ON THE LAW OF PATENTS.

1. An objection may be alleged against this system of granting patents without expense, that they would multiply in amount to a mischievous extent-that the whole ground of improvement would be occupied by designing schemers, not intending to work inventions, but anxious to make a profit by selling previously secured rights to men really intending to work. This difficulty occurs also under the present system, and although the exaction of high fees certainly has a tendency to prevent the schemes of rogues being so widely extended, yet, at the same time, it offers almost insurmountable obstacles to the pursuits of poor but worthy men. It is clear that if men could make themselves masters of certain rights-probably profitable ones

at a small expense, many would be the claimants; but it would not be difficult, and without injustice, to put a check on this. After the lapse of a certain period of time from the date of the patent, the patentee might be called on for a certain amount of fees proportioned to the extent and value of the invention, and in default of payment his patent should become void, and the right accrue to the public at large. If the patent were worth any thing the fees would be paid, and if it were worth nothing, the inventor would lose nothing but his time and the small sums paid as fees of registration. Under such an arrangement patents might be made a source of very considerable revenue to the public, which being raised from newly. created wealth, and not from overburdened industry, would not be obnoxious. The same principle should be applied to patents, which ought to be applied to public water, or gas, or railroad companies. The public grants a monopoly in a thriving business, and it has a claim to some advantage in return, but it would be hard indeed if it were to claim con-" tributions from the companies, before they had commenced working; before they were making a profit. It is true that the inventor renders the public a service, by producing a new commodity or labour-saving machine, but when he obtains a monopoly he closes the door against the chances of any other person inventing it. In the space of fourteen years it is probable that large numbers of persons would be engaged in working out the same idea, and many of them might be successful, but if the first obtains the monopoly all the others are thrown out. Whenever any new invention engages the peculiar attention of the public, numbers of patents for similar things follow in its train. The great hardship is, that while some inventions are enormously and disproportionately recompensed, and others of probably equal utility do not repay the inventor his outlay, the same amount of tax is collected from all alike.

It is a maxim in English jurisprudence that every man is bound to know all the laws, i. e. every man is liable to all the penalties incurred by breaches of the laws, even though it is in some instances morally impossible to know them. This is a difficulty which cannot be altogether avoided, for it is clear that if pleading ignorance were held a sufficient answer, it would be difficult to convict any one. The penalties of the laws would become mere nullities. But it is at least the duty of legislators to take all possible pains to promulgate a knowledge of the laws in every practicable mode. And thus in the case of patents it should be the duty of the legislative body to remove all difficulties from inventors arising from circumstances over which they have no control. An inventor requires to know what ground has been trodden before him, or he will waste his time unprofitably in re-inventing. It is usual for patent agents to possess lists of all the patents which have ever been taken out, and to these the poor man cannot get access. public record office should possess this work of reference, as to titles; and yet more, it should possess a descriptive catalogue properly classed. With such a guide, the valuable time of an inventor would be saved, and his spirit remain unbroken; and if any inventor applied for a patent for any thing before done, the registering officer ought, as a matter of duty, to point it out to him, when refusing to comply with the application.

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Grievous indeed are the hardships under which the poor inventor labours. He has no hope of raising himself above daily labour, but by his knowledge and skill; and yet, although he may exercise them for the benefit of others, he may not reap himself any corresponding advantage. The patent laws, as at present existing, are a contrivance where. by a capitalist may increase his capital, but which leave the poor inventor wholly dependent on the capitalist. He who is already helped may help himself, while he who needs help cannot procure it. This blot should forthwith be removed from the national escutcheon, or the shield of freedom which Britannia is made to wear under the cap of liberty, must be held but as an escutcheon of pretence. Give to the mechanics fair play, and the nation will soon find the advantage of it in the compound progress which will be made in all the arts tending to human convenience or human happiness. It is a claim of policy upon the worldly wise, and of justice upon the high-minded.

