A short time before I left France, a person came to me from London with plans and drawings for an iron bridge of one arch over the river Thames at London, of 60, feet span, and sixty feet of height from the cord line. The subject was then before a committee of the house of commons, but I know not the proceedings thereon.

As this new construction of an arch for bridges, and the principles on which it is founded, originated in America, as the documents I have produced sufficiently prove, and is becoming an object of importance to the world, and to no part of it more than to our own country, on account of its numerous rivers, and as no experiment has been made in America to bring it into practice, further than on the model I have executed myself, and at my own expense, I beg leave to submit a proposal to congress on the subject, which is,

To erect an experiment rib of about 400 feet span, to be the segment of a circle of at least 1000 feet diameter, and to let it remain exposed to public view, that the method of constructing such arches may be generally known.

It is an advantage peculiar to the construction of iron bridges, that the success of an arch of a given extent and height, can be ascertained without being at the expense of building the bridge; which is, by the method I propose, that of erecting an experiment rib on the ground where advantage can be taken of two hills for butments.

manner.

I began in this manner with the rib of 90 feet span, and 5 feet of height, being a segment of a circle of 410 feet diameter. The undertakers of the Sunderland bridge began in the same They contracted with the iron-founder for a single rib, and finding it to answer, had five more manufactured like it, and erected into a bridge consisting of six ribs, the experiment rib being one. But the Sunderland bridge does not carry the principle much further into practice than had been done by the rib of 90 feet span and 5 feet in height, being, as before said, a segment of a circle of 410 feet diameter; the Sunderland bridge being 206 feet span and 34 feet of height, gives the diameter of the circle of which it is a segment, to be 444 feet, within a few inches, which is but a larger segment of a circle of 30 feet more diameter.

The construction of those bridges does not come within the line of any established practice of business. The stone architect

can derive but little from the theory or practice of his art that enters into the construction of an iron bridge; and the ironfounder, though he may be expert in moulding and casting the parts, when the models are given him, would be at a loss to proportion them, unless he was acquainted with all the lines and properties belonging to a circle.

If it should appear to congress that the construction of iron bridges will be of utility to the country, and they should direct hat an experiment rib be made for that purpose, I will furnish the proportions for the several parts of the work, and give my attendance to superintend the erection of it.

But, in any case, I have to request, that this memoir may be put on the journals of congress, as an evidence hereafter, that this new method of constructing bridges originated in America. THOMAS PAINE.

Federal city, Jan. 3, 1803.

N. B. The two models mentioned in the memoir, will, I ex pect, arrive at Philadelphia, by the next packet, from the federal city, and will remain for some time in Mr. Peale's museum.

USEFUL AND ENTERTAINING HINTS.*

"The real value of a thing,

Is as much money as 'twill bring.",

In the possession of the Philadelphia Library Company is a cabinet of fossils,† with several specimens of earth, clay, sand, &c. with some account of each, and where brought from.

I have always considered these kind of researches as productive of many advantages, and in a new country they are particularly so. As subjects for speculation, they afford entertainment

* Published in the Pennsylvania magazine, Feb. 1775.

† In the catalogue it is called a collection of American fossils, &c. but a considerable part of them are foreign ones. I presume that the collector, in order to judge the better of such as he might díscover here, made first a collection of such foreign ones whose value were known, in order to compare by: as his design seems rather bent towards discovering the treasures of America than merely to make a collection.

483

to the curious; but as objects of utility they merit a closer atten tion. The same materials which delight the fossilist, enrich the manufacturer and the merchant. While the one is scientifically examining their structure and composition, the others, by industry and commerce, are transmuting them to gold. Possessed of the power of pleasing, they gratify on both sides; the one contemplates their natural beauties in the cabinet, the others, their re-created one in the coffer.

'Tis by the researches of the virtuoso that the hidden parts of the earth are brought to light, and from his discoveries of its qualities, the potter, the glassmaker, and numerous other artists, are enabled to furnish us with their productions. Artists, considered merely as such, would have made but a slender progress, had they not been led on by the enterprising spirit of the curious. I am unwilling to dismiss this remark without entering my protest against that unkind, ungrateful and impolitic custom of ridiculing unsuccessful experiments; and informing those unwise or overwise pasquinaders, that half the felicities they enjoy, sprung originally from generous curiosity.

