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"60 M 




AkfOR. Lb.sOX AND 










• • • » • • • 


Ibe liaiQlllig l>jr Pmfciwir Julius Sclinnlor. >;isq , 

lit iliB Ameilcui MtiButitu ot 




II. The Century's Pkogrbss in Astronobty 44 

III The Century's Progress in Paleontology .... 88 

IV. The Century's Progress in Geology 128 

V. The Century's Progress in Meteorology .... 157 
VL The Century's Progress in Physics. The "Impon- 
derables" 192 

VIL The Ether and Ponderable Matter 280 

VIII. The Century's Progress in Chemistry 252 

IX. The Century's Progress in Bioixksy. Theories of 

Organic Evolution 288 

X. The Century's Progress in Anatomy and Physi- 
ology 821 

XI. The Century's Progress in Scientific Mkdicine . 354 
XII. The Century's Progress in Expkkimental Psychol- 
ogy 895 

XIII. Some Unsoi-ved Scientific Problems 488 

I. Solar and Telluric Problems 435 

n. Physical Problems 443 

m. Lssnt Problems 449 

iMDBL 459 






















390. 2— SIDEREAL TIME, 17 HOURS, 50 MINUTES . . . 




HUD0ON 94 


I « 




KOTA 101 

MING 108 




STONE 118 






[ 135 






> 141 



TIME 147 

DON 161 












































































Not many months ago word came out of Germany of 
a scientific discover}' that startled the world. It came 
first as a rumor, little credited; then as a ])ronounced 
report; at last as a demonstration. It told of a new 
manifestation of energy, in virtue of which the interior 
of opaque objects is made visible to human eyes. One 
had only to look into a tube containing a screen of a cer- 
tain composition, and directed towards a peculiar electri- 
cal apparatus, to acquire clairvoyant vision more won- 
derful than tlie discredited second sight of the medium. 
Coins within a purse, nails driven into wood, spectacles 
within a leather case, became clearly visible when sub- 
jected to the influence of this magic tube; and when a 
human hand was held before the tube, its bones stood re- 
vealed in weird simplicity, as if the living, palpitating flesh 
about them were but the shadowy substance of a ghost. 

Not only could the human eye see these astounding 
revelations, but the impartial evidence of inanimate 

A 1 


chemicals could be brought forward to prove that the 
mind luirbored no illusion. The photographic film re- 
corded the things that the eye might see, and ghostly 
j)ictures galore soon gave a quietus to the doubts of the 
most sce])tical. AVitliin a month of the announcement 
of Professor Jitrntgen's experiments comment upon the 
** X ray" and the ** new ])liotography " had become a 
l)art of the current gossip of all Christendom. 

It was but natural that tiioughtful minds should have 
associated this discovery of our boasted latter-day epoch 
with another <lisc()very that was nnule in the earliest in- 
fancy of our c(Miturv. In the year 1801 Mr. Thomas 
AVedgwood, of the world -renowned family of potters, 
and Humphry Davy, the youthful but already famous 
chemist, madr experiments which siiowed that it was 
possibli^ to secure tii(> imprint of a translucent body 
upon a cliemiciilly prepared plate by ex])()sure to sunligiiL 
In this way translucent pictures were copied, and skcla 
tal imprints were s(»eur(Ml of such objects as leaves and 
the Winers of insiM-ts - imprints strikingly similar to the 
*' shad(»wirrjip]is" of more op;u|U<' objects which we se- 
cure by menus of tln^ '* new photo^^-raphy " to-day. But 
these experimenters liitl<^ dreamed of tln^ real signifi- 
cance of their oi)s»'rvations. It was forty velars l)efore 
l)racti(*al ]»liotogra]>hy, whicli these obstM'vaticms fore- 
shadowed, was (l(»ve!<»pr»d and made of any use outside 
th(» laboratory. 

It seems strange enough now that imaii^i native men — 
and Davy surely was such a mini siiould have paused 
on the very brink of so great a dise<»verv. Ihit to harbor 
that thought is to misjudge the nature of the human 
mind. Things that have once been done* seem easy; 
things that have not been (h)ne are <lifricult., though they 


Tnmi th« pttlatlo^ by H. Howard 




m i ■ 









_biil a hair's breiitltti <iff the beaten track. Who can 
|ky foretell whiil revelation fi may be iniictc, wiuit use- 

"arts ilevelopecL furty years hence t.fintugh the agency 
bf whiiL ue now call the new^ phatognijJiy i 

It h no part of niy |)urposi% htnvever, to attempt the 
impoc^ible fe^it of casting a htiroscope for tlie new pho- 
togmphy. My present theme is reminiscent, not pro- 
plit*iic, I wish to recall what know ledge of the sciences 
fnt*n liaci in the days when thut iliseovery tjf Weilgwood 
and Ihvvy wjis in:Mle, almost a hniHlred years ago; to 
incjuire what was the scientiHc horizon of n pei'son 
jtUimiing at the threshold of our own century. Let us 
ghmce briefly at each main ileparlnient of the science uf 
that time, thai we may know wljiilier men's numis were 
trending in tlRise closing days of the eighteenth century, 
and what were the chief scien title legacies of that cen- 
tury to its successor. 

