Betty Leicester by Sarah Orne Jewett

THERE was a gnarled old pear-tree of great age and size that grew near Betty Leicester's east window. By leaning out a little she could touch the nearest bough. Aunt Barbara and Aunt Mary said that it was a most beautiful thing to see it in bloom in the spring; and the family cats were fond of climbing up and leaping across to the window-sill, while there were usually some birds perching in it when the coast was clear of pussies.

One day Betty was looking over from Mary Beck's and saw that the east window and the pear-tree branch were in plain sight; so the two girls invented a system of signals: one white handkerchief meant _come over_, and two meant _no_, but a single one in answer was for _yes_. A yellow handkerchief on the bough proposed a walk; and so the code went on, and was found capable of imparting much secret information. Sometimes the exchange of these signals took a far longer time than it did to run across from house to house, and at any rate in the first fortnight Mary and Betty spent the greater part of their waking hours together. Still the signal service, as they proudly called it, was of great use.