Holt's New Hotel. our time to the work which our condition re- contemplations of science remains: we are quires, is an important duty, and indicates the possession of practical wisdom. This, however, does by no means hinder us from applying the rest of our time, besides what nature requires for meals and rest, to the study of science; and he who, in whatever station his lot may be cast, works his day's work and improves his mind in the evening, as well as he who, placed above such necessity, prefers the refined and elevating pleasures of knowledge to the low gratification of the senses, richly deserves the name of a true philosopher. One of the most delightful treats which science affords us is the knowledge of the extraordinary powers with which the human mind is endowed. No man, until he has studied philosophy, can have a just idea of the great things for which Providence has fitted his understanding the extraordinary disproportion which there is between his natural strength and the powers of his mind, and the force he derives from them. When we survey the marvellous truths of Astronomy, we are first of all lost in the feeling of immense space, and of the comomparative insignificance of this globe and its inhabitants. But there soon arises a sense of gratification and of new wonder at perceiving how so insignificant a creature has been able to reach such a knowledge of the unbounded system of the universe-to penetrate, as it were, through all space, and become familiar with the laws of nature at distances so enormous as baffle our imagination—to be able to say, not merely that the Sun has 329,630 times the quantity of matter which our globe has, Jupiter 308, and Saturn 93 times; but that a pound of lead weighs at the Sun, 22 lbs. 15 ozs. 16 dwts. 8 grs. and 3 of a grain! at Jupiter, 2 lbs. 1 oz. 19 dwts. 1 gr. ! and at Saturn, 1 lb. 3 ozs. 8 dwts. 20 grs. part of a grain! And what is far more wonderful, to discover the laws by which the whole of this vast system is held together and maintained through countless ages in perfect security and order. It is surely no mean reward of our labor to become acquainted with the prodigious genius of those who have almost exalted the nature of man above its destined sphere: when admitted to a fellowship with those loftier minds, we discover how it comes to pass that, by universal consent, they hold a station apart, rising over all the great teachers of mankind, and spoken of reverently, as if NEWTON and LAPLACE were not the names of mortal men. raised by them to an understanding of the infinite wisdom and goodness which the Creator has displayed in his works. Not a step can we take in any direction without perceiving the most extraordinary traces of design; and the skill every where conspicuous is calculated, in so vast a proportion of instances, to promote the happiness of living creatures, and especially of our own kind, that we can feel no hesitation in concluding that, if we knew the whole scheme of Providence, every part would be found in harmony with a plan of absolute benevolence. Independently, however, of this most consoling influence, the delight is inexpressible of being able to follow, as it were, with our eyes, the marvellous works of the Great Architect of Nature-to trace the unbounded power and exquisite skill which are exhibited in the most minute, as well as the mightiest, parts of his system. The pleasure derived from this study is unceasing, and so various that it never tires the appetite. But it is unlike the low gratifications of sense in another respect: while those hurt the health, debase the understanding, and corrupt the feelings, this elevates and refines our nature, teaching us to look upon all earthly objects as insignificant and below our notice, except the pursuit of knowledge and the cultivation of virtue; and giving a dignity and importance to the enjoyment of life, which the frivolous and the grovelling cannot even comprehend. Let us, then, conclude, that the pleasures of science go hand in hand with the solid benefits derived from it; that they tend, unlike other gratifications, not only to make our lives more agreeable, but better; and that a rational being is bound by every motive of interest and of duty, to direct his mind towards pursuits which are found to be the sure path of virtue as well as of happiness. HOLT'S NEW HOTEL.