Steel Surveyors' Tape (200-foot and 21-chain trailer tape)

Damage to a steel tape usually occurs because the tape is allowed to rust while in storage or because kinks are allowed to form while coiling or uncoiling the tape, or while working on steep downhill slopes.

To prevent rust ALWAYS DRY the tape before coiling. If the tape is to be stored for any length of time, run an OILY RAG over the tape's entire length before coiling.

Bending and kinking of the tape will be greatly reduced if care is taken during coiling and uncoiling the tape before and after use. To coil is to be properly:

a. With your back turned to the tape and the tape strung out behind your right side, reach across in front of your body with your left hand and hold the zero end with the tabs facing up.

b. With the right hand, reach back along the tape to a convenient tab (3-10 links on topographic tape; 5 or ~ feet on 100-foot tape).

c. Without turning the tape over, bring that tab forward and lay it face up on the first tab, letting the loop fall naturally in a figure-eight.

d. Repeat this until the entire length is coiled.

e. Securely lash the leather thong at the zero end of the tape around the coiled tape.

To throw, grasp the middle of the looped tape with your right hand and at the opposite point on the loop with your left hand; then twist and throw into a circular form with a diameter half that of the original loop.

When uncoiling the tape, carefully reverse the above steps. Do not merely loosen the thongs and drop. This is inviting trouble and extra work.

Broken tapes may be mended by the use of "Eureka" tape splices. To splice a break:

a. Flatten the broken ends of the tape by lightly tapping with a hammer, hatchet or rock.

b. Clean both ends down to base metal with emory cloth or some abrasive.

c. Insert ends of tape into splice sleeve, checking to be sure that the same side of the tape is up in both pieces. Make sure they fit together.

d. Hammer cleeve until it is tight against tape.

e. Hold a lighted match under the sleeve for about 30 seconds.

f. Do not move the tape unti1 the sleeve has cooled.

Small kits of "Eureka" tape splices are available from most engineering instrument firms.

Because of the frequency with which diameter tapes are wound-up and unwound, it is essential that rust and foreign material be kept off the tape. Always keep a light film of oil on the tape. Periodically, a solvent-soaked rag should be used to remove completely the pitch, etc. that has accumulated on the tape.

Diameter tapes are seldom broken through normal usage but usually as the result of gross carelessness. Always hold the tape case so that the tape feeds into the case slot in the normal manner. If the case is held so that the tape must bend sharply to enter the case from the backward side, a slip or fall on your part will probably put a permanent kink or break in the tape. Don't unreel a long portion of tape and throw the case around a difficult corner! Never unreel the tape to measure a 109, tree, etc. and mark the measurement with an axe without first removing the tape. It is inexcusable to chop the tape apart, but it happens!

Broken tapes can be spliced by the use of small copper rivets and an overlapping patch of tape. Special hollow, copper rivets and a punch for making holes and flattening rivets are available. Since the first couple of feet of tape-are the most susceptible to breakage and loss, sections of tape, including the hook and first two or three feet of tape can be obtained for replacement purposes.

When checking the adjustment and condition of a box compass, the following items should be used as a guide to proper functioning.

a. The needle must be straight, sufficiently magnetized and balanced.

b. The pivot point must be sharp.

c. The pivot point must be centered in the graduated circle.

Symptoms and corrective action for some of the common compass troubles are listed below.

Bent Pivot. If the difference between the two end reading of the needle varies at different positions, the pivot is bent. Straighten the pivot until the difference between the end readings is constant at various positions.

Bent Needle. If the constant difference between needle end read

Remagnetize Needle. To remagnetize a needle, pass the south end of the magnet from the center of the needle to the north end, and in a like manner the opposite end of the magnet should be passed over the south end of the needle. Each pass should describe an eight-inch circle. About 35 passes are sufficient to reactivate the needle.

Blunt Pivot. If the pivot is dulled, it can be removed and sharpened; however, it is advisable to replace with a new pivot if possible.

The care of the staff compass is similar to that of the pocket compass; a greater degree of accuracy is expected and a greater degree of care in maintenance and use is essential. Remember that the staff compass is a precision instrument investment which costs more than one-hundred dollars. It should be handled in the same manner as a transit or level. Never have the compass on the staff while driving the staff into the ground. The proper place for the compass is in the case until you have the staff set in the ground. While the compass is on the staff, loosen the clamping screw only when actually using the instrument. Always check to see that the clamping screw is tight before replacing in the case. Always fold down the front sighting vane (With cross hair) first; then the rear vane.

The adjustments of the needle and pivot listed above for the box compass also apply to the staff compass although greater care must be taken in each step. However, there are some additional adjustments to be taken into account with the staff compass.

