theory. How a nerve comes to be sensitive to light hardly concerns us more than how life itself originated."

Not common sense only, but Reason rebels, when required to acquiesce in a theory which supposes that an eye, perfect and elaborately constructed in accordance with occult laws of physics, could have been formed by a series of accidental variations as it would if required to believe that a philosophical instrument made by man could have been evolved by such means.

But there is no difficulty in allowing that the most perfect eye has been gradually developed from the most imperfect, provided we recognise the existence of an agent adequate to the accomplishment or achievement of such development.

The existence of the evidences of design in creation is so much a matter of opinion that it would serve no purpose to discuss it here; if, however, it be once admitted that design is apparent in the different forms of life, the theory that natural selection has been the chief agent in their formation becomes untenable.

It is needless to point out how the above difficulties to the theory of natural selection tend to corroborate the theory advocated in this paper.

When Darwin evades more searching investigation of his difficulties by coming to the conclusion that to attempt to explain them more fully than he does would involve an inquiry into the origin of life itself: when he uses such expressions as "the mysterious laws of correlation ;" when, indeed, he assumes that an organism has the faculty of adapting itself to its condition of life, has the power of improving its members or organs, and altering them to serve for new purposes; when he absolutely founds his theory on the supposition that an organism is endowed with the power, by a long series of efforts, and the inheritance of slight variations, of developing into a new and more highly organised structure, does he not tacitly admit the existence of an inherent force or energy, or, in other words, of a power of expansion? External conditions would have no more effect on organic than on inorganic matter, were not the former endowed with a power of growth, development, expansion. Were organisms merely plastic there could be no progress, no improvement, no ascent to higher forms of life; there might be variety or change, but there would be nothing new or essentially different. "Ex nihilo, nihil fit;" in default of a power of expansion extraneous influences would have nothing to work upon, no energy to direct, no growth to mould to the changing conditions of life.

I have seen it stated that the theory of natural selection does not suppose the individual to be capable of selfimprovement, but that purely fortuitous variations are rendered permanent by inheritance provided they happen to be improvements, and that thus only have the different forms of life been produced. But Darwin certainly believes that some variations are due to effort, or use and disuse, caused, however, entirely by the accidental circumstances of the conditions of life, and that variations that are inherited become characteristics of new species.* Although he has not expressly excluded the possibility of the action of some other agency, the general tenour of his writings is sufficient to convince us that in his opinion natural selection is sufficient to account for the origin of species. The only instances in which he appears to entertain misgivings on this point have been already mentioned.

The chief difficulty of the theory of expansion is the fact of the existence at the present time of the lowest forms of life. Several explanations suggest themselves :—

First. The germs of life may exist inactive for many ages, until activity is set up by some particular cause. Secondly. The germs of life may be capable of spontaneous generation.

Thirdly. Certain germs may have a limited power of development.

Fourthly. Certain germs may be retarded or completely arrested in their development from some cause or other. These suggestions are purely speculative; they are given merely to show that the difficulty admits of explanation in various ways.

I have chosen the word "expansion " as the one open to the fewest objections when used in its mathematical sense. The word "growth" would confuse the age-development with the growth towards maturity of the individual, from which it is quite distinct. The words "development" and "evolution " express only improvement or extension, but "expansion " conveys the idea of development by the action of some force or agent, or else extension according to a definite law, such as the expansion of a binomial into an infinite series.t

* See Preface to second edition of "Descent of Man."

The word "Expansion" has been chosen, also, to distinguish the theory from that of "Progressive Development" advanced by Lamarck, and which he admits to be merely a statement of observed facts, and from those that suppose the existence of an innate tendency to improvement and perfection; in short, to distinguish a process of "unfolding" from one of " addition."

In conclusion, I must remark that it appears to me to be more philosophical, and more in accordance with what we know of the operations of Nature, to believe that species were formed by rigid and unchanging laws, acting through all time, than to suppose them to have been evolved by a series of accidents.

It is, indeed, a tremendous thought, that the highest forms of life have been expanding to their present state of perfection through hundreds of ages; that all forms of life are now unfolding and expanding to higher types,-expanding not by uncertain and fortuitous means, but by laws as immutable and inexorable as those which govern inanimate matter; that the great scheme of evolution had been fully planned and matured when the first minute germs of life, with their mighty destinies, came into active existence in a world which was then a wilderness, but which has since become full of glorious life, of forms most wonderful and beautiful, evolved by the mysterious power acting with ceaseless energy through all the bygone ages.

The imagination is dazzled in the contemplation of results so stupendous from a beginning apparently so insignificant; but the reason must needs bow before the great weight of evidence, and must admit the inevitable conclusion that in every living thing there is a force that for ever works upwards and onwards, that retrogression and decadence are impossible, save for a transient wave of apparent degeneration that seems occasionally to sweep over a race, and which is generally attributable to a temporary extraneous

cause.

