A coin of Julius Cæsar, for instance, brings him closer to our mind than reading his biography would. The principle of curiosity, implanted in our breast, as the prime spring of knowledge also concurs. Cicero of old remarked the pleasure we feel in contemplating spots remarkable for great actions, or other memorable histories; and a similar sensation appears to contribute to antiquarian amusements. Our senses are affected by sensible objects. Hence portraits - tokens of distant friends-relics of saints; but as it is difficult to anatomise such a subject, these few hints only are submitted to the reader's reflection. Its usefulness as a study may be thus deduced. If we cast an eye over the whole circle of the productions of human genius, perhaps we shall perceive none of such great importance and utility to mankind as history. But the very basis of all history is truth, without which, the causes of human actions, nay the actions themselves, are disguised, and the instruction arising from the narration totally lost, or converted into an empty chimera. Now the sole evidence we can have of the veracity of an historian, consists in such collateral documents as are palpable to all, and can admit of no falsification. Such are public memoirs, letters of state, instructions to ambassadors; but as these proofs are liable to accident, mutilation, and loss, their evidence cannot extend to very distant ages. Hence monuments of longer duration are required to evince the veracity of ancient history. Such indeed are public buildings, statues, and inscriptions; but the evidence of these testimonies, though it extends to remote ages, does not extend to remote countries, if we except in a few instances, the two last-named (statues and inscriptions). Medals and coins alone remain as the principal proof of historic truth-their evidence reaching at once to the most remote ages and the most distant countries.

To conclude, we quote an extract from the lines of the learned and elegant Pope, addressed to Addison on his Treatise of Ancient Medals:—

"Ambition sigh'd-she found it vain to trust

The faithless column and the crumbling bust;

Huge moles whose shadow stretched from shore to shore,
Their ruins perished, and their place no more!
Convinc'd she now contracts her vast design,
And all her triumphs shrink into a coin.
A narrow orb each crowded conquest keeps,
Beneath her palm here sad Judea weeps;
Now, scant in limits the proud arch confine,
And scarce are seen the prostrate Nile and Rhine.
A small Euphrates thro' the piece is roll'd,
And little eagles wave their wings in gold.
The medal, faithful to its charge of fame,
Thro' climes and ages bears each form and name;
In one short view subjected to our eye,
Gods', emperors', heroes', sages', beauties' tie:
With sharpened sight, pale antiquaries pore,
Th' inscription value, but the rust adore;
This, the blue varnish-that, the green endears,
The sacred rust of twice ten hundred years."

THE EARL OF ROSSE'S REFLECTING TELESCOPE.

A LETTER from Sir James South has appeared in the public papers, in which he informs us that the leviathan telescope of the Earl of Rosse was, on Wednesday, Sept. 18th, directed to the sidereal heavens, and that with a power of 500, the nebula known as No. 2, Messier's catalogue, was even more magnificent than No. 13 of the same, when seen with the Earl's telescope of 3 feet diameter, and 27 feet focus. "I look forward," says Sir James, "with intense anxiety to witness its first severe trial, when all its various appointments shall be completed, in the confidence that those who may then be present will see with it what man has never seen before. Compared with it, the working telescopes of Sir W. Herschel, which, in his hands, conferred on astronomers such inestimable service, and on himself astronomical immortality, were but as playthings." It will be seen then, from the testimony of Sir James, that through this powerful telescope a new era in the annals of astronomy may be anticipated, and such being the case, we cannot but think a brief outline of its construction will be instructing to our readers.

The deeply interesting field of scientific research opened up to the philosopher by the labours of Sir W. Herschel and his son, in the double and multiple stars, and in the nebula, with some of which latter our entire sidereal sphere is, in comparison, but a speck, rendered it necessary, in order accurately to examine them, to obtain as great a power of sight as possible, and this it was, the Earl of Rosse tells us, that first induced him, in 1826, to make improvements on the telescope. In effecting which it was necessary to keep two objects in view: first, a sufficient aperture for a sufficiency of light; second, to increase sufficiently the magnifying power, which latter an inferior sized instrument might possess, and yet not have enough light to allow a distinct outline of objects. His next consideration was, whether the telescope he was about to construct, should be a refractor or a reflector. On consideration of the difficulties attendant on both, he decided on the latter, which, however, presented great objections, for it is well known that error of form in a reflector, produces an error in the form of the image, more than five times as great as the same error in a refractor would produce. This, the principal difficulty, was overcome in the following manner:

In the first place, experiments were undertaken in the hope of overcoming the obstacles which prevented the application of the brilliant alloy which may be formed by proper proportions of tin and copper, and this was effected by increasing the proportion of copper; the polish, however, would not now remain. Of course the object of first importance was to receive a great quantity of reflected light; and, therefore, a powerful polish was necessary, which also should retain its brilliancy for a length of time. In the course of the construction of three speculæ, where the basis of the mirror was an alloy of zinc and copper, in the proportion of 1 zinc to 2.74 copper, it was ascertained that the difficulties of casting large discs of speculum metal arose from the unequal contraction of the material, which produced imperfections in the castings, and often subsequently caused the destruction of the speculum; and it seemed plain that if the whole of the metal could be allowed to cool at a given temperature at the same time, the contraction would be equal. This clearly could not be exactly fulfilled. But, by abstracting heat from the lower surface, the mass would cool uniformly in a horizontal direction; and, in the vertical, it would vary in degree as the distance from the cooling surface. To effect this, however, it was necessary to have the lower surface of the mould, of iron, by having holes in which, or by forming it of iron plates placed vertically side by side, the air was allowed to escape, and air bubbles prevented. The alloy used was merely tin and copper in the atomic proportions, viz.-one atom of tin to four of copper.