In the iield of astronomy tlie central figure during 
kift closing ejK)cli of the eighteenth century is William 
IIf*rscheU the Hanoverian, whom Enghind has made 
lM?r« by iidoption. He is a man with a positive genius 
fiir 8iilen*al discovi*ry. At fli-st a mere amateur in as- 
)nomy* he snatches time from his duties as mnsjc- 
tljer to grind him a telescopic mirror, and begins gsiz- 
10 stars. Not coTitent willi his first telescope, 
another, and another, ami he lias such genius 
Uie work I hat 1m* soon possesses a better instrument 
in itfls i^ver nitule iR^fore. His patience in grinding 
airriHl reflective surface is monunientaL Some- 
Limei for sixtoen houm together he must walk steadily 
al^iot ibtj mirnf>i% polishing it, without once removing 



Tjom i\ |Miliitlii)j by !*lr Joalnui ttcyiiqida 

his haitds. Meantime his sister, ahvavw his chief lieutet 
ant, cheers liini with her presence, and from time to til 
puts food into his month. The teleseopo comploted^ th 
astronomer turns night into thiy.afid from sunset to sol 
rise^ yoar in and vlkiv out, sweeps tlie lieavcns uucea 


Sjr^ tiiilusd prevtjnted bj cluuils or the bi'igbtness of 

tticMJiu His sister sits always at bis side, reconling 

[ ab^rvntions. They are ia the open air, parched 

at the mouth of the reflector, and sometimes it h 

aid timt the ink freezes in the bottle in Caroline 

chel^ baml ; but the two enthusiasts Imrdly notice 

coinm<in[>]a€e as terrestrial weather, Tliey 

,,,.^ in distant worlds. 

»ult9 i W hat could they be 1! Such enthusiasm 
Pff mf>ve muutj tains. But, after all, the tnoving of 
Ifitains seems a Lilijnitian task etiuipareil with what 
jhel really doe^ with tliuso wonderful telescopes, 
[moves worids, stains, a univ^erse^ — even, if yon please, 
laxy «)f univei-ses; at least ho proves that they 
frc, which seems searcely less wonderful ; and he 
intk iliecosnio«, as man coijceivee it, to thousands 
iines the dimensions it had before. Asa mere be* 
j^ he doubles the diameter of the solar system 
ring the gi-eat outlying ]>lanet whidi we now 
[T^nuius, hut which he christens Qeovgiuni Hidns, 
jr of his sovereign, and which his French con- 
\nm^ not relislung that name, prefer to cull 

idiscovery is but a trifle conipiired with whatJler- 

hiter on, but it gives liini world-wide reputa- 

none the less. <Vimets and moons aside, this is the 

uctditfati to the solar system that has been made 

inn historic times, and it creates a veritable furor of 

liikr interest and enthusiasm. Incidentally King 

te 04ittereil at having a world named after him, 

ht* 8 nil left on tin* astronomer, and comes with his 

Ui havu a look at his namesake. The inspection 

lly satififactory ; and presently the royal favor 


enables tbe astronomer to escape tlie tbraldom of teach- 
in<; music, and to devote his entire time to the more con- 
«^enial task of star-gazing. 

Thus relieved from the bui'den of mundane embarrass- 
ments, he turns with fresh enthusiasm to the skies, and 
his discoveries follow one another in bewildering profu* 
sion. He finds various iiitherto unseen moons of our 
sister planets; he makes special studies of Saturn, and 
proves lliat this planet, with its rings, revolves on its 
axis; he scans the spots on the sun, and suggests that 
they influence the weatiier of our earth ; in short, he 
extends llie entire lield of solar astronomy. But very 
soon this lield becomes too small for him, and his most 
important researches carry him out into the regions of 
space* compared with wiiieh the span of our solar system 
is a mere |)oint. AVitii his perfected telescopes he enters 
al^ysmal vistas which no human eye ever penetrated be- 
fore, w hi( li no human t\vt? had hitherto more than vague- 
ly ima;L^nne(l. lie tells us that his forty-foot reflector 
will l)i"ini^ him li^ht from a distance of ** at least eleven 
and three-fourtiis millions of millions of millions of 
miles ^' lioht which left its source two miUion years 
a,i::o. The smallest stars visible to the unaided eye are 
tliosi* of tiie sixth ma<^nitu(le ; this telesco|)e, he thinks, 
has power to reveal stais of the K542d magnitude. 

Ihit what does Ilerschel learn re^^arding these awful 
<lepths of s])ace and the stars that ])eople them? That 
is what the world wishes to know. Copernicus, Galileo, 
Kepler, have given ns a solar system, but the stars have 
been a mystery. What says the great reflector — are the 
stai-s ])oints of light, as the ancients taught, and as more 
than one philosopher of the eighteenth century has still 
contended, or are they suns, as others hold { Herschel 


xrEvmcwKt, A?fu ttib Bim'icn at the telestopi! 

9 10 


[public LIBRARY. 



rers, thDV are sans, each and every one of all the 
iilUious — suns, many of them, larger tlian the one lljat 
llir e*5ntre of our tiny sysletru Not only so, but tliey 
irc moving suns, Iristeul of lieing Hxed in space, as iias 
BU tbouglit, tliey are \rhirling in gigantic orbits about 
mm e com \ ii o n ce n l re . Is ou r s u n 1 1 1 a t Ci^ n t r c i Fr r f ro i u 
Our sun is only a star, like all the rest, circling on 
rilb its atteuilant satellites- — our giant sun a star, no 
liflTerent from myriad '»iher stars, not even so large as 
lomo; a mere insignificant spark of matter in an infinite 
Miower of s|»arks. 
Nor is this all Looking beyond the tew thousand 
that are visible to the naked eye, Jlerschel sees 
srios after series of more distant stai% nuirshalle<l in 
galaxies of millions; but at last he reaches a distance 

E^yond which the galaxies no longer increase* And yet 
-►so lie thinks— he has not reached the fimits of his vi- 
ion. What then ? He lias come to tlie bounds of the 
idereal system ; seen to the confines of the universe. 
k* Wieves that he can outline this system, this universe, 
mil prove that it has the shape of an irregular globe, 
cibhit^ly flattened to almost disklike proportions, and di- 
rided at one edge— a bifurcation that is revealed even to 
tie nakod eye in the forking of tlie Milky Way. 
This, then, is our universe as Ilei*schel conceives it — a 
rast galaxy of suns, held to one centre, revolving, poised 
I space. But even here those marvellous telescopes do 
lot pattae. Far, far out beyond the conlines of our uni- 
rerse, »o far that the awful span of our own system 
ii»,'ht j&erve as a unit of measure, aix* revealed other sys- 
ems^ other universes, like our o^vn, each composed, as 
thinks^ of myriads of nuns, clustered like our galaxy 
ilo an isolated system— mere islands of matter in an 




infinite ocean of space. So distant from our universe 
are these new universes of Ilerscliers discovery that 
their light reaches us only as a dim nehulous glow, in 
most cases invisible to the unaided eye. About a hundred 
of these nebuhe were known when Ilerschel began his 
studies. ]]efore the close of the century he hjis discov- 
ered about two thousand more of them, and many of these 
had been resolved by his largest telescopes into clusters 
of stai's. ]I<i believes that the farthest of these nebulae 
that he can see is at least 800,000 times as distant from 
us as the nearest fixed star. Yet that nearest star is so 
remote that its light, travelling 180,000 miles a second, 
recjuires three and one half years to reach our planet. 

As if to ijive the linisljin<r- touches to this novel 
scheme of cosmology, Ilei^schel. though in the main 
very little given to unsustiijned theorizing, allows him- 
self the privilege of one belief that he cannot call upon 
his t(^lcscopes to substantiate. He thinks that all the 
myria<l suns of his numb(»rless systems are instinct with 
life in the human S(Mise. Giordano Bruno and a long 
line of his followers had hold that some of our sister 
phuK^ts may be inhabited, but Ilerschel extends the 
thouglit to include the moon, the sun, the stars — all the 
heavenly bodies. U(y bdic^ves that he can demonstrate 
the habitability of our own sun, and reasoning from 
analogy, he is lirmly convinced that all the suns-of all 
the systems are '• well supplied with inhabitants." In 
this, as in some other inferences, Ilerschel is misled by 
the faulty physics of his time. Future generations, work- 
ing with perfected instruments, may not sustain him 
all along the line of his observations even, let alone his 
inferences. lUit how one's egotism shrivels and shrinks 
as one grasps the import of his sweeping thoughts! 



Oonltnuini^ hii^ observations of the itimimerable nf^lm- 
B, ll«^n*cht«l is lt*il [>re^nt)y U* unotlier uuriuus s|wcula- 
I itifBrt*tice, Ui:! mites thiit some star i^nmps utg nuicli 
thickly clustumJ tliati otljeiu uiid lii^ is led to in- 
br Umt such varied clustering tells of varying age^ of 
lie differetlL iiGbiilie. He tliiriks that at tli'st all sjjace 
lay have l>een evenly sprinklfjtl with the stars, and tluit 
be groupings Irns resiiHe*! from the action of gravita- 
tion. Ltioking forward, it a[i[>ears that the time nnist 
>me wbc*n all the suns of a system will be drawn to- 
L*lber II nd tlestroyed by impact at a common centre, 
Llreaiiy. it s^ms to him, the tliickest clusters have 
* outlived their asefnlness,^' and are verging towaixls 
beir doom. 
But again, other nebulge present an appeaj'ance sug- 
ive of an np|>osit6 eonditinn. Tiiey are nut resolva- 
into stales, but present an almogt uniform appear- 
:ico throughout, and ar-e hence believed to be composed 
bt a shining fluid, which in some instances is seen to be 
jndensod at the centre into a glowing mass. In such 
nebula llerscbel thinks he sees a sun in process of 

ien together, these two conceptions outline a nm- 
cycle fjf world hjj-rnation and worUl dest ruction — 
broad tscheine of cosinognny,such as liad been vaguely 
lumbratoil two centuries before by Kepler, and in 
Bore recent times by Wright and Kant and Sweden- 
org. This sO'Callrd ** nebular hypnthesis" assumes 
It in the beginning all space was uniformly tilled 
>mJC matter in a state «>f nebnhir or ^"lire-mist" 
», •* fonnless and viiid/^ It pictures the con* 
Biifiat ion— coagulation, if you will— of portions of this 
fta fnnii «t*gregatetl masses, and the ultimate devel- 


opment out of Uiese masses of the sidereaJ bodies which 
wo sea Thus fur tba mint) fallows readily; but now 
come difficulties. How hap{>ens it, for example, that 

jAMi£^ LQtrra LAuiuicaK 

le coBtnic mass from which was born <Hir Ktilur systern 
•was divideil into several planetary bodies instciid of re- 
maining a single mass? Were the planets struck off 
from the sun by the chance impact of cometft, as Jinffon 



suggested? or thi'own out by explosive volcanic ac- 

pon, in accordance ^vitli the theory of Dn Darwin ? or 

they owe llic3ir origin to some unknown !aw f In 

ly event, how chanc*3il it that all were projected in 

irly the same plane as we now find them ? 

remained for a mathematical astronoirier to sol re 
puzzles, Tli€ man of all others competent to take 
lie Ruhjooi in hand was the French astronotner Laplace. 
f'tir a tpiarter of a century lie had devotetl his transcen- 
!ent mathematical abilities la the solution of problt^ms 
jf nintion of the lieavenly bmlies. Workin*^^ in frienilly 
ivalry with his countryman Lagrange, his only peer 
imnnju: the tnathemalicians of the iipe, he had taken up 
^n*\ soIvlhI one by one the problems titat New tun In ft 
MJSJTtire. Largely through the efforts of these t\\"o men 
lie lust lingerint^ doubts as to the solidarity of the Xew- 
^inian hyputhesis of universal gravitation had l>eeri re- 
lovi^fL The share of Lagrange was hardly less than 
iiat of his co-workcr; Imt Lagrange will hniger be re- 
icmliered, l>ecause he ultimately hrmight his completed 
ibors into a system, and incorporating with them the 
iliomof his contemporaries, produced in the Ifmtm'fue 
V^kMe the undisputed matlietriatieal monument of the 
^ntury, ii fitting complement to the Prh^rqHa of New- 
an, which it supplements and in a sense eom|>letes. 
In ihe closing years of the century Laplace takes up 
khe nebular Ijypothesis of cosmogony, to which we have 
Li&t referred, and gives it iletinitive ]>roportions; in fact* 
lakes it so thoroughly his own that posterity will al- 
vt\y% link it with hii* name. Discnrcling the crade no- 
tions of cometary impact and volcanic eruption, Laplace 
)Mn tip the g3\pa in the hy[Kitla^sis with the aid only of 
vell-knoirn Iiiwh of gravitation and motion. Ue assumes 