-We have given on our first page a correct engraving of this splendid edifice, which was completed during the last year; and as it is one of the most prominent buildings in this city, we have selected it as the first of a series of views in New.York and its vicinity, which we purpose from time to time to present to our readers. Those who have only seen the outside, can form very little idea of the regularity and order which is observed in conducting the internal arrangements. The worthy host appears to have a place for every The highest of all our gratifications in the thing, and every thing in its place; it combines all the advantages of a hotel and boarding house, and to the casual visiter of this city, as well as to those whose ordinary occupations require them to locate in it, or its vicinity, it affords every advantage that could be desired Every delicacy can be obtained by, and every atter tion is paid to, the wishes of the guest. As we conceive a detailed description o the building may be interesting to our readers, we shall subjoin one we have been favored with from a source which, we are satisfied, cannot but be correct. It stands on a base of 7 feet, with a foundation of 3 feet-the basement wall is 2 feet 6 inches, and all the main walls are 20 inches thick. The basement and first story are of Hallowell granite-the five stories above, and the tower, of marble; and in order to add to the security of the building, all the main joints of the marble and granite are clamped together, and then made fast to iron straps or bars, which extend, some twenty, others thirty feet, into the partition or division walls, with anchors at the end. The corners are also secured by anchors or bars of iron in each direction, twelve feet in length. For the above purposes alone, ten tons of iron were used. Three of the sides front on three different streets, viz.: Water street, Fulton street, and Pearl street. In the engraving affixed is a view of the front in Water street, and a side view of that in Fulton street. Its breadth in Water street is 85 feet 6 inches-in Fulton street 100 feet—and in Pearl street 76 feet 6 inches; the principal entrances are in Water street. In the relish room there can be found superior accommodation, on terms as reasonable as at any establishment in this city. A great portion of the basement is devoted to cooking rooms and other necessary purposes. In the yard, under a platform, is a steam engine of 12 horse power, which is daily used to bore for pure water-already it has penetrated upwards of 500 feet into the earth; it is applied also to turning of spits-to grinding and cleaning knives; it abridges labor by carrying up the dishes, when cooked, to each story-the baggage also is in this manner conveyed to their several places of destination. On the Pearl street and Fulton street sides are several stores, which are let out for various purposes of trade. In the 2d story will be found a dining room 100 feet in length, fronting Fulton street; the Water street side is a large room, in which there is daily a Public Ordinary, and to which resort many of the most respectable and influential men of the city. There are also other rooms used as parlors, with the privilege of a private staircase and a spacious Hall. In the 3d story are apartments judiciously constructed for the use of families, consisting of elegant and pleasant sitting rooms, and one, two or more bed rooms, as may be necessary, with every convenience that can be desired. The 4th, 5th and 6th, are also divided into parlors and bed rooms to suit the convenience of smaller families, and of travellers who wish to have private apartments. Three hundred persons may be accommodated with lodgings; and one thousand can sit at the different tables, at the same time. On the roof, enclosed by a substantial iron railing, is a spacious promenade, for the convenience of visiters, which will accommodate 500 persons; when the weather permits, it commands a beautiful prospect of the surrounding country, and of the shipping in the river, and much amusement is afforded by witnessing the bustle below of arrivals and departures of steamboats and other conveyances. In the attic story there is a saloon provided with refreshments of all kinds for the accommodation of visiters to the promenade. There are also separate bathing rooms. The dome is built immediately over the basement, and in it there is room for a full band of musicians. The height of the building from the first floor is 135 feet; and for convenience of arrangement, or excellence of construction, it is undoubtedly equal to any other edifice in this country. As this magnificent mansion has been reared by the persevering industry and economy of one individual, we think that a short account of his progress in life since his first arrival in this city cannot fail to be interesting, and it will afford an additional proof of what can be accomplished by such means, and more especially exhibit to our younger readers the value of pursuing through life an undeviating course of integrity and honor. It is by such a course only that they can arrive at that high distinction which Mr. Holt has arrived at, viz. to be respected, and enjoy the good wishes of all that have the pleasure of knowing him. It was our intention to have accompanied the preceding with a brief memoir of the MECHANIC and Gentleman, who, by quiet industry, has accomplished so much in a few years, notwithstanding he once, in the mean time, lost every thing he possessed, by fire, but want of room compels us to defer it until another time. [From the London Mechanic's Magazine.] SOUTHWARK IRON BRIDGE. Architect, Rennie. 