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TRACTABILITY OF BALLOONS-COMPARATIVE SAFETY OF MONTGOLFIER AND

GAS-BALLOONS, &c.

Sir,-Your correspondent, "Umbra Montgolfieri," takes, on the whole, a fair view of the ballooning subject of my last communication; but some of his remarks and facts require emendation.

I do not state that no degree of motion whatever can be imparted to a balloon through the "vigorous manoeuvring" of properly constructed flappers by the persous in the car. But it must be in a perfect calm, such as "Umbra" himself says that Messrs. Roberts were favoured with in June, 1784, when they travelled 2000 yards in 35 minutes by means of their oars. This may be; but I should like to have seen the operation! I have a shrewd suspicion that the air was not fectly quiescent; and that what little motion it had was in favour of the rowers. "Umbra Montgolfieri" did not see, either this operation or that of M. Testu; I wish he had! The flying gods and devils of our pantomimes are seen to apply themselves most vigorously to manoeuvring their wings;" but I doubt its being through their aid that they fly from one side of the stage to the other!

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per.

With regard to the comparative danger of the fire and the gas balloon, "Umbra" is not quite correct in cases which he quotes. Pilatre de Rozier lost his life by ascending with a double, or rather with two balloons-one of hydrogen gas, the other à la Montgolfier. In this strange conceit, I forget which of the two he placed uppermost, but the fact was, that the gas caught fire and exploded so as to destroy the whole conceru. I have no encyclopedias to refer to, but I remember, thirty years ago, reading the account of this catastrophe, as given in the Philosophical Transactions by Mr. Cavallo, the electrician and chemist, who was an eye-witness of it. When Blanchard and an Englishman passed in a gas-balloon from Dover to Calais, they were dragged through the water more than half of the distance; although, to increase the buoyancy of the balloon, they divested themselves even of their clothes.

Madame Blanchard was killed at Paris (in 1816, I think) through the gas taking fire. It is true, the car was illuminated, and I think she had some fireworks to throw down! Mademoiselle Garnerin,

whom I also knew very well, shared a similar fate, though I do not remember the particulars. Her father, Garnerin, a professed aeronaut, came to England some years ago, about a pasteboard gun (!) of his invention.

The most distinguished of all the early aeronauts was the rich and scientific experimenter, Count Zambeccari, of Bologna, who was a near relation of my father. The Count constructed several balloons, both à la Montgolfier and gas. At that time it was a serious expense to fill a balloon with gas, which was ob tained by the decomposition of water by means of iron and sulphuric acid. I have above noticed the circumstance of Blanchard and his companion having been dragged through the water, on their way from Dover to Calais. I now mention the name of Zambeccari, in order to draw the attention of your intelligent readers to a circumstance which it would be well to investigate, before our aeronauts again venture in a gas-balloon to cross the sea. This distinguished experimentalist made several ascents in a Montgolfier balloon, with which he exhibited the faculty of continually rising and falling in a most satisfactory manner. With his gas balloon, however he was twice in imminent danger of perishing. A south-west wind carried him from Bologna over the Adriatic

sea.

No sooner had the balloon got fairly over the water about six miles from shore, and although it was at the height of 5000 feet, it suddenly began to descend. In vain did the acronaut hasten to throw out his ballast, for notwithstandthe ejection of every particle, together with some provisions, bottles, extra clothing, and even barometer, thermometer, &c., the car soon touched the water, and Zambeccari, half drowned, was taken up by his boats. Struck by this apparent anomaly in aerostatics, and with a view of discovering some circumstance that might account for the fact which he had witnessed, Zambeccari, nothing daunted, made another ascent, with a south-west wind which speedily put him on his way to shores of Dalmatia. He had some fast going feluccas to attend him, which, with all canvas set and nimble oars, followed him with almost the swiftness of the sea-gull's flight. The balloon was kept as full of gas as safety from expansion would possibly allow. But all

