The pond had in the meanwhile skimmed over in the shadiest and shallowest coves, some days or even weeks before the general freezing. The first ice is especially interesting and perfect, being hard, dark, and transparent, and affords the best opportunity that ever offers for examining the bottom where it is shallow; for you can lie at your length on ice only an inch thick, like a skater insect on the surface of the water, and study the bottom at your leisure, only two or three inches distant, like a picture behind a glass, and the water is necessarily always smooth then. There are many furrows in the sand where some creature has travelled about and doubled on its tracks; and, for wrecks, it is strewn with the cases of caddis-worms made of minute grains of white quartz. Perhaps these have creased it, for you find some of their cases in the furrows, though they are deep and broad for them to make. But the ice itself is the object of most interest, though you must improve the earliest opportunity to study it.