a flower, an emblem infinitely more beautiful than the trite one of an anchor, which is the symbol of Patience not of Hope. Abundance is imaged as a sedate matron, with a cornucopia in her hands, of which she scatters the fruits over the ground; but does not hold it up, and keep its contents to herself, as many poets and painters have represented her. Security stands leaning on a pillar, indicative of her being free from all designs and pursuits; and the posture itself corresponds to her name.

Coins also present us with countries and rivers admirably personified, On the reverse of a colonial coin, rude in execution, of Augustus and Agrippa, inscribed IMP. and DIVI. F., the conquest of Egypt is represented by the apposite metaphor of the crocodile, an animal almost peculiar to that country, and at that period esteemed altogether so, which is chained to a palm-tree, at once a native of the country, and symbolic of victory Moreover, a cabinet of medals, of which Rubens is said to have possessed a very magnificent one, may be considered as forming the classic erudition of a painter. We may add, that almost all the uses which connect the science of medals with painting render it also subservient to the art of the sculptor, who cannot less than profit by the study of the Greek coins in particular. The connexion of the study of ancient coins with architecture consists in the views of many of the ancient edifices, which are found in perfect preservation on medals. Froelich observes that the coins of Tarsus are very remarkable for a kind of perspective in the figures. On others are found triumphal arches, temples, fountains, aqueducts, amphitheatres, circuses, palaces, columns, obelisks, baths, seaports, pharoses, and the like.

The study of medals affords such a variety of amusement and of instruction, that we may naturally suppose it to be nearly as ancient as medals themselves; and yet ancient writers do not furnish us with a single hint of collections of this kind. In the days of Greece a collection of such coins as then existed would not be regarded as an acquisition of any great value, because it must have consisted only of those that were struck by the innumerable little states which then used the Greek characters and language, and of course it would be considered as a kind of domestic coinage, precluded from extension by the narrow limits of the intercourse that subsisted between different provinces and countries. As soon as any communication was opened between the Romans and the Greeks, the Grecian coins were imitated by the Roman workmen, and preserved in the cabinets of their senators among the choicest treasures. In a more advanced period of the Roman empire, individuals must have formed

collections of Roman coins; for we find that a complete series of silver was lately found in our island, containing inclusively all the emperors down to Carausius. From the decline of the Roman empire, most branches of science were enveloped in darkness till the revival of letters towards the end of the fifteenth century. When literature began to be cultivated in Italy, the study of medals, connected with that of ancient erudition, also began to engage attention. Accordingly Petrarch, who in modern times was amongst the first persons in Europe that aspired to the celebrity of learning and genius, was likewise the first to revive the study of medals. This eminent man, having been desired by the emperor Charles IV. to compose a book that should contain a history of the coins of illustrious men, and to place him in the list, is said to have returned for answer, that he would comply with his desire whenever the emperor's future life and actions deserved it. Availing himself of this circumstance, he sent that monarch a collection of gold and silver coins of celebrated men. "Behold," said he, "to what men you have succeeded! Behold whom you should imitate and admire! to whose very form and image you should compose your talents! The invaluable present I should have given to no one but yourself; it was due to you alone. I can only know or describe the deeds of these great men; your supreme office enables you to imitate them." In the next age, Alphonso, king of Arragon, caused all the ancient coins that could be discovered throughout the provinces of Italy to be collected, which he placed in an ivory cabinet, and always carried about with him, that he might be excited to great actions by the presence, as it were, of so many illustrious men in their images.

To those who are desirous of gaining information upon this interesting branch of antiquarian research, we recommend Mr. Pinkerton's 'Essay on Medals.'

Having been led to offer these observations on ancient medals, we may perhaps be allowed to make one other digression on a subject naturally suggested by a visit to the vicarage of our reverend antiquary. The reader has been told that "around his house he had arranged several precious relics, amongst which was an ancient cross, raised upon a platform on three steps."

There is much obscurity with regard to the origin and uses of these stone crosses. We are, however, not disposed to enter into a discussion of such difficulty; but the reader may be gratified in having presented to him, in one view, a collection of such crosses as still exist in various parts of Cornwall.

Note 9, p. 49.-BODIES REVOLVE ON THE SHORTER AXIS.