Were a man to propose, or set out to bore his lands, as a carpenter does a board, he might probably bring on himself a shower of witticisms; and though he could not be jested at for building castles in the air, yet many magnanimous laughs might break forth at his expense, and vociferously predict the explosion of 2 mine in his subterraneous pursuits. I am led to this reflection by the present domestic state of America, because it will unavoidably happen, that before we can arrive at that perfection of things which other nations have acquired, many hopes will fail many whimsical attempts will become fortunate, and many reasonable ones end in air and expense. The degree of improvement which America has already arrived at, is unparallelec and astonishing, but 'tis miniature to what she will one day boast of, if heaven continue her happiness. We have nearly one whole region yet unexplored: I mean the internal region of the earth. By industry and tillage we have acquired a considerable knowledge of what America will produce, but very little of what it contains. The bowels of the earth have been only slightly inquired into: we seem to content ourselves with such parts of it as are absolutely necessary, and cannot well be imported, as brick, stone, &c., but have gone very little further, except in the article

E

of iron. The glass and the pottery manufactures are yet very imperfect, and will continue so, 'till some curious researcher finds out the proper material.

Copper, lead, and tin articles valuable both in their simple state, and as being the component parts of other metals (viz. brass and pewter) are at present but little known throughout the continent in their mineral form: yet I doubt not, but very valuable mines of them, are daily travelled over in the western parts of America. Perhaps a few feet of surface conceal a treasure sufficient to enrich a kingdom.

The value of the interior part of the earth, like ourselves, cannot be judged certainly of by the surface; neither do the corresponding strata lie with the unvariable order of the colors of the rainbow, and if they ever did, which I do not believe, age and misfortune have now broken in upon their union; earthquakes, deluges, and volcanoes have so disunited and re-united them, that in their present state they appear like a world in ruins-yet the ruins are beautiful; the caverns, museums of antiquity.

Though nature is gay, polite, and generous abroad, she is sullen, rude, and niggardly at home: return the visit, and she admits you with all the suspicion of a miser, and all the reluctance of an antiquated beauty retired to replenish her charms. Bred up in antediluvian notions, she has not yet acquired the European taste of receiving visitants in her dressing-room: she locks and bolts up her private recesses with extraordinary care, as if not only resolved to preserve her hoards, but to conceal her age, and hide the remains of a face that was young and lovely in the days of Adam. He that would view nature in her undress, and partake of her internal treasures, must proceed with the resolution of a robber, if not a ravisher. She gives no invitation to follow her to the cavern-the external earth makes no proclamation of the interior stores, but leaves to chance and industry, the discovery of the whole. In such gifts as nature can annually re-create, she is noble and profuse, and entertains the whole world with the interest of her fortunes; but watches over the capital with the care of a miser. Her gold and jewels lie concealed in the earth, in caves of utter darkness; and hoards of wealth, heaps upon heaps, mould in the chests, like the riches of a necromancer's cell. It must be very pleasant to an adventurous speculist to make excursions into these Gothic regions; and in his travels he may

possibly come to a cabinet locked up in some rocky vault, whose treasures shall reward his toil, and enable him to shine on his return, as splendidly as nature herself.

By a small degree of attention to the order and origin of things, we shall perceive, that though the surface of the earth produces us the necessaries of life, yet 'tis from the mine we extract the conveniences thereof. Our houses would diminish to wigwams, furnished in the Indian style, and ourselves resemble the building, were it not for the ores of the earth. Agriculture and manufactures would wither away for want of tools and implements, and commerce stand still for want of materials. The beasts of the field would elude our power, and the birds of the air get beyond our reach. Our dominion would shrink to a narrow circle; and our mind itself, partaking of the change, would contract its prospects, and lessen into almost animal instinct. Take away but the single article of iron, and half the felicities of life fall with it. Little as we may prize this common ore, the loss of it would cut deeper than the use of it: and by the way of laughing off misfortunes 'tis easy to prove, by this method of investigation, that an iron age is better than a golden one.

Since so great a portion of our enjoyments is drawn from the mine, it is certainly an evidence of our prudence to inquire and know what our possessions are. Every man's landed property extends to the surface of the earth. Why then should he sit down contented with a part, and practise upon his estate those fashionable follies in life, which prefer the superfice to the solid? Curiosity alone, should the thought occur conveniently, would move an active mind to examine (though not at the bottom) at least to a considerable depth.

The propriety and reasonableness of these internal inquiries are continually pointed out to us by numberless occurrences. Accident is almost every day turning out some new secret from the earth. How often has the ploughshare or the spade broken open a treasure, which for ages, perhaps for ever, had lain but just beneath the surface? And though every estate have not mines of gold or silver, yet they may contain some strata of valuable earth, proper for manufactures ; and if they have not those, there is a great probability of their having chalk, marl, or some rich soil proper for manure, which only requires to be removed to the surface.