they are absolutely stationary. No system, in short, appears, and no general law seems to direct their motions. By the observations and inquiries of astronomers, however, during successive ages, a regular system has been recognised in this chaos of moving bodies, and the magnitudes, distances, and revolutions of every planet which composes it has been determined with the most extraordinary accuracy. Minds fitted and prepared for this species of inquiry are capable of understanding the great variety of evidence by which the truth of the planetary system is established; but thousands of individuals who are even distinguished in other branches of knowledge are incapable of such researches, and view with a skeptical eye the great and irrefragable truths of astronomy. That the sun is stationary in the centre of our system, that the earth moves round the sun, and round its own axis,-that the earth is 8000 miles in diameter, and the sun one hundred and ten times as large, that the earth's orbit is 190 millions of miles in breadth, and that if this immense space were filled with light, it would appear only like a luminous point at the nearest fixed star, are positions absolutely unintelligible and incredible to all who have not carefully studied the subject. To millions of our species, then, the great book of nature is absolutely sealed, though it is in the power of all to unfold its pages, and to peruse those glowing passages which proclaim the power and wisdom of its mighty Author. The book of revelation exhibits to us the same peculiarities as that of nature. To the ordinary eye it presents no immediate indications of its Divine origin. Events apparently insignificant→ supernatural interferences seemingly unnecessary -doctrines almost contradictory-and prophecies nearly unintelligible occupy its pages. The history of the fall of man-of the introduction of moral and physical evil-the prediction of a Messiah-the actual advent of our Saviour-his instructions-his miracles-his death-his resurrection-and the subsequent propagation of his religion by the unlettered fishermen of Galilee, are each a stumblingblock to the wisdom of this world. The youthful and vigorous mind, when first summoned to peruse the Scriptures, turns from them with disappointment. It recognises in them no profound science—no secular wisdom-no Divine eloquence-no disclosures of nature's secrets-no direct impress of an Almighty hand. But, though the system of revealed truth which this book contains is, like that of the universe, concealed from common observation, yet the labours of centuries have established its Divine origin, and developed in all its order and beauty the great plan of human restoration. In the chaos of its incidents we discover the whole history of our species, whether it is delineated in events that are past or shadowed forth in those which are to come,-from the creation of man and the origin of evil, to the extinction of his earthly dynasty and the commencement of his immortal career. The antiquity and authenticity of the books which compose the sacred canon,-the fulfilment of its prophecies, the miraculous works of its founder,— his death and resurrection, have been demonstrated to all who are capable of appreciating the force of historical evidence; and in the poetical and prose compositions of the inspired authors we discover a system of doctrine and a code of morality traced in characters as distinct and legible as the most unerring truths in the material world. False systems of religion have indeed been deduced from the sacred record, as false systems of the universe have sprung from the study of the book of nature,-but the very prevalence of a false system proves the existence of one that is true; and though the two classes of facts necessarily depend on different kinds of evidence, yet we scruple not to say that the Copernican system is not more demonstrably true than the system of theological truth contained in the Bible. If men of high powers, then, are still found, who are insensible to the evidence which sustains the system of the universe, need we wonder that there are others whose minds are shut against the effulgent evidence which intrenches the strongholds of our faith. If such, then, is the character of the Christian faith, we need not be surprised that it was embraced and expounded by such a genius as Sir Isaac Newton. Cherishing its doctrines, and leaning on its promises, he felt it his duty, as it was his pleasure, to apply to it that intellectual strength which had successfully surmounted the difficulties of the material universe. The fame which that success procured him he could not but feel to be the breath of popular applause, which administered only to his personal feelings; but the investigation of the sacred mysteries, while it prepared his own mind for its final destiny, was calculated to promote the spiritual interests of thousands. This noble impulse he did not hesitate to obey, and by thus uniting philosophy with religion, he dissolved the league which genius had formed with skepticism, and added to the cloud of witnesses the brightest name of ancient or of modern times. CHAPTER XVII. The minor Discoveries and Inventions of Newton-His Researches on Heat-On Fire and Flame-On Elective Attraction-On the Structure of Bodies-His supposed Attachment to Alchymy-His Hypothe sis respecting Ether as the Cause of Light and Gravity-On the Excitation of Electricity in Glass-His Reflecting Sextant invented before 1700-His Reflecting Microscope-His Prismatic Reflector as a Substitute for the small Speculum of Reflecting Telescopes-His Method of varying the Magnifying Power of Newtonian Telescopes -His Experiments on Impressions on the Retina IN the preceding chapters we have given an account of the principal labours of Sir Isaac Newton; but there still remain to be noticed several of his minor discoveries and inventions, which could not properly be introduced under any general head. The most important of these, perhaps, are his chymical researches, which he seems to have pursued with more or less diligence from the time when he first witnessed the practical operations of chymistry during his residence at the apothecary's at Grantham. His first chymical experiments were probably made on the alloys of metals, for the purpose of obtaining a good metallic composition for the specula of reflecting telescopes. In his paper on thin plates he treats of the combinations of solids and fluids; but he enters more largely on these and other subjects in the queries published at the end of his Optics. One of his most important chymical papers is his Tabula quantitatum et graduum caloris, which was published in the Philosophical Transactions. This short paper contains a comparative scale of temperature from that of melting ice to that of a small kitchen coal-fire. The following are the principal points of the scale, the intermediate Z degrees of heat having been determined with great care. Degrees of Heat. 1 45 Equal Parts 0 Freezing point of water. 12 Blood-heat. 24 Heat of melting wax. 48 Melting point of equal parts of tin and bismuth. 96 Melting point of lead. 192 Heat of a small coal-fire. The first column of this table contains the degrees of heat in arithmetical progression, and the second in geometrical progression,-the second degree being twice as great as the first, and so on. It is obvious from this table, that the heat at which equal parts of tin and bismuth melt is four times greater than that of blood-heat, the heat of melting lead eight times greater, and the heat of a small coal-fire sixteen times greater. This table was constructed by the help of a thermometer, and of red-hot iron. By the former he measured all heats as far as that of melting tin; and by the latter he measured all the higher heats. For the heat which heated iron loses in a given time is as the total heat of the iron; and therefore, if the times of cooling are taken equal, the heats will be in a geometrical progression, and may therefore be easily found by a table of logarithms. He found by a thermometer constructed with linseed oil, that if the oil, when the thermometer was placed in melting snow, occupied a space of 1000 parts, the same oil, rarefied with one degree of heat, or that of the human body, occupied a space of 10256; in the heat of water beginning to boil, a space of 10705; in the heat of water boiling violently, 10725; in the heat of melted tin beginning to cool, and putting on the consistency of an amalgam, |