383 FEDBBAL REPORTER. �braies in recent years, in connection with air and other power mechanically applied, is net a fair test of their relative ad- Tantages in former years when hand power exclusively was used; since, with the air power, the retarding force can be controUed to a nicety, and applied simultaneously to ail the wheels of the train, so that a much less force on each wheel is BufiScient to stop the train, and the risk of sliding wheels is much diminished. Nor do the special experimenta made by the defendant with the two brakes alternately, convince us that there is no choice between them in respect to causing brftkes to slide. In these experiments neither f orm of brake caused any wheels to slide. This the complainants contend is to be accounted for by the fact that the brake shoes used wereimade of hard polished steel, different from those for- merly used on the same railroad, and that the car being qiiite heavy it was hardly possible to apply force enough to make the shoes hold the wheels so as to cause any of them tp slide, There seems to us to be force in this suggestion. It a|)pear8 highly improbable that the defendant, having special need of the best form of brake, should, for nearly 30 years, have voluntarily and continuously used the Stevens brake on ail its passenger cars in the face of threatened litigation from the beginning, in the face of the decree of Judge Drummond in 1866 sustaining the patent and awarding $50 per car per year against the Chicago, Burlington & Quincy Eailroad Com- pany as the profits accruing to that railroad from its use, and in the face of the suit instituted against the defendant in this court in 1864, unless there had been very decided advantagea to be derived from its use. �The validity of the complainants' patent bas been estab- lislied: by the decrees heretofore passed in these cases, and the defendant is now before us in the attitude of a wrong- doer. It is necessary only for the complainants to show to the court before its master, by testimony, facts upon which compensation is to be based, and by which it may be computed, as clearly as circumstances will permit. That he has been wronged has been decided. The pecuniary meas- ure of that wrong is ail we have to ascertain. To prove accu- ��� �
