An Introduction to the History of Science Part 10

In this same year of 1743 an eclipse of the moon, which could not be seen at Philadelphia on account of a northeast storm, was yet visible at Boston, where the storm came, as Franklin learned from his brother, about an hour after the time of observation. Franklin, who knew something of fireplaces, explained the matter thus: "When I have a fire in my chimney, there is a current of air constantly flowing from the door to the chimney, but the beginning of the motion was at the chimney." So in a mill-race, water stopped by a gate is like air in a calm. When the gate is raised, the water moves forward, but the motion, so to speak, runs backward. Thus the principle was established in meteorology that northeast storms arise to the southwest.

No doubt Franklin was not oblivious of the practical value of this discovery, for, as Sir Humphry Davy remarked, he in no instance exhibited that false dignity, by which philosophy is kept aloof from common applications. In fact, Franklin was rather apologetic in reference to the magic squares and circles, with which he sometimes amused his leisure, as a sort of ingenious trifling. At the very time that the question of the propagation of storms arose in his mind he had contrived the Pennsylvania fireplace, which was to achieve cheap, adequate, and uniform heating for American homes. His aspiration was for a free people, well sheltered, well fed, well clad, well instructed.

In 1747 Franklin made what is generally considered his chief contribution to science. One of his correspondents, Collinson (a Fellow of the Royal Society and a botanist interested in useful plants, through whom the vine was introduced into Virginia), had sent to the Library Company at Philadelphia one of the recently invented Leyden jars with instructions for its use. Franklin, who had already seen similar apparatus at Boston, and his friends, set to work experimenting. For months he had leisure for nothing else. In this sort of activity he had a spontaneous and irrepressible delight. By March, 1747, they felt that they had made discoveries, and in July, and subsequently, Franklin reported results to Collinson. He had observed that a pointed rod brought near the jar was much more efficacious than a blunt rod in drawing off the charge; also that if a pointed rod were attached to the jar, the charge would be thrown off, and acc.u.mulation of charge prevented. Franklin, moreover, found that the nature of the charges on the inside and on the outside of the gla.s.s was different. He spoke of one as plus and the other as minus. Again, "We say _B_ (and bodies like-circ.u.mstanced) is electricized positively; _A_ negatively." Dufay had recognized two sorts of electricity, obtained by rubbing a gla.s.s rod and a stick of resin, and had spoken of them as vitreous and resinous. For Franklin electricity was a single subtle fluid, and electrical manifestations were owing to the degree of its presence, to interruption or restoration of equilibrium.

His mind, however, was bent on the use, the applications, the inventions, to follow. He contrived an "electric jack driven by two Leyden jars and capable of carrying a large fowl with a motion fit for roasting before a fire." He also succeeded in driving an "automatic"

wheel by electricity, but he regretted not being able to turn his discoveries to greater account.

He thought later--in 1748--that there were many points of similarity between lightning and the spark from a Leyden jar, and suggested an experiment to test the ident.i.ty of their natures. The suggestion was acted upon at Marly in France. An iron rod about forty feet long and sharp at the end was placed upright in the hope of drawing electricity from the storm-clouds. A man was instructed to watch for storm-clouds, and to touch a bra.s.s wire, attached to a gla.s.s bottle, to the rod. The conditions seemed favorable May 10, 1752; sparks between the wire and rod and a "sulphurous" odor were perceived (the manifestations of wrath!). Franklin's well-known kite experiment followed. In 1753 he received from the Royal Society a medal for the identification and control of the forces of lightning; subsequently he was elected Fellow, became a member of the Academie des Sciences, and of other learned bodies. By 1782 there were as many as four hundred lightning rods in use in Philadelphia alone, though some conservative people regarded their employment as impious. Franklin's good-will, clearness of conception, and common sense triumphed everywhere.

