delivered the opinion of the court. He stated the facts in the foregoing language, and continued:

We are of opinion that the patent is open to the fatal objection that the device covered thereby did not, in vieiv of the ■ state of the art, involve the exercise of invention, and Avas therefore not patentable.

The simply working of a capstan by means of steam is not claimed, but, in the amended specification filed February 7, 1856, is expressly disclaimed. The capstan and the auxiliary *248 engine are both old, the device, consisting in an arrangement of shafts and cog wheels by which the power of the engine is applied to the capstan, was, as averred in the answer, in common public use in flour and grist mills, and cotton and woollen factories, long prior to the alleged invention of McMillin. The testimony shows that both capstans and auxiliary engines have been commonly placed forward of the boilers of the boat, and that, as early as the year 1847, an auxiliary engine had been used for rotating a windlass, both the engine and the windlass being forward of the boilers. ■ •

In view of these facts, which are either matters of common khowledge or well established by the evidence, the only field of invention left for the patent to cover was the application, by the old and familiar arrangement of shafts and cog wheels, of the power of an auxiliary engine to a capstan instead of a windlass. A capstan differs from a windlass in this respect only, that its barrel or shaft is vertical, while that of the windlass is usually horizontal. It is plain, therefore, that no such ingenuity as merited the issue of a patent was required for- this improvement, but only the ordinary judgment and skill of a trained mechanic.

The following cases illustrate the grounds upon which we base this conclusion:

It was said by Mr. Justice Bradley, in delivering the judgment of this court in Atlantic Works v. Brady, 107 U. S. 192: “ The process of development in manufactures creates a constant demand for new appliances which the skill of ordinary head workmen and engineers is generally adequate to devise, and which, indeed, are the natural and proper outgrowth of such development.1 Each step forward .prepares the way for the next, and each is usually taken by spontaneous trials and attempts in a hundred different directions. To grant to a single party a monopoly of every slight advance made, except where the exercise of invention somewhat above ordinary mechanical or engineering skill is distinctly shown, is unjust in principle and injurious in its consequences.”

In Pennsylvania Railroad v. Locomotive Truck Co., 110 U. S. 490, Mr. Justice Gray, speaking for the court, declared *249 it to be tbe result of the decisions of the court that “ the application of ian old process or machine to a similar or analogous subject, with no change in the manner of application and no result substantially distinct in its nature, will not sustain a patent, even if the new form of result has not been before contemplated.”

In Hailes v. Van Wormer, 20 Wall. 353, where the patentee had taken a fire-pot from one stove, a flue from another, and a coal reservoir from the third, and had put them into a new stove, where each fulfilled the office it had fulfilled in its old situation, and nothing more, the patent was held void for want of invention.

In the case of Phillips v. Detroit, 111 U. S. 604, the patent' sued on was for an improvement in street and other highway pavements. The improvement consisted in using round blocks of wood, formed of the sections of small trees, set vertically upon a foundation of -sand or gravel, and filling the spaces between the blocks with sand or gravel. The court said that the use of blocks, such as were described, set vertically, was old, that the foundation was old,-and the use of filling between the blocks was old, and that the' only thing left for the patent tp cover was the bringing together, in the construction of a pavement, of these three old and well-known elements; and held that, this did not require invention, and that the patent was void. See also Hotchkiss v. Greenwood, 11 How. 248; Phillips v. Page, 24 How. 164; Smith v. Nichols, 21 Wall. 112; Dunbar v. Myers, 94 U. S. 187; Heald v. Rice, 104 U. S. 737, 754-756.

Hpon the ground stated, we think the letters patent upon which this suit is based are void. The decree of .the Circuit Court, by which tbe patent was sustained, must therefore be reversed, and

The cause remanded with directions to dismiss the bill; and it is so ordered.