Practical Observations concluding John Davies's Patent Cases (1816)
Installment 5 of 6: Enablement and Best Mode

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 fifth installment concerns the case law requiring inventors to supply specifications that enable those with ordinary skill in the art to construct the invention, and requiring the specification to explain the best mode. It seems that judges in the period 1785—1816 were very strict in applying these enablement and best mode requirements: deficiencies in the specification resulted in the patent being deemed invalid.

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We now come to treat upon a very important part of the subject, and one upon which most of the cases have chiefly turned, and which consequently requires the greatest attention in order to support a patent, namely, what is the description required in the specification.
It was said by Lord Eldon, in Cartwright v. Amatt, that patents are to be considered as bargains between the inventors and the public, to be judged on the principle of good faith, by making a fair disclosure of the invention, and to be construed as other bargains.
It is clearly settled as law, that a man to entitle himself to the benefit of a patent must disclose his secret, and specify his invention in such a way that others may be taught by it to do the thing for which the patent is granted: if the specification be in any part materially false or defective, the patent cannot be supported; but if the specification be such that mechanical men of common understanding can comprehend it, to make the thing by it, it is sufficient; but it must be such that they may be able to make the thing by the specification, without any new inventions or additions of their own. [NOTE: Mr. Justice Buller, in The King v. Arkwright, p. 105.]
A specification is insufficient if a man of ingenuity be required to supply its defects. If sensible men that know something of the business, and mechanics in general, cannot by the specification make the thing invented, it is not so described as to support the patent. [Ibid. p. 128.]
The clearness of the specification must be according to the subject matter of the invention; it is addressed to persons in the profession, having skill in the subject, not to men of ignorance, and if it is understood by those whose business leads them to be conversant in such subjects, it is intelligible. [NOTE: Lord Loughborough, in Arkwright v. Nightingale, p. 56.]
If it appears that a mechanic could not from the specification make an engine with equal effect, or if it required expense and experiments before it could be done, either of those facts would avoid the patent. [NOTE: Mr. Justice Buller, in Boulton v. Bull, p. 194.]
But if the specification be such as to enable artists to adopt the invention, and make the manufacture, it is sufficient; the specification is to be considered as part of the patent. The benefit to the public is from the specification disclosing to the world how others may make and use the same manufacture. To learn what the patent is, you may read the specification and consider it as incorporated with the patent. [NOTE: Mr. Justice Grose, in Hornblower v. Boulton, p. 228, 229, 230.] The patent is nothing without the specification; whether the patent call the manufacture by its name, or style it an invention, a mode, a method, or in any other manner, it signifies nothing, for the specification describing the thing must be resorted to, and my fairly be deemed a part of the patent itself. [NOTE: Ibid. 235.]
It is incumbent on the patentee to give a specification of the invention in the clearest and most unequivocal terms of which the subject is capable; and if it appear that there is any unnecessary ambiguity in the specification, or any thing which tends to mislead the public, the patent is void. [Mr. Justice Ashhurst, in Turner v. Winter, p. 151.] Also if the process as direct by the specification does not produce that which the patent professes to do, the patent is void. The terms of the specification should express the invention in the clearest and most explicit manner, so that a man of science may be able to produce the thing intended, without the necessity of trying experiments. [NOTE: Ibid. p. 152.]
If a thing could only be made with two or three ingredients specified, and the patentee has inserted others which will not answer the purpose, that will avoid the patent. So if he makes the article with cheaper materials than those he has enumerated, although the latter will answer the purpose equally well, the patent is void, because he does not put the public in possession of his invention, or enable them to derive the same benefit which he himself does; slight defects in the specification will be sufficient to vacate the patent. [NOTE: Mr Justice Buller, in Turner v. Winter, p. 154, 155.]
In a case before Lord Mansfied, for infringing a patent for steel trusses, it appeared that the patentee in tempering the steel rubbed it with tallow, which was of some use in the operation, and because this was omitted, the specification was held to be insufficient, and the patent was avoided. [NOTE: Liardet v. Johnson, cited by Mr. Justice Buller in Turner v. Winter, p. 155.]
If a concealment in a specification is not fraudulent but merely inadvertent, if the patentee actually know and meant to practice that mode, and inadvertently did not state the whole in his specification, he must answer for is inadvertence. [Sir Vicary Gibbs, in Bovill v. Moore, p. 414.]
