Page:Thoreau - As remembered by a young friend.djvu/55

 here, glue, with a little spermaceti, or bay berry wax, was used. The Thoreaus procured that clay, stamped with a crown as a royal monopoly, and baked it with the lead, and thus got a harder, blacker pencil than any here, but gritty. Then it appears they invented a process, very simple, but which at once put their black lead for fineness at the head of all manufactured in America. This was simply to have the narrow churn-like chamber around the mill-stones prolonged some seven feet high, opening into a broad, close, flat box, a sort of shelf. Only lead-dust that was fine enough to rise to that height, carried by an upward draught of air, and lodge in the box was used, and the rest ground over. I talked with the mechanic who showed me this, and who worked with the Thoreaus from the first, was actively helpful in the improvements and at last bought out the