The early science of snowflakes.
Snow crystals, these pieces of visible magic, this cloth of dreams, which conjures up images of Christmas, of rosy cheeks, red robins, excitement and raging fires that would make the inside otherwise dreary. Like all magic, it can be somewhat malevolent. In proper quantities and in remote places it mocks humanity’s self assurance, and can try a soul to its limits. No other substance on earth, save perhaps it’s mother; water, is so inhospitable to life and yet so desired. Like all things that bring pleasure and pain, snow has fascinated all that have ever seen it. As a natural phenomenon, scientist and layman can derive something different from it. But most of all it is something that many of us discover as children, and those magical hours it allowed us to fill leave us chasing snowflakes for the rest of our lives.
When he was still living in Sweden, Olaus Magnus would often sit by a window and watch the ice form on the pane. As a Scandinavian by birth, he was well acquainted with ice and snow in its varied forms, much more so than many of his more southerly contemporaries. In his ‘Description of the Northern Peoples’ Olaus Magnus wanted to explain his mysterious birthplace to his peers, and casting his aged mind back to the dark winters of his youth, he penned a mighty work, printed in 1555 concerning his homeland. In it he theorised broadly about different phenomena, one of which were theories regarding the causes of ‘images of snow’. A rich mix of theory, observation and not a little theology, relying on Augustin and Aristotle as his basis, this was the first attempt to explain the science behind snowflakes. To the best of his knowledge he understood snow to form from pressurised, frozen vapour at the behest of the ‘hidden commands of God’ and the ‘breezes grow white’ with frost. Putting the movements of the cosmos as the prime instigator of all earthly happenings. The forms and images of frost and snow was to be ‘amazed’ at rather than ‘enquired’ into. Nevertheless he had a go, and wrote that when created out of ‘soft and small’ things these marvels of nature surpassed artistic endeavour. At his window-side Magnus stared for long hours, marvelling at the ‘wondrous artistry of nature’ as it decorated the glass. Though admitting st all times the superior mastery of nature, he noted that the people of the north, Scandinavians, had by virtue of their intelligence and observation created patterns in their decoration with such skill and detail and that put other nations to shame, in metal work and woollen and linen cloths of ‘great value’ embroidered with ‘remarkable and beautiful pictures’. Not only inspired by it but the northern people also enjoy playing in it, and back then people seemed to take their snow – fights seriously.
A gift of Snow.
Approaching the new year of 1611 Johnannes Kepler was looking for a present. We have all done that, and we all have that one person who seems to have everything, or want nothing. The mathematician was looking for a gift for a man whom he called ‘A devotee of nothing’. Having considered many possible objects of pleasing simplicity, Kepler crossed a bridge and as he did:
‘water vapour was condensed by the cold into snow, and specks of down fell here and there on my coat, all with six corners and feathered radii.’
And so it was settled, Kepler would send a New Year gift in the shape of an essay about the six cornered snowflake. The nature and formation of which was baffling to him. Why should they always fall as six pointed starlets? He mused on the psalmist, humorously discarding Aristophanes and Socrates in favour of the hand which wrote of ‘snow that falls like wool’.
Naturally ‘the stuff of snow is vapour, which is wafted up from the earth and hangs in the air as a liquid mass, not distinct.’ As a mathematician, Kepler was most interested in finding a solution as to why six was the most convenient number, and fancifully cited many shapes in nature, from pomegranate seeds to beehives and flowers, that logically produce models that come out in fives and sixes. In terms of the creation, cold, he decided, provided the atmosphere for vapour to form snow, but it did not create the shape. Nor did anything else. Instead he summed up by saying
‘I conclude thus: the cause of the six sided shape of a snowflake is none other than that of the ordered shapes of plants and of numerical constants… nothing occurs without supreme reason, not, to be sure, such as discursive reasoning discovers, but such as existed from the first in the Creator’s design.’ Highlighting the formative faculty of the Earth ‘its carrier is vapour as the human soul is the carrer off the spirit’.
Why? Because ‘formative reason does not act only for purpose, but also to adorn. It does not strive to fashion only natural bodies, but is in the habit also of playing with the passing moment.’ Strange words from a man of science perhaps, but in those days the cause of science was not altogether removed from the cause of the soul.
The creation of the crystal was part of a bigger picture. ‘She took much forethought to fall decently.’ Each snowflake, falling on its road to destruction was Polyxena in Euripides. Nevertheless the ‘how’ was puzzling. Not being able to examine snow at its genesis, Kepler was left to muse that either the three diameters met in the air to form the six pointed star, or it originated whole, in that manner.
‘For as I write it has begun to snow, and more thickly than a moment ago. I have been busily examining the little flakes. Well they have, all of them, been falling in radial patterns; but two kinds, some very small with prongs inserted all the way round, indefinite in number, but of simple shapes without plumes or stripes, and very fine but gathered in the centre into a slightly bigger globule. These formed the majority. But scattered among them where the rarer six-cornered starlets of the second kind, and not one of them was anything but flat.’
Once more geometry puzzled Kepler, who was fascinated by the meaning of a flat object created in nature with such delicately precise shapes, mused onwards. It is a rambling, stumbling discourse on the matter of nothing, for he had no hard data to study except the finished particles he could observe as they fell. His musings lead him into many branches of science all of which left more questions than answers. In the end it couldn’t be more than an examination of nothing. And indeed he ended the essay with the words ‘Nothing to follow’.
‘These were little plates of ice, very flat, very polished, very transparent, about the thickness of a sheet of rather thick paper… but so perfectly formed in hexagons, and of which the six sides were so straight, and the six angles so equal, that it is impossible for men to make anything so exact… I only had difficulty to imagine what could have formed and made so exactly symmetrical these six teeth around each grain in the midst of free air and during the agitation of a very strong wind, until I finally considered that this wind had easily been able to carry some of these grains to the bottom or to the top of some cloud, and hold them there, because they were rather small; and that there they were obliged to arrange themselves in such a way that each was surrounded by six others in the same plane, following the ordinary order of nature.’
A little magnification.
Had you been able to see Robert Hooke in one of the little ice ages frequent frozen downpours, you would have had the diversion to observe a man dressed in his baroque finery of curled wig, full bottomed coat and stockings etc, wandering around with a piece of black cloth, or sweeping off his hat, catching snowflakes, which he would then subject to an examination through his magnifying glass. It was by this method he was able to include snowflakes in his remarkable 1665 Micrographia, a folio full of what he had seen through his glass and microscope, illustrated with exquisite and highly accurate renderings of things as small as a flea. Things few people had seen at close range before we’re brought into focus. Through this method of observation Hooke wrote that he could ‘very easily, and I think truly, deduce the cause of the curious sixangular figures of Snow,’ he continued in much plainer, more academic prose than Kepler, nevertheless it is pleasing to note that after his piercing observations as to the makeup of snowflakes, he never lost his sense of wonder:
‘I have very often in a Morning, when there has been a great hoar-frost, with an indifferently magnifying Microscope, observ’d the small Stiriæ, or Crystalline beard, which then usually covers the face of most bodies that lie open to the cold air … Exposing a piece of black Cloth, or a black Hatt to the falling Snow, I have often with great pleasure, observ’d such an infinite variety of curiously figur’d Snow, that it would be as impossible to draw the Figure and shape of every one of them, as to imitate exactly the curious and Geometrical Mechanisme of Nature in any one.’
Happy Holidays Everyone!
(With special thanks to Llewelyn Morgan)