unnecessary, and the addition of more powerful clamps, for the
purposing of rendering it more stable. A still more stable form,
however, coupled with even less weight, was designed by Mr. W. D.
Johnson, of the U. S. G. S. and was immediately adopted. This is
substantially a modification of the ball and socket movement. It
consists of two cups of large size fitting closely to one another and
working within one another in such a way as to allow of the adjustment
in level, and the clamping of the level adjustment independently of the
azimuth movement, clamps for both level and azimuth adjustments being
underneath the instrument. This form is extremely stable, admits of
quick adjustment and leveling, and it has been from the time of its
invention in general use in this state and elsewhere in the Survey.
In the undulating, forest-covered, region in the southeastern part of
the state it was found impracticable to use economically the method of
intersections, and resort was had to the traverse method for making
locations. In this method, as is well known, one station is located
from another by the measurement of a distance and direction, the line
of stations being connected at each end either upon stations in the
triangulation or upon other lines, while from the stations in these
traverse lines, points off the lines are located by intersections, if
practicable, or by distance and direction measurement. For this kind of
work the plane table, at least such a plane table as is generally in
use is an inconvenient instrument. The plane table with the telescopic
alidade is too cumbersome an instrument to be carried about and set up
as frequently as is necessary in this work. Therefore for this purpose
theodolites, fitted with stadia wires and stadia rods, have been used.
Distances are measured by the angles subtended by the stadia wires upon
the rod, whose divisions are of known length, while the directions are
measured by the compass attached to the theodolite, and differences of
elevation by spirit level and vertical angles. With this instrument
lines were run along all the roads and along the principal streams in
this part of the state and from these lines the country lying between
them was located and sketched.
In the northeastern and in much of the middle portion of the state a
mixed method of work was employed, the plane table being used for
carrying on the intersection work wherever it could be done, while by
traversing the roads, their details, which could not be obtained by the
plane table in this region, were reached. These traverses were platted
in the office and the maps drawn from notes and sketches made in the
field.
The degree of accuracy of the map depends upon the accuracy of the
locations, their number and the uniformity of their distribution. Of
their accuracy it is only necessary to state that their errors are not
sufficiently large to be appreciable upon the scale of the map, for
instance the scale being one inch to a mile, an error of 50 feet in the
location of a point would be upon the map but one hundredth of an
inch,--a barely appreciable quantity, and it is of course easy to make
the locations within this limit. Of the number of locations per unit of
map surface I shall give statistics drawn from the full experience of
the Survey in this state. The area surveyed by the method of
intersections exclusively comprises 3,500 square miles, or about
two-fifths of the state. In this area 3,123 stations were occupied with
the plane table, or slightly less than one to a square mile, or,
measured upon the map, one to a square inch. Besides these, 17,846
points were located in this area by intersections, making, with the
occupied stations, a total of 20,969 locations within the area, or 6.2
horizontal locations per square inch. In the same area the heights of
34,893 points were measured, being 10 per square inch. I am expressing
these figures in terms of inches of the final map, because it is the
map with which we are concerned.
The area surveyed by the traverse method is 2500 sq. miles. In this
area 5615 miles of traverse lines were run, being 2.2 linear inches per
square inch of the map. In running these lines 46,524 stations were
made with the theodolite, being 8.3 per linear mile of traverse and
18.6 per sq. inch of map. The number of measurements of height was
92,561, being 37 to the square inch.
The area surveyed by the mixed method comprised 3000 sq. miles. In this
900 stations were made with the plane table, and from them 3718 points
were located by intersection, making altogether 4618 points located
with the plane table. In addition to this, 6767 miles of traverse were
run, being 2.2 linear miles per square mile of area. In these traverses
31,708 instrumental stations were made, or 4.7 per linear mile and 10.6
per sq. mile. The sum of the plane table stations, locations, and the
traverse stations, which makes up the total of horizontal locations in
this area, is 36,326, being a total of 12.1 points per sq. inch of map.
The number of measurements of height in this area is 67,119, being 22.4
per sq. inch. It will be seen that the number of horizontal locations
and of height measurements in the area traversed is much greater than
in that surveyed by the intersection method, and it might be inferred
that the former work is better controlled than the latter. I do not
judge, however, that this is the case, owing to the fact that traverse
stations are not of as much value for purposes of location as those by
intersection. The latter are selected points. The former are not
selected points, but on the contrary, a large proportion of them are
located simply for carrying forward the line and are of no further
service, and very few of them are such as would be fitted for the
purpose of controlling areas.
Within the area surveyed by traverse nearly every mile of road has been
run. With the exception of those in the cities, nearly every house and
every church in the commonwealth has been located, either by
intersection with the plane table or by traverse.
The organization of the surveying parties has been of the simplest
character. Plane table work has been carried on by one man with an
assistant, the latter doing little more than attend the plane tabler
and assist him in carrying the instruments. Each of these little plane
table parties was furnished with a horse and buggy for transportation.
The organization for traverse work has been equally simple, consisting
of a traverse man and a rodman. As a horse and buggy would be an
impediment in this work, this feature of the outfit has been omitted.
In the mixed work the traverse men have been under the immediate
control of the plane tabler, so that their movements have been directed
by him in detail. The average output per working day of the plane
tabler has been for the whole survey 3.1 sq. miles, and of the traverse
man 2.8 sq. miles, and, as the expenses of the former have been
slightly greater than those of the latter, the cost per square mile of
the two methods of work has been substantially the same.
The average cost per square mile of the survey of the State has been a
trifle less than $13. This includes the salaries of all men engaged
upon the work during the field season, their traveling, subsistence and
all other expenses, the salaries of the men engaged in drawing the maps
in the office, the cost of supervision and of disbursement,--in short
all expenses of whatever character, incurred in the production of the
map.
PROCEEDINGS OF THE NATIONAL GEOGRAPHIC SOCIETY.
ABSTRACT OF MINUTES.
_First Regular Meeting, Feb. 17, 1888_.--Held in the Law Lecture room
of Columbian University, the president, Mr. Hubbard, in the chair.
The president delivered an inaugural address.
Major J. W. Powell lectured on the Physiography of the United States.