Many moons ago in the last century, I used a tool called a chain to measure distances. I learned that one could throw a chain, break chain, cut a foot, even add a foot, but few could afford to damage one. Linear measurement is one of the three vital components of Surveying, with angular and vertical measurements rounding out the necessities. Here is the type of steel tape (chain) I speak of.
Note the current price. In 1980 they cost $89.00. A young field hand making $3.65 an hour (then) dare not destroy this tool.
When you bought a chain the first thing you did was gingerly unwind the tape from the reel and inspect it. The next thing an “old school” surveyor would do is throw the reel away, tie a leather thong on each end and proceed to throw the chain. Here’s how that is done.
Right handed people, grab the zero end of the tape in your left hand with the zero mark under your thumb and the end pointing away from your body. Take your right thumb, put in on top of the tape facing your left hand. Push your left hand forward as you drag your right hand back loosely holding the tape (letting it slide in your palm). When your hands are fully stretched, grab the tape with your right hand and bring your two hands together, thumb over thumb. The tape will create a loop ( a figure eight) that dangles. Put the tape (from your right hand) on top of the zero mark and grip it under your left thumb. You should be holding the five foot mark. Repeat for each five foot increment (do the Hokey Pokey and turn yourself around) until you reach the 100 foot mark on top of the pile under your left thumb. Wrap the leather thong around the tape (working from the tip toward the numbers showing ) and secure it with a slip knot. Grab the tape bundle with your right hand and let your left hand grab the loose end of the tape. Bring your hands up in front of your body, parallel to the ground. With a firm grip in both hands, hold the left hand steady while you rotate your right hand toward your body. My first teacher told me, “drink your coffee” (which translated to rotate inward and slightly downward). The tape will spread open and fold onto it’s self and make two loops into one. A small coil proves you have thrown the chain. Take the loose thong and wrap the entire bundle to secure it. In Mr. Roger’s neighborhood, Fred would say, “I knew you could.”
I’ll discuss breaking the chain and cutting a foot in another segment. However, I will tell you how and why to add a foot during a measurement. As mentioned in another segment, a three peg grid must be precisely measured to obtain a true 90% angle. If one crewman is holding zero on stake A, the crew chief will hold 30 (then looping the tape) also hold 31 in the same hand. A third crewman (if lucky enough to have a three man crew) would normally hold the 70 foot mark on stake B (for his 40 foot distance) but in this case must “add a foot” and hold the 71 foot mark on stake B, because the chief has two separate distances converging on stake C. This combination of distances, 50 feet between stakes A and B, 30 feet between stakes A and C, and 40 feet between stakes B and C complete the Pythagorean formula.
One trick of the trade explained. Look for a video Friday on throwing a chain.
Be accurate adventurers