After levelling, the level(s) should remain centered when the instrument is turned in any direction. This requirement is essential to the proper functioning of the sights and needle. There are two causes for failure of this test: levels out of adjustment, or a faulty mounting spindle. If it is the spindle, either new parts or remachining will be necessary.

The level of a compass with two tubular level vials is normally adjustable either by opposing screws or by insertion of thin shims. The principle of reversion is used, just as in adjusting the levels on a transit. Half the deviation after rotating the compass 180 degrees, is corrected by relevelling the compass, and the other half by adjusting the levels themselves. This is done for one vial at a time.

The same principle is followed for those compasses using a single "bullseye" level. However, some of these have no provision for adjustment. For such non-adjustable levels, determine a posit�i�o�n� �w�h�e�r�e� �t�h�e�

�V�e�r�t�i�c�a�l�i�t�y� �o�f� �S�i�g�h�t�s� �

B�o�t�h� �s�i�g�h�t�i�n�g� �5�1� �i�t�s�,� �o�r� �s�l�i�t� �a�n�d� �h�a�i�r�,� �m�u�s�t� �b�e� �t�r�u�l�y� �vertical when the compass is level or the projected line of sight will be erratic, and errors will be introduced into the observed bearings.

The test is made by sightinq on a plumb line after carefully levelling the compass. First, take a piece of masking tape long enough to cover the slit in the south vane and make a hole about 3/32" in diameter in its center. Lightly stick the strip of tape to the south vane so that the view through the slit is obtained through the peephole. Because the eye is held in vertical position by the hole while observing the relation of the -north sight slit or hair to the plumb line, the lack of verticality in the south sight has no effect on testing the north sight. The south sight is tested by sticking the tape with peephole to the north sight and observing the relation of the south slit to the plumb line. If the north sight has a vertical hair, the peephole can be offset to the side slightly if the hair interferes. It is normally so close to the eye as to be out of focus and almost invisible.

On those compasses with sights mounted on a horizontal plate or extension, the adjustment is simple and positive. Thin pieces of brass (never steel) shim stock (or just paper in emergency) ire inserted under the edge of the sight base to move the sight to a truly vertical position. There should be no sideways play in the hinge joints of a compass with folding sights.

Many compasses now in use have the sight bases screwed to the side of the compass shell. These are held in place by friction and in some cases also by the wedging action of counter-sunk screw heads. Adjusting this type of sight is a trial of the individual's patience and skill. It sometimes requires reshaping of the holes in the sight base' and the sight must be held in exact position while the screws are tightened. This adjustment is made more secure by coating the mating surfaces with a slow-setting varnish and leaving it undisturbed until the varnish is hard.

The Pivot Point. This is the greatest single source of poor directional results in compass surveys. A dulled point results in a sluggish or sticky needle. It should go without saying that a compass should never be carried or subjected to jolts and vibration when the needle is resting on the pivot. When releasing the needle, it should be lowered gently onto the pivot point, not let down suddenly.

1. Remove all ferromagnetic objects such as knives, mechanical pencils, wrist watches, etc., from the person. Obtain a 12 oz. "tin" can (Sheet steel). Set the compass level on a tripod or workbench with the can 28" distant horizontally and magnetic north from the compass. This can be done indoors so long as all ferromagnetic objects remain static in position. Nearby radios or television sets should be kept on or off, because certain components produce a magnetic field.

2. -Rotate the compass so that the north tip of the needle is exactly on a mark when freed and at rest. When the can is moved one foot to east or west, the needle should move slightly off the mark; this test will indicate sensitivity. An exceptionally good compass will react to a 12-oz. can 36" from the north tip of the needle.

3. With the needle free and at rest on a mark, distract it by moving the can near one side and then replacing it in its previous position. The needle should come to rest exactly on the mark ten times out of ten; this test will indicate reliability.

The average compass in general use wi11 fail both of these tests in a most convincing manner.

Correction. Disassemble the compass enough to remove the needle and pivot point. The latter is usually removed by unscrewing from above or below. If stubborn, apply a little kerosene or gun solvent to soften rust and corrosion and let stand for a few hours before removing. Examine the point under magnification. It will often be found to be so blunted that it resembles a crochet needle. It should have such a fine point as to appear absolutely sharp, even under 10-power magnification.

