Pattern Codes at Pine Hollow Trail

A Message Test in the Snow

The Pine Hollow Trail crew needed to send short messages from a bend in a snowy forest trail to a warming hut. Trees blocked the view between the two places, so the crew tested two pattern systems. In the first system, a sender held up a strip of three beads. The receiver read the colors from left to right. In the second system, the sender pulled a cord three times. Each pull was either short or long, and the receiver listened for the order of the pulls.

The crew made a key for four messages. A blue-white-blue bead strip meant “hut open.” A white-blue-blue strip meant “bridge ahead.” A blue-blue-white strip meant “turn back.” A white-white-blue strip meant “group arriving.” For the cord system, short-long-short meant “hut open.” Long-short-short meant “bridge ahead.” Short-short-long meant “turn back.” Long-long-short meant “group arriving.” A pause separated one message from the next.

First, the crew tested both systems in calm weather. Each system sent twelve messages. The bead system was understood correctly 11 times, and each message took 7 seconds to send. The cord system was understood correctly 9 times, and each message took 5 seconds. Next, light snow began to fall. The bead system was understood correctly 8 times, and each message took 8 seconds. The cord system was understood correctly 6 times, and each message took 6 seconds.

The crew kept the trail distance, the four messages, and the number of trials the same in both weather tests. The snowfall changed between the two rounds. The crew also noticed that the falling snow made it harder to see bead colors. Wind pushed snow against the trees near the receiver, and some cord pulls were harder to hear. The crew recorded these observations but did not test each cause separately.