It would seem that Tennyson, with the divine inspiration of the poet, had some dim conception of the great truth when he wrote

"A monstrous eft was of old the Lord and Master of Earth,

For him did his high sun flame, and his river billowing ran,
And he felt himself in his force to be Nature's crowning race.
As nine months go to the shaping an infant ripe for his birth
So many a million of ages have gone to the making of man :
He now is first, but is he the last? is he not too base?"

III. THE PORT OF YMUIDEN.

By F. C. DANVERS, Assoc. Inst. C.E.

or

EW people will recognise in the above name the great and important engineering work which has, since 1865, been under construction in Holland, and which has been more familiarly known as the "Amsterdam "North Sea Canal." Since the construction of the Suez Canal no hydraulic work of greater, or even equal, importance has been undertaken, and its successful completion reflects no little credit upon Sir John Hawkshaw and the able engineers who have been associated with him in the undertaking. A brief retrospect will show the necessity that existed for this work.

In the sixteenth century Amsterdam stood first of all the commercial cities of Europe. Its prosperity, however, gradually began to decline, partly from the rise of other ports, but principally from the difficulties of navigation caused by the silting up of the Zuyder Zee, and above all by the formation of the Pampas Bar. Large vessels could, in consequence, no longer get up to Amsterdam with their cargoes, but were obliged to discharge outside the bar, when they were floated over it by means of " camels," which, when the water was pumped out of them, raised the vessel with them. The trade of Amsterdam was fast being diverted to Rotterdam, but in 1819 steps were taken to avoid the difficulties of the Zuyder Zee by the construction of the North Holland Canal, which extends from Buiksluyt, opposite Amsterdam, to the Helder, a distance of 51 miles; and this canal has since been extensively used by vessels of large burden seeking the North Sea. It is, however, difficult of passage in winter, and consequently it was at length determined to connect Amsterdam with the North Sea direct by means of a canal passing through the Wijker-meer and the Ij, by the shortest possible route, by the adoption of which the distance to the sea is shortened by no less than 36 miles.

This work was commenced in March, 1865. It consists of two parts, viz., a harbour in the North Sea, at the mouth of the canal, and the canal itself.

The harbour was designed by Sir John Hawkshaw. It consists of two piers stretching out into the sea to the depth of about 26 feet below the level of low water. These piers at their junction with the land, at the foot of the downs on the

beach, are 1312 yards distant from one another. Thence their directions converge, so as to make an angle of 77 degrees with their base line, and at 1312 yards from the shore they are 721 yards apart. From this point they begin to converge more rapidly, so that, with an additional length of 377 yards,-making 1689 yards in total length, -they terminate 284 yards apart at the harbour mouth."

The piers consist of a solid sea wall, 27 feet wide at top, and increasing in thickness downwards by one-seventh of their height. They are formed as follows:-First of all a foundation of basalt rock was thrown into the sea, about 40 yards wide and I yard in thickness. On this a superstructure is raised, formed of concrete blocks, varying from 4 to 10 tons in weight. The rubble foundation was levelled by divers, by whom also the blocks below low water were fitted, without any cement in their joints, the blocks being let down to their site by a powerful steam crane called a "Titan." From low water the blocks are laid in cement; for the lowest joints-which are only a few hours above water-a quick-setting Medina cement was used, and for the higher joints Portland cement. The top of the piers is generally 13 feet 6 inches above the Amsterdam pile (datum). The parapet on the top of each pier consists entirely of concrete, moulded on the spot in frames erected in situ. Behind this is a pavement of brick in cement, supported by a band of granite along the inner top line. In the construction of each of the two piers there has been used 433,600 yards of concrete blocks, 77,700 tons of cement, 229,000 cubic yards of shingle, 130,900 cubic yards of basalt, and 19,035 cubic yards of broken bricks, the last-named being used in the formation of the concrete blocks placed in the middle of each pier.

In order to afford further protection to the piers against the force of the waves, a slope of rubble rock has been thrown into the sea on the outside of each pier, the lower blocks of these wave-breakers being 10 tons each in weight, and those above low water about 20 tons each. The harbour will afford berths for three hundred large vessels.

The canal, in passing from the harbour through the downs, runs eastward at first in the direction of an arc of a circle, with the concave side turned southwards, for a distance of 1300 yards, at the end of which are the North Sea locks. The curved form of the canal in this portion serves principally to protect the locks from the force of the waves. From this point the canal runs for some distance in a straight line, and afterwards sometimes in curves, with occasional straight reaches, to Amsterdam-a total distance of 25,919 yards.