The Faber Book of Science

by John Carey

  In the dull catalogue of common things.

  Philosophy will clip an angel’s wings,

  Conquer all mysteries by rule and line …

  These Romantic outbursts suggest a profound ignorance of Newton, who was, in fact, acutely aware of the mystery of the universe. Colour itself, he points out in the Optics, is mysterious. What we call ‘colour’ in an object is merely ‘a disposition to reflect this or that sort of rays more copiously than the rest’, and the rays themselves are not really ‘coloured’, but set up a motion that, when it meets our eye, gives us the sensation of colour – ‘as sound in a bell or musical string, or other sounding body, is nothing but a trembling motion’. Why particular objects should reflect particular rays, and how they affect the eye to suggest colours, Newton found inexplicable.

  In the twentieth century Alfred North Whitehead rephrased this problem, and its implications for poets, in his Science and the Modern World:

  There is no light or colour as a fact in external nature. There is merely motion of material. Again, when the light enters your eyes and falls on the retina, there is merely motion of material. Then your nerves are affected and your brain is affected, and again this is merely motion of material … The mind, in apprehending, experiences sensations which, properly speaking, are qualities of the mind alone. These sensations are projected by the mind so as to clothe appropriate bodies in external nature. Thus the bodies are perceived as with qualities which in reality do not belong to them, qualities which in fact are purely the offspring of the mind. Thus nature gets credit which should in truth be reserved for ourselves: the rose for its scent; the nightingale for his song; and the sun for his radiance. The poets are entirely mistaken. They should address their lyrics to themselves.

  How little Newton’s discoveries had diminished his sense of mystery, he himself explained not long before his death:

  I don’t know what I may seem to the world, but, as to myself, I seem to have been only like a boy playing on the sea shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.

  Sources: William Stukeley, Memoirs of Sir Isaac Newton’s Life, 1752. Sir Isaac Newton, Optics, 1704. A. N. Whitehead, Science and the Modern World, Cambridge, Cambridge University Press, 1926.

  The Little Red Mouse and the Field Cricket

  Gilbert White (1720–93) was the first great English field naturalist. A country parson, he spent virtually all his life in the Hampshire village of Selborne, and his letters to two fellow naturalists about the local fauna and flora were published in 1788 as The Natural History of Selborne. Among the British species that he was the first to identify was the little red mouse or harvest mouse (Micromys minutus.)

  November 4, 1767

  I have procured some of the mice mentioned in my former letters, a young one and a female with young, both of which I have preserved in brandy. From the colour, shape, size, and manner of nesting, I make no doubt but that the species is nondescript [not previously identified]. They are much smaller and more slender than the mus domesticus medius of Ray; and have more of the squirrel or dormouse colour: their belly is white, a straight line along their sides divides the shades of their back and belly. They never enter into houses; are carried into ricks and barns with the sheaves; abound in harvest, and build their nests amidst the straws of the corn above the ground, and sometimes in thistles. They breed as many as eight at a litter, in a little round nest composed of the blades of grass or wheat.

  One of these nests I procured this autumn, most artificially platted, and composed or the blades of wheat; perfectly round, and about the size of a cricket-ball; with the aperture so ingeniously closed, that there was no discovering to what part it belonged. It was so compact and well filled, that it would roll across the table without being discomposed, though it contained eight little mice that were naked and blind. As this nest was perfectly full, how could the dam come at her litter respectively so as to administer a teat to each? Perhaps she opens different places for that purpose, adjusting them again when the business is over: but she could not possibly be contained herself in the ball with her young, which moreover would be daily increasing in bulk. This wonderful procreant cradle, an elegant instance of the efforts of instinct, was found in a wheat-field, suspended in the head of a thistle …

  January 22, 1768

  As to the small mice, I have farther to remark, that though they hang their nests for breeding up amidst the straws of the standing corn, above the ground; yet I find that, in the winter, they burrow deep in the earth, and make warm beds of grass: but their grand rendezvous seems to be in corn-ricks, into which they are carried at harvest. A neighbour housed an oat-rick lately, under the thatch of which were assembled near an hundred, most of which were taken; and some I saw. I measured them; and found that, from nose to tail, they were just two inches and a quarter, and their tails just two inches long. Two of them, in a scale, weighed down just one copper halfpenny, which is about a third of an ounce avoirdupois: so that I suppose they are the smallest quadrupeds in this island. A full-grown mus medius domesticus weighs, I find, one ounce, lumping weight, which is more than six times as much as the mouse above; and measures from nose to rump four inches and a quarter, and the same in its tail.

  Selbourne, Sept. 2, 1774

  … As my neighbour was housing a rick he observed that his dogs devoured all the little red mice that they could catch, but rejected the common mice: and that his cats ate the common mice, refusing the red …

  *

  There is a steep abrupt pasture field interspersed with furze close to the back of this village, well known by the name of the Short Lithe, consisting of a rocky dry soil, and inclining to the afternoon sun. This spot abounds with the gryllus campestris, or field-cricket; which, though frequent in these parts, is by no means a common insect in many other counties.