that the primitive mass of cosmic matter which was 
destined to form our sohir system was revolving on its 
axis even at a time when it was still nebuhir in charac- 
ter, and filled all space to a distance far beyond the 
present limits of the system. As this vaporous mass 
contracted through loss of heat, it revolved more and 
more swiftly, and from time to time, through balance 
of forces at its periphery, rings of its substance were 
whirled off and left revolving there, to subsequently 
become condcmsed into planets, and in their turn whirl 
off minor rings that became moons. The main body of 
the original mass remains in the present as the still con- 
tracting^ and rotating: bodv which we call the sun. 

The nebular hypothesis thus given detailed comple- 
tion by I.aplace is a worthy comphMuent of the grand 
cosmologic scheme of Iloischel. Whether true or false, 
the two conc(*ptions stand as the final contributions of 
th(> eight(MMilh ci'ntury to the history of man's ceaseless 
<»fforts to solve the mysteries of cosmic origin and cosmic 
structure. The world listens eagerly and without preju- 
dice to the new doctrinc^s ; and that attitude tells of a 
marvellous intt'lleetual growth of our race. Mark the 
transition. In tin? year Ulon, Urnno was burned at the 
stake for teaching that our (»ai-th is not the ctMitre of the 
nniv<*rse. In 17<H), Newton was pronounced ''impious 
and h(M'eti(^al " by a larger srliool of philosophers for 
declaring that the forces which holds the planets in their 
orbits is universal gravitation. In isoo, Laplace and 
Ilerschel are honored for teaching that gravi tuition 
built up th<^ system which it still controls; that our 
univei*se is but a minor nebula, our sun but a minor star, 
our earth a mere atom of matter, our race only one of 
myriad races peopling an infinity of worlds. JJoctrines 



wbiclj bnt tliB sjian of two luimaii lives bofoit3 woiikl 
M bnuii^ht their enunciatoi^is lo the Blake were now 
MitiLMNi not impious, but iiubliine. 

On« ini^ht naturally suppose that the science of tlii^ 
trtb, wliich lies at man's fi^tft, would at letist have kept 
lc5G with the sci<mcc; of tlistunt stars. Bat ]>erliaps the 
iry obvioufiness of tlio }ihenotnena delayaii tho study 
the crust of tlie earth. It is the miattidnabte tiiat 
Fluriiis ami niystiJies and enchants the di^velojung niind, 
fbe proverl>i:d rliild s[mu"m*s its toys and cries for the 

[Sa in those closing days of the eitrfiteenth century, 

b(*n a'^tpononiers hud gone so far toward.^ explaining 

i« my^terie^ of the distant portions of tlie univorsts 

find a chao« of opinion reganling the structure and 

■ fi of the earth » Guesses w^ere not wantinj^ to 

khe firnnatitni of the wodd, it is true, hut, ^vith 

or two ttxccptiuns, these are biMrre indeeii One 

suppose! 1 the oartli to have been at first a solid 

'of ice. wliieh t^ecame animated only after a couiet 

III ihtjihed atjainst iL Other iheoriea conceived the 

igimil *:^lobe as a miss of water, o^er which floated 

ipore con tain ini^ tlio solid elements, which in due time 

!re precipitated nn a crust ij|n>n tlje wiitei^?. In a 

Ur%U thtt Various schemes supptisinl the nripniU mass to 

n iee, or water, or a conglomerate ol* >vatt>r ?md 

, .,. t:ording to the random fancies i»f the tlieorists; 

the Hnal separation into hinil and water was con- 

iv«fd to have taken place in all tlie ways which fancy, 

JiU! ttncfaecked by any tenable data, could invent. 

n ' 17 



Whatever important changes in the /general characi 
r>f tlie surface of tbe *^Uj\m were conceived to hav*^ taken I 
plac6 8inc(3 its creation were generally associated with 
the Mosaic dehj*^e, and the theories which attetnivtod to I 
explain thiii natastroplie were quite on a par with those | 
which dealt with a remoter period of tho earth's history, 


:e at the begin rsriNG of the centum v 

>me specula tois, lioUling that the interior of the globe 
i Agnsat abyss ef watei^, CMfutrivetl that the crust bad 
Iroppad into this chmm and had tlius been inuTHhited. 
>ibers bekl that the earth had ori«rJnaIly revolved on 
vertica! axis, and that the sutbhvn changes to its pres- 
et imfeiition had caused tlje caUis;trophic ghifting of 
riceans. Hut |3i3rha|>s the favorite tliuory ^vas that 
fbich suiiposed a comet to have wandered near the 
irtb^and in ivbirhng about it to have carritnl the wa- 
rrs, thruiitrb gi*avitat!uii, in a vast tide uver the conti- 
Tbuii bUnflly y^rnped the major Jty of eighteenth^cen- 
irj' {)hilusi>plu3rs iti ihoir attempts to study wimt we 
>w temi geology. Deluded by the oh J deductive 
aL'llHKls^ they founded not a science, but the ghost of a 
rienco, as imnraterial and as iinliko anything in nature 
hif luiy oilier |>ljantom that could be conjured frt^ju the 
pplh« iif the «jit?fnilati ve imagination. And all the while 
Iioning earth lay beneath the feet of these vision- 

Lut their eyes were iixed in air. 

