Before the sun was come to its setting he began to see outlines that had been familiar to him all bis life. On the moor he had seen only those that he had learnt in his previous tramp across. Presently the smoke of the village came in view, lying heavily in its valley. He passed the point at which he had left Mike and Sarah standing to watch his going when he had fared away from Noricott-going, as he had told himself a hundred times in the last twenty-four hours, on the very suggestion of Tim, who now ! Fool that he had been! He despised himself for his blindness in going. Why had he not trusted to the instinct that had bidden him refuse this job because Tim had been the one to offer it? He thought of his beautiful wife of accorded right the most beautiful woman in Noricott. What would he do with the hammer? Would he deal two blows with it, or one? Of the one he had no question. That part of the tragedy he had rehearsed in his mind till he was nigh dazed with it; but as for the other, for the woman, his decision was not taken even now that he had passed the last ridge of moorland, and was on his downward way right to the village.

His cottage was at the hither end of it as he approached, and rather apart from the other houses. He saw no one as he came along the road, and passed through the little garden gate that stood, as it had stood for years, broken and open. He stepped aside off the little path, stole to the window exactly as he had planned to do in his walk across the moor, and looked within. Already a candle had been lighted in the room, though there was still light in the sky out of doors, and the fire threw flickering beams about it. Sarah was lying on the dilapidated 'sofy' before the fire, asleep. He looked about for Tim, but there was no sign of him. Probably he was not come in yet from his work. He was a good worker always, as Stephen reflected, and at the thought held his hammer at a handier balance. Then Stephen heard the well-remembered click of the door that shut off the stairway leading to the upstairs room, and his pulse went fast at the thought that now he should see Tim appear. But it was not Tim. To his surprise it was a girl of the village whom he knew well, Mary Taylor. What should she be doing in his house? She glanced at Sarah a moment; then, seeing her sleeping, went to close the cottage door which stood open. Before doing so she took a look without, and in that look espied Stephen.

Stephen,' she exclaimed. 'Be that you?'

Stephen was turning to her even as she spoke.

"Ees, it be,' he said, speaking painfully, with a throat as dry as a kiln. 'Where be Tim?'

'Tim,' she replied as if the question were a natural one enough to ask. "Ee'll be along d'rectly, I reckon. Do 'ee come inside, Stephen.'

Along d'rectly, will 'ee? 'Ees, I'll come inside.'

He came, and when he had made two steps across the room he stopped abruptly. Beside the sofa on which Sarah slept was a tiny cot, and in the cot, sleeping also, a baby of a few days old.

Helplessly Stephen gazed for a full half minute. Then he said to the girl beside him, in a dry whisper, with an unconscious point of his hammer at the tiny thing. 'Be that Sally's?'

''Ees fai', it be, Stephen,' she said, laughing under her breath. 'Why, didn't 'ee know?'

'No, I didn't know nothing, Mary Taylor. How was I for know?'

'Sally said as 'er'd a-wrote it to 'ee on her letters, on'y 'er said as 'er wasn't sure whether you'd rightly understand. And it baint Mary Taylor no longer, neither, Stephen. I be married to Tim now. You 'avent a-heard that neither, maybe.'

'No, for sure I 'avent,' Stephen said weakly. All his grasp of life seemed to be going from him, and as if to express his bewilderment on the physical side the hammer went from his hand and fell with a clang on the floor. At the sound, both sleepers awoke ; the baby began a little feeble cry, and Sarah, turning herself painfully towards the child, caught sight of Stephen and gave a cry too, but of delight.

'Oh, my dear,' she exclaimed in a weak voice of purest joy. 'Do'ee come here then. It be bootiful for see 'ee.'

She put up her arms about his neck very feebly, but very lovingly, and began to tell him all sorts of things, of the kindness of Tim and Mary, and how she had hoped he would come, and then suddenly, in the middle of telling him, she checked herself. And aw, Stephen,' she said pitifully, 'us 'ave lost the poor old Mike. Us was bound for put un out of the 'ouse and Tim told un for go over to 'ees 'ouse and thought as 'ee'd find un there, and 'e went and no one's ever seed un again.'