  As their cheerful summer cry cannot but draw the attention of a naturalist, I have often gone down to examine the œconomy of these grylli, and study their mode of life: but they are so shy and cautious that it is no easy matter to get a sight of them; for, feeling a person’s footsteps as he advances, they stop short in the midst of their song, and retire backward nimbly into their burrows, where they lurk till all suspicion of danger is over.

  At first we attempted to dig them out with a spade, but without any great success; for either we could not get to the bottom of the hole, which often terminated under a great stone; or else, in breaking up the ground, we inadvertently squeezed the poor insect to death. Out of one so bruised we took a multitude of eggs, which were long and narrow, of a yellow colour, and covered with a very tough skin. By this accident we learned to distinguish the male from the female; the former of which is shining black, with a golden stripe across his shoulders; the latter is more dusky, more capacious about the abdomen, and carries a long sword-shaped weapon at her tail, which probably is the instrument with which she deposits her eggs in crannies and safe receptacles.

  Where violent methods will not avail, more gentle means will often succeed; and so it proved in the present case; for, though a spade be too boisterous and rough an implement, a pliant stalk of grass, gently insinuated into the caverns, will probe their windings to the bottom, and quickly bring out the inhabitant; and thus the humane inquirer may gratify his curiosity without injuring the object of it. It is remarkable that, though these insects are furnished with long legs behind, and brawny thighs for leaping, like grasshoppers; yet when driven from their holes they show no activity, but crawl along in a shiftless manner, so as easily to be taken: and again, though provided with a curious apparatus of wings, yet they never exert them when there seems to be the greatest occasion. The males only make that shrilling noise perhaps out of rivalry and emulation, as is the case with many animals which exert some sprightly note during their breeding time: it is raised by a brisk friction of one wing against the other. They are solitary beings
, living singly male or female, each as it may happen: but there must be a time when the sexes have some intercourse, and then the wings may be useful perhaps during the hours of night. When the males meet they will fight fiercely, as I found by some which I put into the crevices of a dry stone wall, where I should have been glad to have made them settle. For though they seemed distressed by being taken out of their knowledge, yet the first that got possession of the chinks would seize upon any that were obtruded upon them with a vast row of serrated fangs. With their strong jaws, toothed like the shears of a lobster’s claws, they perforate and round their curious regular cells, having no fore-claws to dig, like the mole-cricket. When taken in hand I could not but wonder that they never offered to defend themselves, though armed with such formidable weapons. Of such herbs as grow before the mouths of their burrows they eat indiscriminately; and on a little platform, which they make just by, they drop their dung; and never, in the day-time, seem to stir more than two or three inches from home. Sitting in the entrance of their caverns they chirp all night as well as day from the middle of the month of May to the middle of July; and in hot weather, when they are most vigorous, they make the hills echo; and, in the stiller hours of darkness, may be heard to a considerable distance. In the beginning of the season, their notes are more faint and inward; but become louder as the summer advances, and so die away again by degrees.

  Sounds do not always give us pleasure according to their sweetness and melody; nor do harsh sounds always displease. We are more apt to be captivated or disgusted with the associations which they promote, than with the notes themselves. Thus the shrilling of the field-cricket, though sharp and stridulous, yet marvellously delights some hearers, filling their minds with a train of summer ideas of everything that is rural, verdurous, and joyous.

  About the tenth of March the crickets appear at the mouths of their cells, which they then open and bore, and shape very elegantly. All that ever I have seen at that season were in their pupa state, and had only the rudiments of wings, lying under a skin or coat, which must be cast before the insect can arrive at its perfect state (We have observed that they cast these skins in April, which are then seen lying at the mouths of their holes.) From whence I should suppose that the old ones of last year do not always survive the winter. In August their holes begin to be obliterated, and the insects are seen no more till spring.

  Not many summers ago I endeavoured to transplant a colony to the terrace in my garden, by boring deep holes in the sloping turf. The new inhabitants stayed some time, and fed and sung; but wandered away by degrees, and were heard at a farther distance every morning; so that it appears that on this emergency they made use of their wings in attempting to return to the spot from which they were taken.

  One of these crickets, when confined in a paper cage and set in the sun, and supplied with plants moistened with water, will feed and thrive, and become so merry and loud as to be irksome in the same room where a person is sitting: if the plants are not wetted it will die.

  White is still quoted as an authority on the field cricket in some twentieth-century works on entomology. During the Second World War, as a prisoner of war in Bavaria, R. D. Purchon made a study of the field cricket which confirmed White’s observations. Purchon found that the adult crickets die in August, and the young ones continue active until late autumn, when they hibernate in their pupa state.

  Source: Gilbert White, The Natural History of Selbourne, 1788.

  Two Mice Discover Oxygen

  Joseph Priestley (1733–1804) was a Unitarian minister and schoolteacher. A keen supporter of the American and French Revolutions, he confessed that he had tended, from an early age, ‘to embrace what is generally called the heterodox side of almost every question’.

