246 POWER OF LOCOMOTIVE-ENGINES ON LEVELS AND INCLINED PLANES. a point B. In the one the strain is constant, and may be represented by a, whilst the other is varied by ascents and descents, but so that the total expenditure of mechanical power is the same; hence it is evident that the ascents upon the latter must be more abrupt than on the former, or else they will not compensate for the descents. Assuming these data, there cannot be a question that the lesser and more uniform strain is best adapted to locomotive power, both as regards speed and load, for the following reasons: 1st. As regards speed. It is evident that, to render this comparison perfectly fair, it is only necessary to assume two engines of equal power and load to start simultaneously from A to B, and then assuming that on every part of each line the engine to be capable of exerting its whole power, that is, both on the ascents and descents of the undulating line, while she proceeds uniformly on the other line. On this assumption, as equal power will be so exerted in equal times by each engine, and as the total expenditure between A and B is the same, they would then both arrive at B together. But in the case of the undulating line this hypothesis cannot hold, except within certain limitations, for it is manifest that in practice a variety of circumstances limit the speed at which an engine can be allowed to travel, both as regards safety, wear and tear of machinery, and also the arrangement, Especially of the slides for the admission of steam to the cylinders. ex For these and other reasons, a speed of 35 or 40 miles per hour is as much as can be travelled safely, especially on descending planes, in the present state of our perience; hence, in order to compensate for the slowness of ascending speed, the accelelerated velocity may be far beyond that which can be permitted with prudence; hence the difference of time consumed on the descending planes by the regulated velocity, and the extreme accelerated velocity is lost on the ndulating principle. For instance, between London and Brighton, by Sir John Rennie's and Mr. Stephenson's proposed lines of railway, the respective distances from London Bridge to Sir John Rennie's terminus at Brighton is 49 miles, 68 chains; and from Nine Elms to the back of Brunswick-terrace, by Mr. Stephenson's line of railway, is 54 miles, 68 chains; and going and coming the respective distances, therefore, are 99 miles, 56 chains, and 109 miles, 56 chains. There are on Sir John Rennie's line, as described by Dr. Lardner, 32 miles of gradients to be characterised by to•. On Mr. Stephenson's, 28 miles by 330. line of an equal power and with the same load, with which load on the level it can travel at a speed of 40 miles an hour, using its whole power, then assuming the friction to be 9lbs. per ton, or, and that its whole power is consumed, the distance to and from Brighton will be travelled on each at a speed of 40 miles per hour, and the respective times will be 2. 29. 30. and 2. 44. 30. without adding for delay on the Croydon inclined plane. But this assumes that on Sir John Rennie's descending planes the engine to travel 720 miles per hour. Whereas we will suppose them limited on each to 40 miles per hour; hence in going and coming there will be 32 miles of descending planes, the time to be added will be the difference between travelling 32 miles, at 720 miles per hour, and at 40 miles per hour, that is, of 45 minutes, 20 seconds, making the total 3. 14. 50. by Sir John Rennie's line; whilst on Mr. Stephenson's the time to be added is the difference between travelling 28 miles at 16 miles per hour, and at 40 miles per hour, that is, of 31 minutes, 30 seconds, making the total time 3 hours, 16 minutes. To this must be added the time consumed in stoppages, that is, on Stephenson's, 2 +3 minutes, being once at the Southampton Junction, and once for water. On Sir John Rennie's, 3+3 - 9 minutes, being once at Greenwich Junction, once Croydon at the station, and once for water; besides delay on Croydon incline, for which 5 minutes will be a very moderate allowance. Thus by Rennie's line...... By Stephenson's... 3 14 50 3 16 0 3 22 0 And on Stephenson's .. 113 which would make the time a little more favourable to Stephenson's line of railway. Now, it may be observed, that the foregoing calculations are altogether independent of a difference of opinion as regards proportion of power of engines to what they are ordinarily called upon to exert, or of their varying power at different speeds, because this is equally applicable to each line; but rest upon clear mechanical principles, independent of all hypothesis. Next, if the comparison be as regards load, then the thing is very simple; for the load is either measured by the adhesion of the wheels, or else by the pressure of steam in the cylinder; in either case, the engine being identi IMPROVEMENTS ON THE ELECTRICAL APPARATUS FOR DANCING-IMAGES. Sir,-In using the plates for the small dancing-images in electricity, I found great inconvenience in using them of sufficient size to cause the figures to perform to advantage; for if not of considerable diameter, they were liable to leap off the lower plate-and if very large, then the view was obstructed, and the figures could only be seen by stooping down and peeping underneath the upper metallic plate. I thought that by using a flat plate of window-glass, and applying slips of tinfoil on both surfaces, they would be seen to much greater advantage; and I have constructed one accordingly, which answers as well as could be desired. In fig. 1, abc, ab'c', and xyz, and a'a, represent pieces of tinfoil pasted on each side of the glass; a hole P being cut in the centre of the glass to pass the tinfoil a a' through, and thereby connect the metallic circular slips. In fig. 2, the rod and crook SH represents the suspending wire, which is screwed into a circular flat piece of brass, upon which the glass plate lies. The slips or rings of tinfoil do not come close to the edge of the glass, which greatly assists in keeping the figures upon the plates, because they will generally touch the tinfoil, as being more charged than the glass. If a similar glass plate be used for the lower plate, it would be a further improvement. W. ETTRICK. High Barns, near Sunderland. 