NOVELTY IN PATENTS. 613 



shield, over which those two knights of old story wrangled so long, 

 an inspection of the subject from two points of observation decidedly 

 simplifies matters. The first of these methods of studying the subject 

 I would designate the negative, and the second the positive method. 

 By the negative method we deduce certain principles in regard to 

 cases which have at first sight a color of novelty, but are not novel, so 

 as to be patentable. By the positive method we arrive at certain con- 

 clusions in regard to what actually constitutes novelty in a patentable 

 sense. 



I propose to discuss, first : What cases, at first sight possessing 

 novelty, do not actually possess novelty ? A study of cases warrants 

 us in accepting, as a first principle, that every change or mere substitu- 

 tion of a mechanical equivalent is not necessarily a patentable novel- 

 ty ; for it may not be substantially unlike some prior thing. We may 

 have, for instance, a machine, comprising, say, three distinct parts. 

 A man, not the inventor, substitutes for each of these parts other 

 equivalents, producing the same results. This is not a patentable in- 

 vention. Even if the products be better or cheaper, it is at most only 

 an improvement upon a former invention, and can be used only with 

 the permission of the former patentee. 



I spoke above of a "mechanical equivalent." This needs to be 

 defined in order that we may have a clear comprehension of the above 

 principle. To define it, however, is not so easy. Mr. Parsons has said 

 that " he would be a very acute man who could certainly discern, or a 

 very bold man who would certainly assert, what is meant by a mechan- 

 ical equivalent." At the risk of being considered bold, certain judges 

 have, nevertheless, ventured to attack the Gordian knot. We find one 

 definition in Smith vs. Downing, 1 Fisher's Patent Cases, 87 : " By 

 equivalents in machinery is usually meant merely the substitution of 

 one mechanical power for another, or one obvious and customary mode 

 for another, of effecting a like result." This definition is not sufficient- 

 ly explicit. A better one is to be found in Carter vs. Baker, 4 Fisher's 

 Patent Cases, 409 : "When, in mechanics, one device does a particular 

 thing, or accomplishes a particular result, every other device known 

 and used in mechanics, which skillful and experienced workmen know 

 will produce the same result, or do the same particular thing, is a 

 known mechanical substitute for the first device mentioned for doing 

 the same thing, or accomplishing the same result. It is sufficient to 

 constitute a known mechanical substitute that, when a skillful mechanic 

 sees one device doing a particular thing, he knows the other device, 

 whose uses he is acquainted with, will do the same thing." 



This definition not only covers those elements which come strictly 

 under the head of mechanics, but is also our guide in determining 

 what constitutes an equivalent in an " art," or a " manufacture," or a 

 " composition of matter." The definition of an equivalent of any sub- 

 stance in a composition made of several ingredients, for example, is, in 



