Lean back and set 'em down
March from the waist down
40 inches back to chest
Take a 30 inch step
That's how the cadence goes and each instructor has a little different take on the rhythm and tune. It's an easy reminder of some often overlooked details of marching. It's focuses on fours distinct areas of importance: How the foot contacts the ground when a step is taken forward, role of the upper body in marching, distance and alignment, and length of step.
Lean back and set 'em down is a reminder of a concept not often taught withing Pathfinder drill. This is the specific way a foot should contact the ground when taking that marching step forward. Now, the words don't really say anything about the feet but it is a reference to the way the footfall should be taught. When first being instructed on the proper footfall patterns, Pathfinders will be told to take slow steps and lean back slightly from the waist. This helps the Pathfinder develop the best muscle memory for farther down the road. Specifically, that the heel should be the first thing to contact the ground as a Pathfinder takes a step forward. Leaning back helps subtly move the center of gravity back and helps prevent a flat foot fall that is associated with a center of gravity too far forward. The lean also helps the Pathfinder have a straight leg when the foot hits the ground.
March from the waist down is the idea that all the mechanics of marching should happen below the waist. The arms move but that only helps in creating a smooth movement and maintains the center of gravity. Otherwise, movement should be confined to the lower extremities. It extends the basic concepts going back to facing movements where Pathfinders are taught to initiate the turn from the ground up and not from the shoulders. There should be no twisting of the body through turns both at the halt and marching. Commonly, Pathfinders get sloppy and develop (for various reasons) turns initiated from the shoulders and that throws the feet off from properly executing the turn. The difference is slight and would only be noticed by seasoned instructors but it appears sloppy on large formations even to the casual observer.
40 inches back to chest is a reminder for Pathfinders to always be aware of spacing. Since drill manuals like their rules and specific directions, the proper distance from the pack of one person in a formation and the chest of the person standing behind them is exactly 40 inches. And believe me when I say the measuring tape does come out for that. Pathfinders have a more relaxed interpretation of the spacing concept which (because of the large size differences in Pathfinders) can be said as "average arm length, plus change". Each unit or club will have a slightly different spacing but for the most part it will be uniform with the arm length rule as long as Pathfinders are evenly distributed. The idea of putting all sizes together may sound good in principle and may aid to advanced drill routines but causes mis-alignment in club and unit drill.
The last line take a 30 inch step is pretty clear. The United States Army specifies a 30 inch step be taken measured from heel to heel as a soldier marches forward. Pathfinders have adopted a 24 inch step to help younger pathfinders with shorter legs to march comfortably. This line simply reminds of the need to be thinking about the size of your steps and not give in to the tendency to shorten them.