For simple, vast, it soothes what it disturbs, Hail! Genius of New Worlds! but works more grand And nobler visions than thou yet hast seen, Else the nice essence, irresponsible, Yet some there are, who from the sense set free, -Thus Poets dream-but to such lofty height The Bard shall shrink not-nor endure in vain. Smile at the threats of Man, the strokes of Time; Laugh at the storms that rage 'gainst them and thee. The nations tremble- thou hast never feared— N. S. VOL. I. L L Why shouldst thou dread the issues of the wrath? Each true and perfect, loving and complete. The Earth is shaken! Truth hath blown a blast-- While He who made, swore that his creature Man No more rude Nature should subdue the mind, Come! Genius! come-O winged Child! away, Bring with thee Will, and Pleasure bring with thee, And let us seek young Love,-for where is he? -Young Love! which Love? Lo, there twin brethren stand; Each like to each, as hand is like to hand! One Eros is-one Anteros they name Which woos thy heart with most congenial claim? Choose now-for on thy choice how much depends; The earthly Love, or heavenly, thee attends. -This, like an ardent seraph, ever burns With light and life, like flames from burial urns; Though fixed and bound to caskets deftly wrought, Still chased and chasing, each revolving ray Falls-like heaven's flash on earth's polluted shrine Smites and consumes the altar's impious feast, -Happy the Bard, obedient to their sway, A miracle remains, as when a child. ; One such I know. To Care and Sorrow bred, His mind would commune with the immortal Dead, For therein he was happy, and their Voice Bade manhood early waken, and rejoice. With none to cherish, solace or admire, His heart consumed within him, as with fire: And o'er his lips song gushed from boyhood's hour, Resolved, howe'er unjust mankind might be, For Truth he loved and Virtue he esteemed, It sought to free from Death, and Sin, and Pain,— And glorious still,-when Suns shall cease to shine! CENSUS OF SCIENTIFIC THEORIES. No. 1.-THE UNDULATORY THEORY OF LIGHT. BY CHARLES TOOGOOD DOWNING, M.R.C.S.—Author of the “Fanqui in China,” &c. (Continued from page 227.) It may be unnecessary to remind the reader, that when a ray of light is incident upon a polished surface, a considerable portion is thrown back, or, as it is called, reflected; and thus we are able to distinguish its shape and colour. The various phenomena resulting from this law are comprehended under the term Catoptics, and constitute a considerable branch of the science of Optics. It is not intended to dwell upon this subject further than is absolutely necessary in order to explain the Huygenian doctrine of reflection. The general opinion that prevailed before the time of Newton was, that light was reflected by striking or impinging upon the solid parts of the reflecting surface, in the same manner as a billiard ball is reflected from the sides of the table. Huygens, as well as Sir Isaac, perceived the improbability of this supposition; and that if it were true, the reflection from polished surfaces would not be so regular as it is. The latter has shown, that however carefully a glass is polished, this is effected by grating and scratching it with powders, so as to remove its protuberances. Thus when it is polished, its protuberances, which cause the roughness, are brought to a very fine grain, and thus the marks and scratchings of the surface are rendered too small to be visible to the eye. Now it is manifest, that if these little pits and protuberances bear any sensible proportion to the magnitude of the particles of incident light, and the particles of light impinged against them, they would be scattered as much by the most polished as by the roughest glass. As Sir Isaac Newton, however, perceiving that the light is more perfectly reflected from polished surfaces, concluded that this regular reflection of light was not owing to single parts of the body acting upon single particles, but to some power of the body evenly diffused over all its surface, and by which it acts upon rays without immediate contact, this supposition was necessary in order to explain reflection by the corpuscular doctrine; but Huygens, on the contrary, has endeavoured to show that a perfectly polished surface is not necessary to an equal and regular reflection. According to the undulatory theory, it is believed that the solid particles of the ethereal matter are much smaller than those of the reflecting surface, and that this surface consists of particles of matter put together, and smaller or ethereal particles over and above them. Thus, if we take the reflecting surface of mercury, for example, we are to consider its particles as so minute that we may conceive millions of them arranged like a mass of grains of sand, in the smallest visible space, and having their surface smoothened as much as possible. This surface will then become uniform, like that of polished glass; and though it is always rough in relation to the ethereal particles, yet the centres of all the particular spheres of reflected undulation are nearly in the same uniform plane, and their common tangent will touch them as perfectly as is necessary to the production of light; for all that is necessary is that some of the motion reflected from all points shall not produce any opposite effect. When light falls upon a polished surface, only part of the rays are reflected, some of them being transmitted and thus subjected to refraction, while others are dispersed in all directions by the inequalities. The proportion of those rays which are reflected varies according to the nature of the substance, and also to the angle at which they are incident. Thus, if we take a polished surface of glass, we find that twenty-five rays in every 1000 are reflected while the greater part of the remainder are transmitted, when the light falls at a perpendicular incidence. But at very great angles of incidence, such as 8740, it reflects 584 rays. This is the reason why rough glass, which will scarcely reflect a single ray at small angles of incidence, reflects it most copiously and appears perfectly polished when viewed at an angle of 70° or 80°. If in the place of glass we substitute water, and let the light fall perpendicularly, 982 out of the 1000 rays are transmitted, and only 18 are reflected. When the same pencil is incident at an angle of 40°, 22 rays are reflected; at an angle of 75°, 211 rays; while at an angle of 89°, 692 rays are reflected. Thus it may be seen, that bodies reflect more in proportion to their refracting power, although they reflect less light than water at very great angles of incidence. With these preliminaries, we may now proceed to the mathematical theory of reflection, according to the undulatory system of Huygens. It is acknowledged to be very ingenious, and to be more consistent with the phenomena than that of the corpuscular. The |