Elevation indicator

An elevation indicator comprising a supporting base, a reservoir for holding liquid supported on the base, an elongated staff and a flexible tube extending from the staff to the reservoir. An elongated scale is mounted on the staff for longitudinal movement relative to the staff and a transparent tube is also mounted on the staff and extends along one side of the staff adjacent the scale. A check valve is located at the top of the transparent tube and the bottom of the transparent tube is connected to the flexible tube, so that liquid can flow between the reservoir and the transparent tube.

BACKGROUND OF THE INVENTION 
This invention relates generally to apparatus for measuring the elevations 
of land structures and the like, for the use of architects, builders, 
engineers, surveyors, construction workers, farmers and other persons 
whose jobs require an accurate elevaton-indicating instrument at a 
reasonable cost. 
The invention is particularly directed to an elevation indicator which 
makes use of liquid and comprises a reservoir for containing the liquid 
and supported at a base elevation, a staff provided with a scale and clear 
tube, extending along the scale, and a flexible tube extending from the 
reservoir to the clear tube on the staff. Liquid flows from the reservoir 
to the clear tube through the flexible tube, so that the water level in 
the clear tube is the same as the water level in the reservoir. The liquid 
level in the clear tube is defined by the meniscus. The top of the 
reservoir and the top of the clear tube are generally vented to prevent an 
air lock at either end of the system and to allow the meniscus in the 
clear tube to move freely relative to the clear tube as it maintains the 
same level as the level of liquid in the reservoir. 
One difficulty encountered with prior art devices is that elevation 
readings and settings are generally difficult to obtain because the 
devices only give a level point. In most cases, a measurement must then be 
subtracted or added in order to obtain an elevation measurement between 
two different points. However, in the case of levels in which the clear 
tube is moved relative to the staff, readings are difficult to obtain 
because of the bouncing of the meniscus as it is moved vertically. The 
device cannot be read accurately until the meniscus is allowed to settle 
down after movement. In at least one case where a scale was used on the 
staff, it was necessary to use a non-standard, calibrated scale. In 
addition, all of these solutions add greatly to the cost and complexity of 
the indicator. These and other difficulties experienced with the prior art 
elevation indicators have been obviated in a novel manner by the present 
invention. 
It is, therefore, an outstanding object of the invention to provide an 
elevation indicator which is reliable and easy to use. 
Another object of this invention is the provision of an elevation indicator 
in which the meniscus in the clear tube on the measuring staff moves 
freely, so that it reaches the level of the reservoir quickly and 
accurately without danger of loosing fluid from the system. 
A further object of the present invention is the provision of an elevation 
indicator, in which elevation readings can be taken directly from the 
scale on the measuring staff. 
It is another object of the instant invention to provide an elevation 
indicator, in which the measuring staff has an adjustable scale which is 
easy to use, and which maintains its accuracy over an extended period of 
use. 
A still further object of the invention is the provision of an elevation 
indicator capable of measuring a greatly increased range of elevation, 
without changing the location of the reservoir. 
It is a further object of the invention to provide an elevation indicator, 
having a support for the reservoir which also functions as a carrying case 
for various elements of the indicator. 
It is a still further object of the invention to provide an elevation 
indicator which is simple in construction, which is inexpensive to 
manufacture, and which is capable of a long life of useful service with a 
minimum of maintenance. 
With these and other objects in view, as will be apparent to those skilled 
in the art, the invention resides in the combination of parts set forth in 
the specification and covered by the claims appended hereto. 
SUMMARY OF THE INVENTION 
In general, the invention consists of an elevation indicator having a 
reservoir for holding a quantity of liquid and supported on a base, a 
measuring staff, and a flexible tube operatively connecting the reservoir 
to the measuring staff. The surface area of the reservoir has a specific, 
selected ratio to the area of the cross-section of the tube, the ratio 
being very large. The measuring staff is provided with a measuring scale 
mounted on the staff of longitudinal movement relative to the staff and 
with a transparent tube extending along one side of the staff adjacent the 
scale. A check valve is carried at the top of the transparent tube. The 
flexible tube is connected to a bottom opening of the reservoir and is 
connected to the transparent tube, so that liquid can flow between the 
reservoir and the transparent tube. The invention also consists of an 
elevation indicator which includes a measuring staff, having a scale which 
is mounted on the staff for a longitudinal movement relative to the staff 
along a flattened loop from a first end of the tape and the back side of 
the staff over the top of the staff, down the front side and under the 
bottom of the staff to a second end of the tape at the back side of the 
staff. The first and second ends of the tape are spaced and are connected 
by a tension spring. 
