This cause presents issues as to validity and infringement of claim 23 of the Stephens reissue patent, No. 16,360, for 'an improvement in needles and its (sic) method of use.' The Stelos Company, owner of the patent, sued Hosiery Motor-Mend Corporation and others for infringement. The District Court adjudged the claim invalid by reason of failure to make proper disclosure of the alleged invention, and anticipation; and also thought that, if the claim were sustained, the defendants did not infringe, and dismissed the bill. The Circuit Court of Appeals held the prior art required so narrow a construction of the claim as to exclude the method charged as an infringement and affirmed the decree. We granted certiorari to resolve a conflict with a decision of the Court of Appeals of the District of Columbia. In support of the judgment, the defendants might have urged the point as to invalidity, decided against them in the Circuit Court of Appeals, without applying for a cross-writ of certiorari. Out of excess of caution, however, they prayed for the writ. Since both writs would run to but one judgment and bring up the same record, we granted the prayer in No. 653.
To knit is to form a fabric by the interlacing of a single yarn or thread in a series of connected loops. In knitted articles, of which a silk stocking is an example, a break in the thread anywhere in the fabric will cause a number of loops to pull out, leaving in their place parallel threads. The consequent defect is called a ladder or a run. The only possible method of repair consists in picking up the thread at the end of the run and reknitting by reforming the loops throughout the ladder, fastening the thread upon the completion of the operation. It has long been known that this could be accomplished by the use of a needle having a hook at the end resembling an ordinary crochet needle, but the task involved difficulties and the result was often unsatisfactory.
Stephens' patent is for an improved latch needle for this work and for a method of executing the repair. Twenty-two claims for the needle are not in issue. Claim 23, which covers the method, is the basis of the suit. The method is stated in the patent to consist:
'In stretching the fabric over a suitable holder,
'Inserting a repairing device having a hook and pivoted latch through a loop formed in the run or raveling,
'Continuing this movement on through the fabric while holding the device laterally out of alignment with the run or raveling until the loop has slid back over the end of the latch and beneath the latter, 'Then reversing the movement of the device through the loop,
'Catching the next forward thread in the hook while the loop is being pulled over the latch causing the latch to close over the thread, and the loop to be cast off over the end of the device, the thread caught in the hook thereupon forming a new loop, taking the place of the first-described loop,
'Then reinserting the device into the fabric as before, and repeating the operating until the run or raveling has been repaired,
'And finally fastening the thread.'
In the commercial method practiced by the owner of the patent and its licensees, the fabric is stretched over the top of a china or porcelain eggcup held in the left hand. The degree of stretching can in this way be adjusted for the first step in the process and increased or relaxed as the work progresses. The needle is held in the right hand at an angle to the plane of the fabric and worked back and forth through the material. Whether the needle is also inclined laterally out of the line of the run is disputed. The patentee says this is unnecessary and is not in fact practiced. The defendants disagree, and contend that a pivoted latch needle will not otherwise perform its function. The alleged infringers employ a metal holder shaped like an eggcup and a sliding latch needle, which they punch through the material and draw back at approximately a right angle to the fabric.