sive contract is not all performed by Mr. Russell himself, but is distributed among firms eminent for their various kinds of business. Thus, Messrs. Ferguson, the celebrated mast-makers, supply the masts and spars; and one of the wooden masts, be it noted, (the ship has three of wood, and three of iron,) is supposed to be the best and finest ever seen; it is formed of a single tree, a Canada pine, about 130 feet high, and proportionately thick. Messrs. Westhorpe take the rigging, Messrs. Hall the sails, Watt and Co. the screw engines, Mr. Russell the paddle engines, and so on; each firm sending its best work of the best material.

The strongest and the wisest man in the world is less thought of at first sight, if arrayed in shabby garments, than if he has a good coat on his back. The proprietors of the "Great Eastern" have accordingly given an extensive order to the ship's tailor to make her a smart outer garment, only the tailor in this case is the painter. To complete his contract, he will be obliged to use more than six tons of paint to give one coat to the interior ironwork, and nearly eight tons, to give one coat to the outside, from the water line to the bulwarks.

Thus, then, we have in this gigantic, and, I may say, national undertaking, an example of what man in a high state of civilization can do; we have before us the result of human thought, foresight, and calculation, embodied in a colossal but yet graceful and useful form. Weeks, months, nay, years of hard labour, their allotted duty on this earth, have been expended by thousands of human beings on the construction of this gigantic ship. "In the sweat of his brow"-his proper destiny has man called into existence this emblem of peace and of the progress of civilization throughout the whole world. May good fortune attend her in her voyages; and may she long serve to remind us of the great Master-mind who called us, his creatures, into existence, and who has given us power, first to conceive, and then to carry out an undertaking so vast, so pregnant with good-will to all mankind. As a contrast to the "Great Eastern," we give an engraving of the "Persia," which, until recently, was the largest of our ocean-steamers. Our readers will also be interested by the representation of a new tubular steamer, on an entirely new principle, in course of construction in America, of which possibly we shall hear more hereafter.

CLOCKS, AND HOW WE CAME BY THEM. SUN-DIALS appear to have been in use at a very early age. The first of which there is any record is that of Ahaz, who lived 742 years before Christ, though there is no reason for supposing that they vere thus early constructed on mathematical prin

ciples. As the world grew older, and mankind grew more sensible of the importance of time, they naturally sought for superior modes of measuring it. Clepsydræ, or water-clocks, which in a rude form had been coeval with the sun-dials, were made by the Alexandrians, to measure short periods of time with something like accuracy, and their use was adopted at about the same date (10) years B.C.), by the Greeks, to measure time in th.. courts of justice at Athens. Sand-glasses, y which time was measured by the dropping sand through a tube, were invented about the same time, and after an interval of two thousand years they are still the clock of the indigent poor.

The water-clock, in an immense variety of forms, seems to have occupied the attention of inventive minds for many succeeding centuries. Coggel wheels were made to receive their impetus from falling water, and thus regularity of motion wa continuously maintained, with a want, however, equality of force. Great improvements were ma in these clocks during the eighth and nisi centuries. In the year 807, the renowned calipHaroun Alraschid, sent as a present to Charkmagne a curious clock, in which wheels were set in motion by the fall of water, and which was the wonder of the world for a time. In the dial we twelve small doors, forming the divisions for the hours; each door opened at the hour marked by the index, and let out small brass balls, which falling on a bell, struck the hours. The doc remained open until twelve, when twelve figure® of knights on horseback came out and parade. round the dial-plate.

Even in modern times the water clock has de served to rank among the most ingenious contrivances. Vailly, a Benedictine mouk, is said t have given it the character of a scientific instra ment, about 1690. His clock was made of tin, an consisted of a cylinder divided into several sma cells, and suspended by a thread fixed to its axis. in a frame on which the hour distances, found by trial, were marked. As the water flowed from one cell into the other, it slowly changed the centre/ gravity of the cylinder, and put it in motion & as to indicate the time on the frame. He subsequently added an alarum and a dial-plate, and thus in some degree realized the advantages of o common clock.

Who first set the example of constructing cloc moved by weights, is not known. It is said that such clocks, which struck the hours, were know. in Italy in the latter part of the twelfth century but the poet Dante, who was born in 1265 a died in 1321, is the first writer who alludes to striking clock. We know that clocks were in use in our own country as early as 1288; for in that year a fine imposed on the Chief Justice of the King's Bench was appropriated to defray the cost of a clock for the clock-house near Westminste Hall, which clock was to be heard by the courts of such consequence in the reign of Henry VI, whi law. The Westminster clock was considered of commenced in 112, that he gave the keeping c it, with the appurtenances, to William Warly, dean of St. Stephen's, together with sixpence

a-day, to be received at the Exchequer. In the year 1326, Wallingford, Abbot of St. Albans, invented a clock which not only showed the hours, but the apparent motion of the sun, the changes of the moon, the ebb and flow of tides, etc: but the most ancient clock of which there is any detailed description is that of Henry Vic, or De Wyck, a German, erected in the tower of the palace of Charles v, King of France, in 1379. This was but a rude and imperfect machine; but it contained, in the principles of its construction, the germ of our modern time-keepers, and we must glance at its mechanism for a moment.