1814-20. For several centuries the only direct means of communication from the Borough of Southwark to the city of London was by passing over London Bridge, the then only Bridge across the river Thames. Since the time of Stowe, however, (who mentions that bridge with particular satisfaction,) the rapid extension of the Borough had frequently suggested the great necessity of some more direct means of communication to the heart of the city. But it was to our own times that the ultimate execution of his design was reserved. The successful projector of the scheme was Mr. John Wyatt, proprietor of the Repertory of Arts. In 1807, that gentleman first turned his attention to the subject, and labored incessantly, and in spite of every obstacle, till the year 1811, when an Act of Parliament was obtained, authorizing the necessary sums to be raised, amounting in the gross to 400,000l. in transferable shares of 1001. each; and containing permission to raise (by way of mort. gage or annuities) the sum of 100,000l. should such further sum be required to complete the works with its necessary approaches, and for securing the subscribers against extra calls over and above the amount originally stipulated for. The Committee of the proposed Bridge consisted of the following gentlemen :-Sir J. Jackson, Bart. chairman; John Allnut, Esq. Chas. Barclay, Esq. M. P. Samuel Davis, Esq. East India Director; Robert Pott, Esq. Henry Perkins, Esq. Charles Price, Esq. George Ranking, Esq. John Ramsbottom, Esq. M. P. William Salte, Esq. William Slade, Esq. John Taylor, Esq. M. P. Wil. liam Williams, Esq. Banker; and Sir Joseph Yorke, Bart. M. P. Whether any other committee was formed prior to this I am unable to determine, but the before mentioned names agree with those given in the "Repertory," as also in the copy of a Prospectus now before me. Mr. Wyatt, it appears, was at the time personally acquainted with the late John Rennie, Esq. who, at his (Mr. Wyatt's) recommendation, had professional conferences with the Committee of management, on the propriety of erecting the bridge, and the nature of its construction. Mr. Rennie was, of course, satisfied that a bridge was required, and the Committee being satisfied that the care of its execution could not well be placed in abler hands, gave the necessary directions for designs and drawings to be prepared for their inspection. Accordingly Mr. Rennie furnished two designs for the intended bridge; one of stone, to consist of five arches, and one of iron, to consist of three arches, with granite piers. The latter design was preferred and carried into execution. (See above engraving of centre arch.) The works, however, were not co.nmenced until the year 1814-operations being stayed by parliament till such time as all the shares were disposed of. It must be admitted that this undertaking of Mr. Rennie's was bold and arduous in the extreme. Little is known at present as to the best mode of constructing bridges of iron. The great number of the parts, and the paucity of scantling compared with stone bridges, and the immense labor in fixing those parts, render it, in many respects, a distinct arrangement in bridge-building. Also, if we consider the enormous spans of the arches of Southwark Bridge, and the number of them (only three,) we cannot withhold our commendation from the scientific individual who conceived and carried into execution so bold a project. The invention of iron bridges is due to British mechanics. It is said that the first bridge of this description was invented by Mr. Thomas Paine, and intended for America as the subjoined list will show. The repeated failures of iron bridges show clearly that experience is still wanting to render them of sufficient permanency. The following are the most remarkable bridges of iron not of the suspension kind : Architects or J. Rennie. Southwark, London Builders. Dates. 1814,20 1773 Darby. Tame, Herefordshire [From the American Railroad Journal.] MR. EDITOR-Should you consider the following formulas, relating to the effect of grade and curvature upon the motion of Railroad cars, to be of any value to the readers of your Journal, they are offered to you for insertion. In estimating the effect of curvature, it is necessary to have a general formula for the value of the centrifugal force. Take V= the velocity of a car in miles per hour; R = the radius of curvature of the track in feet; w = the weight of the car in lbs. ; and f= the centrifugal force in lbs. From known principles, the following expression for the value of ƒ is obtained: f = w x V3 15 R Now the effect of the force f is to produce a continued pressure upon the bearing of the axles of the wheels, and also upon the flange and edge of the exterior rail. Take therefore T to denote the friction caused by that pressure, and which amounts to the increase of traction arising from centrifugal force. Although the pressure may be nearly the same at both of the points just mentioned, yet it may perhaps be sufficient to take the amount of friction equal to of the whole centrifugal force,* in which case the following