At last, however, there came a man who had the 

L^notratton to see that the i>hantom science of geology 

^eti*deil liefore all eke a body cur|>oreiiband who took to 

^iiii.M4f the task of su})[>lyrng it Tbih was ]}i\ James 

[uiUin, of Edinburgh, physician, farmer, and manufact 

ttmist ; patient, enthusiastic, level-beaded devotee 

e. Inspii'cd l>y his love of cltemistry to study 

ie chummier of rocks and soils, Dutton had not gone far 

fare the earth stood revealed to hirn In a new light. 

fe gatv, what generations of predecessors had blindly 

Huseii tc> »ee, that the face of nature everywhere, 

iead of being rigid and immutable, is perennially 

and year by year is undergoing inetamorphic 



changes. The solidest rocks are day b}' day disinte- 
grated, slowly, but none the less surely, by wind and 
niin and frost, by mechanical attrition and chemical 
decomposition, to form the pulverized earth and clay. 
This soil is being swept away by perennial showers, and 
carried ofT to the oceans. The oceans themselves beat 
on their shores, and eat insidiously into the structure of 
sands and rocks. Everywhere, slowly but surely, the 
surface of the land is being worn away; its substance is 
being carried to burial in the seas. 

Should this denudation continue long enough, thinks 
Ilutton, the entire surface of the continents must be 
worn away. Should it be continued long tuongh! And 
with that thought thei'e flashes on his mind an inspiring 
conception — the idea that solar time is long, indefinitely 
long. That seems a simple enough thought — almost a 
triiism — to the nineteenth-century mind; but it required 
genius to conceive it in the eighteenth. Ilutton pon- 
ilered it, grasped its full import, and made it the basis of 
his hypothesis, his '* theory of the earth.'' 

The hyp()th<*sis is this -that the observed changes 
of the surface the earth, continued through indefinite 
lapses of time, must result in conveying all the land at 
last to the sea; in wearing continents away till the 
oceans ovcM-ilow them. What then? Why, as the con- 
tinents wear down, the oceans are filling up. Along 
their bottoms the detritus of wasted continents is de- 
l)osited in strata, together with the bmlies of marine 
animals and vegetables. Why might not this debris 
solidify to form layers of rocks -the basis of new con- 
tinents ? AVhy not, indeed \ 

But have we any proof that such formation of rocks 
in an ocean-bed has, in fact, occurred ? To be sur(» we 



It is furnish eci by every lM*tl uf liiiiestune, every 
LTOiii»ifi«t fnit^iaonl tif fossil-bearing njok, every strati- 
») cliir How rise tluin througlj mwh fdnHjitiun in an 
N>4in4>eil cuiuo these rocks to be ^tnailied? ILmv else 
caini^ they tt> CDntaiit the shells of once living' or*;anisnis 
iNeilcUwl in their ileplhs'^ Tlie ancientSi tindiiii^ fossil 
i*nibe*dded In I lie rocks, expliiimttl them as mere 
c»f ** ruitiire and tlie sUir?i/* I^ess siipcrsliLious 
giiiionLtions hud rejuitiiuted this explanation, hut hful 
faih*<l hi give a tenjihle solulion of the mysten. To 
Ha turn it is a niystei'y no lunger. To iiitn ii seems 
dear Ihiit tho biisis of lim pnmmt eontinents wms hiid in 
rit Kt?a beds, formed of the detritus of continents 
rr"^ iiii^l^^ ancient. 
IjuI two liriics are still wanting to complete the chain 
ilittUiQ*^ liypotliesia. TIirou*^h wliat agency has the 
kt>r the ocean-bed l^een transfofiiied into solid rock J 
lit tliriMJgh what aj^eriey hits this rock beeti lifted 
i»W Uii* surface of tlie water, to form new continents i 
[nfU>n hiok^ about liini for a clow, nnd soon he finds 
Kveryivhere about us there are outcropping rocks 
It ttr»! not stratified, but wliich give evideuee to the 
ervant e^'^e of having onee l>een in n im*\U'u stiite. 
|jff«mnt minerals are mixed tfjgether; pel>hles are 
itliired through masses of rock like plums in a pud- 
ding; irregfihir cnndces in otherwise solid masses of 
fvjck — iso^'udled v**ining!^ — are seen to be filled witti 
loally »)Iid granite of a difFprent variety, which can 
l?» gotten there in no conceivable way, so Ilutton 
kinfci* btit by rnnning in while molten, as liquid mtHal 
mUi thi* mf>ulds of the founder. Even the strati- 
ffki^, tbotigb they seemingly have not been meltcil, 
fftt (iridoiico in ?*ome instances of having been sub- 


jected to the action of heat. Marble, for example, is 
clearly nothing but calcined limestone. 

With such evidence before him, Hutton is at no loss 
to complete his hypothesis. The agency which has solid- 
ified the ocean-beds, he says, is subterranean heat. The 
same agency, acting excessively, has pro<luced volcanic 
cataclysms, upheaving ocean-beds to form continents. 
The rugged and uneven surfaces of mountains, the tilted 
and broken character of stratified rocks every where, are 
the standing witnesses of these gigantic upheavals. 

•And with this the imagine<l cycle is complete. The 
continents, worn away and carried to the sea by the action 
of the elements, have been made over into rocks again 
in the ocean-lxnls, and then raised once more into conti- 
nents. And this massive cycle, in llutton's scheme, is 
supposed to hav(> occui'red not once onl>% but over and 
over again, times without number. In this unique view 
ours is indeed a world without beginning and without 
end ; its continents liave been making and unmaking in 
endless series since time began. 