As the processes for grinding and polishing specula had hitherto depended on manual dexterity, and were therefore uncertain, a machine was constructed in 1827, by which means a close approximation to the parabolic figure can be obtained. The principles upon which it acts are simply these:

The speculum revolves slowly, the polishing tool is drawn backwards and forwards by one crank, and from side to side slowly by another. Being fixed to the crank by a ring, it is allowed to revolve by a rotatory motion, which it receives from the speculum, its

pressure on which is about one pound for every circular superficial foot; the motion of the speculum and the polishing tool are relatively so adjusted as that the focal length of the speculum should gradually become slightly larger, and the figure greatly depends upon the rapidity with which this increase is made. It is evident that a surface originally spherical, will soon become parabolic, provided that under the action of a polisher an alteration in the focal distance take place under certain conditions.

In grinding, the powder employed runs loose between two hard surfaces; but in polishing, the particles of power are lodged in the comparatively soft material of the polishing tool, and in consequence of the extreme accuracy of contact between the polishing tool and the speculum, the particles are completely imbedded. It is very necessary to sustain this accuracy, or the speculum would be scratched, and the process one of fine grinding.

While it is essential that the surface in contact with the speculum should be as hard as possible consistent with its retention of the polishing powder, it is also necessary that it should yield where requisite, or accuracy of contact could not be preserved. Both conditions are obtained by forming the surface of two layers of resinous matter, of different degress of hardness; the first, common pitch made consistent by adding spirits of turpentine or rosin; the other, of rosin, spirits of turpentine, and wheat-flour, as hard as possible, so as to retain the polishing powder.

"A speculum of three feet diameter," says Earl Rosse, and confirmed, as we have seen, by Sir James South, "thus polished, has resolved several nebulæ, and in a considerable portion of the others has shown new stars, or some other new feature."

REVIEW OF BOOKS.

Lectures on the Conversion of the Jews. By MINISTERS OF DIFFERENT DENOMINATIONS. Published under the sanction of the British Society for the Propagation of the Gospel among the Jews. London: AYLOTT & JONES.

A LEARNED French atheist, once unwittingly acknowledged that the events which are recorded in the annals of the Jews, combined with their present state, constitute the most wonderful and unaccountable anomaly to be found in the history of the world. And for once the infidel was right. The extraordinary dispersion of the Jews, not only throughout all civilized and semi-civilized countries, but in regions the most unlikely for them to be found, so that they tread the snows of Siberia, and the sands of the burning desert, and we even hear of their existence in the central unknown of Africa, to which no European traveller has ever yet penetrated;—their unparalleled sufferings, for in all countries and in all times they have been exposed to famine and pestilence, rapine and murder, fire and sword, and every species of individual torture and wholesale massacre ;—their signal preservation, so that they have been like the bush seen by Moses, ever burning, and yet never consumed-never amalgamated, as in every other recorded instance, with the nations among whom they have been scattered, at this moment as distinctly Jews, as when they inhabited their own city and their own land; and what is yet more wonderful, notwithstanding all the slaughters, all the barbarities, all the persecutions of seventeen hundred years, continuing still as numerous as they were at the destruction of Jerusalem; their constant, inveterate, and, except in a very, very few authenticated instances, their miserable unbelief, their unrelenting, and perhaps, it may be added, their malignant rejection of the proofs which establish the claims of Jesus of Nazareth to be the promised Messiah-all combine to point out these Jews, not only as the most astonishing people upon the surface of the globe, and as the melancholy mementos of bygone ages of suffering and crime, but also as the living and breathing demonstrations of the truth of revelation, and the justice of the retributive providence of God.

And yet the finger of inspired prophecy positively directs our attention to an approaching period when a mighty revolution, tantamount to the entire conversion and restoration of the whole aggregate of the nation, shall be accomplished in the history of the Jews; and it must also be stated, that, at the present period, some ominous signs are discernible among this remarkable people, which indicate that such an auspicious event may be much nearer than is generally anticipated. We know

that among a very large proportion of the Jews in London, the authority of their Mishna and Gemarra is giving way; their ancient, and, in many instances, their monstrously absurd superstitions, are abandoned; and the recent schism which has taken place among the metropolitan Jews, and to which we cannot now more particularly refer, although it has effected a complete separation in their body, materially confirms our expectations that a decisive change is at hand.

