of the opinion and decision of the Commissioner, stating the particular grounds of his objection, and the part or parts of the invention which he considers as not entitled to be patented. And the said board shall give reasonable notice to the applicant, as well as to the Commissioner, of the time and place of their meeting, they may have an opportunity of furnishing them with such facts and evidence as they may deem necessary to a just decision; and it shall be the duty of the Commissioner to furnish the board of examiners with such information as he may possess relative to the matter under their consideration. And on an examination and consideration of the matter by such board, it shall be in their power, or of a majority of them, to reverse the decision of the Commissioner, either in whole or in part; and their opinion being certified to the Commissioner, he shall be governed thereby, in the further proceedings to be had on such application; Provided, however, That before a board shall be instituted in any such case, the applicant shall pay to the Commissioner the sum of

dollars, which shall be in full compen. sation to the persons who may be so appointed, for their examination and certificate as aforesaid.

Sec. 8. And be it further enacted, That whenever an application shall be made for a patent, which, in the opinion of the Com-missioner, would interfere with any other patent for which an application may be pending, or with any unexpired patent which shall have been granted, it shall be the duty of the Commissioner to give notice thereof to such applicants, or patentees, as the case may be; and if either shall be dissatisfied with the decision of the Commissioner on the question of priority or right of invention, he may appeal from such decision, on the like terms and conditions as are provided in the preceding section of this act: and the like proceedings shall be had to determine which, or whether either of the applicants is entitled to receive a patent as prayed for.

Sec. 9. And be it further enacted, That before any application for a patent shall be considered by the Commissioner as aforesaid, the applicant shall pay into the Treasury of the United States, or into the Patent-office, or into any of the deposit banks, to the credit of the Treasury, if he be a citizen of the United States, or an alien, and shall have been resident in the United States for one year next preceding, and shall have made oath of his intention to become a citizen thereof, the sum of forty dollars: if a subject of the King of Great Britain, the sum of five hundred dollars; and all other persons the sum of three hundred dollars; for which payment duplicate receipts shall be taken, one of which to be filed in the office of the

Treasurer. And the monies received into the Treasury under this act shall constitute a fund for the payment of the salaries of the officers and clerks, herein provided for, and all other expenses of the Patent-office, and to be called the Patent Fund.

Sec. 10. And be it further enacted, That where any person hath made, or shall have made, any new invention, discovery, or improvement, on account of which a patent might by virtue of this act be granted, and such person shall die before any patent shall be granted therefor, the right of applying for and obtaining such patent shall devolve on the executor or administrator of such person, in trust for the heirs at law of the deceased, in case he shall have died intestate; but if otherwise, then in trust for his devisees, in as full and ample manner, and under the same conditions, limitations, and restrictions, as the same was held, or might have been claimed or enjoyed by such person in his or her lifetime; and when application for a patent shall be made by such legal representatives, the oath or affirmation provided in the third section of the beforementioned act, shall be so varied as to be applicable to them.

Sec. 11. And be it further enacted, That every patent issued in pursuance of this act shall be assignable in law, either as to the whole interest. or any undivided part thereof, by any instrument in writing; which assignment shall be recorded in the Patent-office within three months from the execution thereof, for which the assignee shall pay the Commissioner the sum of dollars.

Sec. 12. And be it further enacted, That any citizen of the United States, or alien, who shall have been resident in the United States one year next preceding, and shall have made oath of his intention to become, a caveat setting forth the design and purpose thereof, and its principal and distinguishing characteristics, and praying protection of his right, till he shall have matured his invention; which caveat shall be filed in the confidential archives of the office, and preserved in secrecy. And if application shall be made by any other person within one year from the time of filing such caveat, for a patent of any invention with which it may in any respect interfere, it shall be the duty of the Commissioner to give notice to the person filing the caveat, of such application and of such supposed interference, who shall, within two months after receiving the notice, if he would avail himself of the benefit of his caveat, file his description, specifications, drawings, and model; and if, in the opinion of the Commissioner, the specifications of claim interfere with each other, like proceedings may be had in all respects, as are in this act provided in the case of interfering appli

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cations: Provided, however, That no opinion or decision of any board of examiners, under the provisions of this act, shall preclude any person interested in favour of or against the validity of any patent which has been or may hereafter be granted, from a citizen thereof, who shall have invented any new art, machine, or improvement thereof, and shall desire further time to mature the same, may file in the Patent-office the right to contest the sathe in any judicial court, having jurisdiction of the subject-matter.