Upon this subject the reader is requested to turn to page 139, where it is stated that a body will permanently rotate only on its shortest axis. The philosophy of the fact is simply this-while a body revolves on its axis, the component particles of its mass move in circles, the centres of which are placed in the axis; a centrifugal force therefore is generated, which is resisted by the cohesion of the parts of the mass, and this tendency of each particle to fly off is expended in exciting a pressure upon the axis; and it is this strain which produces the effect in question, the axis of least pressure being alone the permanent axis.

Note 10, p. 62.-MOMENTUM AND THE MECHANICAL POWERS.

Mechanical powers are simple arrangements by which we gain power at the expense of time; thus, if a certain weight can be raised to a certain height by unassisted strength, and the same thing is afterwards done with one-tenth part of the exertion, through the use of a mechanic power, it will be found to occupy ten times as much time. In many cases, however, loss of time is not to be put in competition with the ability to do a thing; and since the advantages which the mechanical powers afford to man, by enabling him to perform feats which, without their assistance, would have been for ever beyond his reach, are incalculably great, the waste of time is overlooked, and is much more than balanced in the general result. It is true that, if there are several small weights, manageable by human strength, to be raised to a certain height, it may be full as convenient to elevate them one by one, as to take the advantage of the mechanical powers in raising them all at once; because the same time will be necessary in both cases: but suppose we should have an enormous block of stone, or a great tree, to raise; bodies of this description cannot be separated into parts proportionable to the human strength without immense labour, nor, perhaps, without rendering them unfit for those purposes to which they are to be applied; hence then the great importance of the mechanical powers, by the use of which a man is able to manage with ease a weight many times greater than himself.

To understand the principle of a mechanical power, we must revert to the doctrine of momentum. It will be remembered that a small ball weighing only two pounds, and moving at the rate of 500 feet in a second, will produce as much effect as a cannon-ball of ten pounds in weight, provided it only moved at the rate of 100 feet in the same time. In like manner, a ball weighing one pound may be made to balance another of five pounds, by placing it five times farther from the centre of motion; for in such a case, for every inch of space through which the large ball passes, the small one will traverse five inches, and will thus generate five times the momentum. This may be rendered still more evident by turning to page 163, where the see-saw is described, which, in fact, is a true mechanical power, and constitutes the simplest, but not the least important, of these powers. Besides which there are five others, viz. the wheel and axle; the inclined plane; the screw; the pulley; and the wedge; out of the whole, or a part of which, it will be found that every mechanical engine, or piece of machinery, is constructed; but for

an account of them we must refer the student to any elementary work on mechanics. It is however obvious, from what has been stated, that they are all founded upon the principle that the lengths of circles are in proportion to their diameters.

In connection with the subject of Momentum, a toy termed the Bandilor, or more correctly, perhaps, Bandalore, for it is of French origin, is described at page 67. Since the text was printed, Lord John Russell's Memoirs, Journal, and Correspondence of T. Moore,' have appeared; in which occurs so curious and interesting a notice of this toy, that its introduction in this place must be acceptable to our readers. "The first instance I can recall of any attempt of mine at regular versicles was on a certain toy very fashionable about the year 1789 or 1790, called in French a' bandalore,' and in English a 'quiz.' To such a ridiculous degree did the fancy of this toy pervade at that time all ranks and ages, that in the streets numbers of persons of both sexes were playing it up and down as they walked along, or, as my very young doggrel described it

The ladies, too, when in the streets, or walking in the GREEN,
Went quizzing on to show their shapes and graceful mien.'"

And Mr. Moore adds, he was informed by Lord Plunkett that the Duke of Wellington (then Captain Wellesley, or Wesley?) was in 1790 one of the aid-de-camps of the Lord Lieutenant, and a member of the Irish House of Commons, and that during the whole time of the sitting of one of its committees he was playing with one of these toys called quizzes.

Note 11, p. 76.-CENTRE OF GRAVITY.

Those who have been in the habit of inspecting the works of the statuary must frequently have detected the art which he has displayed in imparting stability to his figures, by lowering their centre of gravity. The bronze figure of Achilles, in Hyde Park, affords a very striking illustration of such ingenuity it is evident, from the position and height of the figure, that, had not a mass of matter been added to its base, its stability would have been extremely precarious, since the slightest movement might have thrown its line of direction beyond the base; but the addition at the base renders such an accident impossible, by lowering its centre of gravity. Other examples of similar contrivance are presented in several celebrated statues, wherein stability is ensured by the judicious distribution of the draperies. In the celebrated statue of Peter at St. Petersburgh, the equilibrium of the mass is thus sustained by the introduction of a serpent twin