"With the work I am now composing, I go on much faster and better than I expected, so that in two or three months, if my health continues as it now is, I hope to have it ready for the press, though I shall hardly proceed to print it till we have dispatched the notes.
"It is upon the same plan with that of Socrates and Jesus compared, considering all the more distinguished of the Grecian sects of philosophy, till the establishment of Christianity in the Roman empire. If you liked that pamphlet, I flatter myself you will like this.
"I hope it is calculated to show, in a peculiarly striking light, the great advantage of revelation, and that it will make an impression on candid unbelievers if they will read.
"But I find few that will trouble themselves to read anything on the subject, which, considering the great magnitude and interesting nature of the subject, is a proof of a very improper state of mind, unworthy of a rational being."
I send you this extract for several reasons. First, because you set him upon this work. Secondly, because I wish you to endeavor to bring it to light and get it printed. Thirdly, because I wish it may stimulate you to pursue your own plan which you promised to Dr. Rush.
I have not seen any work which expressly compares the morality of the Old Testament with that of the New, in all their branches, nor either with that of the ancient philosophers. Comparisons with the Chinese, the East Indians, the Africans, the West Indians, &c., would be more difficult; with more ancient nations impossible. The documents are destroyed.
TO MR. ISAAC M'PHERSON.
Monticello, August 13, 1813.
Sir,—Your letter of August 3d asking information on the subject of Mr. Oliver Evans' exclusive right to the use of what he calls his Elevators, Conveyers, and Hopper-boys, has been duly received. My wish to see new inventions encouraged, and old ones brought again into useful notice, has made me regret the circumstances which have followed the expiration of his first patent. I did not expect the retrospection which has been given to the reviving law. For although the second proviso seemed not so clear as it ought to have been, yet it appeared susceptible of a just construction; and the retrospective one being contrary to natural right, it was understood to be a rule of law that where the words of a statute admit of two constructions, the one just and the other unjust, the former is to be given them. The first proviso takes care of those who had lawfully used Evans' improvements under the first patent; the second was meant for those who had lawfully erected and used them after that patent expired, declaring they "should not be liable to damages therefor." These words may indeed be restrained to uses already past, but as there is parity of reason for those to come, there should be parity of law. Every man should be protected in his lawful acts, and be certain that no ex post facto law shall punish or endamage him for them. But he is endamaged, if forbidden to use a machine lawfully erected, at considerable expense, unless he will pay a new and unexpected price for it. The proviso says that he who erected and used lawfully should not be liable to pay damages. But if the proviso had been omitted, would not the law, construed by natural equity, have said the same thing. In truth both provisos are useless. And shall useless provisos, inserted pro majori cautela only, authorize inferences against justice? The sentiment that ex post facto laws are against natural right, is so strong in the United States, that few, if any, of the State constitutions have failed to proscribe them. The federal constitution indeed interdicts them in criminal cases only; but they are equally unjust in civil as in criminal cases, and the omission of a caution which would have been right, does not justify the doing what is wrong. Nor ought it to be presumed that the legislature meant to use a phrase in an unjustifiable sense, if by rules of construction it can be ever strained to what is just. The law books abound with similar instances of the care the judges take of the public integrity. Laws, moreover, abridging the natural right of the citizen, should be restrained by rigorous constructions within their narrowest limits.