"Ees they 'ave then,' said Stephen, smiling at her. 'I've a-seed un myself, and that not more'n two or three hour ago.' So then there was a deal of explanation to be done on Stephen's part. In the middle of all that, Tim came to the door, on his way back

from work, to see if he could bring his wife anything, as she was sleeping there for the time being. At sight of Stephen he had to come into the room to welcome him, his wife, who had taken the baby from its cot, explaining to him volubly the while that Mike was no longer lost. Stephen returned Tim's look a little sheepishly as the other took him by the hand, and said, 'Well I be main glad for see 'ee, sure enough. Us all be.' Then Tim's foot struck some object on the floor. He stooped to pick it up.

'Why, whatever be that?' he asked, holding up the hammer. 'Aw, that!' said Stephen. 'Tis something as I 'appened for bring along-by mistake.'

MATTER, MOTION, AND MOLECULES.

Change is everywhere; everything is and is not. There is no stability. Even in the same river one cannot bathe twice, nor even once.'

IN his Presidential Address delivered before the members of the British Association at their meeting in South Africa, Professor Darwin recently reminded us of the tremendous scope of modern speculations as to the constitution of matter. At one end of the scale we contemplate in the heavens arrangements of matter on schemes so vast that no mind can picture them. At the other end, according to the 'corpuscular hypothesis,' we find in the chemical atoms yet other constellations, which, though they are individually smaller than the heavenly arrangements, are not less complex nor less numerous; whilst in between these two extremes matter occurs in a multitude of phases, physical and chemical, so great and so varied that the task of discovering their relations has taxed to the utmost the powers of the greatest minds right through the ages. It is to this middle field that the molecular kinetic theory,' or, briefly, the 'kinetic theory,' more particularly applies, helping us first to get a picture of the relations of the solid, liquid, and gaseous states of matter, and then, as will be shown on some subsequent occasion, to unravel some of the complexities which underlie chemical phenomena.

Anyone who has watched a thermometer plunged in a vessel filled with crushed ice will remember how steadily the mercury stands at the zero point until all or nearly all the ice has melted. He may remember, too, that this is equally the case whether the ice melts slowly or quickly; that it makes no difference whether the experiment be made in cool air in the open or in a warm room, and that even if the vessel be placed over a flame the result is the same; that in any case and in every case, provided only that the general temperature does not fall below the freezing-point and that a sufficient supply of ice is available, it is impossible under ordinary circumstances to raise the temperature of ice or of a mixture of ice and water above 0° C. Now, this curious fact, which was discovered by Dr. Hooke in the latter part of the seventeenth

century, does not stand alone. Other solids in thousands behave in a similar manner, and the change of a liquid into a steam during the process of boiling is accompanied by corresponding phenomena. Boil water, for example, how you may, quickly or slowly, by means of a coal fire, a gas flame, or an electric furnace, in every case you will find it impossible to raise its temperature above a fixed point. This point may vary slightly from day to day, rising a little when the barometer is high, falling a little when the barometer is low, but, at or near the sea-level, it is never very much above nor very much below 100° on the Centigrade scale.

These facts about the melting of ice and the boiling of water, discovered, as I have said, by Hooke in the seventeenth century, were used by Newton as the standards by which the 'fixed points' of thermometers might most conveniently be determined; but their meaning remained hidden till it was revealed by Dr. Black in a memoir read before a literary society in Glasgow in 1760. This memoir, a classic among the classics, forms one of the foundation-stones of the 'kinetic theory'; that is to say, of modern physics. Put briefly, Dr. Black's explanation was as follows: The heat which disappears when ice is melted combines with the ice, just as one element combines with another when a compound is formed. Water is a sort of compound of ice and caloric, in which these two are united in definite doses like the elements in a chemical compound. We no longer regard heat, or caloric, as only a more subtle, imponderable form of matter. Hence we no longer consider water to be a compound of ice and caloric, in the sense in which we believe ice to be a compound of hydrogen and oxygen. And thus Black's hypothesis takes to-day a different form. But we agree with Black that in the melting of ice, or any other solid, a definite dose of something-call it heat-actually is received by the solid and in some way hidden, or rendered latent, within it. Thus Black's idea still lives, and Black himself must be regarded as the first of the founders of the great theory which forms the subject of this article. His name must be associated with those of John Dalton of Manchester and Amadeo Avogadro of Turin, who contributed the atomic-molecular hypothesis, and with those of the great physicists of the Victorian era who developed the modern doctrine of 'energy.'

I must now ask those of my readers who are not already equipped with clear ideas as to the meaning of the terms 'matter' and 'energy' to give their attention for a few moments to the two