Newton at the same time made great contributions to the subject of geometrical optics, decomposed white light by means of a prism, investigated the colours of thin plates, and some cases of diffraction, and speculated on the nature, properties, and functions of the ether, which was equally necessary to the corpuscular as to the undulatory theory of light, if any of the phenomena of interference were to be explained. The velocity of light was first measured by Roemer, in 1676. The camera obscura was invented by Baptista Porta, a wealthy Neapolitan, in 1560; and Kepler explained the action of the eye as an optical instrument, in 1604. Antonio de Dominis, Archbishop of Spalatro, discovered the fringe of colours produced by sunlight once reflected from the interior of a globe of water, and this led, in Newton's hands, to the complete explanation of the rainbow.

The germ of the mechanical theory of heat is to be found in the writings of Lord Bacon. The first thermometers which were blown in glass with a bulb and tube hermetically sealed, were made by a craftsman in Florence, in the time of Torricelli. The graduations on these thermometers were made by attaching little beads of coloured glass to their stems, and they were carried about Europe by members of the Florentine Academy, in order to learn whether ice melted at the same temperature in all latitudes.

In electricity the attraction of light bodies by amber when rubbed, was known at least six hundred years before the Christian era, and the shocks of the torpedo were described by Pliny and by Aristotle; but the phenomena were not associated in men's minds until recent times. Dr. Gilbert, of Colchester, Physician to Queen Elizabeth, may be regarded as the founder of the modern science. He distinguished two classes of bodies, viz. electrics, or those which would attract light bodies when rubbed; and non-electrics, or those which could not be so excited. The first electric machine was constructed by Otto von Guericke, the inventor of the Magdeburg hemispheres, who mounted a ball of sulphur so that it could be made rapidly to rotate while it was excited by the friction of the hand. He observed the repulsion which generally follows the attraction of a light body by an electrified object after the two have come in contact. He also noticed that certain bodies placed near to electrified bodies possessed similar powers of attraction to those of the electrified bodies themselves. Newton replaced the sulphur globe of Otto von Guericke by a globe of glass. Stephen Gray discovered the conduction of electricity, in 1729, when he succeeded in transmitting a charge to a distance of 886 feet along a pack-thread suspended by silk strings so as to insulate it from the earth. Desaguliers showed that Gilbert's "electrics" were simply those bodies which could not conduct electricity, while all conductors were "non-electrics;" and Dufay showed that all bodies could be electrified by friction if supported on insulating stands. He also showed that there were two kinds of electrification, and called one vitreous, the other resinous. Gray, Hawksbee, and Dr. Wall all noticed the similarity between lightning and the electric discharge. The prime conductor was first added to the electric machine by Boze, of Wittenberg; and Winkler, of Leipsic, employed a cushion instead of the hand to produce friction against the glass. The accumulation of electricity in the Leyden jar was discovered accidentally by Cuneus, a pupil of Muschenbroeck, of Leyden, about 1745, while attempting to electrify water in a bottle held in his hand. A nail passed through the cork, by which the electricity was communicated to the water. On touching the nail after charging the water, he received the shock of the Leyden jar. This brings the history of electrical discovery down to the time of Franklin.

ROBERT BOYLE.

Robert Boyle was descended from a family who, in Saxon times, held land in the county of Hereford, and whose name in the Doomsday Book is written Biuvile. His father was Richard Boyle, Earl of Cork, to whom the fortunes of the family were largely due. Richard Boyle was born in the city of Canterbury, October 3, 1566. He was educated at Bene't College (now Corpus Christi College), Cambridge, and afterwards became a member of the Middle Temple. Finding his means insufficient for the prosecution of his legal studies, he determined to seek his fortune abroad. In 1595 he married, at Limerick, one of the daughters of William Apsley, who brought him land of the value of £500 per annum. In his autobiography the Earl of Cork writes:—

When first I arrived at Dublin, in Ireland, the 23rd of June 1588, all my wealth then was twenty-seven pounds three shillings in money, and two tokens which my mother had given me, viz. a diamond ring, which I have ever since and still do wear, and a bracelet of gold worth about ten pounds; a taffety doublet cut with and upon taffety, a pair of black velvet breeches laced, a new Milan fustian suit laced and cut upon taffety, two cloaks, competent linen, and necessaries, with my rapier and dagger. And since, the blessing of God, whose heavenly providence guided me hither, hath enriched my weak estate, in beginning with such a fortune, as I need not envy any of my neighbours, and added no care or burthen of my conscience thereunto. And the 23rd of June, 1632, I have served my God, Queen Elizabeth, King James, and King Charles, full forty-four years, and so long after as it shall please God to enable me.

Richard Boyle's property in Ireland increased so rapidly that he was accused to Queen Elizabeth of receiving pay from some foreign power. When about to visit England in order to clear himself of this charge, the rebellion in Munster broke out; his lands were wasted, and his income for the time destroyed. Reaching London, he returned to his old chambers in the Middle Temple, until he entered the service of the Earl of Essex, to whom the government of Ireland had been entrusted. The charges against him were then resumed, and he was made a prisoner, and kept in confinement until the Earl of Essex had gone over to Ireland. At length he obtained a hearing before the queen, who fully acquitted him of the charges, gave him her hand to kiss, and promised to employ him in her own service; at the same time she dismissed Sir Henry Wallop, who was Treasurer for Ireland, and prominent among Boyle's accusers, from his office.

A few days afterwards, Richard Boyle was appointed by the queen Clerk to the Council of Munster, and having purchased a ship of Sir Walter Raleigh, he returned to Ireland with ammunition and provisions.

"Then, as Clerk of the Council, I attended the Lord President in all his employments, and waited upon him at the siege of Kingsale, and was employed by his Lordship to her Majesty, with the news of that happy victory; in which employment I made a speedy expedition to the court; for I left my Lord President at Shannon Castle, near Corke, on the Monday morning, about two of the clock, and the next day, being Tuesday, I delivered my packet, and supped with Sir Robert Cecil, being then principal Secretary of State, at his house in the Strand; who, after supper, held me in discourse till two of the clock in the morning; and by seven that morning called upon me to attend him to the court, where he presented me to her Majesty in her bed-chamber, who remembered