a very important experiment. In the shutter of a dark room a small horizontal slit is made about two inches in length. Through this slit a stream of sunlight is allowed to pass. In the path of the beam of light is placed a piece of glass of triangular shape, called a prism. On the wall opposite to that in which the slit is made a very beautiful appearance is at once produced. The thin beam of light from the small slit is seen to be expanded into a long band of various colours or tints, seven in number. Taken in order, these tints are violet, indigo, blue, green, yellow, orange, and red. Now if you place a green ribbon in the red portion of this coloured band, the ribbon will appear black, and similarly a red ribbon will appear black in the green part of the band. Now all the tints of the band are produced by little waves of light, but each tint by waves of a particular length. Now a red object absorbs or destroys the waves which produce green, and reflects the waves which produce red, hence the green ribbon appears black in the red and the red ribbon black in the green part of the band. All the varied and infinite tints which make nature in all her forms so beautiful to the eye are the result of the destruction of certain light-waves and the reflection of others to the eye. A black object is black because it destroys nearly all the waves which fall upon it, and a white object is white because it sends back to the eye all the light-waves which strike it. You see, then, how greatly God has blessed man by giving him light; for it not only reveals the objects of the world to him, but also clothes them in beautiful colours, according to the nature of the objects which receive the light. You will perhaps expect me to say something about the rainbow now that I am touching upon the nature of colours. Well, the rainbow is perhaps one of the most beautiful of the natural phenomena which appeal to our sense of sight. Now this fine appearance which assumes the form of a perfect arc spanning the heavens is the combined effect of the refraction and reflection of light. The rainbow appears in the sky when rain is falling, and the sun is always somewhat low down in the sky. Now a bright beam of sunlight falls upon the falling rain-drop, and on entering the drop it is refracted, then on being reflected at the back of the drop it is again refracted, and on passing out is resolved or split up into the colours which compose it. Rainbows are seen also in waterfalls and fountains, and the explanation of the phenomena is the same as for the celestial rainbow. Now a word before we close about the nature of light. The great Newton supposed "light to consist of elastic particles of inconceivable minuteness shot out with inconceivable rapidity by luminous bodies, and that such particles impinging upon smooth surfaces were reflected in accordance with the ordinary law of elastic collision." But since Newton's time a simpler theory has been advanced, called the wave theory. On this assumption, it is believed that all space, even that which exists between the molecules or constituent particles of bodies, is filled with an exceedingly elastic ether. This ether is regarded as the medium by which the motion of the particles of a body which are vibrating sufficiently rapidly to produce the sensation of light is communicated to the intensely sensitive part of the eye called the retina. The motion imparted to the ether is sent onward from the body in all directions in the form of extremely minute waves; these waves strike the nervous network of the eye, and produce the sensation which results in vision. The minuteness of these waves is one of the wonders of nature. Professor Tyndall says: "The shortest waves of the visible spectrum (that is, the coloured band which we have described) are those of the extreme violet; the longest those of the extreme red. The length of a wave of the extreme red is such that it would require 36,918 of them placed end to end to cover one inch; while 64,631 of the extreme violet waves would be required to span the same distance. Now the velocity of light in round numbers is 190,000 miles per second. Reducing this to inches, and multiplying the numbers thus found by 36,918, we find the number of waves of the extreme red, in 190,000 miles, to be four hundred and fifty-one millions of millions. All these waves enter the eye and strike the retina at the back of the eye in one second. In a similar manner it may be found that the number of shocks corresponding to the impression of violet is seven hundred and eighty-nine millions of millions." Well may we exclaim, Before Thee, O Lord, we are as nothing; wondrous is Thy wisdom, and mighty is Thy might. ISAIAH TANSLEY. SERMON AT KERSLEY. SUNDAY, DECEMBER 8, 1878. OPENING OF NEW CHURCH BY THE REV. J. BAYLEY, M.A., PH.D. "Let your light so shine before men, that they may see your good works, and glorify your Father who is in the heaven."-MATT. v. 16. WHAT is that wondrous thing called Light? Such is the yearning question put by one of our poets into the mouth of a blind maiden. It is a question to which our text invites us, for it assumes that we have sought and obtained light, and it directs us how to use it when we are thus its happy possessors. Let your light so shine before men that they may see your good works. So will they recognise that you are the loving servants, the true disciples of the Most High, and glorify your Father in the heavens, for that is the true reading of the text. In venturing to draw your attention to the subject of Light, I have no desire to dwell upon a philosophical reply to the question, What is light? but only to consider what light is beneficially to us. And I would remark, first, that light is the sphere of brightness from the sun, which makes nature resplendent, and discloses form, colour, and beauty. In darkness all hues are alike. When the first streaks of dawn announce the break of day how strikingly beautiful is the scene! The young light chases the obscurity, gradually increases its own extent, and reveals the heavens, the hills, the trees, the hill-sides, the plains, and earth rejoices in the splendour of a new day. How lovely is the green! how gorgeous the flowers! how sublime and grand when the sun has fully risen over the horizon and advances every moment more majestically, the image of the glory of its Maker in the