Surveyor's level with constant instrument height and method

A surveyor's instrument such as a surveyor's level (10) and method is disclosed wherein a constant instrument height may be provided during repeated set ups of a tripod (22) at different locations at a job site. An adjustable elevating device (24) is provided which mounts a surveyor's level (10) in a manner that its vertical position is changed. The elevating device includes an adaptor base cap (30) which adapts to a tripod collar (20) having a hollow sleeve (32). A shaft (28) which carries an adapter collar (26) is slideably received in the sleeve (32) and set in a desired vertical position by set screw (38) or a gear drive (50, 46, 40). The surveyor's level (10) is affixed to an adapter collar (26) by a level base cap (18).

BACKGROUND OF THE INVENTION 
The invention relates to the field of surveying and to a surveyor's level 
or transit for use in surveying and method by which surveying calculations 
may be based on a constant instrument height in reference to a prescribed 
benchmark despite moving of the tripod to different locations and 
elevations at a job site. 
Prior survey levels and transits have been utilized which mount on the top 
of a tripod. The conventional surveyor's level is fixed and reads an 
instrument height on the surveyor's rod at a benchmark. Each time that the 
tripod is taken down and set up, a new instrument height is read at the 
benchmark since it is impossible to set the tripod up at the same exact 
location and elevation. When surveying is begun again, a new set of 
calculations must then be started with a new instrument height. The prior 
calculations of the surveyor at the job are lost. 
In completing even a small job, a surveyor may make from thirty to several 
hundred readings. When the surveying instrument is set up, the surveyor 
first turns to the benchmark and reads the surveyor's rod to get the 
height of the surveying instrument. He then turns to the job site and 
makes the numerous readings which are required for the job. These readings 
are all based on the instrument height as previously determined from the 
exact location at which the tripod is set. During the day or week while 
the surveyor is on the job it becomes necessary for the tripod including 
level to be moved and set back up frequently. Each time that the 
surveyor's level is set back up there is a new instrument height since the 
tripod cannot be set back up in the same exact location. This means that 
the surveyor must start a new set of calculations for the numerous 
readings he must make on the site based on the new instrument height. All 
of the previous grade readings and calculations read by the surveyor 
before he moved the surveying level are lost. He must now start a new set 
of calculations and grade readings depending on the new instrument height 
of the survey level. It is typical for an engineer to have several pages 
of grade readings at the end of each day's work which are lost when he 
begins the next day's work and the instrument is set back up. All of this 
can become very time consuming and tedious work, often frustrating the 
surveyor if the tripod has to be moved frequently. 
Even minor situations such as taking a lunch break or moving the surveyor's 
level to allow a truck to pass by require that a new instrument height and 
new calculations be made. 
Accordingly, an object of the invention is to provide a surveyor's level 
and method by which grade readings and calculations on a job are not lost 
when the tripod is moved to a new location and elevation. 
Another object of the invention is to provide a surveyor's level which may 
set at the same instrument height each time the tripod is moved. 
Still another object of the invention is to provide a surveyor's level 
which is elevatable and adjustable on a tripod so that it may be set in 
reference to a benchmark at a desired instrument height and reset to that 
same exact instrument height even after the level has been taken down and 
set back up at different locations and elevations at the job site. 
Still another object of the invention is to provide a survyor's level which 
may be adjusted in its vertical position to follow successive courses of 
brick or other building block material to determine if the mortar joint 
between the courses is level. Often the mortar joint becomes off-grade so 
that the walls become unlevel and the bricks at the various intersecting 
walls do not match up with each other. 
