Circumstances occurred previous to his appointment that may be worthy of remark. The purchase of the bridge patent, before alluded to, was for the sum of forty thousand dollars, to be paid in annual instalments. A few years after the purchase some defects showed themselves in the bridges that had been erected on this plan, and many prominent engineers had come to the conclusion that it was not superior to, if it equalled, the truss plan of Col. Long, the arch and truss of Burr, or the lattice plan of Ithial Towne, and the firm of Boody, Stone & Co. began to fear that they had made a bad bargain in the purchase of the patent. Mr. Stone, in relating the incident to a friend, said: "I came to the conclusion that something must be done or there must be a failure, and it must not be a failure. The night following was a sleepless one, at least until three o'clock in the morning. I thought, and rolled and tumbled, until time and again I was almost exhausted in my inventive thoughts, and in despair, when at last an idea came to my mind that relieved me. I perfected it in my mind's eye, and then came to the conclusion that it would not only restore the reputation of the Howe bridge, but would prove to be a better combination of wood and iron for bridges than then existed, and could not and would not in principle be improved upon. Sleep immediately came. I afterwards, with models, proved my conclusions and have not, up to this time, changed them." It seems that the invention consisted in the introduction of longitudinal keys and clamps in the lower chords, to prevent their elongation, and iron socket bearings instead of wooden for the braces and bolts, to avoid compression and shrinkage of the timber, which was the great defect in the original invention, and the adoption of single instead of double intersection in the arrangement of the braces, the latter being the arrangement in the original invention.