and upon the method by which thought is expressed, after a very few struggles, gave way to the more active faculties devoted to physical nature.

Some have objected to such characters by saying that they result from a want of full development of the faculties, from a one-sidedness of the mind; but what man in this short life can cultivate one faculty highly without depriving the others of nutriment, or cultivate every faculty equally without stinting them all?

In Dalton we have found a mind which has shewn itself, as well in its operations as in its results, to be of the very highest scientific class.

CHAPTER XIV.

ARRANGEMENT OF THEORIES.

To those who have attended to the history of ideas, it must always seem a remarkable thing that in early times, among certain truths, the very culminating point should have been sometimes attained by one grand bound over all the difficulties of the journey, leaving undescribed all the ruggedness of the ground passed over. To those who have been born on this summit, there is the same difficulty in passing down to the plain, as there is for us to pass upwards: the same blasting of rocks and filling up of morasses. To say that the history of the struggle is lost to us does not explain all. In these three words, already quoted, "measure, weight, and number," as applied to creation, we see that men had looked long and carefully on the world, had admired its beauty, and believed that everything was arranged with scrupulous accuracy. The context shows that the fundamental idea was a moral one, and the reasons we now have were not then in existence; but in general terms there is the eminence seen on which they stood; we move back towards the plain, or try to reach the summit, measuring, weighing, and numbering, and proving the great mountain view to be true to the minutest particle of matter.

The scientific mind seeks to repeat the order of thought by which the divine mind arranged the universe; the artistic mind sees it completed, and rejoices in its beauty. The scientific mind has the work of the six days of creation, the artistic mind lives in the Sabbath of rest. The poetical mind refuses this class of limitation.

These remarks are called forth by the peculiar progress of some of the early opinions and the difficulties encountered when experiment began. We may arrange the numerous theories spoken of in the following manner, seeking the spirit or fundamental idea of each.

First we have one matter out of which all the others were made. This in early times was real substantial matter, as water and earth; afterwards a dynamical water or earth, or a natural force corresponding to them or underlying them. Then the four elements were made the origin of all things; but convertible. These theories, although under some aspects going under various heads, may be conveniently put under one and be called the Allhylic. (aλos and λn, interchangeable (ἄλλος elements.)

The next, although allied, claims for itself a separate place. When there is recognised a universal matter, a prima materia' from which all things are made, and which itself has no substantial qualities, but is capable of assuming all, it may be called the prothylic theory. (πpwrn vλn, first element as it was called.)

When matter is made up of indivisible particles, the name atomic is already appropriately given. (a and róμos, uncut.) When particles are infinitely divisible, it may be useful to call this theory the dia-tomic. (dià and rouos cut through.) When we find the original matter to be a force only, whether represented by a number, a point, a line, a geometrical figure, or a more abstract idea, this is the dynamical theory.

When there are neither forces nor atoms, nor distinct elements, nor universal and insuperable laws, nor a substratum of primary matter, the mystic theory seems an appropriate name.

In the early atomic theories, the only difference recognised in atoms is their shape. These theories are mechanical. Now we recognise many original differences forming elements. This is a polyhylic atomic theory.

No theory can entirely get rid of Dynamics, but it would only introduce confusion into the historical account, if we said more of it than the promoters themselves.

The old theories were after all exceedingly indefinite, notwithstanding the appearance of exactness. The Daltonian theory is remarkable chiefly for its idea of quantity. It defines composition and combination by quantity. It is mechanical, because it unites pieces of matter in a masonlike style; it fits every part and breaks none, but it is not merely mechanical. Force is required, and this is of a different kind with every species. It is polyhylic. It unites therefore more qualities than previous theories. There has never been any progress made in ascertaining in what essentially consists the peculiarity of the forces in each element. That remains for future inquiry. The inquiry has chiefly had relation to weight, and for that reason I have called Dalton's the quantitative atomic theory. Mr. Joule's discoveries in heat, although not purely chemical, have begun to introduce into chemistry, through physics, forces that can be exactly calculated other than weight.

I think it of importance that Dalton's theory as adopted by chemists should have a distinct adjective to express it. The term quantitative atomic connects itself with analysis which in every case leads us to the use of the theory, although the most convenient term for general use, by which also we do honor to the originator, is the Daltonian theory. It represents the mode of discovery by weighing and calculating, and the greatest fact treated of with regard to atoms, as viewed by chemists, that they are comparative quantities measurable by the balance: it represents also the state of chemistry since the theory was propounded, a wonderfully elaborate collection of orderly arrangements of bodies distinguished principally by their quantities. I have left out as unnecessary to this history such of the characters of atoms as Dalte, held more as hypothetical than theoretical.

Those theories, which now appear only as histories, are not of necessity all extinct; for some of them a resurrection day will in all probability arrive, when their forms will be beautified and their powers exalted. It may be, too, that in the confusion of transition or the difficulties of progress, various inferior appearances may be looked on as the final triumph, and be hailed by the hasty and the short-sighted, although seen by the clearer judgment to be mere phantoms by the way, specimens of the mystic theory. The time may come when the old theory of the prima materia, which has deluded so many, may have a higher existence, and alchemy again become the "true philosophy." Over this, too, the dynamical theory may rise, grasping them all, and by giving clearer ideas of force, thrust into an inferior position both quantity and matter, and show us, with greater certainty, the true position of abstract power and of mind.

THE END.