Ilutton f<)rniulat(Hl his hypothesis while yet a young 
man, not long after the middle of tlie century. He 
first gave it publicity in 1781, in a paper before the 
Royal Soci(^ty of Kdinbui'gh, a paper which at the mo- 
ment neither fii(Mid nor foe deigned to notice. It was 
not published in book form till the last decjide of the 
century, when Ilutton liad lived with and workeil over 
his theory foi* almost fifty years. Then it caught the 
eye of the world. A school of followers expoundeil the 
lluttonian doctrines; a rival school, under Werner, in 
Germany, opposed some details of the hypothesis; and 
the educated world as a whole viewed disputants 
askance. The very novelty of the new views forbade their 


itnetliate acceptance. Bitter attacks wore made upoti 
110 '* heresies j" aiHl that was meant to be a s<jberly tem- 
' idgnient whicli in 1800 pronounced Huttoa^s 
'^ not only hostile to sacred liistory, but equally 
slale to the principles of probability, to the results of 
" st ulhservatiinis on the kingduni, and Uj 
.. latesol rational philosuphy/' And uJt thi^ be- 
Uuttoii'3 theory presupposed the earth to have 
been iti exisUinco more than six thousand years. 

Tiiuf$ it appears that though the tbouglits of men had 
htlenod, in these closing days uf tlio eigliteenth cen* 
f^ to include the stars, they bud not as yet expundeil 
nve the Hvost [latent recortb that are written 
^whei^ cm the surface of the earth, Uefore Hut- 
I's views could be accepted, his pivotal conception 
It time is long must be estabhshed by convincing 
ifa. Tbe evidence was being gathered by William 
itth, CuTier, ami other devotees of the budding science 
tmleontology in the last days of the century, but tbe 
ifil of their completed labors belongs to another 

The eighteenth - century philosopher made great 

■ities iQ his studies of tbe pliysicul properties uf inat- 

~ the application of tliese properties in mechun- 

' ' ^^ '*fmm*enginc, the balloon, the optic telegraph, 

be b _ jenny, the cotton-gin, the chronometer, the 

cted com|>ass, tbe Leyden Jar. the lightning-rod, 

I a houl of minor inventions testify. In a speculative 

•V he liatl thuutrht out more or less tenable concejj- 

Dti$as to the ultimate nature of matter, as witness tbe 

ries of Leibnitx and Boscovich and Davy, to which 


wc may recur. But he had not as yet conceived the 
notion of a distinction between matter and energy, 
which is so fun(hunental to the physics of a later epoch. 
He did not speak of lieat, light, electricity, as forms of 
iMiergy or ** force"'; he conceived them as subtile forms 
of matter — as highly attenuated yet tangible fluids, sub- 
ject to gravitation and chemical attraction ; though he 
had h'arned to measure none ol' them but heat with ac- 
curacy, and this one he could test only within narrow 
limits until late in the century, when Josiah Wedgwood, 
the famous potter, taught him to gauge the highest teni- 
l)eratures with tiie clay pyrometer. 

He spuke of the matter of iieat as being the most uni- 
versally distributed Huid in nature; as entering in some 
degree into the cuinposition of nearly all other sub- 
stances; as being sometimes licpiid, sometimes con- 
(l(Mise<l or solid, and as having weight that could be de- 
tected with the balance. Following Newton, he spoke 
of light as a ** corpuscular emanation ■' or fluid, composeil 
of shining particles which possibly are transmutable 
into particles of heat, and which enter into chemical 
combination with tin* particles of other forms of matter. 
Electri(.-ity In* considered a still more subtile kind of mat- 
ter — perhaps an attenuated form of light. Magnetism, 
'* vital llnid," and by some* even a " gravic fluid," and a 
fluid of sound, were placed in the same scale; and taken 
together, all these supposed subtile forms of matter were 
classed as "imponderables." 

This view of the nature of the ^Mmpcmderables " was 
in some measure a retrogression, for many seventeenth- 
century philosophers, notably Hooke and Iluygens and 
Boyle, had held more correct views; but the materi- 
alistic conception accorded so well with the eighteenth- 



sritury tendencies of tljoujglit tliat only here and there 
a pJjflosnplier, like Killer, ealled it in qiie^vtfon, mi til well 
tinvattis ihe eluse of tlu; centiiry. Current s^peech re- 
fermtl to tfie iniitcnality of the ** iinpoMilor;iljl<*s*' un- 
fiuestjoningly. Sfnilents of meteornloi!:y — a science that 
was jiist dawiiing--ex|>laiiietl utruostjheric phenomena 


on the supposition that heat, the heaviest imponderable, 
predominated in the lower atmosphere, and that light, 
electricity, and magnetism prevailed in successively 
higher straUi. And Lavoisier, the most philosophical 
chemist of the century, retained heat and light on a par 
with oxygen, hydrogen, iron, and the rest, in his list of 
elementary substances. 

But just at the close of the century the confidence in 
the status of the imponderables was rudely shaken in 
the minds of philosophers by the revival of the old idea 
of Fra Paolo and Hacon and Hoyle, that heat, at any 
rate, is not a material fluid, but merely a mode of mo- 
tion or vibration among the particles of "ponderable" 
matter. The new champion of the old doctrine as to 
the nature of heat was a very distinguished philosopher 
and diplomatist of the time, who, it may be worth re- 
calling, was an American, lie was a sadly expatriated 
American, it is true, as his name, given all the official 
appendages, will amply testify ; but he had been born 
and reared in a Massachusetts village none the less, and 
he siiems always to have I'etained a kindly interest in 
the hind of his nativity, even though he lived abroad in 
the service of other powers during all the later years of 
his life, and was knighted by England, ennobled by Ba- 
varia, and honored by the most distinguished scientific 
bodies of Euroi)e. The American, then, who cham- 
pioned the vibratory theory of heat, in opposition to all 
current opinion, in this closing era of the eighteenth 
century, was Lieu tenant-General Sir Benjamin Thomp 
son. Count Rumford, F. 11. S. 

