Part 9

member at least of the characteristic group, the _Dictyota atomaria_ ought to be--as it really is--both rare and beautiful. The ancient _nomen triviale_ of _Phasiana_ expresses well, in its allusion to the plumage of that handsome bird, the barred and zigzag markings caused by the scattering in the substance of the frond--almost as one would cast grains of sand or seeds by the hand--of the dark-coloured spores or germs. The whole plant, too, exhibits those most delicate gradations of the primitive hue which are not the least remarkable characteristic of all sea-weeds. And in what are our designers more deficient--especially those employed in the decoration of our houses--than in simple and delicate contrasts, or more especially in those almost insensible gradations of colours which are so admirable in their effect, and which are so invariably presented to us alike in the sombre olive and in the bright greens and reds of the sea-weeds? We have no power to express these natural gradations in our woodcuts, but there is certainly much in this way worthy of patient study. In this large and extensive family there are yet more instances of how various sections and magnificent portions may possess artistic value. The section of a sorus of _Stilophora rhizodes_ seems, for example, so like the representation of a fragment of jewellery, that it cannot fail to excite wonder that a source so prolific should have been neglected by our workers in gold and silver, and our setters of pearls and precious stones.

The _Mesogloia vermicularis_, one of the gelatinous _Chordariaceæ_, is an ugly weed, but the filaments of the fronds are worthy, notwithstanding, of being placed under the power of the microscope and viewed by an artist.

So, too, with the hollow cottony _Leathesia_, looking like a macerated walnut tufting the surface of the rock: only peer into it with microscopic vision, and a forest of crystal fibres, composed of divided cells, the lower ones long and slender, the upper shorter, and supporting little hyaline half-moons on their cusps, springs into existence. The tiny tufts of the _Elachista_ and _Myrionema_ abound in bead-chain fibres, while the genera _Cladostephus_ and _Sphacelaria_ offer more visible patterns of a kind at once unleaf-like and novel. The _Sphacelaria plumosa_, so wiry and feathery, resembles those curious members of the animal kingdom, the _Sertulariæ_, as which it is almost as rigid and as elegant; while the small tufts of the rare _Sphacelaria ramosa_ are again charming microscopic objects.

The family _Ectocarpaceæ_ contains a fund of marvellous ideas. One more genus of British olive weeds alone remains to be mentioned, consisting of two little parasitic species not uncommon on the fronds of _Chorda lomentaria_; but though curious and singular in construction, they offer nothing so tempting as many of those we have been compelled to pass over in silence.

For the purpose of study, the _Melanosperms_ offer a never-failing supply, always accessible at low water; but should opportunity arise of acquiring a knowledge of the _Rhodosperms_, with their fairy forms and brilliant hues, it should not be neglected, for these deep-water algals seldom reach us but in broken plants washed ashore; and dried specimens, flattened and faded, cease to be models for study. As to the _Chlorosperms_, the _Ulvæ_ are full of grace and beauty, and in the south of England they are served at table as a relish to roast meat, under the title of laver, and which is now sold in many London shops. The _Ulva linza_, figured at p. 107, is a good type of the graceful outline of this elegant family of sea-weeds.

Oft beneath the warm and brilliant rays of summer’s sun, in shallow skiff, I have glided on the calm and polished surface of the sea--the mirror of the glowing sky and heavens beyond--over the dark forests of tangle waving in the tide, and plucked the pellucid limpets browsing on their stems; and, peering down into the rugged dells below, have seen the star-fish crawl with sucker-arms along the rocks, where whelks drill holes in shells of stone-clad molluscs, to feed upon their soft and luscious flesh; where sea-anemones, with outspread tentacles, make gardens of living flowers; and awkward crabs peep out from darksome nooks at glittering fish, then scramble sidelong back again into their holes.

In winter, by the raging waves--when skaters swift o’er slippery ice with rapid pace were gliding; when ears were tingling with the biting cold, and tender people roasting over blazing fires--I have paced along the congealed sands to see the shell-fish frozen hard and fast, glued to the rocks; and sea-weeds, crisp and rigid, recover life and elasticity in the flowing tide.

In time of spring I have hunted over the slippery meadows of our shores for the instinct-led travellers from the deep, coming to the shallow tidal zone to propagate their tribes. And in the golden season I have watched the sportive play, in rocky pools o’ershadowed by these graceful weeds, of iridescent annelide and cilia-paddled beroe--have tracked the skipping shrimps along the silvery sands, or have patiently followed the _Patella vulgaris_ in its solemn march to graze upon the verdant ulvæ, and again returning at the change of tide to adjust its conical house with stately nicety on its proper site.

