over two years, yet my credit was fine. Every store I traded with was always glad to furnish goods, perhaps in amazed admiration of my system of doing business, which was certainly new." After a while Edison got a bookkeeper, whose vagaries made him look back with regret on the earlier, primitive method. "The first three months I had him go over the books to find out how much we had made. He reported $3000. I gave a supper to some of my men to celebrate this, only to be told two days afterward that he had made a mistake, and that we had lost $500; and then a few days after that he came to me again and said he was all mixed up, and now found that we had made over $7000." Edison changed bookkeepers, but never thereafter counted anything real profit until he had paid all his debts and had the profits in the bank. The factory work at this time related chiefly to stock tickers, principally the "Universal," of which at one time twelve hundred were in use. Edison's connection with this particular device was very close while it lasted. In a review of the ticker art, Mr. Callahan stated, with rather grudging praise, that "a ticker at the present time (1901) would be considered as impracticable and unsalable if it were not provided with a unison device," and he goes on to remark: "The first unison on stock tickers was one used on the Laws printer. [2] It was a crude and unsatisfactory piece of mechanism and necessitated doubling of the battery in order to bring it into action. It was short-lived. The Edison unison comprised a lever with a free end travelling in a spiral or worm on the type-wheel shaft until it met a pin at the end of the worm, thus obstructing the shaft and leaving the type-wheels at the zero-point until released by the printing lever. This device is too well known to require a further description. It is not applicable to any instrument using two independently moving type-wheels; but on nearly if not all other instruments will be found in use." The stock ticker has enjoyed the devotion of many brilliant inventors--G. M. Phelps, H. Van Hoevenbergh, A. A. Knudson, G. B. Scott, S. D. Field, John Burry--and remains in extensive use as an appliance for which no substitute or competitor has been found. In New York the two great stock exchanges have deemed it necessary to own and operate a stock-ticker service for the sole benefit of their members; and down to the present moment the process of improvement has gone on, impelled by the increasing volume of business to be reported. It is significant of Edison's work, now dimmed and overlaid by later advances, that at the very outset he recognized the vital importance of interchangeability in the construction of this delicate and sensitive apparatus. But the difficulties of these early days were almost insurmountable. Mr. R. W. Pope says of the "Universal" machines that they were simple and substantial and generally satisfactory, but adds: "These instruments were supposed to have been