More specifically, the clear tube on the measuring staff and the flexible 
tube, extending between the reservoir and the measuring staff is a single 
continuous tube and there is a fixture at the top of the staff for 
supporting the end of this tube. The supporting means for the reservoir 
includes a downardly-extending post from the reservoir, a box having an 
upperly-extending post from the bottom wall, thereof, and an extension 
which is attachable to each of the posts for supporting the reservoir 
above the box. The box is also adapted for storing the reservoir, 
extension and flexible tube.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring first to FIGS. 1-4, which best show the general features of the 
invention, the elevation indicator, generally indicated by the reference 
numeral 10, includes a supporting base 12, a reservoir 13, and a measuring 
staff 18. The reservoir 13 includes a water-tight housing 14 mounted in a 
tray 17. The housing 14 contains a colored liquid 15 and has a bottom 
opening 16. 
The staff 18 is elongated, as shown in FIGS. 1 and 2, and has an H-shaped 
cross section, as viewed in FIG. 3, which defines a groove 20 along the 
front face 22 of the staff and a groove 24 along the back face 26 of the 
staff. The top and bottom of the staff is provided with upper and lower 
rollers 28 and 30, respectively, which are rotatably mounted in the staff. 
The rollers 28 and 30 form upper and lower grooves 32 and 34, 
respectively, which connect the front and back grooves 20 and 24, 
respectively. A flexible flat scale 36 is located in the grooves of the 
staff in a flattened loop which begins from a first end 38 of the tape in 
the rear groove 24 over the upper roller 28, down along the front side 22 
of the staff in the front groove 20, under the bottom roller 30 to a 
second end 40 of the tape in the rear groove 24. The second end 40 is 
spaced from the first end 38. A tension spring 42 extends from the first 
end 38 to the second end 40 to maintain the measuring tape 36 under 
tension on the rollers 28 and 30. The tape 36 can be moved longitudinally 
along the grooves of the staff by means of a finger tab 43 which projects 
forwardly from the face of the tape. 
A flexible transparent plastic tube 44 is mounted on the staff 18 in such a 
manner that it extends along the scale 36. The top of the tube 44 is 
connected to a checkvalve 48 by means of a plumbing fixture 49 supported 
on the staff 18 by means of a spring clamp 50. The tube 44 extends down to 
the bottom of the staff 18, to a guide 51 and is connected to a plumbing 
fixture 52. The plumbing fixture 52 is threaded onto a nipple 53 which 
extends from the opening 16, so that the liquid 15 in the reservoir can 
flow into the tube 44. In the preferred embodiment, the surface area of 
the liquid in the reservoir is in the ratio of 1200-to-1 to the area of 
the cross-section of the tube, this confirming the reading error to 
approximately 0.08%. The reservoir housing 14 has a top opening 54. A 
threaded nipple 55 extends from the top opening 54 and is closed by a 
filling cap 54. The bottom of the tray 17 is provided with a 
downwardly-extending post 60. The supporting base 12 is provided with a 
box-like structure having sidewalls 64 and a bottom wall 62 which supports 
an upwardly-extending post 66. Tubular extension elements 68 are 
engageable with the posts 60 and 66 and enable the reservoir 13 to be 
supported above the box-like structure of the supporting base 12. Each 
supporting element 68 has a reduced end 69 which fits into the opposite 
end of another supporting element or into the downwardly-extending post 
60, as shown in FIG. 1. Additional extension elements 68 are stored at the 
back of the box-like structure and held in place by means of a flexible 
strap 76. These additional extension elements 68 enable the height of the 
reservoir 13 to be increased relative to the supporting base. This 
increased the elevation range of the indicating device without the need 
for moving the supporting base, as will be explained more fully 
hereinbelow. The supporting base 12 also serves as a carrying case for 
most of the elements of the elevation indicator, as particularly shown in 
FIG. 5. Guide elements 72 are located on the inside surface of two of the 
opposite sidewalls 64 of the supporting base 12 for holding the tray 17 of 
the reservoir 13, as shown in FIG. 5. The supporting base 12 also includes 
a carrying handle 70 and a removable cover 78, which is attachable to the 
supporting base by means of latches 80. 
Referring particularly to FIG. 6, the check valve 48 includes a housing 82 
having a top opening 84 and a bottom opening 86 adapted to receive the 
plumbing fixture 49. A valve seat 88 is located between the top and bottom 
openings 84 and 86, respectively, and a ball 90 is located between the 
valve seat 88 and the bottom opening 86. A spring 92 maintains the ball in 
a centered position. The ball 90 has a very low density and is capable of 
floating in the liquid 15, so that as the space 91 between the ball valve 
88 and the bottom opening 86 fills with liquid, the ball 90 is carried 
upwardly by the liquid until it engages the seat 88 in sealing 
relationship. 