One has only to recall that in 1753 he (along with Hunter) was in charge of the postal service of the colonies, that in 1754 as delegate to the Albany Convention he drew up the first plan for colonial union, and that in the following year he furnished Braddock with transportation for the expedition against Fort Duquesne, to realize the distractions amid which he pursued science. In 1748 he had sold his printing establishment with the purpose of devoting himself to physical experiment, but the conditions of the time saved him from specialization.

In 1749 he drew up proposals relating to the education of youth in Pennsylvania, which led, two years later, to the establishment of the first American Academy. His plan was so advanced, so democratic, springing as it did from his own experience, that no secondary school has yet taken full advantage of its wisdom. The school, chartered in 1753, grew ultimately into the University of Pennsylvania. Moreover, it became the prototype of thousands of schools, which departed from the Latin Grammar Schools and the Colleges by the introduction of the sciences and practical studies into the curriculum.

Franklin deserves mention not only in connection with economics, meteorology, practical ethics, electricity, and pedagogy; his biographer enumerates nineteen sciences to which he made original contributions or which he advanced by intelligent criticism. In medicine he invented bifocal lenses and founded the first American public hospital; in navigation he studied the Gulf Stream and waterspouts, and suggested the use of oil in storms and the construction of s.h.i.+ps with water-tight compartments; in agriculture he experimented with plaster of Paris as a fertilizer and introduced in America the use of rhubarb; in chemistry he aided Priestley's experiments by information in reference to marsh gas.

He foresaw the employment of air craft in war. Thinking the English slow to take up the interest in balloons, he wrote that we should not suffer pride to prevent our progress in science. Pride that dines on vanity sups on contempt, as Poor Richard says. When it was mentioned in his presence that birds fly in inclined planes, he launched a half sheet of paper to indicate that his previous observations had prepared his mind to respond readily to the discovery. His quickness and versatility made him sought after by the best intellects of Europe.

I pa.s.s over his a.n.a.lysis of mesmerism, his conception of light as dependent (like lightning) on a subtle fluid, his experiments with colored cloths, his view of the nature of epidemic colds, interest in inoculation for smallpox, in ventilation, vegetarianism, a stove to consume its own smoke, the steamboat, and his own inventions (clock, harmonica, etc.), for which he refused to take out patents.

However, from the many examples of his scientific ac.u.men I select one more. As early as 1747 he had been interested in geology and had seen specimens of the fossil remains of marine sh.e.l.ls from the strata of the highest parts of the Alleghany Mountains. Later he stated that either the sea had once stood at a higher level, or that these strata had been raised by the force of earthquakes. Such convulsions of nature are not wholly injurious, since, by bringing a great number of strata of different kinds today, they have rendered the earth more fit for use, more capable of being to mankind a convenient and comfortable habitation. He thought it unlikely that a great _boulevers.e.m.e.nt_ should happen if the earth were solid to the center. Rather the surface of the globe was a sh.e.l.l resting on a fluid of very great specific gravity, and was thus capable of being broken and disordered by violent movement. As late as 1788 Franklin wrote his queries and conjectures relating to magnetism and the theory of the earth. Did the earth become magnetic by the development of iron ore? Is not magnetism rather interplanetary and interstellar? May not the near pa.s.sing of a comet of greater magnetic force than the earth have been a means of changing its poles and thereby wrecking and deranging its surface, and raising and depressing the sea level?

We are not here directly concerned with his political career, in his checking of governors and proprietaries, in his activities as the greatest of American diplomats, as the signer of the Declaration of Independence, of the Treaty of Versailles, and of the American Const.i.tution, nor as the president of the Supreme Executive Council of Pennsylvania in his eightieth, eighty-first, and eighty-second years.