Eumford showed that heat may be produced in in- 
definite quantities by friction of bodies that do not 
themselves lose any appreciable matter in the process, 



blattiiQfl that this proves the immateriality of beat 
Liter on he added force to the argument by proving, in 
efutation of the experiments of liowditch, that no body 
pther ;^iitis or Idses weiglit in virtue of i)eing hxuitocl 
cooled. He thcHight it proved that heat is only a 
iiide of motion. 

But contemporary judgment, while it listened respect- 
Illy to Uumffii-d, KvuH litlie minded to actiept his yar- 
let. The eberislied l>eliefs of a genenition are not to 
put down with a single Uhnw Whero many minds 
ive a similar ilnft, however, the first blow may precip- 
itafje a generiil conflict; and so it wjis hem. Young 
Uumphry Davy had *ln[»licate(l Kumfor"<r8 experiments, 
Sii reached similar eoncluHiona; and soon others f<^U 
no line. Thi^n, in l>i(>o, Dr. Thomns Young— ^'Phe- 
nometion Young'* limy called him at Cambridge^ because 
he was P^puted to know everything — took up the cuil- 
gek for the vibratory the<iry of light, and it began to 
be clear tliat the two * imponderables,*' heat and light, 
iu«t stand or fnll together; but no one as yet made a 
lim a^iinst the lluiiUty of electricity- 
Bat beft*re this speculative controversy over the nat- 
'^iire of the ** imponderables" had made more than a fair 
ben^innin^, in the last year of the century, a discovery 
vraa anmKinced which giive a new impcttis to physical 
fldetiee:^ mul for tlie moment turned the current of spec- 
tilatjon into another channeh Tfie inventor was the 
Italijin scientist Volta; his invention, the apparatus to 
>ie known in future as the voltaic pile— the Imsis of the 
tnic battery. Ten years earlier Galvani had discov- 
if rTieials phiced in cont^ict have the power to 
ntraction in tho muscles of animals apparently 
Working along lines sufrgested by this discovery, 


Volta develoi>e(l an apparatus coinpose<i of two metals 
joined togetlier and acted on by cliemicals, which ap- 
jKiared to accumulate or store up the galvanic influence, 
whatever it might be. The effect could be accentuated 
by linking together several such ''piles" into a "bat- 

This invention took the world by storm. Nothing 
like the enthusiasm it created in the philosophic world 
had been known since the invention of the Leyden jar, 
more than half a century before. Within a few weeks 
after A'olta's announcement, batteries made according 
to his j)lan were being experimented with in every im- 
])ortant laboratory in Europe. The discovery was made 
in March. Early in May two Englishmen, Messrs. 
Nicholson and Carlyle, practising with the first battery 
ma<l(i in their country, accidentally discovered the de- 
(;onnK)sition of water by the action of the ])ile. And 
thus in its earliest infancy the new science of "galvan- 
ism " had ()p(nied the way to another new science — elec- 

As tin? century closed, half the philosophic world was 
sp(»culating as to whether *' galvanic influence" were a 
new imponderable or (niiy a form of electricity ; and the 
otlKM* half was eagerly s(*eking to discover what new 
marvels the battery might reveal. The least imagina- 
tive man couhl see that herti was an invention that 
would l)e epoch-making, but the most visionary dreamer 
could not even vaguely adumbrate the real measure of 
its importance. Hitherto electricity had been only a 
lalx)ratorv aid or a tov of science, with no su<:i:<j:estion of 
practical utility beyond its doubtful application in medi- 
cine; in future, largely iis the outgrowth of Volta's dis- 
covery, it was destined to become a great economic 



mcy, whose liniitatiuns not even the enlarged Tision 
of our iaUsr century can pretend to outline* 

all Ihe contests that were waging in the various 
jibi of science in tins iconoclastio epociu perhaps U10 
ve*L and most turbulent was that whicli fell within 
ih^ Held of chemistry. Indeed, tliis wiis one of the 
mefnora!>!e warfares in tlio liistory of polemics. It 
a battle veritably NuiHjleoni«3 in its inception, scope, 
wa ineisirenessi. As was titting, it was 11 contest of 
F irainst the woriil ; but the Napoleonic parallel 

t:.,* fre the end, for in this case France won not 

uttly speeilily and nnconi promisingly, but for all time, 
[The main jKiint at issue concerned the central doc- 
iitie of the old chemistry— the doctrine of Becher and 
ibL that the only comlsnstible substance in nature is 
I kind of matUtr called phlogiston, which enters into 
be ccjtii|wj«ition of other l>odies in varving degree, thns 
tt^rmining their inHjininudrility. Tliis theory seems 
t enough now, since wo know that phlogiston was a 
ytrvly flctitious element, yet it served an excellent pur- 
wlien it was propoun<ietl and it held its place as 
be central doctrine of ehemiciil piiilosophy for ahuost a 

the time when this theory was pnt forward, it 

. i^e rf^aHe*!, the old Aristotelian idea that the four 

elements are earth, air, fire, and water still held 

raj as the working fonndation of nU chemical philoso- 

Air aoii water were accepted as simple bodies, 

, few ackls and alkalies were known, and these 

it iroperfoctly ; and the existeiM-e of gases as we now 



know them, other than air, was hardly so ixiiich at* sus- 
|>ected. All tfie known facts of chemistry seerned ihen 


to harmonize with Lht> |ililogiston hyiK>thesia; arid m^ 
later on, did the new phenomena which were discovered 



mch jirofimoii during Urn third quarter of the eigh- 
lib century— the epoch of |meumiitic cbemistry. 
frflrogen ijas, discovered by Cavendish in 177**, and 
llled inflanimable aii\ wfts tSjouglit I13' some chemists 
be ill© very principle of phlugiston itself. Other 
faim*- ivero adjudged *^dephlogisticated'- or ^'phlogig- 
catocK"* in iiropurtioit jis they supported or failed la 
Bpport combustion. The familiar fact of a candle 
itiie ^3irig out when kept in a eouJined si>ace of or- 
iniirv iiir was siud to be due to tfie saturatiou of this 
ir with pblogiiiton. And all tliis s*2emed to tally beau- 
ifully with the prevailing theory. 

