A portable wind-direction recorder

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Material Information

Title:
A portable wind-direction recorder
Physical Description:
Mixed Material
Creator:
Fulton, Robert A
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine ( Washington, D.C )
Publication Date:

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030345403
oclc - 781634549
System ID:
AA00017456:00001


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ET-1 53 January 1 40

Uniited Slates Depiartment of Aqriculture
E.rcau of Entonijlcry and Plant Quarantine


A F)ORTABLE h'ITD-Dl,.L-,,Li 'IC RECORDER

FBy REbert A. Fulton, Division of Truck Crop
.a::3 Carren I1.cect Investigations




.. prtable win.&-i-retion r:-corder was found very useful
in the .'.-.'y of rsal of the beet leafhopper (Eutettix tenellus
(Ea':.)). Z..s -c..sitivw..:s of the instrument should make it capable
of rec.' I":..- at last eight points of the co,:pass. Most commercial
instr-..'..ts for this purpose were too e:,.-,nsive and cumbersome,
owi:.g to the .cmpli:a,'.-d recordii.g devices, which required constant
attention, J...,, i:., s,ce cases, the necessity of using batteries.
Furthermore, there was grcat likelihood of breakage in transport
over rough ,'eert country. One portable instrument has been de-
scr-bed. However, since 'that instrument, on account of the le.-gth
of the box contai>,ii.g the re-cor"ii.g cvice and the total length of
the ascomtled instrument, was not considered suitable for use in the
beet nafh-per investigations, it '.. decided to develop a record-
ing unit which could be mounted on poles in the desert and would
record wind directions accurately in high winds. The instrument
descrI'_ed herein has been amply te-ted by continuous service over a
9-year period in different sectio::s of the country.

The action of the mechanism t.pends upon an offset wind-vane
shaft rev:ol/1L.g directly above a circ.:flar chart, with the center of
rotation mii','ay between the center and the margin of the recording
chart. A cznmercial 8-i:.c. circular chart was used. The radius of
the circle described by the recordi,.c pencil was 2 inches. A circle
of this size was found satisfactory for accurate records, as it is
sufficiently large to reduce to a gi-at deree the blurring cau'ej1
by sudden changes in the direction of the wind. Prevailing winds
usually dXscribe an arc of at least 20 degrees, and, even with an
efficie.-.t stabilizer on the vane, surface obstructions of the ter-
rain cause changes which make it i..po-sible to obtain straight-line
recording. The srall arc de:ribed by the vane-operated recording
pencil is used to determine both time andI direction.

Two vicws of the apparatus c.-re shown in figures 1 and 2,
and a sectional drawing in figure 3. A record from one of the
established instruments is shown in figure 4.

/ C.:.vert., R. Meteo.-rolc.cal Instruments. Journal of t2
Optical Society of America 10(3): 330-532 1925,




-2-


In the construction of the instrument the wind-vane shaft
housing (fig. 3, D) was first made by the use of standard pipe
fittings, including a 1-inch floor flange, a 1-inch nipple 8 inches
long, and a reducing coupling 1 inch to 1/2 inch. Both ends of the
nipple were milled so that a 7/16-inch roller bearing (C) could be
fitted in the ends of the pipe. The wind-vane shaft (B) was made
from 1/2-inch shafting. The ends of the shaft were turned down so
that the shafting would form a tight fit in the roller bearings.
The upper end of the shaft was then milled to 3/8 inch and threaded
to provide a support for the wind vane (A) The bottom of the shaft
(F) was then grooved the width of the pencil arm and threaded to
hold a 1/8-inch machine screw. The pencil arm (G) was made from
an inexpensive compass by cutting the pointed arm about 1- inches
from the hinge. The hinge was made flexible by removing the tension
spring. The recording pencil could then move horizontally but was
held rigid in a vertical position. It is very important to install
this hinge, for without it irregularities in the chart surface
will not be marked by the pencil. The box containing- the clock and
the chart holder were next assembled.

The clock (I) was a regular 7-day movement used in circular-
chart recording instruments. The clock and chart support positions
within the box were found by locating the center of the wind-vane
shaft exactly midway on the radius of the circular chart. The
center of the circular chart was then aligned with the edge of the
box so that when the instrument was placed in the field the shaft
and the center of the chart would be aligned in a known direction.

The wind vane shown in figure 1 was designed to, record
slight deviations on very calm days. The wedge type (commonly used
on weather instruments) would probably be more suitable for general
observations, but in all cases the vane should be balanced to pre-
vent excessive wear on the bearings.

The recording, is translated by means of a flexible glass
guide (fig. 5, B) that has been marked to correspond to the 4-inch
circle that may be described by the pencil of the wind vane. The
circle is then divided into quadrants, N, E, S, and W representing
the four cardinal directions. The flexible glass guide is held in a
fixed position and the chart is rotated under the guide. The co-
incidence of the arc made by the pencil and the circle on the guide
indicates the direction and time of the recording.

For example, if the arc described by the recording pencil
is found to be on the periphery between N and E, a northeast wind
would be indicated. The time of the recording would be obtained at
A in figure 5. The above illustration would be a northeast wind
at 12 midnight Saturday.

In some localities it may be necessary to align the instrument
in an east-and-west direction. If the instrument described above
were used in a region of prevailing southerly winds, the recording
would be confined to a small portion of the chart.







-3-


The instrument was asonembled for approximately SO, in-
cluding the cost of parts and labor, but the clocks may now be
more expensive.

Explanation of Illustrations

Figure l.--General view of portable wind-direction recorder.

Figure 2.--Close-up view showing lower end of wind-vane shaft, pen-
cil arm, chart, chart support, and clock.

Figure 3.--Sectional drawings of portable wind-direction recorder.
A Wind vane.
B Wind-vane shaft.
C Roller bearings.
D Wind-vane shaft housing.
E Wind-vane shaft support.
F Lower end of wind-vane shaft.
G Pencil arm.
H Chart support.
I Clock.

Figure 4.--Chart showing record made by wind-direction recorder.

Figure 5.--Sample chirt and flexible glass guide, illustrating
method of obtaining wind direction and time of recording
from chart.
A Tin.e of recordirg.
A'- Position of center of arc described by recording
pencil.
B Flexible glass guide.


































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Digitized by the Internet Archive
in 2012 with funding from
University of Florida, George A. Smathers Libraries with support from LYRASIS and the Sloan Foundation






















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