When he was eighty-four, as president of the Society for Promoting the Abolition of Slavery, he signed a pet.i.tion to Congress against that atrocious debas.e.m.e.nt of human nature, and six weeks later, within a few weeks of his death, defended the pet.i.tion with his accustomed vigor, humor, wisdom, and ardent love of liberty. Turgot wittily summed up Franklin's career by saying that he had s.n.a.t.c.hed the lightning from the heavens and the scepter from the hands of tyrants (_eripuit clo fulmen sceptrumque tyrannis_); for both his political and scientific activities sprang from the same impelling emotion--hatred of the exercise of arbitrary power and desire for human welfare. It is no wonder that the French National a.s.sembly, promulgators of the Rights of Man, paused in their labors to pay homage to the simple citizen, who, representing America in Paris from his seventy-first till his eightieth year, had by his wisdom and urbanity ill.u.s.trated the best fruits of an instructed democracy.

REFERENCES

American Philosophical Society, _Record of the Celebration of the Two Hundredth Anniversary of the Birth of Benjamin Franklin_.

S. G. Fisher, _The True Benjamin Franklin_.

Paul L. Ford, _Many-sided Franklin_.

Benjamin Franklin, _Complete Works_, edited by A. H. Smyth, ten volumes, vol. X containing biography.

FOOTNOTES:

[2] See _The Advice of W. P. to Mr. Samuel Hartlib for the Advancement of some Particular Parts of Learning_, in which is advocated a _Gymnasium Mechanic.u.m_ or a _College of Tradesmen_ with fellows.h.i.+ps for experts. Petty wanted trade encyclopedias prepared, and hoped for inventions in abundance.

CHAPTER X

THE INTERACTION OF THE SCIENCES--WERNER, HUTTON, BLACK, HALL, WILLIAM SMITH

The view expressed by Franklin regarding the existence of a fiery ma.s.s underlying the crust of the earth was not in his time universally accepted. In fact, it was a question very vigorously disputed what part the internal or volcanic fire played in the formation and modification of rock ma.s.ses. Divergent views were represented by men who had come to the study of geology with varying aims and diverse scientific schooling, and the advance of the science of the earth's crust was owing in no small measure to the interaction of the different sciences which the exponents of the various points of view brought to bear.

Abraham Gottlob Werner (1750-1817) was the most conspicuous and influential champion on the side of the argument opposed to the acceptance of volcanic action as one of the chief causes of geologic formations. He was born in Saxony and came of a family which had engaged for three hundred years in mining and metal working. They were active in Saxony when George Agricola prepared his famous works on metallurgy and mineralogy inspired by the traditional wisdom of the local iron industry. Werner's father was an overseer of iron-works, and furnished his son with mineral specimens as playthings before the child could p.r.o.nounce their names. In 1769 Werner was invited to attend the newly founded Bergakademie (School of Mines) at Freiberg. Three years later he went to the University of Leipzig, but, true to his first enthusiasm, wrote in 1774 concerning the outward characteristics of minerals (_Von den ausserlichen Kennzeichen der Fossilien_). The next year he was recalled to Freiberg as teacher of mineralogy and curator of collections. He was intent on cla.s.sification, and might be compared in that respect with the naturalist Buffon, or the botanist Linnaeus. He knew that chemistry afforded a surer, but slower, procedure; his was a practical, intuitive, field method. He observed the color, the hardness, weight, fracture of minerals, and experienced the joy the youthful mind feels in rapid identification. He translated Cronstedt's book on mineralogy descriptive of the practical blow-pipe tests. After the identification of minerals, Werner was interested in their discovery, the location of deposits, their geographical distribution, and the relative positions of different kinds of rocks, especially the constant juxtaposition or superposition of one stratum in relation to another.

Werner was an eloquent, systematic teacher with great charm of manner.

He kept in mind the practical purposes of mining, and soon people flocked to Freiberg to hear him from all the quarters of Europe. He had before long disciples in every land. He saw all phenomena from the standpoint of the geologist. He knew the medicinal, as well as the economic, value of minerals. He knew the relation of the soil to the rocks, and the effects of both on racial characteristics. Building-stone determines style of architecture. Mountains and river-courses have bearing on military tactics. He turned his linguistic knowledge to account and furnished geology with a definite nomenclature. Alex. v.