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theory is not in accordance with Kepler's laws. Well, I gave up this point to him, which I did the more readily, as I was well convinced it was the fact. But in No. 683 he makes another turn-about, and tells me, 66 that in the end I will find that his theory is not at variance either with the laws of Kepler nor the theory of Newton--that the electrical theory is an extension of the principles of universal gravitation; and that with some qualifications it is in perfect accordance with Kepler's laws," &c.: and how does Mr. Mackintosh prove all this? Why, by informing us, "that the intensity of electricity, like that of gravitation, is in the inverse ratio of the squares of the distances." If this can be called a demonstration, it is not a long one. It belongs to that sort of information which the Scotch Highlanders designate by the name of "Piper's news." But the intensity of magnetism, heat, light, and many more, follow the same law. It appears that Newton made a great many experiments for discovering the law of magnetic action, but he could discover nothing that would render it susceptible of a comparison with the solar force.

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But let us draw the veil a little aside, and see if we can discover whether Mr. Mackintosh's theory has any great claims to originality. In the first place, Mr. M. informs us, that all the planets belonging to the solar system were originally comets revolving round the sun in very elliptic orbits," &c. Now that great cosmographer, William Whiston, sometimes nicknamed "Wise Willie" (the same Mr. Whiston whom your able correspondent, Zeta," speaks of in his letter, No. 670), informs us that our earth had originally been a comet revolv ing round the sun in an elliptic orbit, which gradually was changed so as to come into a circular one at the time of the Mosaic creation," &c. The only difference between the two accounts is, that Mr. Whiston only speaks of the earth being a comet before the Mosaic creation. Mr. Mackintosh assigns no period of time. But besides the earth being a comet, he lugs in all the other planets belonging to the solar sytem. Again, Mr. Mackintosh tells us that all the planets and comets belonging to our system originally formed a part of the body of the sun," &c. Buffon says, "That a large comet coming with great velocity

to its perihelion, fell with such a force obliquely upon one side of the globe of the sun, as to strike off there from in a stream so much matter as the masses of all the planets amount to; that part of this stream being of different densities, were by the force of this impulse driven to different distances from the sun; some of the lightest were carried as far as the orbit of Saturn, and there. by mutual attraction, were compacted together, and formed that with its ring and satellites, and so on of all the other planets. So that it appears that the cosmographical part of Mr. Mackintosh's theory is, with some modifications, only an attempt to revive the philosophical vagaries of Whiston and Buffon. The terrible catastrophe, which, by Mr. Mackintosh's account is to be the fate of all the planets that now belong to our system (or the roasting system, so named by an old corre spondent), is nearly akin to the opinions of Dr. Burnet, another of our great modern cosmographers. The old Scotchwoman's account of the formation of the fixed stars, appears fully as feasible as any of them, who, when asked what be came of all the old moons, glibly replied, "That she did not exactly ken, but to the best of her knowledge and belief, they were all cut up to make stars of." But to be serious. Of all the opinions that have been given on this subject by uninspired writers, both in ancient and modern times, that of Plato for genuine orthodoxy, throws them all in the shade.

Plato asserts, "That the world was created in time, but that the idea thereof subsisted in the divine mind from all eternity; that God, induced by his goodness, created it when he thought fit; that when the matter whereof the world consists was before altogether in a confused chaotic state, the Divine being reduced it into order, and gave it a perfect form, which nothing can impair or change but the same power that made it; and that it will continue in the same state for ever, because it is not reasonable to imagine that a wise and benevolent Being will destroy his own work, which he beheld with pleasure as soon as he had finished it."

