celebrated experiments. Moreover, interesting and ingenious as these experiments were, all were vitiated by a fatal defect. The accuracy of the conclusions reached depends in every case on two chief points. First, correct measurements of the attractive forces of the mountain masses studied are necessary, and this, doubtless, was attained in many if not in every one of the various investigations. Secondly, a fairly correct knowledge of the density of the rocks forming the mountains is required, and here the experiments in every case break down. We cannot learn with certainty the true mean densities of the rocks forming a mountain; at the best we can only make rough guesses at them. Consequently, of late years the attention of astronomers has been turned to the other methods to which I have alluded. These, though equally difficult to carry out, are not subject to this fatal objection. I may point out, however, before we proceed, that it would be quite reasonable, now the weight of the earth has been fixed by these other and sounder methods, to turn the above experiment about and apply the results obtained to the complementary problem of "weighing mountains."

"Of all experiments," exclaimed Professor Boys, a few years ago, in the course of a lecture at the Royal Institution, "the one which has most excited my admiration is the famous experiment of Cavendish." For this method of weighing the earth no costly expeditions to distant mountains, and no elaborate surveys requiring years for their performance are demanded. For the "Cavendish experiment," in fact, nothing is wanted but a few bits of wire, some strips of wood, balls of metal, and a case to protect the apparatus from "the wind," as Cavendish expressed it. If you possess these and certain other similar trifles, and if you possess, also, the genius for experi

menting of a Cavendish or of a Boys, you can weigh the earth. If, in addition, you possess one of the wonderful silica threads discovered a few years ago by Professor Boys, you can construct an apparatus hardly too big to go inside a man's hat-box, with which you may do the thing to a nicety.

That great though most eccentric man, the Honorable Henry Cavendish, was, as I have said, the first to carry out in a laboratory the operation of weighing the earth, but the actual originator of the Cavendish experiment was the Rev. John Michell, who constructed the necessary apparatus, but died before he had an opportunity of testing the value of his ideas by mak ing an experiment. After Mr. Michell's death his apparatus passed into the hands of Dr. Wollaston, and he handed it on to Mr. Cavendish, who, after mak ing some modifications, performed the first "Cavendish experiment" in 179798. Cavendish found the mean density of the earth to be 5.45 times that of water, and we may take it that this was the first really trustworthy meas urement. The experiment, in outline. was as follows:

Two equal balls of lead, each two inches in diameter, were attached to the remote ends of a light wooden rod six feet long, which was suspended horizontally at its centre, by means

a wire forty inches long, inside a nar row wooden case to protect it from draughts. Outside the case two much more massive balls, also of lead, twelve inches in diameter, were suspended by rods from a beam, which worked on a pivot. This pivot was placed above the wire by which the rod carrying the small balls was suspended, so that the large balls could be swung at will into various positions outside the case. For example, they could be placed transversely by putting the two beams at right angles to one another, or brought close up to the smaller balls,

counterpoised by weights, do you think the addition of one middle-sized boy to the population of the scale pan would seem to make much difference to a man who was weighing them? That is the sort of difference that had to be measured a difference of one part in seventy or eighty million parts. It will give a still better idea of the degree of perfection to which the art of weighing was brought by Professor Poynting if I add that the degree of accuracy was such as would be required, in this imaginary experiment, to detect whether or no the boy had both his boots on.

But splendid as this work was, the high-water mark was reached, perhaps, by Professor Boys in a recent repetition of the Cavendish experiment. Cavendish, as I have said, suspended the beam of his "torsion balance," as such an instrument as that used by Cavendish is called, by means of a fine wire, and the accuracy of his results depended on the elasticity of this wire. Now, unfortunately, metallic wires are not perfectly elastic, and when frequently used are subject to “fatigue”; and so there was a defect in the experiment, which remained uncorrected until a few years ago, when Professor Boys discovered how to produce threads not liable to this fault. These astonishing threads, which were made of melted quartz, are finer by far than the finest wire-so fine, in fact, that a single grain of sand spun into one of them might yield a thread a thousand miles long; moreover, they surpass The Cornhill Magazine.

steel in strength, and are marvellously elastic. Armed with quartz threads Mr. Boys was able to reduce the size of the Cavendish apparatus, and at the same time greatly to increase its sensibility. This and great personal skill enabled him to make what is probably the best measurement yet obtained of the earth's mean density-viz. 5.5270.