formula is at once derived from the preceding : From which either of the three quantities, n, V, or R, may be found when the other two are given; and thus it is easy to compute what rades and curvatures are equivalent to each her, as regards traction, with any given velocity. In order to express a general formula for the traction when the road-way has both inclination and curvature, let w m be the traction upon a straight horizontal way. The expres sion for the whole traction T will then evident. ly be as follows: m±n+ 60 R This formula will be of use in all cases where be desirable to compare the traction, may It may perhaps seem at first view, that the in. crease of traction is less than the friction here given, in the ratio of the radius of the wheel to the height of the flange. That, however, would be an error; but whether a different ratio than that of 1 to 4, as here adopted, will best comport with truth, can only be determined from experience. Substitute for Printing.-Patent for a Filtering Machine, &c. under circumstances of various loads, grades, curvatures, and velocities. It may, perhaps, be of some use to investigate a formula for determining the greatest velocity which will comport with safety, upon curves of given radii, and with wheels of given diameters. Let k denote the distance between the axles, and put P= an arc to rad. 1, and k length. The two following theorems will 2 R give the principles upon which the investigation is made. 1st. The force necessary to cause the flange of a wheel to ascend upon the rail is in a ratio compounded of the sub-duplicate ratio of the height of the flange, and the reciprocal subduplicate ratio of the radius of the wheel. 2d. When the force necessary to cause the flange to ascend upon the rail is to the friction of the flange upon the edge of the rail, as radius to Cos. P: then is the car equally liable either to run off the track, or to continue upon it. The demonstration of these two theorems, which, for the sake of brevity, is omitted, may be easily supplied from received principles of mechanics. Now, the friction of the flange is as V2 will, in most cases, be sufficient to take, radius 11 SUBSTITUTE FOR PRINTING.-A new process has been discovered and brought into use at Brussels, whereby French books and journals may be printed with great facility and perfect accuracy. It consists of an operation by which, in less than half an hour, the whole of the let ter press upon a printed sheet may be transferred to a lithographic stone, leaving the paper a complete blank. By means of a liquid, the letters transferred to the stone are brought out in relief within the space of another hour, and then, with the usual application of the ordinary printing ink, 1500 or 2000 copies may be drawn off resembling minutely the original typography. The immense advantages of this discovery, for which M. Mecus Vandermacien has solicited a patent, may be easily conceived. A first application of this discovery has been made by him upon the "Gazette des Tribunaux," which is to appear at Brussels under a new title. [Rep. Pat. Inv. [From the Journal of the Franklin Institute.] AMERICAN PATENTS. For a Filtering Machine to be used in the Art of Manufacturing Paper; Thomas French, Ithica, Tompkins Co., New York, May 26, This machine is to perform the task of what has been usually called a pulp dresser, some of which instruments we have formerly described. A cylindrical vessel of copper, or of brass, is to be made with slots, or openings from top to bottom, exhibiting the appearance of bars about one-fourth of an inch wide, and to Cos. P. a radius of equality; in which case one thirty-second part of an inch asunder. It hmay be made solid, and afterwards cut in this Va -is as R ; that is, V is as R x 8 ; in which A is some ; manner, or it may be composed of metallic bars put together. It may also vary in its form, being either square, polygonal, or other. wise. Its diameter may be fifteen, and its height fourteen inches. constant quantity to be ascertained from experience. With wheels five feet in diameter, and flanges 11 inches in height, and upon a track of 1,000 feet radius, the utmost safe velocity is, perhaps, about 20 miles per hour. Substituting these values in the above equation, the result will give A = 2, very nearly. The general formula will, therefore, be the following: A perforated dasher is to be made to play up and down in this vessel by means of a crank, giving a velocity of from five to six hundred strokes in a minute. The pulp admitted into it is thus forced through between the bars into a vat below, whilst the knobs, &c., are retained, and are removed, when necessary, through a suitable opening. The rim of the dasher stands about half an inch from the sides of the cylinder, and its vibration approaches the bottom within half an inch, and the top within four or five inches. To supply the cylinder with stuff, a conductor of the requisite size passes through the top, or cover, of it. The cylinder is enclosed within a close square |