Sec. 13. And be it further enacted, That whenever any patent which has heretofore been granted, or which shall hereafter be granted, shall be inoperative or invalid, by reason of a defective or insufficient description or specification, or by reason of the patentee claiming in his specification as his own invention, more than he had or shall have a right to claim as new; if the error has, or shall have arisen by inadvertency, accident, or mistake, and without any fraudulent or deceptive intention, it shall be lawful for the Commissioner, upon the surrender to him of such patent, and the payment of a further duty of fifteen dollars to cause a new patent to be issued to the said inventor, for the same invention, for the residue of the period then unexpired for which the original patent was granted, in accordance with the patentee's corrected description and specification. And in case of his death, or any assignment made by him of the original patent, a similar right shall vest in his executors, administrators, or assignees. And the patent, so re-issued, together with the corrected description and specification, shall have the same effect and operation in law, on the trial of all actions relative to the violation of such invention, as, though the same had been originally filed in such corrected form, before the serving out of the original patent. And whenever the original patentee shall be desirous of adding the description and specification of any new improvement of the original invention or discovery which shall have been invented or discovered by him subsequent to the date of his patent, he may, like proceedings being had in all respects, as in the case of original applications, and on the payment of fifteen dollars, as herein before provided, have the same annexed to the original description and specification; and the Commissioner shall certify, on the margin of such annexed description and specification, the time of its being annexed and recorded; and the same shall thereafter stand on the same footing to all intents and purposes as though it had been embraced in the original description and specification.

Sec. 14. And be it further enacted, That whenever in any action for damages for using or selling the thing whereof the exclu

sive right is secured by any patent heretofore granted, or by any patent which may hereafter be granted, a verdict shall be rendered for the plaintiff in such action, it shall be in the power of the court to render judgment for any sum above the amount found by such verdict as the actual damages sustained by the plaintiff, not exceeding three times the amount thereof, according to the circum stances of the case; and such damages may be recovered by action on the case, in any court of competent jurisdiction.

Sec. 15. And be it further enacted, That the defendant in any such action shall bec permitted to plead the general issue, and to give this act and any special matter in evidence of which notice in writing may have been given to the plaintiff or his attor. ney, thirty days before trial, tending to prove that the description and specification filed by the plaintiff does not contain the whole truth relative to his invention, or discovery, or that it contains more than is necessary to produce the described effect; which concealment or addition shall fully appear to have been made for the purpose of deceiving the public; or that the thing patented was nota originally discovered by the patentee, or had been in use, or had been described in some public work anterior to the supposed diseo very thereof by the patentee, or had been in public use or sold with the consent and allowance of the patentee before his applica→ tion for a patent; or that he had surreptitiously or unjustly obtained a patent for that which was, in fact, invented or discovered by another; or that the patentee, if an alien at the time the patent was granted, had failed and neglected, for the space of eighteen months from the date of the patent, to put in operation and use in the United States, and put on sale to the citizens thereof, on reasonable terms, the invention or discovery for which the patent issued; or in case the same, for any period of eighteen months after it shall have been put in operation and use, shall cease to be so used or put on sale; in either of which cases judgment shall be rendered for the defendant with costs; provided, however, that whenever the plaintiff shall fail to sustain his action on the ground that, in his specification of claim is embraced more than that of which he was the first inventor, if it shall appear that the defendant had used or violated any part of the invention justly and truly specified and claimed as: new; it shall be in the power of the court to adjudge and award as to costs as may appear to be just and equitable.

Sec. 16. And be it further enacted, That whenever there shall be two interfering pa tents, or whenever a patent on application shall have been refused on an adverse decision of a board of examiners on the ground

that the patent applied for would interfere with an unexpired patent previously granted, any person interested in any such patent, either by assignment or otherwise, in the one case, and any such applicant in the other case, may have remedy by bill in equity; and the court having cognizance thereof, on notice to adverse parties and other due proceedings had, may adjudge and declare either of the patents void in the whole or in part, and may also adjudge that such applicant is entitled, according to the principles and provisions of this act, to have and receive a patent for his invention as specified in his claim, or for any part thereof, as the fact or priority of right or invention shall in any such case be made to appear. And such adjudication if it be in favour of the right of such applicant, shall authorise the Commissioner to issue such patent, on his filing a copy of the adjudication, and otherwise complying with the requisitions of this act. Provided, however, that no such judgment or adjudication shall effect the rights of any person except the parties to the action, and those deriving title from or under them subsequent to the rendition of such judgment.

Sec. 17. And be it further enacted, That all actions, suits, controversies, and cases arising under any law of the United States, granting or confirming to inventors the exclusive right to their inventions or discoveries, shall be originally cognizable, as well in equity as at law, by the circuit courts of the United States, or any district court having the powers and jurisdiction of a circuit court, which courts shall have power, upon bill in equity filed by any party agrieved in any such case, to grant injunctions according to the course and principles of courts of equity, to prevent the violation of the rights of any inventor as secured to him by any law of the United States, on such terms and conditions as said courts may deem reasonable: Provided, however, That from all judgments and decrees of any such court rendered in the premises, a writ of error or appeal, as the case may require, shall lie to the Supreme Court of the United States, in the same manner and under the same circumstances, as is now provided by law in other judgments and decrees of circuit courts, and in all other cases in which the court shall deem it reason. able to allow the same.