And so we find that the work of Maskelyne, the work of Cavendish, the work of Poynting, that of Boys, and, indeed, that of half a score others about whom I have said nothing, supports, almost without an exception, Newton's guess at the weight of the earth.

We are often told that we live in a material age, that the days of chivalry are gone, and that even science devotes herself to-day to the merely useful, and is too apt to neglect the search after abstract truth. Perhaps this incomplete recital of the progress of a great research during a period of nearly two centuries, including as it does some splendid contributions which have been made within quite recent years, may serve as a reminder that though science reveals herself to many of us chiefly through her more obviously useful and profitable discoveries and inventions, yet those who look for them will still find among us not a few men as ready as any of their predecessors to devote days and nights to hard labor for no other fee than the hope of discovering a new truth, overthrowing an ancient error, or extending in some other way the boundaries of knowledge.

W. A. Shenstone.

gayety, was a delightful object at which all the castle people stared openmouthed. The very sight of him was a relief to Meg. He kissed her hand and looked up in her face with a laugh, as much as to say, "Fear nothing from me, sweet sister." My Lady received Meg's reverence without much expression of any kind, looking upon her gravely, and with the slightest lifting of the brows. "Is this the face that drove away poor Harry's few wits?" might have been the thought in her Ladyship's mind; and indeed Meg's young loveliness had suffered from the mental agony of those six weeks.

The talk at supper was entirely between Sir William Roden and Lady Marlowe, the rest of the company keeping silence, except with their eyes. Antonio's never left Margaret, except for an occasional glance at Isabel, who never once looked towards him. Dick's roving glances found a pleasant object in the sunny looks and fair curls of Alice Tilney, who was not afraid to pay him back in the same coin. Meg's lowered eyelids were lifted for no man.

After supper Antonio helped his old master back to his own room, and with low bows left him and Lady Marlowe together, their chairs on either side of the great chimney.

"Be not far off, Tony, in case I want thee-but no eavesdropping, rascal," said Sir William.

Antonio laughed and went, not so quickly but that he heard the old man say to my Lady: "A clever dog that, a legacy from my son John, who brought him, a little lad, from Italy, picked him up in the street, a beggar foundling. He is of vast use to me. I hope he hath in no way displeased your Ladyship."

"Far from it, Sir William," was the grave reply. "I have found him very capable and well-mannered."

Antonio ran down the stairs smiling, but for all that his teeth were set on

"Here, Italian," he said, as he would have called a dog. "Who was that pretty lady on Mistress Roden's left hand? Not a waiting-maid, sure? She looked well born. Come, you know,-white neck and pink cheeks of Nature's painting—no plastering there, -blue eyes that can laugh back at a man and understand without the need of words-eh? Who is she?"

"That lady, Sir," Antonio answered, "is Mistress Alice Tilney, Mistress Roden's companion and friend."

"Ha! On my life, she's the prettiest maid of the two. Well born, then?" "There is no older name in the Midlands than Tilney of King's Hall." "I thought as much."

Dick turned abruptly away, and Antonio, after a moment's hesitation, slipped up the stairs again and turned along a gallery which led to one of the lower towers, and through this, by two doors and a passage in the thickness of the wall, out into a garden on the southern ramparts of the castle. On this garden. bright in summer with red roses, when the view of the river and meadow and distant forest was green and gay, the windows of Mistress Margaret's own rooms looked down; but they did not overlook it all, one part being screened from sight by the jutting buttresses of the tower.

Here, on this first night of his return, Antonio had a tryst with Alice Tilney; and though the evening was dark and chilly and full of creeping mist from the water, he knew she would keep it faithfully.

She was there indeed before him, and this time she had no reason to complain of his coldness; the sudden flame of