Second, the machine was superabundantly strong and substantial in every part. Third, it was made with absolute mechanical truth. Fourth, the speed was splendid. Fifth, the blow was peculiar. In the Hastings machine the cutting-tool was driven into the stone. In mine it rested on the stone and was moved back horizontally by the feed. This changed slightly the angular position of the tool-holder, so that the blow was received by it at the lower edge of its back. This gave to the tool a motion forward and _upward_, so that the vertical effect on the stone was trifling. This was the vital feature of my improvement, and that in a double sense; for it was only by convincing my associates beforehand that a machine operating in this manner could not break the stone that I was able to obtain their financial support. Sixth, the two-faced hammer saved the stone from all unnecessary force of the blow. The final cause of its success was the two-table system. The two operations of setting and cutting occupied each about the same time, and twenty tables each averaging thirty square feet of surface, measured after being squared up, were easily finished in a day of ten hours. A description of some of the constructive methods employed by me may be interesting: The bar of steel which was to be made into six separate tool-holders had to have eighteen sockets mortised in it. These were 1 inch square. I had made the tools with square shanks so as to insure their proper position. These mortises must be absolutely in line and of equal depth. These objects were accomplished as follows: A cast-iron angle-bar with planed surfaces was first bolted on the table of the drilling-machine, and for drilling the holes the bar of steel was kept in contact with this angle-bar. A uniform depth was insured by employing a bottoming-drill with a collar formed on the shank. The drilling was finished when this collar rubbed on the steel bar.