Sec. 18. And be it further enacted, That there shall be provided for the use of said office, a library of scientific works and periodical publications, both foreign and American, calculated to aid and facilitate the discharge of the duties hereby required of the chief officers therein, to be purchased under the direction of the Committee of the Library of Congress. And the sum of

dollars annually is hereby appropriated for that purpose, to be paid out of the patent fund.

Sec. 19. And be it further enacted, That it shall be the duty of the Commissioner to cause to be classified and arranged, in such rooms or galleries as may be provided for that purpose, in suitable cases, when necessary for their preservation, and in such manner as shall be conducive to a beneficial and favourable display thereof, the models and specimens of compositions and of fabrics and other manufactures and works of art, patented or unpatented, which have been or shall hereafter be deposited in aid office. And said rooms or galleries shall be kept open during suitable hours for public inspection.

Sec. 20. And be it further enacted, That all acts and parts of acts heretofore passed on this subject be, and the same are hereby, repealed: Provided, however, That all a tions and processes in law or equity sued out prior to the passage of this act, may be prosecuted to final judgment and execution, in the same manner as though this act had not been passed, excepting and saving the application to any such action, of the provisions of the fourteenth and fifteenth sections of this act, so far as they may be applicable thereto.

CIRCULATING DECIMALS.

Sir,-Your correspondent, Mr. A. Peacock, seems to be offended at the remarks I made on his rules for circulating decimals. He, no doubt, fancies that it was arrogant in me (a mere country teacher) to dare to question what he, A. P. (a town teacher) chose to assert. He tells me, "that I have done wisely in not giving my name, &c.;" in answer to this I shall only remark, that the scientific readers of the Mechanics' Magazine will be the best judges which of us have most cause to be ashamed of our name.

Mr. Peacock states, "that a very short time enabled him to find out two fractions, which, if not identical, very closely resemble those referred to." Yes, I will allow that all fractions when expanded into decimals, and all agreeing to seven places, must be very nearly equal to one another; so much so, that although we were to prefix as many figures after the seventh place as would extend from Whitechapel to Kensington, we would not increase the sum by the ten thousandth part of a farthing, supposing

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4256781 to be the decimal of a £. Perhaps it might be for some reason of this kind that many of our books of arithmetic and encyclopedias have avoided saying much upon this hair-splitting part of arithmetic. Many writers on arithmetic, however, have gone fully into the subject, among whom we may notice Malcolm, Mair, and Hamilton. The subject has also been fully investigated by many writers on algebra when treating on the subject of geometrical progression. The two fractions Mr. Peacock gives 8302 19503

in answer to my question, are

and

1177 2765 cimals, 425678100+ and 425678119+; but I must inform him, that neither the one nor the other are the fractions, nor are they exactly of the same value to those I had fixed upon-indeed, I would have considered it as nearly approaching to a miracle if he could have found them out. But did he find out the above fractions from his own rule? I say at once he did not. Mr. Peacock rather peevishly remarks, that it was certainly an oversight of his, &c.-see p. 198. Now, Mr. Peacock himself, in illustrating his rule, assumed only seven places of decimals (G. C. L. took the same number); and yet he finds fault with me because I did not give him more than seven places. But I shall tell him why I did not give him more than seven-for this best of all reasons, that neither of the decimals consisted of more than eight places; so that had I given him more than seven, he would have had them altogether. But even with this hint, he cannot yet (with any prospect of certainty) tell me what the two fractions are which I had fixed upon-either by his own rule, or that of continued fractions.

, which produce the corresponding de

I should now go on to notice the false principles which Mr. Peacock has promulgated on incommensurable quantities, but as this subject will occupy a considerable space, I must reserve it for another week.

I am, Sir,

Your obedient servant,

A COUNTRY TEACHER.

SLATE TOP FOR WASH-HAND STANDS."

Sir, The Carnarvon blue slate, like India-rubber, is used for various purposes. Could it not be used for the table part of wash-hand stands ?* Not that it would be as beautiful as white marble, but that it would be handsomer than painted wood, with the paint half washed off, which is too often the case with that article of furniture. After polishing the slate, were figures cut in it, possibly it might be made to retain paint; or a kind of mosaic work might be made of it by inserting pieces of white marble in it; or other means might be used to ornament it. Yours, &c.

AN AMATEUR MECHANIC.

SHORT AND LONG SCREW-DRIVERS.