SUMMARY OF THE INVENTION 
The above objectives are accomplished according to the present invention by 
providing a surveyor's level and method by which the level is elevatable 
on the tripod so that it may be reset to a desired instrument height when 
set up at a new location. In this manner, as the tripod is repeatedly 
taken down and set back up, the level instrument may be adjusted to the 
previous instrument height so that the previous set of grade readings and 
calculations may not be lost eliminating the need to start a new set of 
readings. In a preferred embodiment, the apparatus of the invention 
includes an elevatable support for the surveyor's level which includes an 
adaptor device having an adaptor base cap which threads upon a collar of 
the tripod. The threaded base cap carries an elongated vertical sleeve 
which receives an elongated shaft in a slideable manner. Attached to the 
slideable shaft is a threaded adaptor collar like the threaded collar on 
the tripod. The level base cap may then be secured onto the adaptor 
collar. The vertical position of the elevatable base may be adjusted to a 
desired elevation so that the surveyor's level mounted thereon may be set 
at a desired instrument height. For example, a set screw may be provided 
in the sleeve of the adaptor cap and a groove may be provided in the shaft 
of the adaptor collar. The set screw extends into the groove and fixes the 
vertical position of the adaptor sleeve. Rotation must be prevented 
between the adaptor shaft and adaptor sleeve so that the level does not 
become off level by rotation. Another embodiment of the invention is 
provided whereby the vertical position of the adaptor sleeve may be set in 
positive increments by means of a rack gear and worm gear drive.

DESCRIPTION OF A PREFERRED EMBODIMENT 
The invention relates to the art of surveying and in particular to a 
surveyor's level instrument which is adjustable in a vertical direction so 
that the instrument height may be reset at the same height when the tripod 
is taken down and set back up. The invention also contemplates the 
adapting of a conventional surveyor's level to incorporate the invention. 
FIG. 1 illustrates the prior art which typically includes a level 10 which 
includes a telescope instrument 12 and a spirit level 14 carried on a 
level face 16. A threaded level base cap 18 includes interior threads 
which mate with threads on a tripod collar 20. Tripod further consists of 
tripod legs 22 provided in a conventional manner. The level 10 is taken 
off the tripod during non-use. 
Referring now in more detail to the drawings, an explanation of the 
invention will be had. As can best be seen in FIG. 2, means for adapting a 
surveying instrument so that it may be reset at the same instrument height 
each time it moved at a job is illustrated which includes an adaptor 
device designated generally as 24. Adapter device 24 includes a first 
adaptor member in the form of a threaded adaptor collar 26 having an 
integral collar shaft 28 affixed thereto in central alignment. There is a 
second adaptor member in the form of an adaptor base cap 30 having an 
elongated base sleeve 32 centrally affixed thereto which opens at 34 and 
the top of adaptor cap 30. The elongated collar shaft 28 is slideably 
received in the sleeve 32. In accordance with the method of adapting a 
conventional surveyor's level according to the invention, adaptor base cap 
30 is threaded onto the tripod collar 20 in much the same manner as the 
level base cap 18 of level 10. The level 10 is then mounted directly onto 
adaptor collar 26 by means of threaded level cap 18. 
Elevation adjustment means is provided for adjustment of the vertical 
position of level 10. In the case of FIG. 2, the elevation adjustment 
means includes a groove 36 having a flattened surface 36a to more aptly be 
engaged by a set screw 38. Set screw 38 is threadably encased in adaptor 
sleeve 32. Adapter shaft 28 may then slide in adaptor sleeve 32 and set in 
a desired vertical position by means of a set screw 38. 
Anti-rotation means is provided by set screw 38 received in groove 36 so 
that base 16 of level 10 may not turn while telescope instrument 12 may 
turn freely. This maintains the level of the instrument as initially 
determined by spirit level 14, the advantages of which will become more 
apparent hereinafter. 
FIG. 4 illustrates another embodiment of adjustment means according to the 
invention wherein means for adjusting the height of the instrument in 
position increments is provided by a rack gear 40 affixed to adaptor shaft 
28. A hole 42 formed in adaptor cap 44 is so shaped to accept the gear 
rack 40. A worm gear 46 meshes with the rack gear 40. A small beveled gear 
48 on the end of worm gear 46 meshes with a drive worm gear 50 carried on 
the end of a drive shaft 52 which may be manually rotated by a handle 54. 
In this manner the adjustable vertical position of adaptor collar 26 may 
be positively set in an incremental manner which may be more convenient in 
many applications. In this embodiment, an adaptor sleeve 28 carried by 
adaptor cap 44 will be shaped corresponding to hole 42 to accept the 
adaptor sleeve 28 and rack gear 40. 