80. SAFETY-VALVE AND DAMPER FOR HIGH-PRESSURE BOILERS. Sir, If you think the accompanying sketch of a safety-valve and damper regulator, for high-pressure steam-engine boilers, worthy a place in your valuable The piston B is shown in the position it would assume when the pressure in the boiler is comparatively low; but as the pressure increased, it would rise in the cylinder A until the elasticity of the compressed air above it equipoised the required pressure in the boiler. At the same time, the head of the valve-rod D would come in contact with the bridge in the lower part of the cylinder; and any further ascent of the piston would open the valve C, and allow the steam to escape up the pipe E. When the pressure of the steam in the boiler decreased, the re-action of the compressed air above the piston would force the piston down the cylinder, and the pressure of the steam on the under side of the valve would shut it. During this operation the damper would be shut and opened. AMERICAN LAW OF PATENTS. A Bill to Promote the Progress of the Useful Arts, and to Repeal all Acts and Parts of Acts heretofore made for that purpose. [Drawn by a Select Committee of Congress appointed to take into consideration the State and Condition of the Patent-Office, and the Laws relating to the issuing of Patents for New and Useful Inventions and Discoveries, whose Report we gave in our last week's Number, p.232.] Be it enacted by the Senate and House of Representatives of the United States of Ame. rica, in Congress assembled, That there shall be established, and attached to the Depart ment of State, an office to be denominated the Patent-office; the chief officer of which shall be called the Commissioner of Patents, to be appointed by the President, by and with the advice and consent of the Senate, whose duty it shall be, under the direction of the head of the department, to superintend, execute, and perform, all such acts and things touching and respecting the granting and issuing of patents for new and useful discoveries, inventions, and improvements as are herein provided for, or shall hereafter be, by law, directed to be done and performed, and shall have the charge and custody of all the books, records, papers, models, machines, and all other things belonging to said office. And said Commissioner shall receive the same compensation as is allowed by law to the Commissioner of the Indian Department. Sec. 2. And be it further enacted, That there shall be, in said office, an inferior officer, to be appointed by the said principal officer, with the approval of the Secretary of State, and to be called the Chief Clerk of the Patent-office; who, in all cases during the necessary absence of the Commissioner, or when the said principal office shall become vacant, shall have the charge and custody of the seal, and of the records, books, papers, machines, models, and all other things belonging to the said office. And the said Commissioner may also, with like approval, appoint two other clerks, an examiner of pa tents, a draughtsman, a mechanist, and a messenger. The said chief clerk shall receive the annual salary of 1,700 dollars; two other clerks, 1,250 dollars each; examiner, 1,500 dollars; draughtsman, twelve mechanist, 1,000 dollars; and the messenger, 500 dollars. Sec. 3. And be it further enacted, That the said principal officer, and every other person to be appointed in the said office, shall, before he enters upon the duties of his office, or appointment, make oath or affirmation truly and faithfully to execute the trust committed to him. And the said Commissioner and the chief clerk shall also, before entering upon their duties, severally give bonds, with sureties, to the Treasurer of the United States, each in the sum of lars, with condition to render a true and faithful account to him, or his successor in office, quarterly, of all monies which shall be by them respectively received for duties on patents, and for copies of records and drawings, and all other monies received by virtue of such office. dol Sec. 4. And be it further enacted, That the said Commissioner shall cause a seal of office to be made and provided for the said office, with such device as the President of the United States shall approve; and copies of any records, books, papers, or drawings, belonging to said office, under the signature of the said Commissioner, or when the office shall be vacant, under the signature of the chief clerk, with the said seal affixed, shall be competent evidence in all cases in which the original records, books, papers, or drawings, would be evidence. And any person making application therefor, may have certified copies of the records, drawings, and other papers deposited in said office, on paying, for the written copies, the sum of 10 cents for every page of 100 words; and for copies of drawings, the reasonable expense of making the same. Sec. 5. And be it further enacted, That all patents issuing from said office shall be issued in the name of the United States, and under the seal of