The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1853-08-25

pcgrspher. with his plane table, determines graphi-
caiy. ~ ntersecttng lines, the position Of ell In
porsAns points and objects, sheet Of stretched
drawing paper. on which his triangulati IN psieAs
are du,y projected to scale OF l0,00Oth the nstsr
RAJ Scae- Around the points thus determined Tho
tepoenpher works IN, by the eye aud xuxiIisry =
strumebts the details OF the ground. aud runs kcri-
sostal contour CURVES. or the curves Of nterssetos
with theground surface, cut out by sores OF hot
a0ntal planes taken twenty feet apart.
at this point the photography begins. The souuS-
ing party Is furnished with large sheet Of paper O
which careful projection, or set OF parallels and ms-
rdians, IL drawn. and the several points Of tnangu-
!ation falling within the contemplated field OF sosRd
iDes are urAteiy plotted Plane table points, and
the plane table shore line also furnished in che
same manner, when practicable, 80 that the hydro
grapher starts on secure and labor saving founds~
tion. The requisite points are marked on the ground
by signals and the sounding boat or vessel Starts =
run on ranges sounding a. It goes. The ranges are
at once referred to the Signals both In direction ak
position. or sextant observations are made ut the ex
tremitos of each range, three or moro OF the sx
mails, which give the means Of plotting readily ta
ends Of the range In ofi-shore sounding. signal vea
sells sometimes requisite, their position being e
served from the shore, and the sOundings being 10
ferred first to the sgnal vessels. Still further out Ct
sea- the run Of the vessel combined with latituaes
and longitudes. gives the location OF s0undinSu-
Thus, all the s0undngs are correctly located and
plotted on the large photographic sheets, the scAle
OF l2O 600 being generally employed. Two sex
tan.s, OF the kind In common use, are exhibited 6
Oh
make. Contiguous sheets Of soundings, aocurstedY
determined, being plotted with reference to p0iats
whose positions relative TO EACH other are ful11
known, can be combined without difficulty, 10 70
0ucipg them TO the scales required for publication:
an advantage quite unattainable an extended
coast. by any other method Of surveying than such
systematic triapgulstion This gives unity and
correlation Of parts to the most extensive sur.
veys, as tue peculiaities OF the earhs oru are ID
taken into strict account in the computations suG
the distances being all derived from the standard
bases by accurate and constantly verifying methsds
there is no difficulty in combining tue whole schoua
of points for our entire coasts.
The extensive operations in sounding require 70
be systematically accompanied by observations q
the local tides and currents, as these are OF tho
highest Importance to seaiares, and their thorough
STUDY is essential to accuracy and safe navgatiOa.
At the fair is aef registering tide gauge OF the kind
now In use, which was made by Mr. Saxton. To
accomplished head OF the Instrument Department. 0f
the Coast Survey Office. clock work gives regular.
uniform motion to paper illet. one foot wide, and
the time is recorded by u series Of poiEts, which
prick through this paper rs il progresses. lost u
so connected with the recording pencil that in il
rise and fall with the tide the pencil traverees tho
width of The paper. These two motions-one proper
Tomato to the time and one to the rise or fall OF the
tide, give o resultant record curve on the 0Ilet,
IN which the tide movements are an
clearly seen, and easily measured by . scala.
Six OF these gauges have been sent h tbs
Pacific coast. under Lieut.. Trowbridge, United
States corps Of engineers, to record the tidal move
stations along our entire western sea mArgin-wheG0
the existence OF some quite peculiar tidal anomalies
gives particular importance to careful series Of -
liable records We may remark that Prof. BasAo
has analysed the tidal phenomena Of our coast, with
skill and success in all points equal, ami In soxo
superior, to the very best tide studies ever mads
elsewhere. The observation and study of SEQ ten
perature and currents, including the Gulf Stream.
have been steadily pursued, and with good success.
Numerous specimens of sea bottoms have beoa
brought up with the Steelwagen esd--preserveA u
small rhials, and examined under the microscope -
Prot. Bailey, of West Point, and others, who have
discovered numerous species OF shells and forms n
apimalcular lfe--each locality and depth having .
Characteristic combination of species. A StoelwaNea
lead and come Of the ocean bottom specmeas
brought up by ii, are exhibited at the Crystal Palace
Having now presented general and, as W
know, imperfect view of the organization, methods,
instruments and results of the field work of Tho
coast survey We will defer to future number whist
have to say about its Office organization operar
tons, processes and products This division into
field and office work is q natural one and will ensblo
us to give more detailed information on the MANN
featuring processes which mark the progress OF ms
various coast survey charts exhibited at the Crys
Palace. tnfsl1. III stus.lo y Is.
WASHINGTON NATIONAL MONUMENT.
CONTRIBUTIONS. FL 1851 affe
Contributions for this day. .,..,........ 81 -