We are glad to perceive by the volume before us, that some hopes may now be entertained that the really wicked and shameful inattention of the professedly Christian world to the moral and religious condition of the Jews, is about to be changed for a better and more consistent state of things. The commencement of the operations of the British Society we hail as the commencement of a new era in the annals of this department of Christian philanthropy; the plan which they have adopted to rouse the religious public from its apathy is one of the most efficient they could have chosen; and the volume which has been published under their auspices, is one of the most popularly useful and instructive on the subject to which it refers, which has ever emanated from the British press. It consists of ten lectures, by some of the most able ministers in London, on the Destination, the National Characteristics, the Dispersion, the Present Condition, and the Conversion of the Jews. The last subject, in its different branches, occupies six out of the ten lectures. To make quotations from these lectures is impossible; and, where all are so excellent, it would be invidious to single out any for especial praise. We cordially commend this seasonable and truly valuable publication to the attention of our readers.

We cannot but express our sincere pleasure in finding that the lecturers assert and defend what, in our opinion, are the true principles upon which we are to hope for the accomplishment of the conversion of the Jews. The manner in which the "crotchet" of Dr. Wolff, and of many who think with him relative to the hidden existence of the ten tribes of Israel in some remote part of the world, as exposed in the fourth lecture, is very happy, efficient, and complete.

Young Men engaged in Trade urged to Self-Exertion for Advancement in True Dignity and Excellence. By a FELLOW-LABOURER. pp. 36. 18mo. HAMILTON & Co. Paternoster Row.

THE author of this little work, in introducing it to his readers, modestly grounds his claim to their attention upon his being one of themselves, taking his "daily stand behind a counter, and going through the duties and routine of a subordinate situation." He commences by briefly describing the present mental and moral condition of the young men engaged in trade as assistants, and urging the necessity of a reform from within. He then warmly presses on their attention the claims of religion, stating, "that religion, personal, heart religion, lies at the root, at the very foundation of all true and lasting improvement." He next refers to the culture and discipline of the mind, to the husbanding of time, to the choice and reading of books, to composition and writing, and to the selection of companions. His remarks on dress are appropriate; and all would do well in following his advice relative to the regulation of conduct in general. In fact, it is a complete little manual, which should be the companion of all assistants; a portion of his concluding appeal we here transcribe:

"The evils complained of meet me at every step; they are observable on every hand. While philanthropic efforts are made by the wise and the benevolent to ease our burdens and abridge the hours of toil, I find these evils held up to public view, by parties inimical to our interest, as an abundant reason why even all attempts at improvement should be scouted, and every means of additional relaxation withheld. And when, in addition to this, one not only finds these evils productive of incalculable harm to individuals, but also to be the means of bringing odium on a large class to which he himself belongs, how can he be silent, and not raise a warning voice? Arouse yourselves, then, my brethren; shake off the deadly incubus. By your conduct before all, prevent past errors and follies being again urged as arguments against affording means for your further advancement-cheer and gladden the hearts of all your well-wishers, by an upright, honourable, and Christian cause. But should the great mass remain unaffected, and, continuing deaf to ten thousand calls, remain unaffected, simply go on as before. I can only, in company with those like-minded, weep over them in secret."

THE STUDENT.

THE HARMONY BETWEEN SCIENCE AND RELIGION. It has been said more than once, that religion shuns the light of science. No assertion could be more unfounded. Divine revelation is open to the closest and most searching examination-challenges the most rigid modes of investigation. It has nothing to fear from human inquiry and discovery. The keenest penetration, the minutest and most subtle analysis, will more clearly reveal the evidence on which it rests its claim to universal belief and acceptance. The interpretation put upon its sublime truths may be proved both fallacious and absurd; but this affects not the authenticity of the revelation. Nor does this revelation interfere with the province of reason-does not entinguish this "candle of the Lord" within us-raises no barrier to the onward progress of mind-offers no check to the advance of knowledge-invites the most enlightened and advanced still to persevere, and sheds fresh Fight upon their path; while, in itself, it presents the only science which promises sufficient scope and compass to the powers of our undying intellect. Religion is not only the most eminent science, but it takes the precedence of all other sciences, in their first principles and greatest discoveries.

Let us turn to Geology, the most recent of the sciences, and what does revelation teach us on this interesting subject? We open the inspired volume; and the first intimation we receive from the infallible oracle is" In the beginning God created the heavens and the earth.” Now, at what point in the past we are to fix "the beginning" is not determined; and, therefore, an undefined and undefinable interval of time is left between this first great creative act of Omnipotence, and the condition of the earth when "it was without form and void." Chaos could not be the result of creation-God is not the author of confusion. We cannot, therefore, conceive of the almighty Creator employing his power to produce a rude, inert, shapeless mass, and then putting forth the same power, to give to that mass a subsequent form and fashion. The earth being without form and void, describes but one of those many successive conditions in which it has been involved since "the beginning" while the change which it underwent under the restoring hand of its Creator, when the vital Spirit brooded on the face of the deep, is but one in a series. Each revolution of our globe would necessarily induce new formations, and give birth to new phenomena; and for these formations and these phenomena, revelation sufficiently proNo. 8.

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