Humboldt, Robert Jameson, D'Aubuisson, Weiss (the teacher of Froebel), were among his students. Crystallography and mineralogy became the fas.h.i.+on. Goethe was among the enthusiasts, and philosophers like Sch.e.l.ling, under the spell of the new science, almost deified the physical universe.

Werner considered all rocks as having originated by crystallization, either chemical or mechanical, from an aqueous solution--a universal primitive ocean. He was a Neptunist, as opposed to the Vulcanists or Plutonists, who believed in the existence of a central fiery ma.s.s.

Werner thought that the earth showed universal strata like the layers of an onion, the mountains being formed by erosion, subsidence, cavings-in.

In his judgment granite was a primitive rock formed previous to animal and vegetable life (hence without organic remains) by chemical precipitation. Silicious slate was formed later by mechanical crystallization. At this period organized fossils first appear.

Sedimentary rocks, like old red sandstone, and, according to Werner, basalt, are in a third cla.s.s. Drift, sand, rubble, boulders, come next; and finally volcanic products, like lava, ashes, pumice. He was quite positive that all basalt was of aqueous origin and of quite recent formation. This part of his teaching was soon challenged. He was truer to his own essential purposes in writing a valuable treatise on metalliferous veins (_Die Neue Theorie der Erzgange_), but even there his general views are apparent, for he holds that veins are clefts filled in from above by crystallization from aqueous solution.

Before Werner had begun his teaching career at Freiberg, Desmarest, the French geologist, had made a special study of the basalts of Auvergne.

As a mathematician he was able to make a trigonometrical survey of that district, and constructed a map showing the craters of volcanoes of different ages, the streams of lava following the river courses, and the relation of basalt to lava, scoria, ashes, and other recognized products of volcanic action. In 1788 he was made inspector-general of French manufactures, later superintendent of the porcelain works at Sevres. He lived to the age of ninety, and whenever Neptunists would try to draw him into argument, the old man would simply say, "Go and see."

James Hutton (1726-1797), the ill.u.s.trious Scotch geologist, had something of the same aversion to speculation that did not rest on evidence; though he was eminently a philosopher in the strictest sense of the word, as his three quarto volumes on the _Principles of Knowledge_ bear witness. Hutton was well trained at Edinburgh in the High School and University. In a lecture on logic an ill.u.s.trative reference to _aqua regia_ turned his mind to the study of chemistry. He engaged in experiments, and ultimately made a fortune by a process for the manufacture of sal ammoniac from coal-soot. In the mean time he studied medicine at Edinburgh, Paris, and Leyden, and continued the pursuit of chemistry. Then, having inherited land in Berwicks.h.i.+re, he studied husbandry in Norfolk and took interest in the surface of the land and water-courses; later he pursued these studies in Flanders.

During years of highly successful farming, during which Hutton introduced new methods in Berwicks.h.i.+re, he was interested in meteorology, and in geology as related to soils. In 1768, financially independent, Dr. Hutton retired to reside in Edinburgh.

He was very genial and sociable and was in close a.s.sociation with Adam Smith, the economist, and with Black, known in the history of chemistry in connection with carbonic acid, latent heat, and experiments in magnesia, quicklime, and other alkaline substances (1777). Playfair, professor of mathematics, and later of natural philosophy, was Hutton's disciple and intimate friend. In the distinguished company of the Royal Society of Edinburgh, established in 1782, the founder of dynamic geology was stimulated by these and other distinguished men like William Robertson, Lord Kames, and Watt. The first volume of the _Transactions_ contains his _Theory of Rains_, and the first statement of his famous _Theory of the Earth_. He was very broad-minded and enthusiastic and would rejoice in Watt's improvements of the steam engine or Cook's discoveries in the South Pacific. Without emphasizing his indebtedness to Horace-Benedict de Saussure, physicist, geologist, meteorologist, botanist, who gave to Europeans an appreciation of the sublime in nature, nor dwelling further on the range of Hutton's studies in language, general physics, etc., it is already made evident that his mind was such as to afford comprehensiveness of view.

