same kind of electricity repel each other. If you hang a piece of paper, or better still, a pith ball a, upon a silk thread b, and hold near to it a piece of sealing-wax c rubbed with dry flannel, you will find that the ball will at first be attracted towards the sealing-wax as in 1, Fig. 17, but after a few moments it will be repelled and will draw back as in 2 ; nor will it approach the sealing-wax again till it has been near some other body, and given up part of the electricity it has received. Thus an electrical body, as Guericke pointed out,

Pith-ball, attracted and repelled by rubbed sealing-wax.

attracts one that is not electrified, but repels it again as soon as it has filled it with electricity like itself. He was also the first to notice the spark of fire and crackling sound which are produced by electricity when it passes between two bodies which do not touch each other.

Foundation of the Royal Society of London and other Academies of Science, 1645.-We must now return to England, where about this time an event took place which, though it seemed insignificant at the time, had in the end a great influence upon science. In the year 1642 the unfortunate King Charles I. began that civil war with his people which ended in his being beheaded on January 30, 1649. During these years all England was in a state of turmoil and confusion, and in London especially the riots and disturb

CH. XV. FOUNDATION OF THE ROYAL SOCIETY.

125

ances made it almost impossible for quiet and studious people to live in peace. It was under these circumstances that a small group of scientific men, among whom were Robert Boyle, son of the Earl of Cork, and Dr. Hooke, an eminent English mathematician, began to meet together privately to try and forget public troubles in discussing science. They assembled first in London in 1645, but soon moved to Oxford to be out of the way of the constant riots, and continued to meet there till 1662, after the restoration of Charles II., when they settled in London and formed themselves into a regular Society under a charter from the king.

This was the beginning of the Royal Society of London, which has done so much for science during the last two hundred years, and which is still the leading scientific society of England. The following account of its early meetings is thus given by Dr. Wallis, one of the first members, 'Our business,' he says, 'was (precluding matters of theology and State affairs) to discourse and consider of philosophical enquiries, and such as related thereunto as Physick, Anatomy, Geometry, Astronomy, Navigation, Staticks, Magneticks, Chymicks, Mechanicks, and Natural Experiments; with the state of these studies, and their cultivation at home and abroad. We then discoursed of the circulation of the blood, the valves in the veins, the venæ lactæ, the lymphatic vessels, the Copernican hypothesis, the nature of comets and new stars, the satellites of Jupiter, the oval shape (as it then appeared) of Saturn, the spots on the sun and its turning on its own axis, the inequalities and selenography of the moon, the several phases of Venus and Mercury, the improvement of telescopes and grinding of glasses for that purpose, the weight of the air, the possibility or impossibility of vacuities

and Nature's abhorrence thereof, the Torricellian experiment in quicksilver, the descent of heavy bodies and the degrees of acceleration therein, with divers other things of like nature, some of which were then but new discoveries, and others not so generally known and embraced as they now are; with other things appertaining to what hath been called the New Philosophy, which, from the times of Galileo at Florence and Sir Francis Bacon (Lord Verulam) in England, hath been much cultivated in Italy, France, Germany, and other parts abroad, as well as with us in England.'

How well we can picture from this account (written in 1696), the pleasure which this little group of men, weary of the quarrels and bloodshed of the times, felt in discussing and investigating those laws of nature which seem to bring us into the calm presence of an Almighty Unchanging Power far above the petty wranglings of man! The Royal Society has become, as I have said, one of the grandest scientific bodies in the world; but it has probably never held more earnest or enthusiastic meetings than in the sınall lodgings at Oxford where it first took its rise in the midst of civil war.

England was not long the only country which had a scientific society. Italy had already had two in the time of Galileo and Torricelli, but they had soon been broken up again. In Germany, the 'Imperial Academy of the Curious in Nature' was founded in 1662; and in 1666 the famous 'French Academy of Sciences' was legally established by the French Government in Paris.

All these societies were a great help in spreading the knowledge of scientific discoveries. Men who before were unable to publish what they knew, now sent or read their

CH. XV. EARLY MEMBERS OF THE ROYAL SOCIETY. 127

papers to those who could understand and appreciate them. The Royal Society began from the first to publish useful memoirs in their Philosophical Transactions; and in 1669 we find them bringing out the works of an Italian anatomist, Malpighi, of whom we shall speak presently, and who sent to them works which he could not afford to publish-in Italy. By this means the information scattered about the world was gathered together, and men were encouraged to seek out new truths when there was a chance of their being known and appreciated.

Among the earlier members of the Royal Society there were some whose discoveries we must now consider. These were Boyle and Hooke, whom we have already mentioned; John Mayow, whose experiments in chemistry are especially interesting; Ray, Grew, and Malpighi, naturalists and anatomists; the Dutch astronomer Huyghens; the English astronomer Halley, and last, but not least, England's great philosopher, Sir Isaac Newton.

Chief Works consulted. - Ganot's 'Physics,' 1873; Balfour Stewart on 'Heat,' 1871; Rossiter's Physics,' 1870; Baden Powell's 'Histtory of Nat. Philosophy,' &c.; Cuvier, 'Histoire des Sciences,' &c. ; Birch's 'Hist. of Royal Society;' Thomson's Hist. of Royal Society,' 1812.

CHAPTER XVI.

SCIENCE OF THE SEVENTEENTH CENTURY (CONTINUED). Boyle's Law of the Compressibility of Gases-This same Law discovered independently by Marriotte-Hooke's theory of Air being the cause of Fire-Boyle's experiments with Animals under the Air-pump-John Mayow, the greatest Chemist of the Seventeenth Century-His experiments upon the Air used in Combustion— Proves that the same portion is used in Respiration --Proves that Air which has lost its Fire-air is Lighter-Mayow's 'Fire-air' was Oxygen, and his Lighter air Nitrogen-He traces out the effect which Fire-air produces in Animals when Breathing.

Boyle's Law of the Compressibility of Gases, 1661.—The Hon. Robert Boyle, seventh son of the Earl of Cork, and one of the principal founders of the Royal Society, was born in 1626. He had very delicate health, and when quite young travelled much abroad and learned there a great deal about science even before he was eighteen years of age. He was deeply interested in Galileo's discoveries, and was in Florence when that great astronomer died in 1642.

After his return to England, when he was at Oxford, he read an account of Guericke's air-pump, and was so delighted with this new discovery that he set to work at once to make one without ever having seen the original. He succeeded so well, with the help of his friend and assistant Dr. Hooke, that his air-pump became famous, and many writers have by mistake given him the credit of being the