The operation and advantages of the present invention will now be readily 
understood in view of the above description. To begin with, the elevation 
indicator 10 is carried to a location from which elevation measurements 
are to be made with most of the elements located in the box-like 
supporting base 12 as shown in FIG. 5. The staff 18 (without the flexible 
tube 44) and the valve 48 are carried separately. When arriving at the 
measuring site, the latches 80 are opened and the cover 78 is removed. All 
of the contents within the box-like structure including two of the 
extension elements 68 are removed. The two extension elements 68 are 
mounted on the bottom post 66. The reservoir 13 is tipped upside down, so 
that the opening 16 is in an uppermost position and the fixture 52 is 
connected to the nipple 53. The opposite end of the flexible tube 44, 
carrying the check valve 48, is attached to the staff 18 in the manner 
shown in FIG. 1. The filling cap 56 is removed from the nipple 55 to allow 
liquid to flow through the tube. The reservoir 13 is then mounted on the 
uppermost extension 68, as shown in FIG. 1. The elevation indicator 10 is 
now ready to be used for measuring the difference in elevation between two 
points, as illustrated more clearly in FIG. 7. 
Referring particularly to FIG. 7, the supporting base 12 is placed on the 
ground at a base level B so that the level of the liquid 15 in the 
reservoir lies within a horizontal plane D. The staff 18 is moved to 
location A as shown by dotted lines in FIG. 7, so that the bottom of the 
staff rests on the ground at this location. The scale 36 is shifted 
vertically relative to the staff 18 by grasping the finger tab 43 and 
moving it to the meniscus point in the portion of the tube 44, which 
extends along the staff 18. This point is located at the level D, as 
viewed in FIG. 7. The finger tab 43 is located at the zero mark on the 
scale 36 and the scale reads in both directions from this zero mark, as 
shown in FIG. 1. In this way, readings can be taken directly from the 
scale 36 for measuring a drop in elevation, as well as a rise in 
elevation. In the example shown in FIG. 7, the meniscus and the finger tab 
are located in the upper portion of the staff 18, since the point A is a 
lower elevation than the base point B. Staff 18 is then moved to the 
elevation point C which is to be compared with the point A, as shown by 
full lines in FIG. 7. Since the meniscus point in the tube 44, which 
extends along the staff 18, remains at the reservoir level D, the meniscus 
is located below the zero point at the tab 43 by an amount equal to the 
difference in elevation between points A and C. This difference in 
elevation is represented by the letter X and can be read directly from the 
scale 36. The scale 36 can then be reset by moving the finger tab 
downwardly, so that the zero point on the scale is again aligned with the 
meniscus at the level D. The staff 18 can then be moved to a third point 
for measuring the difference in the elevation between the third point and 
the point C. In this way, continuous measurements in elevation can be made 
by repeating the procedure described above. Each new point is compared 
with the previous point by reading the difference in elevation directly 
from the scale and recording this value for each reading. In the event 
that a point to be measured is located above the level D, so that the 
meniscus drops to the bottom of the scale, the supporting base 12 is 
adjusted upwardly by adding another extension element 68. This raises the 
liquid level in the reservoir 13, an amount approximately equal to the 
length of the extension element 68. In the event that subsequent points to 
be measured are lower, the reservoir 13 can be lowered by removing 
extension elements 68 as necessary. The ability to adjust the reservoir 
level D enables the operator to take elevation readings for a considerable 
range of elevation without moving the supporting base 12 from the base 
location B. However, there are times when the supporting base 12 must be 
moved due to the limited length of the tube 44 or if the points to be 
measured vary too greatly in elevation from the base point B. This has no 
adverse affect on the measurements to be taken, since each measurement is 
compared to the previous measurement. The supporting base 12 is simply 
moved to the last point to be measured and the procedure described above 
is again repeated. 
After all the necessary recordings have been made by the elevation 
indicator 10 of the present invention, the tube 44 and valve 48 are 
disconnected from the staff 18, the reservoir 13 is removed from the 
extension element 68 and turned so that the bottom opening 16 faces 
horizontally. The liquid in the tube 44 is then drained back into the 
reservoir housing 14 and a closure cap 74 is applied to the threaded 
nipple 53. As shown in FIG. 7, the bottom opening 16 and a top opening 54 
are located near the same side of the reservoir housing 14. In this way, 
the reservoir 13 can be tipped so that the top and bottom openings 54 and 
16, respectively, are above the water level in the housing 14. The closure 
cap 56 for the upper opening 54 can thereby be left off, so that the 
liquid can be drained easily from the tube 54 back into the reservoir. The 
closure cap 56 is then applied to the nipple 55 to seal the upper opening 
54. The plumbing fixture 52 is removed from the nipple 53 and the closure 
cap 74 is applied thereto. As shown in FIG. 5, the extension elements 68 
are stored at the back of the box-like structure of the supporting base 12 
behind the flexible strap 76. The flexible tube 44 and valve 48 are then 
placed in the bottom of the box and the reservoir 13 is placed into the 
box, so that the tray 17 rests on the guide 72, as shown in FIG. 5. The 
cover 78 is then applied to the box, so that it covers the reservoir 13 
and is locked into place by closing the latches 80. The entire assembly 
can then be transported by grasping the carrying handle 70. 
It is obvious that minor changes may be made in the form and construction 
of the invention without departing from the material spirit thereof. It is 
not, however, desired to confine the invention to the exact form herein 
shown and described, but it is desired to include all such as properly 
come within the scope claimed.