As can best be seen in FIGS. 5 and 6, another embodiment of the invention 
is illustrated for application with a different type of surveyor's level 
and tripod mount. In this case, the adaptor device includes a triangular 
plate 60 having a central aperature 62. A pivot plate 64 is carried at a 
pivot 66 below aperature 62. In pivot plate 64 is an opening 68 for 
receiving a threaded post 70 forming part of surveyor's instrument 72 
which serves as a means for mounting the surveyor's instrument to the 
pivot plate 64. The adaptor device further includes a short adaptor sleeve 
78 which has an upper treaded portion 80 about which a lock nut 82 is 
threaded. Sleeve 78 is inserted through an opening 84 in tripod plate 74 
and locked by means of lock nut 82 tightly threaded against the bottom of 
the plate as can best be seen in FIG. 6. 
Sleeve 78 is affixed to a face plate 86 which supports triangular plate 60 
in an intergal manner by means of three posts 88. There is an adaptor 
shaft 90 which slides in adaptor sleeve 78 and may be adjusted in its 
vertical position by means of a set screw 92, much as in the case of the 
adaptor device illustrated in FIG. 3. By inserting threaded post 70 of 
surveyor's level 72 in the opening 68 of pivoting plate 64, the surveyor's 
level may be moved around on base plate 60 until its desired disposition 
is had. Thereafter, lock nut 94 may be tightened to lock surveyor's level 
72 in place. 
Referring now to FIG. 7, an embodiment of the invention is illustrated for 
use with a surveyor's transit. A surveyor's transit is illustrated at 96 
having a threaded transit cap 98. In accordance with the invention, there 
is a tripod 100 having a sleeve 102 which is hollow. A slideable shaft in 
this case is provided by a second hollow sleeve 104 slightly smaller and 
slideably received in sleeve 102. In the case of a transit, there is a 
plumb bob 106 depending downwardly from the transit by means of a chain 
108. The construction of the invention illustrated as FIG. 7 is 
advantageous in accommodating plumb bob 106. 
Elevation adjustment means is provided in case of FIG. 7 by a rack of gear 
grooves 110 which mesh with a worm gear manually rotated by handle 112 
much in the same manner as that illustrated in FIG. 4. In this case the 
worm gear meshes with the gear grooves 110. 
While the foregoing description has been in reference to an adaptor device 
for adapting a standard or conventional surveyor's level, it is to be 
understood of course, that the expedient of a constant height surveyor's 
level and construction therefor may be readily had in a surveyor's level 
from an original construction in addition to being able to adapt a 
conventional surveyor's level. 
Referring now to FIGS. 8 and 9, the operation of a surveyor's level 
constructed or adapted in accordance with the invention will now be 
described in reference to laying brick or block in wall structures. In 
FIG. 8, a top course of brick 116 is illustrated with the formation of the 
course being form the right corner of the wall to the left corner. A 
surveyor's level 10 incorporating an elevation adjustable means is 
provided. The telescope instrument is set at a height that corresponds to 
a mortar line 118 at the right hand corner of the wall being formed. The 
mortar joint can be followed as bricks are laid to determine whether the 
joint is level. If each mortar line 118 beginning at the bottom is level, 
then the wall will be square and the corners of the walls will match. 
However, as often happens, if the mortar line begins to fall or rise 
relative to the grade level, this deviation can be detected by the 
surveyor's level and corrected. To survey the next mortar joint, the 
elevation of the level 10 is raised so that the height of the telescope 
instrument is next set on the top of the previously formed course of 
bricks. The instrument height being raised at least 21/4 inches, the 
height of convention bricks, for each course of bricks surveyed. In this 
manner, the grade level of the mortar joint may be read continuously 
across each course of bricks to ensure that the bricks are laid in a level 
manner and match the bricks of the intersecting wall at the corner. 