A patent had been granted for a new manufacture of lace, the specification went generally to the invention of mixing silk and cotton thread upon the frame; it was proved that silk and cotton thread had been mixed upon the same frame prior to the patent, although too coarse for lace. The patent not being for any particular mode of mixing, but for making lace of silk and cotton thread mixed, and it having been proved and admitted that silk and cotton thread were before mixed on the same frame in some mode or other, the patent was declared void. [Mr. Justice Buller, in The King v. Else, p. 143.]
Three objections were taken to a specification; first, that after directing lead should be calcined, it directed another ingredient (minium) to be taken, which would not answer the purpose, neither was it said that the minium should be calcined or fused, but if it had reference to the preceding words, then it should be calcined, which would not produce the effect, fusion being necessary. Secondly, that fossil salt was improperly mentioned, there being many kinds of fossil salt, only one of which (sal gem) would answer the purpose, because it must be a marine salt. And thirdly, that all these things put together did not produce the thing intended, and that the patent was for an invention to do three things in one process, whereas one of them could not be produced at all. If either of these objections are well founded, it will avoid the patent. [NOTE: Mr. Justice Buller, in Turner v. Winter, p. 148, 149.]
If a man states in his specification that which is not new, though it was unnecessary for him to do so, he has overstepped his right, and has included that which is not his invention; in that respect his patent is void. [Lord Ellenborough, in Huddart v. Grimshaw,, p. 279.] If he embraces within his invention, as essential parts, any thing which was a part of a prior invention communicated to the public, he has no right to such benefit: no deceptive things are to be held out to the public, those that are material are to be held out as material. [Ibid. p. 294, 295.]
A patentee is bound to confine himself to that which is his invention, and if in the specification he has exceeded the limits of what he has invented, and of which he is intitled to the sole privilege, though in other respects there may be no objection to his patent, that will overturn it, for he will not then have registered a specification of his invention; it will be irregular, in having exceeded the limits of that invention. [Sir Vicary Gibbs, in Bovill v. Moore, p. 390.]
Although an invention be new and beneficial to the public, yet if the plaintiff has in his specification asserted to himself a larger extent of invention than belongs to him; if he states himself to have invented that which was well known before, then the specification will be bad, because that will affect to give him, through the means of the patent, a larger privilege than could legally be granted to him. [Sir Vicary Gibbs, in Bovill v. Moore, p. 404.]
If there existed at the time of taking out a patent engines of which the subject of the patent was only an improvement, then the patent ought to have been only for the improvement; and if the patent could have been supported for an engine, the specification ought to have pointed out those parts only which were the new invention as those to which the privilege applied. [Ibid. p. 411.]
If any material alteration be made from what was before in use, it ought to be specified. If articles are put into a specification merely to puzzle, or which are not useful for the purpose of the patent, the patent is void; for it is not that fair, full, and true discovery which the public have a right to demand. [Mr. Justice Buller, in The King v. Arkwright, p. 118.]
A patent, the object of which was described in the specification to be a perforation in the hammer of a gun-lock for the purpose of letting the air from the barrel pass through, and at the same time secure the powder from passing through, if the perforation permits the powder to pass through with the air, cannot be supported. [NOTE: Lord Chief Baron Thomson, in Manton v. Parker, p. 332.]
It is not necessary to set forth a model or drawing, provided the patentee so describes the invention as to enable artists to adopt it when his monopoly expires. Had a drawing or model been made, and any man copied the improvement and made a machine in a different form, no doubt this would have been an infringement of the patent, because the mechanical improvement would have been introduced into the machine, though the form was varied; the mechanical improvement, and not the form of the machine, is the object of the patent. [NOTE: Mr. Justice Rooke, in Boulton v. Bull, p. 187.]
Articles of a specification which denote intention only, and do not state the thing to which it is to be applied, will not entitle a patentee to maintain an action for a breach of those articles; for he cannot anticipate the protection before he is entitled to it by practical accomplishment. [NOTE: Ibid. p. 187, 188.]
Another consideration respecting the specification, which is also a material one, is whether the patentee has given a full specification of his invention, not only one that will enable a workman to construct a machine answering to the patent, but one that will enable a workman to construct a machine answerable to the patent to the extent most beneficial within the knowledge of the patentee at the time; for a patentee who has invented a machine useful to the public, and can construct it in one way more extensive in its benefit than in another, and states in his specification only that mode which would be least beneficial, reserving to himself the more beneficial mode of practising it, although he will have so far answered the patent as to describe in his specification a machine to which the patent extends, yet he will not have satisfied the law by communicating to the public the most beneficial mode he was then possessed of, for exercising the privilege granted to him. [NOTE: Sir Vicary Gibbs, in Bovill v. Moore, p. 400.]