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covery of such law; and that, when our knowledge of the weather has thus come to be a portion of scientific knowledge, science will be able to guide and protect the agriculturist, in reference to the future state of the weather, with as much certainty as it now guides and protects the mariner, in reference to the future depth of the water, which will be found at a given time, in the port for which his vessel may be bound.

How science is enabled to do this shall be the subject of my second illustration.

Sir Isaac Newton discovered that all the various portions of matter, of which the mind can acquire knowledge, are imbued with the power of attracting one another; 1 and this power has now been so extensively verified, as to be susceptible of the following precise expression-viz. Every particle of matter in the universe attracts every other particle with a force directly proportioned to the mass of the attracting particle, and inversely to the square of the distance between them.'2 The size of the earth has been ascer

1 Newton's Principia, book i. pro. 17, 75. The argument in this immortal work proceeds by showing first the apparently provisional character of the law of gravitation from a superficial consideration of the lunar orbit (as a circle described with an average mean velocity), and then elevating it to the rank of a general and primordial relation by proving its applicability to the state of existing nature in all its circumstances.-Newton's Principia, by Lord Brougham; Dissertations to Paley's Natural Theology, vol. ii.; Sir J. Herschel's Astronomy (446), 3rd ed., 1850.

2 Sir J. Herschel's Astronomy (445).

'Every doubt which has been raised with regard to the universality and accuracy of the law of gravitation has ended in confirming the rule.'-Whewell's Philosophy of the Inductive Sciences, vol. i. p. 257, 2nd ed., ' Establishment of Universal Gravitation.'

tained by science. The mass and distance of our moon have, by like means, been measured, and the scientific application to these bodies of Newton's great law has shown, that the rising and falling of the water at the mouths of rivers and along sea coasts, so familiarly known to you as the tides, are mainly owing to the attraction exerted by the moon on the earth's surface, whereby the fluid water is drawn away from those parts which lie at the greatest distance from the moon's influence, and is drawn up, in a heap as it were, on those parts which lie vertically under, or nearest to, the moon, forming thereby respectively high and low tides.1 But science has also succeeded in measuring the enormous relative size of our sun, and its immense relative distance from the earth, and has thus been able to ascertain precisely the amount of attraction which the sun exerts upon the earth's surface; and science, having also calculated the respective motions of the earth and moon, can foretell

1 Centripetal tides. The link between celestial and terrestrial physics;' the celestial explanation of a great terrestrial phenomenon.' On this interesting subject of 'The Tides,' see Elements of Physics, by Neil Arnott, M.D., F.R.S., 6th ed., 1865, Longmans, vol. ii.; On Astronomy, The Tides (1309); Sir. J. Herschel's Astronomy (752), p. 497, 3rd ed.; and article 'Waves and Tides' (Prof. Airy), Penny Cyclopædia; and Mrs. Somerville's Connexion of the Physical Sciences, sec. xiii.

Sir W. R. Grove, in his admirable Discourse on Continuity (Longmans, 1867), has ventured upon a prediction to the effect that Saturn's ring may eventually be the means of our discovering how our solar system developed itself. I will venture upon an analogous assertion, viz., That a generally diffused knowledge of the causes of the tides, not simply as fact, but as the philosophy of fact, would in itself be sufficient to banish superstition from the face of educated society.

with certainty their respective future. positions in relation to the sun, and thereby ascertain whether, at any stated future time, the attractive influence of the sun will be in augmentation of the moon's attraction, or whether it will be in direct opposition to it; and can, therefore, with like certainty, predict when and where will happen those very high or spring tides, or those very low or neap tides, of which many of you may have been witnesses, and all must have heard.' And thus a class of phenomena, which little more than a century ago were regarded, like the weather, as inoxplicable, have been traced to the operation of invariable laws, and the great theory of the tides is now shown to have this scientific sanction, viz., the fulfilment of its previsions so exact as to guide our conduct. You can now understand how science is enabled to give such information to the mariner as will enable him to fix beforehand the hour at which his vessel, on arriving in its destined port, shall find suflicient water to allow him. to place it safely in connection with the shore; and you can appreciate how much to science are owing the speed, safety, and precision that characterise the Tidal Services' between this country and the continent.

The human mind, contemplating the two theories, or systems, which I have been contrasting, concerning God's secular providence, and the relation in which man must stand towards them, seems so constituted as to find itself irresistibly impelled to ask the question,

This alternate mutual reinforcement and destruction of the solar and lunar attraction causing what are known as the spring and neap tides, the former being their sum and the latter their difference,' --Herschel's 1stronomy (752).

tained by science. The mass and distance of our moon have, by like means, been measured, and the scientific application to these bodies of Newton's great law has shown, that the rising and falling of the water at the mouths of rivers and along sea coasts, so familiarly known to you as the tides, are mainly owing to the attraction exerted by the moon on the earth's surface, whereby the fluid water is drawn away from those parts which lie at the greatest distance from the moon's influence, and is drawn up, in a heap as it were, on those parts which lie vertically under, or nearest to, the moon, forming thereby respectively high and low tides.1 But science has also succeeded in measuring the enormous relative size of our sun, and its immense relative distance from the earth, and has thus been able to ascertain precisely the amount of attraction which the sun exerts upon the earth's surface; and science, having also calculated the respective motions of the earth and moon, can foretell

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1 Centripetal tides. The link between celestial and terrestrial physics; the celestial explanation of a great terrestrial phenomenon.' On this interesting subject of 'The Tides,' see Elements of Physics, by Neil Arnott, M.D., F.R.S., 6th ed., 1865, Longmans, vol. ii.; On Astronomy, The Tides (1309); Sir. J. Herschel's Astronomy (752), p. 497, 3rd ed.; and article 'Waves and Tides' (Prof. Airy), Penny Cyclopædia; and Mrs. Somerville's Connexion of the Physical Sciences, sec. xiii.

Sir W. R. Grove, in his admirable Discourse on Continuity (Longmans, 1867), has ventured upon a prediction to the effect that Saturn's ring may eventually be the means of our discovering how our solar system developed itself. I will venture upon an analogous assertion, viz., That a generally diffused knowledge of the causes of the tides, not simply as fact, but as the philosophy of fact, would in itself be sufficient to banish superstition from the face of educated society.

with certainty their respective future. positions in relation to the sun, and thereby ascertain whether, at any stated future time, the attractive influence of the sun will be in augmentation of the moon's attraction, or whether it will be in direct opposition to it; and can, therefore, with like certainty, predict when and where will happen those very high or spring tides, or those very low or neap tides, of which many of you may have been witnesses, and all must have heard.1 And thus a class of phenomena, which little more than a century ago were regarded, like the weather, as inexplicable, have been traced to the operation of invariable laws, and the great theory of the tides is now shown to have this scientific sanction, viz., the fulfilment of its previsions so exact as to guide our conduct. You can now understand how science is enabled to give such information to the mariner as will enable him to fix beforehand the hour at which his vessel, on arriving in its destined port, shall find sufficient water to allow him to place it safely in connection with the shore; and you can appreciate how much to science are owing the speed, safety, and precision that characterise the 'Tidal Services' between this country and the continent.

The human mind, contemplating the two theories, or systems, which I have been contrasting, concerning God's secular providence, and the relation in which man must stand towards them, seems so constituted as to find itself irresistibly impelled to ask the question,

1 This alternate mutual reinforcement and destruction of the solar and lunar attraction causing what are known as the spring and neap tides, the former being their sum and the latter their difference.' -Herschel's Astronomy (752).

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