said office, and be signed by the Secretary of State, and countersigned by 250 AMERICAN LAW OF PATENTS. the Commissioner of said office, and shall be recorded, together with the descriptions, specification, and drawings, in the said office, in books to be kept for that purpose. Every such patent shall contain a short description of the invention or discovery, and in its terms grant to the applicant or applicants, his or their heirs, administrators, executors, or assigns, for a term not exceeding fourteen years, the full and exclusive right and liberty of using, and vending to others to be used, the said invention or discovery, referring to the specifications for particulars thereof, a copy of which shall be annexed to the patent, specifying what the patentee claims as his invention or discovery. Sec. 6. And be it further enacted, That any person or persons having discovered or invented any new and useful art, machine, manufacture, or composition of matter, or any new and useful improvement on any art, machine, manufacture, or composition of matter, not known or used by others before his or their discovery or invention thereof, and not, at the time of his application for a patent, in public use or on sale, with his consent or allowance as the inventor or discoverer; and shall desire to obtain an exclusive property therein, may make application in writing to the Commissioner of Patents, expressing such desire, and the Commissioner, on due proceedings had, may grant a patent therefore. But before any inventor shall receive a patent for any such new invention or discovery, he shall deliver a written description of his invention or discovery, and of the manner and process of making, constructing, using, and compounding the same, in such full, clear, and exact terms, avoiding unnecessary prolixity, as to enable any person skilled in the art or science to which it appertains, or with which it is most nearly connected, to make, construct, compound, and use the same; and in case of any machine, he shall fully explain the principle, and the several modes in which he has contemplated the application of that principle, or character by which it may be distinguished from other inventions; and shall particularly specify and point out the part, improvement, or combination, which he claims as his own invention or discovery. He shall, furthermore, accompany the whole with a drawing, or drawings, and written references, where the nature of the case admits of drawings, or with specimens of ingredients, and of the composition of matter, sufficient in quantity for the purpose of experiment, where the invention or discovery is of a composition of matter; which descriptions and drawings, signed by the inventor, and tested by two witnesses, shall be filed in the Patent-office; and he shall, moreover, furnish a model of his machine, in all cases which admit of a representation by model, of a convenient size to exhibit advantageously its several parts. The applicant shall also make oath or affirmation that he does verily believe that he is the original inventor or discoverer of the art, machine, composition, or improvement, for which he solicits a patent, and that he does not know or believe that the same was ever before known or used; which oath or affirmation may be made before any person authorised by law to administer oaths. Sec. 7. And be it further enacted, That, on the filing of any such application, description, and specification, and the payment of the duty hereinafter provided, the Commissioner shall make, or cause to be made, an examination of the alleged new invention or discovery; and if, on any such examination, it shall not appear to the Commissioner that the same had been known and used prior to such alleged discovery thereof by the applicant, or had been in public use, or on sale, with his consent or allowance prior to the application, if he shall deem it to be sufficiently useful and important, it shall be his duty to issue a patent therefor. But whenever, on such examination, it shall appear to the Commissioner that the applicant was not the original inventor or discoverer thereof, or that any part of that which is claimed as new had before been known and used as aforesaid, or that the description is defective and insufficient, he shall notify the applicant thereof, giving him, briefly, such information as may be useful in judging of the propriety of renewing his application, or of altering his specification to embrace only that part of the invention or discovery which is new. In every such case, if the applicant shall elect to withdraw his application, he shall be entitled to receive back dollars, part of the duty required by this act, on filing a notice in writing of such election in the Patent-office, a copy of which, certified by the Commissioner, shall be a sufficient warrant to the Treasurer for paying back to the applicant the said sum of- dollars. But if the applicant in such ease shall persist in his claim for a patent, with or without any alteration of his specification, he shall be required to make oath or affirmation anew, in manner as aforesaid. And if the specification and claim shall not have been so modified as, in the opinion of the Commissioner, shall entitle the applicant to a patent, he may, on appeal, and upon request in writing, have the decision of a board of examiners, to be composed of three disinterested persons, who shall be appointed for that purpose by the Secretary of State, and to be selected for their knowledge and skill in the particular art, manufacture, or branch of science to which the alleged invention appertains; who shall be furnished with a certificate in writing, |