III.

ON THE CRYSTALS OF SNOW AS APPLIED TO THE PURPOSES OF DESIGN.

BY JAMES GLAISHER, F.R.S.

I.

Snow, in the ordinary acceptation of the word, is suggestive of a soft flocculent matter of considerable opacity, falling in flakes, and, as compared with water, of little density--a foot of fresh-fallen snow producing but from a tenth to a twelfth part of water. Snow, however, does not always fall in flakes; under certain conditions of atmosphere and temperature it occasionally falls in groups of slender needle-like particles or spiculæ, which under the microscope exhibit no structural detail worthy of remark, but are irregular and jagged in outline. This is one of the most imperfect forms of snow crystallization, and occurs generally at a temperature but little above freezing, and at the commencement of a severe and continued frost, or immediately preceding a general thaw.

At other times a light feathery snow may be seen to fall, composed almost entirely of stars of six spiculæ or radii, united in the centre by a white molecule. These are seldom less than from four to five tenths of an inch in diameter, and are generally collected in tufts of half-a-dozen or more together, which in calm weather waft uninjured to the ground. Sometimes these are mixed with other stars of more intricate figure, to be spoken of presently. Fig. 1 illustrates this variety, and is enlarged to double the proportions of the original.

Sometimes a heavy fall of ordinary snow may be accompanied by a number of minute specks, glistening among the flakes like fragments of talc or mica, as seen sparkling in a mass of granite. On careful investigation these prove to be thin laminated hexagons of the most perfect delicacy and symmetry of form, as shown in Fig. 2.

The hexagon and star being the base of all the crystals of snow yet observed, we will proceed to show how the more elaborate figures are compounded of these two primary elements.

To explain various peculiarities of structure which occur in several of the larger drawings, we will refer to the process of crystallization as carried on at low temperatures on the surface of still or gently-moving water.

Water freezes at an angle of 60°. On its first congelation, under favourable circumstances for observation, we perceive in parts, generally about the centre and around the margin, a corrugation of its surface. This corrugation presently discovers a series of distinct figures, needle-like in form, and analogous to the spiculæ of snow. As the process continues, to each of these needles, while yet forming, a serrated incrustation of leafy or arborescent character is attaching itself, so that in time the greater number of them become each the centre of a crystalline pinna, not unlike a frond of the lady fern. Fig. 25 (page 140) is a sketch of one, the size of the original, as observed by T. G. Rylands, Esq., of Warrington, and sent to us during the severe winter of 1855. The overlapping observable on one side of the pinna is a peculiarity generally to be found in three out of the six leaves forming the entire crystal.

Fig. 26 (page 141) represents the crystal when complete; the drawing was made by ourselves, and gives with great exactitude the figure of the needles, which, it will be observed, diverge from the main stem uniformly at an angle of 60°. The position maintained by them around the centre of the crystal is beautifully adaptive, and well worth examination.

It is not always that the primitive spiculæ are divergent in groups of six. At times they arrange themselves irregularly in clusters, and crystallization proceeds with results of a character

somewhat different, but scarcely less beautiful, of which Fig. 27 (page 142) may be considered a type. This is analogous to the fanciful forms of frost seen on the interior of a pane of glass, and is frequently to be found where the water is very shallow, and where its mixture with some gritty substance, or blade of grass, or other obstruction, has in all probability interfered with a more geometric arrangement. By degrees the whole surface of the water becomes interlaced with needles and pinnæ, whether singly or in groups, and thin laminated surfaces of ice which cover all interstices. Then, according to external influences, the ice either thickens, obliterating all this beautiful tracery, or it melts away before the rising temperature of the day. It often happens, however, that these processes occur after dark, or that the water freezes so rapidly as to disappoint the wishes of the observer. At moderate temperatures these changes are best observed; but, in our opinion, they are somewhat dependent on other atmospheric conditions. The formation of the needles is common to the freezing of water under all circumstances, and they vary from a few inches to a few feet in length.

To return to the crystals of snow. Fig. 3 (page 136) is another elementary figure, common to temperatures about the freezing-point; it is not often less than half an inch in diameter, and is a miniature copy of the water crystal.

Another simple order of figures, and containing within themselves the germ of the most symmetrical combinations, is that of which Figs. 4 and 5 (page 136) are types; they exhibit secondary spiculæ diverging from the principal radii at an angle of 60°.