Your letter, however, points to a much broader question, whether what have received from Mr. Evans the new and proper name of Elevators, are of his invention. Because, if they are not, his patent gives him no right to obstruct others in the use of what they possessed before. I assume it is a Lemma, that it is the invention of the machine itself, which is to give a patent right, and not the application of it to any particular purpose, of which it is susceptible. If one person invents a knife convenient for pointing our pens, another cannot have a patent right for the same knife to point our pencils. A compass was invented for navigating the sea; another could not have a patent right for using it to survey land. A machine for threshing wheat has been invented in Scotland; a second person cannot get a patent right for the same machine to thresh oats, a third rye, a fourth peas, a fifth clover, &c. A string of buckets is invented and used for raising water, ore, &c., can a second have a patent right to the same machine for raising wheat, a third oats, a fourth rye, a fifth peas, &c? The question then whether such a string of buckets was invented first by Oliver Evans, is a mere question of fact in mathematical history. Now, turning to such books only as I happen to possess, I find abundant proof that this simple machinery has been in use from time immemorial. Doctor Shaw, who visited Egypt and the Barbary coast in the years 1727-8-9, in the margin of his map of Egypt, gives us the figure of what he calls a Persian wheel, which is a string of round cups or buckets hanging on a pulley, over which they revolved, bringing up water from a well and delivering it into a trough above. He found this used at Cairo, in a well 264 feet deep, which the inhabitants believe to have been the work of the patriarch Joseph. Shaw's travels, 341, Oxford edition of 1738 in folio, and the Universal History, I. 416, speaking of the manner of watering the higher lands in Egypt, says, "formerly they made use of Archimedes's screw, thence named the Egyptian pump, but they now generally use wheels (wallowers) which carry a rope or chain of earthen pots holding about seven or eight quarts apiece, and draw the water from the canals. There are besides a vast number of wells in Egypt, from which the water is drawn in the same manner to water the gardens and fruit trees; so that it is no exaggeration to say, that there are in Egypt above 200,000 oxen daily employed in this labor." Shaw's name of Persian wheel has been since given more particularly to a wheel with buckets, either fixed or suspended on pins, at its periphery. Mortimer's husbandry, I. 18, Duhamel III. II., Ferguson's Mechanic's plate, XIII; but his figure, and the verbal description of the Universal History, prove that the string of buckets is meant under that name. His figure differs from Evans' construction in the circumstances of the buckets being round, and strung through their bottom on a chain. But it is the principle, to wit, a string of buckets, which constitutes the invention, not the form of the buckets, round, square, or hexagon; nor the manner of attaching them, nor the material of the connecting band, whether chain, rope, or leather. Vitruvius, L. x. c. 9, describes this machinery as a windlass, on which is a chain descending to the water, with vessels of copper attached to it; the windlass being turned, the chain moving on it will raise the vessel, which in passing over the windlass will empty the water they have brought up into a reservoir. And Perrault, in his edition of Vitruvius, Paris, 1684, fol. plates 61, 62, gives us three forms of these water elevators, in one of which the buckets are square, as Mr. Evans' are. Bossut, Histoire des Mathematiques, i. 86, says, "the drum wheel, the wheel with buckets and the Chapelets, are hydraulic machines which come to us from the ancients. But we are ignorant of the time when they began to be put into use." The Chapelets are the revolving bands of the buckets which Shaw calls the Persian wheel, the moderns a chain-pump, and Mr. Evans elevators. The next of my books in which I find these elevators is Wolf's Cours de Mathematiques, i. 370, and plate 1, Paris 1747, 8vo; here are two forms. In one of them the buckets are square, attached to two chains, passing over a cylinder or wallower at top, and under another at bottom, by which they are made to revolve. It is a nearly exact representation of Evans' Elevators. But a more exact one is to be seen in Desagulier's Experimental Philosophy, ii. plate 34; in the Encyclopedie de Diderot et D'Alembert, 8vo edition of Lausanne, 1st volume of plates in the four subscribed Hydraulique. Norie, is one where round eastern pots are tied by their collars between two endless ropes suspended on a revolving lantern or wallower. This is said to have been used for raising ore out of a mine. In a book which I do not possess, L'Architecture Hydraulique de Belidor, the 2d volume of which is said [De la Lande's continuation of Montucla's Historie de Mathematiques, iii. 711] to contain a detail of all the pumps, ancient and modern, hydraulic machines, fountains, wells, &c., I have no doubt this Persian wheel, chain pump, chapelets, elevators, by whichever name you choose to call it, will be found in various forms. The last book I have to quote for it is Prony's Architecture Hydraulique i., Avertissement vii., and § 648, 649, 650. In the latter of which passages he observes that the first idea which occurs for raising water is to lift it in a bucket by hand. When the water lies too deep to be reached by hand, the bucket is suspended by a chain and let down over a pulley or windlass. If it be desired to raise a continued stream of water, the simplest means which offers itself to the mind is to attach to an endless chain or cord a number of pots or buckets, so disposed that, the chain being suspended on a lanthorn or wallower above, and plunged in water below, the buckets may descend and ascend alternately, filling themselves at bottom and emptying at a certain height above, so as to give a constant stream. Some years before the date of Mr. Evans' patent, a Mr. Martin of Caroline county in this State, constructed a drill-plough, in which he used the band of buckets for elevating the grain from the box into the funnel, which let them down into the furrow. He had bands with different sets of buckets adapted to the size of peas, of turnip seed, &c. I have used this machine for sowing Benni seed also, and propose to have a band of buckets for drilling Indian Corn, and another for wheat. Is it possible that in doing this I shall infringe Mr. Evans' patent? That I can be debarred of any use to which I might have applied my drill, when I bought it, by a patent issued after I bought it?