De Wyck's clock, like the hall and kitchen clock of the present day, was set in motion by the gravity of a weight attached to a cord coiled round a cylinder or drum. The motion thus obtained, and which would continue as long as the weight continued to fall, was communicated from one wheel to another of the whole apparatus by means of their toothed edges, until it reached the crown or escapement wheel. The crown wheel is so constructed and situated as to act with its teeth on two small levers or pallets projecting from the pright spindle or axis of the balance, and to convert what would else be a circular motion of the balance wheel into an alternating or vibratory one. It is this alternating motion that causes the icking of clock or watch. But a weight heavy Enough to set all the wheels in motion, unless it were subjected to some check, would rapidly run down, and with a celerity increasing until the whole of the cord was uncoiled from the drum; and in fact, this is what does take place in modern clocks, whenever the pendulum is taken away and the weights remain attached to the cylinders. To prevent this rapid running down of the works, De Wyck loaded his balance with two weights; the farther these weights were placed from the axis or spindle, the more powerfully they resisted the rapidity of the rotation of the crown wheel, and therefore of all the wheels; and they could be so adjusted, with very little trouble, as to cause the wheels to move neither too fast nor too slow, but at the desired rate.

From this period, until the middle of the seventee nth century was approaching, there seem to have been few discoveries of any very grave importance in the art of clock-making. It is true that in this long interval some extraordinary undertakings were conceived and executed by the horologists of different countries. Thus, before the end of the fourteenth century, the famous Strasburg clock was erected in the cathedral church of that city. It was a complicated piece of mechanism, the plate exhibiting a celestial globe, with the motions of the sun, moon, earth, and planets, and the various phases of the moon, together with a perpetual almanack, on which the day of the month was pointed out by a statue; the first quarter of the our was struck by a child with an apple, the second by a youth with an arrow, the third by a man with the tip of his staff, and the last quarter by an old man with his crutch. The hour itself was struck on a bell by a figure representing an angel, who opened a door and saluted the Virgin

Mary; near to the first angel stood a second, who held an hour-glass, which he turned as soon as the hour had finished striking. In addition to these was the figure of a golden cock, which, on the arrival of every successive hour, flapped its wings, stretched forth its neck, and erowed twice. The Strasburg clock did not stand alone in its glory. About the same time another mass of complicated machinery, though differing considerably in its catalogue of performances, was erected in the cathedral church of Lyons. Indeed, the wealthy towns of France, Germany, and the Low Countries now began to vie with cach other in the construction of huge cathedral or municipal clocks, and to boast of the multiplicity of exploits performed by their favourites. Yet none of these vaunted mechanical wonders were to be relied upon for true information as to the time of day; it being a fact, that up to the middle of the sixteenth century scarcely a clock was in existence which did not depart from accurate time as much as forty minutes in the twenty-four hours, and those were thought models of precision which did not exceed that rate of variation.

It is the discovery of the phenomena of the pendulum by Galileo, which marks the grand era in the construction of clocks. In the year 1650, or thereabouts, Galileo, then a medical student, was sitting in the cathedral church at Pisa, and while apparently lost in devout attention to the service, was keenly speculating on the swinging motion of the lamps, as they waved from side to side. It struck him that the oscillations of the long pendulums, whatever was the distance travelled by the weight, were always performed in the same space of time by the same pendulum. He tested his theory by measuring the vibrations of the lamps as they swung, with the beatings of his pulse, and found that it was correct. He afterwards discovered what was ultimately demonstrated by Newton, that, "the shorter the pendulum, the less is the time of its vibration;" or, in other words, that the number of oscillations performed by a pendulum in a given time depends upon its length, four times the length producing twice the number of oscillations. Here was a most important and valuable discovery; but it is by no means clear that Galileo was the first person who thought of applying it to the construction of clocks; and the merit of the invention of pendulum clocks is generally attributed to Huygens, a learned Dutchman, in 1657. The invention is also claimed on behalf of Richard Harris, a London artist, who, it is affirmed, made a long-pendulum clock in 1611, seventeen years before the date at which Galileo describes himself as directing the construction of one.

The first application of the pendulum to clocks was far from a perfect success. There were radical defects in the clock of Huygens, which prevented its accurate performance; he had constructed his pendulum on an impracticable plan, which deprived it of the influence it should have had upon the wheels. Some few years after, a superior method was invented, by a London clock-maker of the name of Clement, who was enabled to increase the weight of the pendulum employed, and thus by its