The 4th declares that letters patent shall not give privilege to the patentee to use an invention for which patent has been obtained by another.
The 5th relates to the manner in which letters patent become void, if divided into more than a certain number of shares. The number of such shares used to be five, but all patents sealed since May, 1832, allow the interest to be divided between twelve persons or their representatives. This part also relates to the granting of licences.
The 6th contains a proviso that a full and accurate description or specification shall be enrolled by the patentee in a specified time.
The 7th directs the patent to be con strued in the most favourable manner for the inventor, and provides against inad vertency on the part of the clerk of the crown iu enrolling the privy seal bill.
Letters patent then only grant the sole use of an invention for a certain time, provided that the statement in the decla ration be true, that the title give a dis tinct idea of the invention, and that the specification be enrolled within a certain time mentioned in the patent, generally two months for England, four for Eng land and Scotland, and six for the three countries together. This time depends on the attorney or solicitor general, a longer or shorter period being granted according to the extent or difficulty of the invention ; in some instances two years have been allowed for specifying.
The object of the specification is two fold:— First, it must show exactly in what the invention consists for which a patent has been granted, and it must give a detailed account of the manner of effecting the ob ject set forth in the title. It must describe exactly what is new and what is old, and must claim exclusive right to the former : the introduction of any part that is old, or the omission of any part that is new, equally vitiates the patent.
In the second place, a patent is granted for a certain number of years on the con dition that such full and accurate inform ation shall be given in the specification as will enable any workman or other quali fied person to make or produce the object of the patent at the expiration of that Utrm without any further instructions. A specification is bad if it does not describe the means of doing all that the Ctle sets forth : it is equally bad if it describes the means of effecting some object not stated in the title: it is in complete if it mentions the use of one substance or process only, and it can be proved that the inventor made use of another, or that another known substance or process will answer the purpose as well ; and it is false if more than one substance or process is described as producing a certain effect, and it is found that any one of them is unfit to the purpose. Patentees frequently render their patents invalid by claiming too much; thus, after describ ing one substance or process which will answer a certain purpose, they often con clude by some such expression as " or any other fit and proper means." The follow ing is an instance in which a patent was set aside by such an expression. In spe cifying a machine for drying paper by passing it against heated rollers by means of an endless fabric, the inventor, after describing one sort of fabric, the only one in fact which he used, went on to say that any other fit and proper material might be used. Now if he used any other means
of effecting his object, such means should have been distinctly described. This alone rendered his specification incom plete ; but, besides this, it was proved that no other fabric would answer the pur pose, or rather, that no other was known, and the patent was annulled accordingly. The cases which have been already men tioned as -instances of bad titles will, by supposing the title to be good, be con verted into instances of bad specifications, as the invalidity arises from the title and specification not agreeing with each other.
The patentee may describe his inven tion just as he pleases, and he may illus trate such description by drawings or not ; but he should be careful to use words in their most common acceptation, or if some technical use should have pervert& d their meaning, he should make it appear distinctly that he intends them to be taken in such perverted sense. Subjoined is the form of the other part of the speci fication:— " To all to whom these presents shall come greeting, 1 the said (patentee's name and residence) send greeting. Whereas her most excellent Majesty Queen Vic toria, by her letters patent under the great seal of Great Britain, bearing date at Westminster, the day of in the year of her reign, did give and grant unto me, the said A. B., my execu tors, administrators, and assigns, her spe cial licence, full power, sole privilege, and authority, that I the said A. B., my executors, administrators, and assigns, and such others as I the said A. B., my exe cutors, administrators, and assigns, should at any time agree with, and no others, from time to time, and at all times here after during the term of years therein mentioned, should and lawfully might make, use, exercise, and vend within England, Wales, and the town of Berwick upon Tweed, and also in all her said Ma jt sty's colonies and plantations abroad (if such be the case), my invention of (here insert the title set forth in the letters patent verbatim); in such letters patent there is contained a proviso that 1 the said A. B. shall cause a particular descrip tion of the nature of my said invention, and in what manner the same is to be performed, by an instrument in writing under my hand and seal, to be enrolled in her said Majesty's High Court of Chan cery within calendar months next, immediately after the date of the said in part recited letters patent, reference being thereunto had may more fully and at large appear. Now know ye, that in compliance with the said proviso, I the said A. B. do hereby declare the nature of my invention and the manner in which the same is to be performed are particu larly described and ascertained in and by the following description thereof, refer ence being had to the drawings hereunto unnexed, and the figures and letters marked thereon, that is to say, my inven tion consists (here insert the description of the invention). In witness whereof I the said A. B. have hereunto set my hand and seal this day of , 1846.