Around the simple it frequently happens that a secondary and smaller star is arranged, as in Fig. 6 (page 136), the radii of which are intermediate between those of the former. An angle of 30° is, however, of unfrequent occurrence, and it seems probable that in this and similar cases it is the union of two crystals of distinct hexagonal formation.

Sometimes it happens that the secondary spiculæ, which we see in Figs. 4 and 5, are continued down the main radii until they form a contact with each other, as in Fig. 7 (page 137). The star thus enclosed about the centre generally becomes laminated and of great transparency. In other varieties, as in Fig. 8 (page 137), it is intersected by the rays of the secondary or intermediate crystal.

Having traced the elementary principles of these figures to the first formation of a simple nucleus, we will proceed to the consideration of the more compound varieties, in which the nucleus is a conspicuous element of construction.

The figures we have been considering, although possessed of unity of design in a high degree, are found to exhibit no great perfection of structural detail when examined beneath a lens; those that we are about to inquire into belong to a more perfect order, much more minute and very compound.

Fig. 28 is a figure of this class, much enlarged and drawn as seen beneath a microscope. It was highly crystallized, and the angles and planes of which it is composed were sharply and well defined. The prisms at the end of the radii were cut into facets, and glistened with brilliancy, as did the six prisms around the centre. The radial arms were sharply cut, six-sided shafts, very different from the snowy rounded spiculæ of the elementary figures. It was easily discernible to the naked eye, and principally those parts which are white in the engraving, and which communicate to the copy very much the effect of the original when under the full influence of direct light. The centre is laminated, hexagonal in form, and within it we perceive the secondary star of prisms; also that each addition to the radii diverges at an angle of 60°.

Fig. 29 is another, highly crystallized, and composed of parallel prisms, divergent from the radial arms at an angle of 60°, and without nucleus. The irregular blade-like terminations arise from an ill-advised eagerness in the observation of their originally very complicated structure, by which they were in a moment dissolved, without injury, however, to the symmetry of the figure.

Fig. 30 is a beautiful compound of the higher order of crystallized bodies with the more elementary, the nucleus belonging to the former, and the radii at their extremities to the

latter. This at first sight appears an anomaly; but we explain it on the supposition that the entire structure of the original crystal has been of a high order, the shafts six-sided, as they remain still at their base, and the leafy incrustrations to have been regularly distributed prisms, as in the preceding figure; that the crystal, in its descent, has passed through various temperatures of intense cold, probably exchanged for a warmer at one instant of time, in which it has partially thawed, and again passing into a cold stratum in approaching the ground, has been once more congealed, giving rise to the white opacity and irregular form of its terminations. And this explanation is the more reasonable, as will be gathered from a description of the dissolving or thawing of these bodies.

Fig. 31 is a crystal seen just previous to its returning to the primitive drop of water. Originally composed of the ordinary radial arms, each supporting prisms of the form seen in Fig. 29, and with a simple hexagonal nucleus, under the influence of a very slightly increased temperature the rigidity of each line has become relaxed, whilst the crystalline matter, all but fluid and no longer heaped up into prisms, is distributed over a wider area, according to the laws of attraction and corresponding area of surface.

A very different order of figures are those of which Figs. 32, 33, 34, and 35 are types. The originals were exceedingly small--so minute, indeed, that the specks containing all these beauties of detail were almost inappreciable to the naked eye. It will readily be perceived that they differ greatly from the order arising out of the primitive star or its secondary radii. The base of these must be referred to the hexagon, as shown at Fig. 2. The most highly elaborate of our illustrations, shown at Fig. 33, exhibited a succession of planes raised one above another, the centre of each radial arm intersected by a slender crystalline shaft laden with delicate prisms. Fig. 35 preserves more the form of the ordinary hexagon, and was cut very regularly into facets. Of Figs. 34 and 35 we were unable to observe the exact disposition of the raised surfaces, and have delineated the outline only: these figures fell, with several others far more complicated, during the continuance of a very unusual degree of cold for these latitudes.

II.