  Introduced to science by Benjamin Franklin, whom he met in London, Priestley made experiments on the ‘air’ (the current name for a gas) given off by the fermenting liquors in the brewery next door to his house in Leeds. This was carbon dioxide and, dissolving it in water, Priestley invented soda water, for which the Royal Society gave him a medal in 1773.

  He then turned his attention to the ‘airs’ given off when various substances were heated. To examine these he constructed a simple apparatus, described in his Experiments and Observations on Different Kinds of Air (1775), consisting of a trough full of mercury, over which glass vessels could be inverted to collect the gas. The substance to be heated was placed in another glass vessel on the surface of the mercury, and Priestley focused the sun’s rays on it using a 12-inch lens.

  To test his gases Priestley employed mice, which he caught in wire traps, and introduced into the gas-filled vessels. Should the gas be likely to prove noxious, he warned, ‘it will be proper (if the operator be desirous of preserving the mice for further use) to keep hold of their tails, that they may be withdrawn as soon as they begin to show signs of uneasiness’.

  When Priestley heated red mercuric oxide (which he calls mercurius calcinatus per se), using his apparatus, it gave off a colourless gas which, as he describes in the following account, made a candle flame burn brightly. Like other eighteenth–century scientists, Priestley believed that all combustible materials contained an element called ‘phlogiston’, which was given off when they burned. Air in which things had been burned became less able to support combustion because, it was thought, it was saturated with ‘phlogiston’. Accordingly Priestley called his gas in which a candle flame burned brightly ‘dephlogisticated air’. In fact it was oxygen.

  The contents of this section will furnish a very striking illustration of the truth of a remark, which I have more than once made in my philosophical writings, and which can hardly be too often repeated, as it tends greatly to encourage philosophical investigations viz. that more is owing to what we call chance, that is, philosophically speaking, to the observation of events arising from unknown causes, then to any proper design, or pre-conceived theory in this business.

  For my own part, I will frankly acknowledge, that, at the commencement of the experiments recited in this section, I was so far from having formed any hypothesis that led to the discoveries I made in pursuing them, that they would have appeared very improbable to me had I been told of them; and when the decisive facts did at length obtrude themselves upon my notice, it was very slowly, and with great hesitation, that I yielded to the evidence of my senses … [Priestley then recounts the construction of the mercury-trough apparatus described above.]

  With this apparatus, after a variety of other experiments, an account of which will be found in its proper place, on the 1st of August, 1774, I endeavoured to extract air from mercurius calcinatus per se; and I presently found that, by means of the lens, air was expelled from it very readily. Having got about three or four times as much as the bulk of my materials, I admitted water to it, and found that it was not imbibed by it. But what surprised me more than I can well express, was, that a candle burned in this air with a remarkably vigorous flame …

  I cannot, at this distance of time, recollect what it was that I had in view in making this experiment: but I know I had no expectation of the real issue of it. Having acquired a considerable degree of readiness in making experiments of this kind, a very slight and evanescent motive would be sufficient to induce me to do it. If, however, I had not happened, for some other purpose, to have had a lighted candle before me, I should probably never have made the trial; and the whole train of my future experiments relating to this kind of air might have been prevented …

  In this case, also, though I did not give sufficient attention to the circumstance at that time, the flame of the candle, besides being larger, burned with more splendour and heat… and a piece of red-hot wood sparkled in it, exactly like paper dipped in a solution of nitre, and it consumed very fast …

  On the 8th of this month [March, 1775] I procured a mouse, and put it into a glass vessel, containing two one-ounce measures of the air from mercurius calcinatus. Had it been common air, a full-grown mouse, as this was, would h
ave lived in it about a quarter of an hour. In this air, however, my mouse lived a full half hour; and though it was taken out seemingly dead, it appeared to have been only exceedingly chilled; for, upon being held to the fire, it presently revived, and appeared not to have received any harm from the experiment.

  … By this I was confirmed in my conclusion, that the air extracted from mercurius calcinatus, &c. was, at least, as good as common air; but I did not certainly conclude that it was any better; because, though one mouse would live only a quarter of an hour in a given quantity of air, I knew it was not impossible but that another mouse might live in it half an hour; so little accuracy is there in this method of ascertaining the goodness of air …

  For my farther satisfaction I procured another mouse, and putting it into less than two ounce-measures of air extracted from mercurius calcinatus and air from red precipitate (which, having found them to be of the same quality, I had mixed together) it lived three quarters of an hour. But not having had the precaution to set the vessel in a warm place, I suspect that the mouse died of cold. However, as it had lived three times as long as it could probably have lived in the same quantity of common air, and I did not expect much accuracy from this kind of test, I did not think it necessary to make any more experiments with mice.

  It may hence be inferred, that a quantity of very pure air would agreeably qualify the noxious air of a room in which much company should be confined, and which should be so situated, that it could not be conveniently ventilated; so that from being offensive and unwholesome, it would almost instantly become sweet and wholesome. This air might be brought into the room in casks; or a laboratory might be constructed for generating the air, and throwing it into the room as fast as it should be produced. This pure air would be sufficiently cheap for the purpose of many assemblies, and a very little ingenuity would be sufficient to reduce the scheme into practice …