In the case of normal surveying operation, the operation of the invention 
will now be explained in reference to a simple survey job illustrated in 
FIG. 10 and FIG. 10a. FIG. 10a represents a map of the topography being 
surveyed in FIG. 10. There is a floor 120 which has been laid in the form 
of a slab on a previously graded ground surface. There is a bench mark 113 
which is 210'.00". The surveyor's rod B is set up on the bench mark and 
the instrument height of telescope 12 is set at any desired reading on 
surveyor's rod B. It may be desirable to set the instrument height at 
benchmark 210'.00". The operation of the device will be described with the 
bench mark set at 210'.00". With the height of telescope 12 set on the 
bench mark, the telescope is turned around to surveyor's rod B on slab 
120. If slab 120 is on grade (205'.00"), the surveyor should get a grade 
reading of five feet on the surveyor's rod B. A typical surveyor's rod is 
twelve feet having markings in feet, tenths of feet, and hundredths of 
feet. By having the instrument height of the surveyor's level set at the 
bench mark, the surveyor may get the grade readings directly as they are 
on the map in FIG. 10. For example, there is a sewer line 122 which has a 
pipe opening at a grade reading of 200'.00" which has a slope down to the 
grade reading of 198'.00". The surveyor may turn quickly to a surveyor's 
rod at the sewer pipe openings and check for grade by getting a grade 
reading of ten feet on the surveyor's rod. Next, the fall of sewer line 
122 may be checked by reading surveyor's rod to get a twelve feet grade 
reading corresponding to the grade of 198'.00". 
This is a very simplified illustration of the advantages of the invention. 
Typically, a surveying job at a building site will require several hundred 
readings rather than the several readings illustrated. Each reading may be 
read several times during the day as work and changes are made at each 
reading site. In the case of a conventional surveyor's instrument, the 
instrument is first set up and an instrument height is read at surveyor's 
rod B. However, as the elevation of the surveyor's level is not 
adjustable. The instrument height would typically include tenths and 
hundredths of a foot. For example, in the case of FIG. 10, the instrument 
height may read 212'.52". This means that the instrument height is 2.52 
feet above the bench mark. Once the instrument height is determined, the 
surveyor then engages in a number of calculations and grade readings based 
on this instrument height which the surveyor has no control over. When the 
surveyor has to move the surveyor's level and tripod, a new instrument 
height is read and a whole new set of calculations and grades must be 
started. This means that the surveyor has lost all of his prior 
calculations and grade readings for the sites previously read. He must 
start new calculations based on the new instrument height. In one day, a 
surveyor can have many, many pages of calculations which are lost. In 
accordance with the present invention, no calculations are lost and the 
surveyor may start at the same instrument height each day and time that 
the tripod is set up by adjusting the vertical position of the surveyor's 
instrument 10. 
In accordance with the invention, a highly advantageous method of surveying 
may be had using a surveying instrument mounted on a tripod in which the 
instrument may be reset to a prescribed height in reference to a 
prescribed benchmark upon relocation of the tripod to different locations 
and elevations at a job site. The method includes mounting the surveying 
instrument on the tripod in a manner that the instrument may be adjusted 
in its vertical position relative to the tripod. The tripod is set up at a 
first location and the surveying instrument is adjusted vertically on the 
tripod so that the instrument is set at a prescribed instrument height. 
Grade readings may then be taken at a job site. The tripod may be moved at 
a job site as needed over the duration of surveying operations at the job 
site. The instrument may be readjusted on the tripod vertically to the 
prescribed instrument height as needed each time the tripod is moved so 
that surveying calculations at the job site may be based on a constant 
instrument height during repeated moving of the tripod. The previous set 
of calculations and grade readings based on the same instrument height may 
be used. 
In an advantageous form of the invention, a method of surveying with a 
surveying instrument mounted on a tripod is provided in which surveying 
calculations may be based on a constant instrument height despite moving 
of the tripod. The method includes adapting the tripod to support the 
surveying instrument in a elevatable manner. Means are provided for 
adjusting and fixing the elevated position of the surveying instrument to 
the tripod so that the height of the instrument may be set at a 
prescribred instrument height relative to a prescribed benchmark at the 
job site. Each time the tripod is moved to a new location at the job site, 
the instrument may be adjusted to the same instrument height. 
In accordance with the invention, it is highly advantageous that the 
surveying instrument can be set at a selected instrument height. 
Thereafter, on each reading, the rod man, by knowing the constant 
instrument height, can tell the surveyor what grade to read through the 
instrument. Little or no calculations are necessary as in the case of 
conventional surveying instruments and techniques. 
While a preferred embodiment of the invention has been described using 
specific terms, such description is for illustrative purposes only, and it 
is to be understood that changes and variations may be made without 
departing from the spirit or scope of the following claims.