We have thus far endeavoured to show the true bases of construction, and how that crystallization proceeds onwards from the simple forms to the more complex, and have selected from numerous varieties a few of the best types illustrative of this progress. Our limits will scarcely permit us further to individualise these beautiful creations; yet, not to mislead, it is necessary to refer to an intermediate order, in which the hexagon star is laden with divergent spiculæ between groups of prisms. Fig. 36, selected from this very numerous class of figures, was one of several observed during the cold weather, following upon the general thaw, which terminated the long-continued and severe frost of 1855. The spiculæ were icicle-like, of the utmost delicacy, opaque, and well defined; the prisms, on the contrary, were watery, almost rounded, and, as it seemed, on the verge of dissolution. The entire figure had the appearance of two distinct orders of formation--the prisms which belong to a very low temperature, and the spiculæ which are commonly formed at and about the freezing-point. Fig. 37 is another of the same class, and in a very intermediate state; the additions to the main radii are neither prisms nor spiculæ, yet partaking of the character of both: its peculiarity consists in the tertiary incrustations being placed downwards towards the centre. This form has been observed only during very severe cold.

Fig. 38 is somewhat analogous to the crystals of water; its centre is hexagonal, but the prisms are irregular crystalline incrustations of the utmost delicacy and transparency; it was of large size, fully half an inch in diameter, and glistening like a fragment of talc among the snow-flakes, was discernible at a considerable distance.

Fig. 39 (page 156) is a specimen of a double crystal; that is, two similar crystals united by an axis at right angles to the plane of each. It is highly complex, and the effect of each is more than doubled by the arrangement. Crystals so united are not unfrequent in severe weather.

During one winter our observations numbered nearly two hundred varieties.

The series of small drawings given on pages 137, 138, and 139, were made with a lens of moderate power, but they are not equal in value or structural detail to those drawn beneath the microscope. They are among the most elementary figures observed; and, as illustrative of the first principles of formation, are chiefly worthy of consideration. Of more elaborate figures drawn beneath the microscope, besides those more immediately referred to in the text, examples are given in Figs. 40, 41, and 42.

The idea of observing snow crystals is by no means original. We know for certain that Aristotle observed them; also Descartes, Greu, Kepler, and Drs. Nettes and Scoresby of modern times. Sir Edward Belcher also devoted a considerable degree of attention to the study of the crystals of snow in the Arctic regions. There the radial arms were seldom less than an inch in length, and might be seen, according to Sir Edward Belcher, drifted in heaps into the crannies and recesses of the ice. They were seldom to be obtained in a perfect condition, generally separating, by reason of their weight and size, on descending to the ground.

III.

Having brought to a close all that is here necessary to say respecting the formation of these bodies, and the position they occupy in regard to scientific inquiry, we may now turn to a consideration of their capabilities to suggest new forms in decorative design, as applied to the industrial arts. Being ourselves desirous to promote the adoption of the appropriate as well as the simple beauty of truth in ornament, we will first inquire how far these figures are in accordance with those general principles of arrangement of form which in all ages and countries have constituted the truly beautiful in art.

These are summed up briefly in the propositions contained in the opening chapter of Mr. Owen Jones’s “Grammar of Ornament.” We extract the following:--

“Proposition 3.--As Architecture, so all works of the Decorative Arts should possess fitness, proportion, harmony, the result of all which is repose.

“Proposition 5.--Decoration should never be purposely constructed: that which is beautiful is true, that which is true is beautiful.

“Proposition 8.--All ornament should be based upon a geometrical construction.

“Proposition 9.--As in Architecture, so in the Decorative Arts, every assemblage of forms should be arranged on certain definite proportions; the whole and each particular member should be a multiple of some particular unit.

“Proposition 10.--Harmony of form consists in the proper balancing and contrast of the straight, the inclined, and the curved.”

Further on, from the same high authority, we receive as an axiom--“That there can be no perfect composition where either of the three primary elements is wanting--the straight, the inclined, and the curved, or where they are not so harmonized that the one preponderates over the other two.” In the crystals of snow we perceive these last conditions are implicitly fulfilled, inasmuch as they include the varieties, straight, angular, and curved, of which the angular has a decided preponderance.

With regard to the proportions of number on which these figures are based, we shall find them almost all deficient in the maintenance of a ratio, water crystallizing at an angle of 60°, a fact exemplified in the radial arms and the secondary and tertiary additions, which, always produced at the same angle, are characteristic of the greater number of these crystals. Thus they can be considered suggestive only of more complete designs--the centre, in fact, of a bordering or pattern-work, to be completed round them according to the intended application, and with due reference to those ratios of number which are found most acceptable in composition.

Founded upon a strictly geometric base, and a uniform repetition of a certain concordant irregularity of parts, bound together in one harmonious unity by the laws of circular composition, which serve to lend beauty to their constructive details, and constitute the archeus of the figure, we are impressed with a conviction of their truth and conformity to the natural principles of beauty.