The inventions for which valid patents have been granted may be roughly divided into the following classes :

1. New contrivances applied to new objects or purposes. 2. New contrivances applied to old objects or purposes. 3. New combinations of old parts, the subject-matter consisting either of material objects or of processes.

4. New methods of applying an old thing.

5. Processes or methods differing from old processes or methods only by the omission of a step.

6. Chemical processes, usually but not always in combination with mechanical contrivances.

The reader may like to have some illustrations of these classes of inventions, and we shall proceed to offer the following:

1. Of a new contrivance applied to a new object or purpose, the following is an instance:

Lace made from cotton had the defect of being covered with a kind of down, which injured its appearance and diminished its value. A similar defect was removed from muslin by passing it over rollers of heated iron, and from mits and stockings by the action of flame, fed by oil or alcohol. It occurred to Mr. Hall that the flame of gas might be employed in the manufacture of cotton lace; and after some failures he succeeded in inventing a method for removing the unsightly fibres by the flame of gas. A patent obtained for this invention was held good. (Hall v. Jarvis, 1 W. P. C. 100.)

2. A new contrivance employed to effect a well-known object to make, for instance, an article previously made in a different way-is also patentable, provided that the new contrivance is attended with some degree of utility; for example, that it accomplishes the result more cheaply than the old contrivance. This is, perhaps, the largest class of patented inventions. "There may be a valid patent" (said Lord Eldon in Hill v.

Thompson, 1 W. P. C. 237) " for a new combination of materials previously in use for the same purpose, or for a new method of applying such materials."

3. A combination of known parts, producing a new result, or producing an old result in a more economical manner or more perfect form, whereby articles cheaper or better than had ever before been produced are rendered accessible to the public, such combinations will be held meritorious and patentable inventions. It was held in Crane v. Price (1 W. P. C. 408) that the combination of the hot-air blast with stone coal in the smelting of iron (the hot-air blast and stone coal having been separately in use before, but the combination being previously unknown) was an invention intended by the statute, and such as might well become the subject of a patent. It was said by Tindal, C. J., that there were numerous instances of patents where the invention consisted in no more than in the use of things already known, and acting with them in a manner already known, and producing effects already known, but producing those effects so as to be more economically or beneficially enjoyed by the public.

That the novel combination of old parts having a useful result may form the subject of a valid patent has been again and again decided. (Lister v. Leather, 8 E. and B. 1004; Newall v. Elliott, 10 Jur. N. s. 954; S. C. 13 W. R. 11; Murray v. Clayton, L. R. 7 C. 570; Cannington v. Nuttall, L. R. 5 H. L. 205.) "If there be" (said Lord Westbury in Spencer v. Jack, 3 De G. J. & S. 346) "a combination of several things previously well known, which combination is attended with such results of utility and advantage to the public that the combination itself is rightly denominated a substantial improvement, it is impossible to deny that that is the subject of a patent." And see further as to combinations in the chapter on the Complete Specification.

4. A new mode of applying a known thing may be the subject of a patent, provided that some ingenuity, some novelty, is exhibited in the mode of making that application, and that the application is attended by some useful result. In Watt's patent for a new method of lessening the consumption of steam and fuel in steamengines, the enclosing of the cylinder in a case of wood, or any other material that transmits heat slowly, was claimed, and allowed to be a patentable invention. (Boulton v. Bull, 2 H. Bl. 463, 1 Carp. 117.) In Forsyth's patent, for a method of discharging fire-arms, the patentee claimed the use and application of certain known fulminating compounds for this purpose. It was contended that, since the properties of detonating powder were well known for other purposes, the using of such materials to discharge fire-arms was not a new manufacture for which a patent could be supported. But Abbot, C. J., stated that if the invention (i.e. this particular application of detonating powder) were new, it was such an one as might be secured by patent. The jury having found the invention to be a new one, the patentee had a verdict. (Forsyth v. Riviere, 1 Carp. 404.)

Charcoal had been used in refining sugar previously to Derosne's patent; but the old method was to mix charcoal powder with the syrup, and the new was to pass the syrup through beds of charcoal constructed in a particular manner. By the old process a considerable quantity of charcoal was taken up by the syrup, and this was an injury to the sugar. In Derosne's process this objection did not arise; and, moreover, it was applicable not only to the refinement of coarse sugar, but to the original manufacture of sugar out of cane-juice. In an action brought for infringing the patent, the originality of the invention was held not to be impeached by showing that there had been an earlier use of charcoal in the refinement of sugar. No

evidence was given that any other person, before the date of the plaintiff's patent, ever applied in use the particular mode of filtering syrup which the patent was intended to introduce: and in the absence of such evidence, Lord Abinger directed the jury to find for the plaintiff. (Derosne v. Fairie, 1 W. P. C. 154.)

In the case of Cornish v. Keene, a patent for improvements in the manufacture of elastic fabrics was contested. The patentee's object was to produce cloth from cotton flax, or other suitable material, not capable of felting, in which should be interwoven elastic cords of India-rubber coated with filamentous material. He described the mode of effecting this object to be by introducing into the fabric threads of India-rubber, applied as warp or weft, or as both, according to the direction of the elasticity required—the India-rubber threads having been stretched to their utmost tension and rendered non-elastic before being introduced into the fabric, and then being rendered elastic by the application of heat. It was contended that this was not a new manufacture; that it was neither a new manufacture, nor an improvement of an old manufacture, but was merely the application of a known material, in a known manner, to a purpose known before. "That it is a manufacture" (said Tindal, C. J., delivering the judgment of the Court of Common Pleas) "can admit of no doubt; it is a vendible article, produced by the hand and art of man. Whether it is new or not, or whether it is an improvement of an old manufacture, was one of the questions for the jury, upon the evidence before them; but that it came within the description of a manufacture, and so far is an invention which may be protected by a patent, we feel no doubt whatever. The materials, indeed, are old, and have been used before; but the combination is alleged to be, and if the jury are right in their finding, is new;

and the result or production is equally so. The use of elastic threads or strands of India-rubber, previously covered by filaments wound round them, was known before; the use of yarns of cotton, or other non-elastic material, was also known before; but the placing them alternately side by side together as a warp, and combining them by means of a weft when in extreme tension, and deprived of their elasticity, appears to be new; and the result, viz. a cloth in which the nonelastic threads form a limit up to which the elastic threads may be stretched, but beyond which they cannot, and therefore cannot easily be broken, appears a production altogether new. It is a manufacture at once ingenious and simple." (1 W. P. C. 517.)

A patent was granted for an improved mode of, and apparatus for, bending wood for the handles of walking sticks, &c., and the specification described the apparatus as being a vice for holding a stick, previously softened in moist sand, placed close to a hollow mandril, on which the bending was effected by sending a jet of lighted gas into it, and then securing the stick on the mandril by a strip of steel. The heat stiffened the fibres of the wood and the curvature was rendered permanent. In a suit to restrain the defendants from infringing the patent, its validity was called in question, on the ground that the invention was not new; but Page Wood, V.C., granted the injunction, saying: "When it is stated that because wood is bent by coachmakers and others in a variety of ways by the application of heat, you cannot have a patent for the application of heat to the bending of walking sticks, that is the same sort of reasoning that was pressed on the Court with reference to an invention for an improvement on navigation. It was said that the operation of a propelling power by presenting a screw propeller to the action of water was nothing new