passes without our hearing or seeing something, which, if properly attended to, might lead to useful discoveries. By thus committing his ideas to writing, his mind was left at liberty to think. No extraordinary effort of memory was, even on the greatest occasions, requisite.*

On the whole, the most effectual way to acquire a good memory is by constant and moderate exercises of it; for the memory, like other habits, is strengthened and improved by daily use. It is scarcely credible to what a degree both active and passive memory may be improved by long practice. Scaliger reports of himself that in his youth he could repeat above one hundred verses, having but once read them; and Boëthius declares, that he wrote his comment on Claudian without consulting the text. The extraordinary memory of Magliabechi is well known. That of Jediah Buxton was of a peculiar kind; so long was it habituated to numbers, that it could fix on nothing else. To hope, however, for such degrees of memory as these, would be equally vain as to hope for the strength of Hercules, or the swiftness of Achilles. There are clergy

* Chiefly by Miss Edgeworth.

men who can get a sermon by heart in two hours, though their memory when they began to exercise it, was rather weak than strong: and pleaders, with other orators, who can speak in public extempore, often discover, in calling instantly to mind all the knowledge necessary on the present occasion, and every thing of importance which may have been advanced in the course of a long debate, such powers of retention and recollection as, to the man who has never been obliged to exert himself in the same manner, are altogether astonishing. As habits, in order to be strong, must be formed in early life, the memories of children should therefore be constantly exercised; but to oblige them to commit to memory what they do not understand, prevents their faculties, and gives them a dislike to learning. In a word, those who have most occasion for memory, as orators and public speakers, should not suffer it to lie idle, but constantly employ it in treasuring up and frequently reviving such things as may be of most importance to them; for by these means, it will be more at their command, and they may place greater confidence in it on any emergency.

*The Idler.

CHAPTER XI.

THE MECHANIC'S STUDIES CONTINUED.

NATURAL PHILOSOPHY is commonly defined to be that art or science which considers the powers and properties of natural bodies, and their mutual action on each other. Moral Philosophy relates to whatever concerns the mind and intellect; Natural Philosophy, on the other hand, is only concerned with the material part of the creation. The moralist's business is to inquire into the nature of virtue, the causes and effects of vice, to propose remedies for it, and to point out the mode of attaining happiness. The naturalist, on the contrary, has nothing to do with spirit; his business is confined to body or matter. The first and principal part of this science is to collect all the manifest and sensible appearances of things, and reduce them into a body of Natural History.

Natural Philosophy differs from Natural History in its appropriated sense, the business of the latter is only to observe the appearance of natural bodies separately, and from these

appearances to class them with other bodies to which they are allied. Natural Philosophy goes farther, and recites the action of two or more bodies upon each other; and though it can neither investigate nor point out the causes of those effects, whatever they be, yet from mathematical reasoning combined with experience, it can be demonstrated, that in such circumstances such effects must always take place

Natural Philosophy, till lately, has been divided into four parts, commonly called the four branches, viz.-1. Mechanics; 2. Hydrostatics; 3. Optics; and 4. Astronomy; and these again subdivided into many parts. Modern discoveries have added, however, two more parts, viz., 1. Magnetism; 2. Electricity and Galvanism. Every one is acquainted with the benefits derived from the sciences of Mechanics, Hydrostatics, and Hydraulics, to which we are indebted for many useful inventions. Among these are wind and water mills, aqueducts, pumps, fire engines, steam engines, &c., &c.

Pneumatics supply, even to a superficial enquirer, much instruction and amusement. Surely all are interested in the nature and properties of a fluid which is necessary to every moment of our existence.

How great would have been the surprise of the ancients, could they have conceived the effects which are now produced by the reflection and refraction of light! By a skilful management of these properties, telescopes, and various optical instruments are constructed. Objects too remote to be perceived by the naked eye, are enlarged and rendered visible. The satellites of Jupiter and Saturn, the mountains and cavities in the moon, and the changes which take place on the sun's disc, are thus discovered, and afford subject for admiration and inquiry. Neither is the delightful scene of Optics confined to the contemplation of distant objects. Minute animals, the vessels of plants, and, in short, a new world in miniature is disclosed to our view by the microscope, and an inexhaustible fund of rational entertainment and knowledge is brought within the spere of our senses.

Of all the sciences to which geometry imparts the solidity of its principles, and the clearness of its proofs, the most beautiful and the most sublime is Astronomy. This is perhaps the most exact and most definite part of natural philosophy: for it rectifies the errors of sight, with respect to the apparent motions of the planets; explains the just dimensions.