Before the pivot can be properly sharpened, it must first be clamped into some sort of holder. A good holder for most pivots can be made from an ordinary "lead" pencil stub. Split a pencil of appropriate lead diameter lengthwise along the glued seam and remove the lead. The pivot shank is inserted in the open end, and clamping action is supplied by tightly wound rubber bands. Once in its "handle", the pivot may be carefully sharpened on a fine stone such as a razor or Arkansas stone. The common stones sold for sharpening knives are much too �c�o�a�r�s�e�.� �T�h�e� �p�i�v�o�t� �i�s� �r�o�t�a�t�e�d� �w�h�i�l�e� �s�t�r�o�k�i�n�g� �o�n� �t�h�e� �s�t�o�n�e� �t�o� �p�r�o�d�u�c�e� �a� �u�n�i�f�o�r�m� �c�o�n�i�c�a�l� �p�o�i�n�t�.� �I�t� �s�h�o�u�l�d� �b�e� �h�e�l�d� �a�t� �a�p�p�r�o�x�i�m�a�t�e�l�y� �3�0�ýÿ �f�r�o�m� �t�h�e� �s�t�o�n�e� �t�o� �p�r�o�d�u�c�e� �a� �p�o�i�n�t� �w�i�t�h� �a�b�o�u�t� �6�0�ýÿ �i�n�c�l�u�d�e�d� �a�n�g�l�e�.� �(�S�e�e� �d�i�a�g�r�a�m�.�)� �K�e�e�p� �t�h�e� �p�o�i�n�t� �a�n�g�l�e�d� �s�l�i�g�h�t�l�y� �i�n� �t�h�e� �d�i�r�e�c�tion of stroking to avoid building up a burr on the tip. Bear in mind that sharpening tends to shorten the pivot, thus lowering the needle tips.

The needle center-bearing (usually agate) is cleaned by rotating a round toothpick wrapped with lint-free tissue or cloth in the socket. The final cleaning is done with tissue or cloth dampened with lighter fluid or alcohol. All oily residue must also be removed from the pivot point if good needle-action is expected.

When reassembling, place the needle on the raised lifter rather than directly on the pivot point, and then lower onto the pivot. Failure to follow this procedure has spoiled many sharp pivots. Before all adjustments are complete, the needle may have to removed and replaced a number of times. A needle with a good pivot is slow to settle, so release it when pointing northward to minimize swing.

Horizontal Alignment. A ree needle properly made and in good adjustment will have the tips level with, or very lightly above, the u per surface of the graduated circle when the compass is level. if much above or at all below, the resulting parallax can cause inaccurate observations. If properly constructed, a line through the upper surface of the tips will be coincident with the junction of pivot and bearing. This will result in no relative movement between the needle tips and the graduated circle although the needle is still vibrating at right angle to its long axis. This residual vibration or "shimmy" for sometime after the needle stops swinging can be noted by watching the reflected light from its upper surface, or that of the pivot jewel. The presence of the phenomenon indicates a good pivot.

Some sources recommend bending the ends of the needle upward (or downward) to make the tips run level with the graduated circle. Any such bending will destroy the alignment between tips and pivot in the horizontal plane. The proper way to accomplish this objective is to raise or lower the pivot. When the pivot point is too low from repeated sharpening (or too high for some reason), it is best to balance the needle so that the top of the north tip is level with, or about 1/64" above the circle and forget about the south end. Proper compass practice dictates exclusive use of the north end of the needle, observed while standing at the south end. compass with a pivot of adjustable height would be superior to the current offerings.

Once the needle is balanced by the sliding counterweight on the south end, it need not be changed while working in the same general area (normally within a hundred-mile radius). However, there may be occasions where the needle is found to be very badly out of balance for no apparent reason. This is nearly always the result of a static electric charge on the cover glass. Such a static charge can develop almost spontaneously during periods of low humidity. To dissipate the static, merely moisten a finger tip and rub it around the cover glass about three times, and the needle will assume its proper attitude.

Vertical Alignment. The essential element of alignment in the vertical plane is for the graduated circle to be concentric with the rotational point (pivot assembly) of the needle. If this criterion is not met, the compass will have a built-in variable bearing error depending on the direction sighted. It is analogous to eccentricity in the plate of a transit.

Test. The north and south tips of the needle should cut opposite graduations when the compass is pointed in any direction. If they do not, corrective measures must be made. The south tip of the needle has value, but for test and adjustment purposes only.

Correction. Rotate the compass with needle free until the position of greatest deviation between the tips is found, and note the position. Place the north tip on the nearest mark and observe the direction of error of the south tip. Remove the needle and gently bend the pivot at right angles to where the long axis of the needle was located and opposite to the error observed in the south tip. This is a trial and error proposition, so proceed slowly, making adjustments a little at a time. Replace the needle and check, repeating as needed. Holding ferromagnetic metal object near the north end of the needle can help to make the needle come to rest more rapidly; proper manipulation will require a little practice.

g� �t�i�m�e� �w�i�t�h� �a� �m�i�n�i�m�u�m� �o�f� �r�e�p�a�i�r� �a�n�d� �a�d�j�u�s�t�m�e�n�t�.� �T�h�e�r�e� �a�r�e� �t�h�r�e�e� �a�d�j�u�s�t�m�e�n�t�s� �t�h�a�t� �c�a�n� �b�e� �m�a�de to ensure proper functioning: (1) mirror slide, (2) height of vial, (3) bubble. When it is necessary to make all three adjustments, they should be made in the order listed.