He expressed the wish to induce men who had sufficient knowledge of the particular branches of science, to employ their acquired talents in promoting general science, or knowledge of the great system, where ends and means are wisely adjusted in the const.i.tution of the material universe. Philosophy, he says, is surely the ultimate end of human knowledge, or the object at which all sciences properly must aim.

Sciences no doubt should promote the arts of life; but, he proceeds, what are all the arts of life, or all the enjoyments of mere animal nature, compared with the art of human happiness, gained by education and brought to perfection by philosophy? Man must learn to know himself; he must see his station among created things; he must become a moral agent. But it is only by studying things in general that he may arrive at this perfection of his nature. "To philosophize, therefore, without proper science, is in vain; although it is not vain to pursue science, without proceeding to philosophy."

In the early part of 1785 Dr. Hutton presented his _Theory of the Earth_ in ninety-six pages of perfectly lucid English. The globe is studied as a machine adapted to a certain end, namely, to provide a habitable world for plants, for animals, and, above all, for intellectual beings capable of the contemplation and the appreciation of order and harmony. Hutton's theory might be made plain by drawing an a.n.a.logy between geological and meteorological activities. The rain descends on the earth; streams and rivers bear it to the sea; the aqueous vapors, drawn from the sea, supply the clouds, and the circuit is complete. Similarly, the soil is formed from the overhanging mountains; it is washed as sediment into the sea; it is elevated, after consolidation, into the overhanging mountains. The earth is more than a mechanism, it is an organism that repairs and restores itself in perpetuity. Thus Hutton explained the composition, dissolution, and restoration of land upon the globe on a general principle, even as Newton had brought a ma.s.s of details under the single law of gravitation.

Again, as Newton had widened man's conception of s.p.a.ce, so Hutton (and Buffon) enlarged his conception of time. For the geologist did not undertake to explain the _origin_ of things; he found no vestige of a beginning,--no prospect of an end; and at the same time he conjured up no hypothetical causes, no catastrophes, or sudden convulsions of nature; neither did he (like Werner) believe that phenomena now present, were once absent; but he undertook to explain all geological change by processes in action now as heretofore. Countless ages were requisite to form the soil of our smiling valleys, but "Time, which measures everything in our _idea_, and is often deficient to our schemes, is to nature endless and as nothing." The calcareous remains of marine animals in the solid body of the earth bear witness of a period to which no other species of chronology is able to remount.

Hutton's imagination, on the basis of what can be observed to-day, pictured the chemical and mechanical disintegration of the rocks; and saw ice-streams bearing huge granite boulders from the declivities of primitive and more gigantic Alps. He believed (as Desmarest) that rivulets and rivers have constructed, and are constructing, their own valley systems, and that the denudation ever in progress would be eventually fatal to the sustenance of plant and animal and man, if the earth were not a renewable organism, in which repair is correlative with waste.

All strata are sedimentary, consolidated at the bottom of the sea by the pressure of the water and by subterranean heat. How are strata raised from the ocean bed? By the same subterranean force that helped consolidate them. The power of heat for the expansion of bodies, is, says Hutton (possibly having in mind the steam engine), so far as we know, unlimited. We see liquid stone pouring from the crater of a lofty volcano and casting huge rocks into mid-air, and yet find it difficult to believe that Vesuvius and Etna themselves have been formed by volcanic action. The interior of the planet may be a fluid ma.s.s, melted, but unchanged by the action of heat. The volcanoes are spiracles or safety-valves, and are widely distributed on the surface of the earth.

Hutton believed that basalt, and the whinstones generally, are of igneous origin. Moreover, he put granite in the same category, and believed it had been injected, as also metalliferous veins, in liquid state into the stratified rocks. If his supposition were correct, then granite would be found sending out veins from its large ma.s.ses to pierce the stratified rocks and to crop out where stratum meets stratum. His conjecture was corroborated at Glen Tilt (and in the island of Arran).

