« AnteriorContinuar »
ment which history painting and statuary have met with in the United States. We are still, in one sense of the word, in a state of nature, and while we possess and express so much of her native manner in the countenance, we stand in no need of copies of it. The child that is still in the lap of its mother, can have no relish for her face upon marble or canvass.
I am the more disposed to admit the truth of my remarks upon this subject, from their tendency to appreciate the two imitative professions that have been mentioned, and to suggest a reason why such precious and expensive talents are given for the purpose of exercising them. They appear to have a much higher office assigned to them than simply to please the eye, or to pamper the pride of wealth. To restore the knowledge of the human countenance, defaced by folly and vice, the Creator of the world kindly confers upon the pencil and the chessel the deputy-power of creating a resemblance of it, in order to remind the votaries of art, that not only Nature, but Nature's God “still lives," and that he continues to will the happiness of his creatures, by this representative mode of calling their admiration and love to the wisdom, variety and beauty of his original works.
With the greatest respect and esteem for your professional talents, and personal character, I am, dear sir,
Your sincere friend,
A CITIZEN OF PHILADELPHIA. Philadelphia, Jan. 24, 1810.
CORRESPONDENCE FOR THE PORT FOLIO.
Account of French's improvement on the Steam Engine, in a letter
from Dr. Mitchell to James Sharpless, Esq. That useful machinician, Daniel French, after a number of years study and labour in inventions, has succeeded in improving the steam engine, so as to make it one of the most simple machines in use. It is now of very little expense and work to build, compared to other forms of the engines now in use; and may be reckoned as one of the first and most important discoveries of modern American ingenuity, being so happily constructed that with the utmost ease it can be adapted and accommodated to move any machinery whatever, and work in any situation at pleasure.
Some of the most important features and principles of this important and simplified engine are the following: viz. The main cyllinder of the engine has two gudgeons on opposite sides on which it is suspended and movable. To one side of said main cyllinder is joined a small cyllinder, or tube, to convey steam to each end of said main cyllinder. To put the piston in motion, the steam is introduced into the small cyllinder by a short pipe joining it at, and parallel with, the centre of the gudgeons on which the main cyllinder is suspended. This short pipe receives the end of another which joins the boiler.
The piston rod of the main cyllinder, at its outer end, has a perforation and receives the end of the crank of the balance wheel, to give it motion ; and as the crank revolves round its centre, carrying the end of the rod with it, it causes a vibratory motion of the main cyllinder on its gudgeons. In this way the great lever beam, with its numerous appendages, is dispensed with, and becomes of no use.
Steam is lét in and out of the main cyllinder thus: on a straight rod passed into the small cyllinder are made fast two pistons, exactly fitting the bore of the cyllinder, and so situated and corresponding to two perforations from the small to each end of the main cyllinder, as that when it is in one situation, it admits steam in at one end and out at the other, and the rod with the pistons being shifted a little, reverses it, and lets in and out at the other ends.
Motion is given to the rod of the cyllinder, as required, by means of a single lever being joined at right angles to it, one end of which lever is fixed and movable in a piece joined to one end of the main cyllinder; the other end moves through and back and forward in a crooked and curve lined channel, slit, or groove, of such form as to shift or change the situation of the rod and pistons as occasion requires, by the vibratory motion of the cyllinders, and it may be done without any lever, by having a projection on and at right angles with the length of the rod, the said projecting part moving in said crooked channel, and thus with a single rod only can be performed all the movements necessary to give and let off steam, and all that multiplicity of work, parts, and movements in other forms is dispensed with, and of no use. This form is admirably adapted to give motion to boats, as it can be done without any expense of machinery, except the steam engine, as the balance wheel may at the same time be the wheel to drive the boat, so admirably is this engine constructed.
Mr. French expects to be able to build steam engines with equal power for less than one half that the other forms in use come at, and to make it useful for all purposes where a cheap power is wanted to move any kind of machinery.
Anecdote of the late Mr. Rumsey, and remarks on the steam engine,
in a letter from James Sharpless, esq.to Dr. Mitchell, dated NewYork, Oct. 3, 1809.
DEAR SIR, As I expressed to you in a desultory conversation on Sunday last, several objections to the applications made by the ingenious Mr. Fulton for impelling boats by steam, which I presume you did not wholly comprehend, on account of my defective mode of expressing myself, I take the liberty of endeavouring more fully to explain myself and offer my reasons for the preference I give to the applications of the late Mr. Rumsey, in order that, if my observations should be found correct, some advantages may be thereby derived to society.