Electric or minor elementary matter lessens pressure on a body, owing to the momentum of its atoms being as their size; to which may be added, the farther from the source of power, the more reduced is the effect, which is exempli fied in any system of machinery depending on a single motive power, and turning an extended spindle, the motion of which keeps remote mechanism in motion. The more simple exemplification is that of a turn-screw and the hand. The carpenter imagines, that with equal force of hand a long turn-screw is more powerful than a shorter, because the longer turns a rusty screw, which by a shorter cannot be moved. The fact is, power is lost by the long one: resistance it is which is reduced. The longer is the lesser power. In screwing, the force is in the direction of the required effect forward; in unscrewing, it is the same to produce the contrary effect. A screw of difficult removal is much pressed in a direction the contrary of what is wanted; to make it ascend is the object-pressing it into the wood, the act. In unscrewing, the hand uses its force in two directions -forward, to keep the tool in the slit of the screw; rotary to produce the turning, and consequent ascent of the screw. Lessening the forward force on a screw is the object gained by the longer instru ment; the whole of which forward force is got rid of, when the screw has a head

This application of slate has already been made by Mr. Stirling. See Mech. Mag. p. 231.

which admits of a winch.

The tool may be uselessly long; the forward force by the hand being as before, it may be insufficient to command the position of the tool in the slit, and too weak to produce any turning effect; or should the slit be deep enough, the greatest effect will be on some part of the blade of the tool in a twisting direction. The carpenter little thinks that his exertion is employed oppositely to his intention or against himself, the turning effort by one hand having to overcome the forward effort by the other. -Pasley's Natural Philosophy.

RECENT AMERICAN PATENTS. (Selected from the Franklin Journal, for May.)

DOFFER FOR WOOL-CARDING MACHINES, Stephen R. Parkhurst, Providence, Rhode Island.-Instead of a continuous cylinder, this doffer is composed of a set of wheels, or pulleys, of equal diameter with the common doffer, covered with a card in the same way, of three or four inches thickness at the rims, to revolve like the common doffer, placed upon their shaft, an ineh or an inch and a half apart, and at a small angle and parallel with each other, and making such an angle with the shaft as that the spaces between may be fully compensated in their revolution, and the whole surface of the main cylinder be passed over by them; and their rims, or outer surfaces, must be parallel to their shaft, so as to conform to the surface of the main cylinder. Next, there is a set of pulleys, called division rollers; these may be about four inches in diameter, for a common doffer, of the same thickness with the spaces between the different rims, or pulleys, of the doffer, placed upon their shaft at the same angle, turned by a belt, or gear, placed before the doffer, with their shaft a little lower than the shaft of the doffer, and so placed that their outer edges will be a little within the rims of the doffer, for the purpose of keeping the wool on the different parts, or wheels, of the doffer, entirely separate, as it is taken off by the top rolls, hereinafter described. The next are a set of pulleys, or wheels, or rims, called the top rolls; they are equal in number to the different rims of the doffer, four or five inches in diameter; they may be a little less in thickness than

the width of the different rims of the doffer, so that the division rolls may revolve freely between them, placed so as to revolve in contact with their correspondent rims of the doffer, for the pur pose of taking the wool from it, and so placed as that they will so bear upon the shaft of the division rolls as to be turned by it. A comb, if necessary, may be attached to this doffer, to clear the wool from it. The wool taken from the doffer by these top rolls, kept in separate laminæ, or flakes, by the division rolls, drawn over the shaft of the division rolls, may be passed through a tube, or a belt, and then run on a spool, or spools; or, by a flyer properly placed, it may be at once twisted into a thread. By regulating the feed of the card, and the speed of the division rolls, the size of the roping, and of thread, i. e. the fineness of them, may be regulated, or adjusted, to suit the work required.

OBTAINING A POWER FOR PROPELLING CARS, BOATS, &c., Alexander M'Grew, Cincinnati, Ohio. My improvement does not consist in the employment of any newly-invented machinery, but in the using of such power from falls, or currents of water, or other natural or artificial sources of power, as has here. tofore been allowed to run to waste, and employing the same for the purpose of condensing of air into suitable receivers; the elastic force of which condensed air is to be subsequently applied to the purposes herein designated. In numerous situations in the courses of canals and railroads, and of other roads and water courses, there are falls of water, waste weirs, dams, sluices, &c., the power from which, if economised, would be ample for the attainment of all the ends proposed by me; I bring this into use by taking the waste power from wheels, or other machinery already erected, or by erecting others where they do not already exist, using any of the known constructions of such wheels, or other machinery, as may be best adapted for the particular situations in which they are to be employed; these I connect in the ordinary way with the piston, or pistons, of condensing engines, constructed for the condensing of air, and force air thereby into suitable receptacles, or reservoirs, furnished with the requisite tubes, valves, or other appendages, by which they are