sun of heaven! "Oh, blest be His Name who in sorrow's stern hour Bless, bless His Name." We would remark, secondly, Light is essential to vegetation. Great numbers of flowers close up in a rest analogous to sleep when the sun goes down. Trees seek the light. Not only do the tops reach up and seek it, but the side branches follow the light, and grow and extend where the light is the greatest. Where there is much light on one side and little on the other, the tree grows one-sided; where there is light equally on every side, the tree throws out its branches, and attains roundness, evenness, and beauty of form. A cloudy shady season makes thin rings of timber; and were there continuous darkness, there would be no growth. Cattle could not be fed, and all life would wither and die. How important, then, is this wondrous element! Well might Milton, who knew its loss as well as its emblematical character, exclaim "Hail, holy light! offspring of heaven, first born! May I express thee, unblamed? since God is Light." Thirdly, we remark light is essential to health. If plants and flowers receive little light they become weak, blanched, and faded. There is a proverb in Italy that says, “Where the sun does not go the physician must." Light has a healthy, bracing action on the skin, and I believe many an unhealthy system would be relieved if there were on a larger portion of it the play of heaven's holy light. A friend of mine, who is himself unable to see, but who manages with great success a leading institution for the blind, insisted that in the building every part should be well supplied with windows. Persons said, "What do you want with all those windows when you can none of you see?" His reply was, "We must not have one less. Experience has taught me that light is essential to health." There are diseases, no doubt, in which shade is needful for a time, but as a rule invalids require light, and flowers, and beautiful things to cheer their spirits and to animate the mind. Miss Nightingale, both in Turkey and in the hospitals of this country, has insisted upon provision being made for the healthful operation of light. For body as well as for mind we should seek for light-plenty of light. Let light penetrate everywhere. Obscurity must alternate with light for repose, and to give zest to the return of glorious day, but enjoyment is at its highest when day has returned. We come now to remark that spiritual light is as needful for the soul as natural light for the body. Spiritual light is truth intelligently perceived in the mind. Spiritual light flows from the Sun of heaven, and enters the thoughtful mind, as outward light enters the observing eye. Spiritual light is indispensable to spiritual clearness, spiritual growth, and spiritual health. Nothing can be more forcible or more tender than the numerous passages of the Holy Word in which this lesson is set forth. "The Lord is my Light and my Salvation, whom shall I fear?" "Send out Thy Light and Thy Truth, let them lead me." "Light is sown for the righteous, and gladness for the upright in heart." "Arise, shine, for thy Light is come, and the glory of the Lord hath risen upon thee." In the New Testament the exhortations to seek and to follow the Light are equally numerous and equally cogent. "Through the tender mercy of our God, whereby the Dayspring from on high hath visited us, to give LIGHT to them that sit in darkness and in the shadow of death, to guide our feet in the way of peace." "He that doeth truth cometh to the LIGHT, that his deeds may be manifest that they are wrought in God." "Jesus said, He that seeth Me, seeth Him that sent Me. I am come a LIGHT into the world, that whosoever believeth on Me should not abide in darkness." "Let thine eye be single, and thy whole body" (thy spiritual body) "shall be full of LIGHT." This is equally the language of the Bible and of common sense. He who desires to be free, to be clear, to be intelligent, wise, and happy, must come to the light by coming to the Lord Jesus, the Divine Light, which "enlighteneth every man that cometh into the world." The spirit in which to seek the light is the spirit of diligence, perseverance, but especially the spirit of humility. How plainly does the Lord teach this in the beginning of the present chapter. "Blessed are the poor in spirit, for theirs is the kingdom of heaven." A gentleman of considerable intellectual power, having heard a preacher highly prized by some, said to a friend: "You go and hear so-and-so. I have heard him too. A clever man remarkable preacher-very clever man ; but I LET NO MAN TEACH ME." The reverse of this is the true spirit. We should let every one teach us who can help us to higher truth. "The Lord hides His lessons of wisdom from the wise in their own conceit and reveals them unto babes" (Matt. xi. 25). Babes rejoice in the light, and they are earnest and diligent in learning to walk. When the children of Israel went over Jordan, they took twelve stones out of the bed of the river, and Joshua placed them in Gilgal, and said to them: "When your children shall ask their fathers in time to come, What mean these stones? then ye shall let your children know, saying, Israel came over this Jordan on dry land that all the people of the earth might know the hand of the Lord, that it is mighty; that ye might fear the Lord your God for ever." In the crisis of Israel's history that was the significance of their twelve stones and of their altar set up in Gilgal. You, my beloved friends, have erected many stones, a noble structure, commodious and beautiful; you have effected a striking and a goodly object. Your neighbours may ask now, and your children may ask hereafter, "What mean ye by this convenient, elegant, and impressive structure?" Your answer must be, "We have constructed this house to gather men who seek the light, who pray for love, who live for heaven. This building is to be a great centre of light—an immense golden candlestick. We hope to see thousands who come to this house like those Greeks who spoke to Philip and said, 'Sir, we would see Jesus,' and to whom the Lord Jesus Himself will say, 'The hour is come that the Son of Man should be glorified' (John xii. 23); and they will hail Him in His glory as King of kings and Lord of lords, exclaiming each one 'I came to Jesus, and I found In Him my Star, my Sun; And in that LIGHT OF LIFE. I'll walk |