I should now go on to make some observations on the mechanism which Mr Mackintosh asserts gives motion to the different planets belonging to our system,

ON THE TRANSPORT OF HEAVY BURTHENS UPON ICE. BY THOMAS JEFFERSON CRAM, PRIN. ASSIST. PROF. OF NAT. AND EXP. PHILOS., U. S. MILITARY ACADEMY. (From the Journal of the Franklin Institute.) For ordnance purposes, it became necessary, on the 13th of January, 1835, to transport a heavy piece of artillery (an iron 24-pounder) across the Hudson, from West Point to Cold Spring Foundry. To insure safety, two ox sleds were connected, one after the other, and upon which two timbers were longitudinally placed and secured; between these timbers, the gun, previously dismounted from its carriage, was swung, by resting its trunnions upon them, at such points that the whole pressure was distributed, as uniformly as possible, upon the ice which sustained it. A pair of horses were attached to another sled, which was connected with the foremost of those beforenamed, by a rope about thirty feet in length.

The ice over which the gun was taken, had been chiefly formed during that intensely cold week (in January, 1835), when the mercury in Fahrenheit's thermometer ranged, here, between 21 and -15. The effects of the pressure upon the ice were carefully observed, by myself, along the entire route, and were such as to induce the belief, that an idea of its strength could be formed with sufficient certainty to be of practical utility, in all cases where the safety of transporting any load upon ice might be jeoparded.

The ice was drilled through, and its thickness measured, to a tenth of an inch, at intervals of two hundred paces and less, along the whole extent of the track. From the place of departure to the channel of the river, the thickness diminished from 16:5 inches down to 8 inches, and no signs of cracking or bending were observed in the ice the horses going at the rate of about four miles an hour. Across the channel, the thickness increased from eight inches to 12 inches, and no evidence of breaking or bending was exhibited, -the load moving with a speed of about eight miles an hour. From the west edge of Cold Spring flats, to the vicinity of the entrance of a creek, the thick

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ness varied from 12 inches up to 15.5 inches, and no indications of yielding were perceived, the horses going at a gentle trot. Near the entrance of the creek, for an extent of fifty paces, the average thickness of the ice was only 5.56 inches, and it was covered with a sheet of snow water, two inches in depth. This fifty paces of ice was observed to bend so much under the gun, that I was very apprehensive of its breaking; indeed, had the load been stopped for a few seconds only, it undoubtedly would have gone to the bottom. The depression along here was at least two inches, and the flexure of the ice under the foremost of the sleds, bearing the gun, was less than that under the hindmost, owing to its being weakened by the former, ere the latter came upon it. On crossing this weak spot, the horses had become so much fatigued, and the resistance increasing, by being drawn up the inclined surface of the bending ice, that, with much whipping and shouting they were barely urged to drag the gun safely over, at a velocity of about four miles an hour.

To determine the pressure sustained by a given superfices of the ice under consideration, it is to be remarked, first, that from the dimensions of the bottom surfaces of the four sled runners under the gun, the whole surface of ice in contact with these bottom surfaces, at the same time, was 6·458 square feet. 2nd. That the weight of the gun is marked 5579 lbs., and the sleds supporting it, together with the timbers, lashing chains, wedges, blocks, &c., weighed, in all, 1624 lbs., one sled weighing as much as the other. 3rd. That the horses and their sled were so far in advance, the pressure arising from this cause may be neglected, inasmuch as it did not act at the same time, and upon the same ice, with that arising from the gun.

Therefore, the whole pressure sustained by the 6.458 square feet of ice, at the same time, was equal to 5579 +1624lbs., or equal to 7203 lbs. ; and admitting, what was very nearly the truth, that the pressure was distributed uniformly, and dividing 7203 by 6.458, we shall have 1115-361 lbs., for the pressure sustained by each square foot; at all events, 1115 361 lbs. will be the average pressure sustained by a square foot of the ice.

From the observed effects upon the fifty paces of ice at the entrance of the creek, one can form a pretty accurate estimate of the least thickness upon which we can safely bring a pressure (of 1115·361 + 10) equal to 1125-361 lbs., (the ten additional pounds being the allowance for the covering sheet of water). It is evident that the ice will not be safe, if its thickness be not above 5.56 inches.

From the foregoing facts, which were obtained with the greatest care, it may be in