When this patent, after protracted fighting, was sustained by Judge Green in 1893, the Electrical Engineer remarked that the General Electric Company "must certainly feel elated" because of its importance; and the journal expressed its fear that although the specifications and claims related only to the maintenance of uniform pressure of current on lighting circuits, the owners might naturally seek to apply it also to feeders used in the electric-railway work already so extensive. At this time, however, the patent had only about a year of life left, owing to the expiration of the corresponding English patent. The fact that thirteen years had elapsed gives a vivid idea of the ordeal involved in sustaining a patent and the injustice to the inventor, while there is obviously hardship to those who cannot tell from any decision of the court whether they are infringing or not. It is interesting to note that the preparation for hearing this case in New Jersey was accompanied by models to show the court exactly the method and its economy, as worked out in comparison with what is known as the "tree system" of circuits--the older alternative way of doing it. As a basis of comparison, a district of thirty-six city blocks in the form of a square was assumed. The power station was placed at the centre of the square; each block had sixteen consumers using fifteen lights each. Conductors were run from the station to supply each of the four quarters of the district with light. In one example the "feeder" system was used; in the other the "tree." With these models were shown two cubes which represented one one-hundredth of the actual quantity of copper required for each quarter of the district by the two-wire tree system as compared with the feeder system under like conditions. The total weight of copper for the four quarter districts by the tree system was 803,250 pounds, but when the feeder system was used it was only 128,739 pounds! This was a reduction from $23.24 per lamp for copper to $3.72 per lamp. Other models emphasized this extraordinary contrast. At the time Edison was doing this work on economizing in conductors, much of the criticism against him was based on the assumed extravagant use of copper implied in the obvious "tree" system, and it was very naturally said that there was not enough copper in the world to supply his demands. It is true that the modern electrical arts have been a great stimulator of copper production, now taking a quarter of all made; yet evidently but for such inventions as this such arts could not have come into existence at all, or else in growing up they would have forced copper to starvation prices.[11]