Hutton was so elated at the verification of his view that the Scotch guides thought he had struck gold, or silver at the very least. In the bed of the river Tilt he could see at six points within half a mile powerful veins of red granite piercing the black micaceous schist and giving every indication of having been intruded from beneath, with great violence, into the earlier formation.

Hutton felt confirmed in his view that in nature there is wisdom, system, and consistency. Even the volcano and earthquake, instead of being accidents, or arbitrary manifestations of divine wrath, are part of the economy of nature, and the best clue we have to the stupendous force necessary to heave up the strata, inject veins of metals and igneous rocks, and insure a succession of habitable worlds.

In 1795 Dr. Hutton published a more elaborate statement of his theory in two volumes. In 1802 Playfair printed _Ill.u.s.trations of the Huttonian Theory_, a simplification, having, naturally, little originality. Before his death in 1797 Hutton devoted his time to reading new volumes by Saussure on the Alps, and to preparing a book on _The Elements of Agriculture_.

Sir James Hall of Dungla.s.s was a reluctant convert to Hutton's system of geology. Three arguments against the Huttonian hypothesis gave him cause for doubt. Would not matter solidifying after fusion form a gla.s.s, a vitreous, rather than a crystalline product? Why do basalts, whinstones, and other supposedly volcanic rocks differ so much in structure from lava? How can marble and other limestones have been _fused_, seeing that they are readily calcined by heat? Hutton thought that the compression under which the subterranean heat had been applied was a factor in the solution of these problems. He was encouraged in this view by Black, who, as already implied, had made a special study of limestone and had demonstrated that lime acquires its causticity through the expulsion of carbonic acid.

Hall conjectured in addition that the rate at which the fused ma.s.s cooled might have some bearing on the structure of igneous rocks. An accident in the Leith gla.s.s works strengthened the probability of his conjecture and encouraged him to experiment. A pot of green bottle-gla.s.s had been allowed to cool slowly with the result that it had a stony, rather than a vitreous structure. Hall experimenting with gla.s.s could secure either structure at will by cooling rapidly or slowly, and that with the same specimen.

He later enclosed some fragments of whinstone in a black-lead crucible and subjected it to intense heat in the reverberating furnace of an iron foundry. (He was in consultation with Mr. Wedgwood on the scale of heat, and with Dr. Hope and Dr. Kennedy, chemists.) After boiling, and then cooling rapidly, the contents of the crucible proved a black gla.s.s. Hall repeated the experiment, and cooled more slowly. The result was an intermediate substance, neither gla.s.s nor whinstone--a sort of slag.

Again he heated the crucible in the furnace, and removed quickly to an open fire, which was maintained some hours and then permitted to die out. The result in this case was a perfect whinstone. Similar results were obtained with regular basalts and different specimens of igneous rock.

Hall next experimented with lava from Vesuvius, Etna, Iceland, and elsewhere, and found that it behaved like whinstone. Dr. Kennedy by careful chemical a.n.a.lysis confirmed Hall's judgment of the similarity of these two igneous products.

Still later Hall introduced chalk and powdered limestone into porcelain tubes, gun barrels, and tubes bored in solid iron, which he sealed and brought to very high temperatures. He obtained, by fusion, a crystalline carbonate resembling marble. Under the high pressure in the tube the carbonic acid was retained. By these and other experiments this doubting disciple confirmed Hutton's theory, and became one of the great founders of experimental geology.

It remained for William Smith (1769-1839), surveyor and engineer, to develop that species of chronology that Hutton had ascribed to organic remains in the solid strata, to arrange these strata in the order of time, and thus to become the founder of historic geology. For this task his early education might at first glance seem inadequate. His only schooling was received in an elementary inst.i.tution in Oxfords.h.i.+re. He managed, however, to acquire some knowledge of geometry, and at eighteen entered, as a.s.sistant, a surveyor's office. He never attained any literary facility, and was always more successful in conveying his observations by maps, drawings, and conversation than by books.