Practical Observations concluding John Davies's Patent Cases (1816)
Installment 2 of 6: Unpatentable Subject Matter and “Principles”

Reproduced below is material from Practical Observations concluding John Davies, A Collection of the most Important Cases relating to Patents of Invention (1816). In view of its length and detail, this concluding section of the book is being posted on the blog in six installments.
This second installment concerns what is patentable subject matter. Case law started to develop distinguishing between processes and improvements to processes that resulted in vendible manufactures, considered to be eligible subject, and “principles”, considered to be ineligible subject matter. The cases most often cited by John Davies are Boulton v. Bull and Hornblower v. Boulton.

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Having shewn what is the subject of a patent, it now becomes necessary to cite some authorities shewing what is not the subject of a patent.
A principle cannot be a ground for a patent, because it is the first ground and rule for arts and sciences, or, in other words, the elements and rudiments of them: a patent must be for some new production from those elements, and not for the elements themselves. [NOTE: Mr. Justice Buller, in Boulton v. Bull, p. 196.]
If a principle alone be the foundation of a patent, it cannot possibly stand, though the invention may be a great improvement, yet the patent must be void ab initio. [NOTE: Ibid. p. 197.]
A patent must be for vendible matter, and not for a principle. The organization of a machine may be the subject of a patent, but principles cannot. A patent for the application of a principle, must be as bad as a patent for the principle itself. It seems impossible to specify a principle and its application to all cases; which furnishes an argument that it cannot be the subject of a patent. [NOTE: Mr. Justice Heath, in Boulton v. Bull, p. 192, 193.]
There can be no patent for a mere principle; but for a principle so far embodied and connected with corporeal substances, as to be in a condition to act and to produce effects, there may be a patent. [NOTE: Sir James Eyre, in Boulton v. Bull, p. 212.]
But if a patentee sets forth his invention intelligibly, his specification should be supported, though he professes only to set forth the principle. The term “principle” is equivocal; it may denote either the radical elementary truths of a science, or those consequential axioms which are founded on radical truths, but which are used as fundamental truths by those who do not find it expedient to have recourse to first principles. [NOTE: Mr. Justice Rooke, in Boulton v. Bull, p. 186.]
If a mechanical improvement is intelligibly specified, whether the patentee calls it a principle, invention, or method, or by whatever other appellation, the court are not bound to consider his terms, but the real nature of his improvement, and the description he has given of it, and may protect him without violating any rule of law. [Ibid. p. 187.]
A patent cannot be granted for a mere principle; yet if the thing is to be made or done by a manufacture, and the mode of making that manufacture is described, it then becomes an effect, but whatever name it may be called, not a patent for a mere principle, but for a manufacture, for the thing so made, and not for the principle upon which it is made. [Mr. Justice Grose, in Hornblower v. Boulton, p. 234, 235.]
It appears, therefore, from these authorities, that there cannot be a patent for a mere philosophical principle, neither organized nor capable of being so; but that a patent for a machine improved by a philosophical principle, though the machine existed before, is good.
The grant of a method is not good because uncertain; the specification of a method or of the application of a principle is equally so. [Mr. Justice Heath, in Boulton v. Bull, p. 198.]
The method or mode of doing a thing are the same, a patent cannot be supported for a method only, without having carried it into effect, and produced some new substance. Unless a patent can be supported for a manufacture, it cannot be supported at all. [NOTE: Mr. Justice Buller, in Boulton v. Bull, p. 198.] A method of doing a thing, without the thing being done, or actually reduced into practice, is not a good foundation for a patent; when the thing is done or produced, then it becomes the manufacture, and is the proper subject for a patent. [NOTE: Ibid. p. 199.]
In words the privilege granted is to exercise a method of making or doing any thing, yet if that thing is to be made or done by a manufacture, and the mode of making that manufacture is described in the specification, it then becomes an effect, but whatever name it may be called [NOTE: Mr. Justice Grose, in Hornblower v. Boulton, p. 235.]
Patents for a method or art of doing particular things have been so numerous, that method may be considered as a common expression in instruments of this kind; it would therefore be extremely injurious to the interests of patentees, to allow this verbal objection to prevail. [NOTE: Mr. Justice Rooke, in Boulton v. Bull, p. 185.]
Mr. Hartley,s invention for securing buildings from fire is no substance or composition of things, it is a mere negative quality, the absence of fire: the effect is produced by a new method of disposing iron plates in buildings, the patent therefore could not be for the effect produced, nor for making the plates of iron, which, when disposed in a particular manner, produce the effect, for those are things in common use; but for the method of disposing those plates of iron so as to produce the effect, and that effect being a useful and meritorious one, the patent was very properly granted to him for his method of securing buildings from fire. Plates of iron are the means employed, but he did not invent those means; the invention wholly consisted in the new method of using, or rather disposing of a thing in common use, which every man may make. [NOTE: Sir James Eyre, in Boulton v. Bull, p. 208, 209.]
It appears therefore that if a patentee denominate his discovery “a method,” when in fact the thing invented is something substantial, or a new and useful effect, produced by a new application of means before in use, the verbal inaccuracy will not vitiate the grant.
If a man by science devise the means of making a double use of a thing known before, he could not have a patent for it. [NOTE: Mr. Justice Buller, in Boulton v. Bull, p. 197.]