To make the zero mark on the vial appear opposite the cross line: set the Index arm at zero, loosen the mirror lock screw. Slide the screw backward or forward as required, and tighten.

To center the vial zero mark on the horizonta1 axis: the height of the vial should be adjusted so that the ends of the zero mark appear to remain at the level of the cross line as shown.

Upward Slope Level Downward Slope

The need for this adjustment is apparent only when the Abney is sighted at a steep angle. To adjust, turn capstan, screws, holding vial, equal amounts in the same direction until the desired condition is obtained. (This can be accomplished only on Abneys in which both ends on the bubble vial are adjustable in height, e.g. K. & E.)

To make the bubble center when the index is at zero and the line of sight is horizontal, select two trees about 50-100 feet apart on fairly level ground. Mark on tree one a target "A". Set the Abney at zero, steady it against the side of the second tree, and by trial, find a point apparently at the some height as "A". Mark the point as target "B". In the same manner, go to the first tree and find a point "C" apparently at the height of "D". Mark a point "D", on the first tree half-way between "A" and "C". The line "BD" will be level to matter how much the Instrument Is out of adjustment initially.

Turn the capstan screws holding the level vial equal amounts in opposite directions until, when the instrument is held 1cvel at "D", the line of sight will strike "B". A rapid, rough, check of proper bubble adjustment may be made on any smooth surface. Set the Abney down, draw a line on the smooth surface along one side of the Abney and across the ends, and center the bubble under the vial mark. Observe this reading carefully. If the instrument is in adjustment, a reading of the same magnitude and opposite sign should be observed when the Abney is reversed in the same position and the bubble re-centered.

All adjustments of the Abney should be made with the proper sized Abney adjusting pin. Sharpened nails, etc. wil1 damage the instrument and are apt to give unsatisfactory results.

1 .The needle of the compass is never released or allowcd to swing free except when the compass is firmly mounted on the staff and in a level position.

2. To set up a compass:

a. Force staff firmly in the ground, generally at an angle so the compass is over the stake marking the station.

b. Remove compass from belt case; the compass is always carried In a case secured to the person when moving from station to station.

c. Mount compass on staff swivel.

d. Secure socket to swivel by tightening set screw.

e. Raise sight vanes.

f. Level compass

g. Orient the right vanes in the approximate direction to the next station and release the needle and let 1t come to rest.

h. Read to the nearest 15 minutes.

3. To move a compass to the next station:

a. Tighten needle clamp screw to lift needle off the pivot.

b. Lower sight vanes (cross-hair vane on the bottom).

c. Loosen socket set screw.

d. Place compass in case on your belt.

e. Pick up staff and move to next station.

To take a sight with a hand compass, hold it somewhere between the belt and the chest. Hold it level with both hands, with elbows supported against the body -far enough from thc body to avoid the magnetism of jackknife, keys, and magnetic attractions In vest pockets. Keep the line of sight at right angles to the body and turn your whole body with the compass as you seek the sight ahead, in the desired bearing on the compass. When on the sight ahead or the desire�d�

Pacing furnishes a convenient means of obtaining approximate distances which is quite useful in forest surveying. It can be used to obtain a rough check on more accurate measurements made with a tape. For the timber cruiser pacing is indispensable.

1. Be systematic. Because the method is crude, it should not be rendered valueless by careless recording of paces, ignoring changes of slope and cover, or by failing to check paced measurements against measured distances at every opportunity.

2. On level ground adopt a pace that can be held all day. This should be your NATURAL STRIDE. Do not try to take an even three-foot step. Some people use a single-step pace instead of the two-step pace. On flat open ground pace repeatedly over a measured distance until an accuracy of 1 to 100 can be obtained.

3. Pacing in mountainous brushy terrain is not the same as pacing on flat open ground. It is not often that a normal step can be taken in the woods. Thus, one must use other procedures to help, such as estimating by eye the number of paces ahead to some recognizable point. A stick can promote more accurate pacing in brush or on steep slopes.

4. It is suggested that pacing results be regularly recorded and checked against known distances under various conditions. If possible, a pacer should check his pace every day and preferably both morning and afternoon because of fluctuation as the day wears on.

5. A pace is a measurement of horizontal distance. Regardless of the slope, it is always in terms of horizontal distances.

1. Make a "Pacing Table" in your field book for O, 10, 2O, 30, 40 and 50 percent slopes. See example notes attached to this sheet.

2. Determine the number of paces per l0O feet on courses that you have measured. Take an average of five trials over each course and enter your results in "Personal Pacing Table".