The float boards of Mr. Fulton's engine, as near as I can recollect, pass through the water at the rate of seven miles per hour, and it is to be presumed that the power of the engine would support this velocity of the float boards, though the boat were at rest. Then this striking force of the boards against the water is seven at the commencement of action, but when the boat has attained its utmost velocity of five miles per hour, its striking force, or resistance to the water is only two: for when the boat has attained this uniform velocity of five miles per hour, the water in respect of it is passing on in the contrary direction at five miles per hour, and the propeling power is diminished in the same ratio, hence it is evident that two sevonths of the power of Mr. Fulton's engine would be necessary to sustain the same boat at five miles per hour, provided the apparatus were so constructed as to support a uniform action from the commencement, so that the reacting inert force should be the same with whatever velocity the boat might be sailing at. This property I have always considered Mr. Rumsey's plan to possess, which is extremely simple, ingenious, and philosophical. His inventions were carried into effect about twenty
years ago, upon a small scale, both in America and England; and had he not been injured in his constitution by intense study, and in his pecuniary circumstances by a constant change of his mechanical pursuits, he probably would have enriched himself, and have been considered as one of the greatest ornaments of his countryDrawings of his hydraulic inventions were laid before the society for the encouragement of arts, and a committee appointed to inspect them, and they were considered so ingenious and of such general importance that the society petitioned him to give an explanatory lecture. He appointed an evening ; his drawings were spread on the table ; at the time appointed the society and a number of visitants interested in mathematical and mechanical subjects, were collected; a pause of perfect silence marked the general esteem, as the self taught philosopher approached. He commenced with modest confidence; but, unused to the sound of his own voice in public, and struck with the respectability of the assembly to whom he was acting as preceptor, his extreme sensibility overcame him, and a few sentences that he uttered were his last! He spoke no more! and the tears of general sympathy and regret were increased by the peculiar circumstances of his death.
LEVITY--FOR THE PORT FOLIO. MR. OLDSCHOOL,
In the last number of your Port Folio, I met with a meteorological journal, which a gentleman of this city kept of his wife's temper-now supposing you not to be prejudiced in favour of 'either sex, I send you the following table in which I have noted as accurately as possible the variations in the temper of a husband, whose disposition you may form some idea of, when you have examined the table, and pronounce without much difficulty whether I live in a temperate, torrid or frigid zone.
Sunday. Extrem'in at th.
o te all day. Wednesday. cing—inclined to storm. Afternoon-dark and gloomy.
Thursday. Morning-very dull and heavy. Afternoon-cleared off a little.
Friday. Remarably dry and rather cold,
Saturday. Morning-at 32o. Afternoon-sudden change to warm ; but towards night, frequent blasts.
FOR THE PORT FOLIO.
THE POST-OFFICE ESTABLISHMENT.
When we look back to see what our country was a few years ago, and consider what it is now, we cannot fail to be astonished at its growth. The old world furnishes no example of the kind. Indeed, so rapid is the advance of improvement, that our minds are scarcely able to keep pace with its progress, and we are almost led to deny the evidence of our senses. The traveller, as he proceeds on his journey, passes a wilderness ; and behold! on his return, as if by magic, the wilderness is converted into a fruitful garden, and blossoms with a thousand sweets.
One hundred years ago, the whole importations into North-America did not amount to two millions of dollars annually. Fifty years afterwards, the imports had increased to twenty millions of dollars ; and in 1807 the duties alone on imports into the United States (making no deduction for drawbacks) exceeded twenty-six millions of dollars! a sum equal to the export trade of Great Britain to all the world a century ago.
Should no untoward circumstance interrupt the prosperity of our country, a few years will place us entirely independent of the products of Europe, and our physical strength may bid defiance to the united efforts of her arms.
Among the improvements in the United States, there is, perhaps, no one that has advanced more rapidly, or proved more extensively useful, than that of the transportation of the mail. There is not a man of lite.... ure or business in the nation who does not constantly expi sevt. -its benefits. Yet very few give themselves the trouble to in moment on its importance. In point of public utility, it ids a rank but little inferior to printing. Copies may be multiplied at the press, but, without this establishment, how limited must be their distribution! By the extensive and rapid transportation of the mail, the transactions of each part of the country