Note 9 — PART I. (continued 2)
Reading edition
On the 17th of February, 1899, four days after the greatest snow storm in Philadelphia in many years, I noticed that the snow on my roof solidified slowly into a mass of ice which contained a good many air-bubbles. It strikingly resembled the ice of the Ice Gulch, only that it was more solid and did not have more than half as many air-bubbles.