But presently the new facts began, as new facts al- 
ruys wlII^ to devoto]> an iamoclastic tendency. The 
^togisWn theory had detbroned lire from its primiicy 
^-ment by alleging that llanie is due to a union 
.ii-ment beat witb the element ptilogiston. No\r 
lbs were decomposed, air and water were shown to 
» compound Ixxlieg, and at last the existence of phlo- 
l^lon itaelf was to bo called in question. The structure 
the old chemical philosophy had been completely rid- 
illed; il was now to be overthrown. The culminating 
oljMfrviitiMit which l>rought matters to a crisis was the 
diisooyery of oxygen, which was made by Priestley in 
Eogkuid andScheele in Sweden, working independently, 
in the year 1 774. Priestley called the new element '' de- 
pidogisucateti air''; Scheelo called it "empyreal air." 

Bat neitber Priestley nor Scbeele realized the full im- 
port of this discovery; nor, for that matter, did any 
one els<? at the nioment- Very soon, however, one man 
U lea^st had an inkling of it. TIjis was the great French 
ebemist Antoine l^aurent Lavoisier. It has sometimes 
hmn ebiiiiieti that be himself discovered oxygen inde- 
^- ^^ - U 


|)endently of Priestley and Sclieele. At all events, ho at 
once began experinienting with it, and very soon it 
dawned upon him tiiat tiiis remarkable substaiice might 
furnish a key to tlie explanation of many of the puzzles 
of chemistry. He found that oxygen is consumed or 
transformed during the combustion of any substance in 
air. lie reviewed the phenomena of combustion in the 
light of this new knowledge. It seemed to him th«it 
the new element explained them nil without aid of the 
supposititious element phlogiston. What proof, then, 
have we that phlogiston exists? Very soon he is able 
to answer that there is no ])roof, no i^eason to believe 
that it exists. Then why not denounce phlogiston as a 
myth, and discard it from the realm of chemistry? 

Precisely this is what Lavoisier purposes to do. He 
associates with him three other famous French chemists, 
Berthollet, Guyton de Morveau, and Fourcroy, and sets 
to work to (h^velop a complete system of chemistry baseil 
on the new conce|)tion. In 1T8S the work is completed 
and given to the worhl. It is not merely an epoch-mak- 
ing book; it is revolutionary. It discards phlogiston 
altogetlHM\ alleging tliat the elements really concerned 
in coml)nstion are 'oxygen and heat. It claims that 
acids are comi)()un(ls of oxygen with a base, instead of 
mixtures of ** earth '' and water; that metals are simple 
elem(»nts, not compounds of "earth" and '* phlogiston ■'; 
and that water itself, like air, is a compound of oxygen 
with another element. 

In applying these ideas the new system proposes an 
altogether new nomenclature for chemical substances. 
Hitherto (he terminology of the scicMicii has been a mat- 
ter of whim and caprice. Such names as *' liver of sul- 
phur," " mercury of life,'' '• horned moon," '* the double 


reC ** the salt of many virtues," and the like, 

dti? been accepted without protest by the chemical 

irorUL With such a term i no logy coutiiiucH.1 progress 

WHS SIS im^iossible as human [srogmss without speectu 

he new chemistry of Lavoisier and his ^ymfVeres^ Uil- 

n*r the model set hy /.oology half a century earlier, 

jnaU's each ,substance hy a name instead of a phrase, 

ilics theso namea acc^u'dintf to tixed rules, and^ in 

kort, claiif?ifies tlie cheniica! kncuvkKlge of the time and 

rings it into a ^yst<?rn, lacking which no famiy of knowl- 

Igf! hiiM full title to the nauje *if science, 

Tbcfii^h I^nvfii.sier was not alone in developing this 

rointionary scbenie^ posterity remorabers him as iu 

biginator, II is dazzling and comprehensive genius oh- 

iirtnl the feebler lights of his t'tmfrere^. Perhaps, too, 

;tnig^tc fate was not without influence in augmenting 

posthumous fame. In ITU4 iie fell by the guillotine, 

liltiei^ of any crime bnt patriotism — a victim of the 

^It*%n of Terror/' "The Repubhc has no need of 

|itf«iw^V^ remarked the funeti(*nary who signed the 

ih'Warrunt of tfie most famous chemist of the een- 


The U*4ider i)( the reform movement in chemistry 

iuB ilml at tlie hands of bigotry and famiticism— 

lUief, let im say, as tlie victim of a national fren?.y — 

ihjlt? the cause lie championed was young, yet not too 

m U> itee tlm victory as good as won. The main body 

Fn»nch chemists liad accept-Cil the nev\^ iloctrines al- 

St from the Rmt, nud elsewhere the oppf>sition bail 

BO of that tierce, eager type which soon exhausts itself 

tbe f^fTorL At Berlin they began by burning Lovoi- 

9r in olHgy, but they ended speedily by accepting tlie 

^w ilieuriefi. In England the fight was more stubborn, 

c 33 


but equally decisive. At first the new chemistry was 
opposed by such great men as Black, of " latent heat " 
fame ; Kutherford, the discoverer of nitrogen ; and Cav- 
endish, the inventor of the pneumatic trough and the 
discoverer of the composition of water, not to mention 
a coterie of lesser lights ; but one by one they wavered 
and went over to the enemy. Oddly enough, the 
doughtiest and most uncompromising of all tiie cham- 
pions of the old *' phlogistic '" ideas was Dr. Priestley, 
the very man whose discovery of oxygen had paved the 
way for the **antij)hlogistic'' movement — a fact which 
gave rise to Cuvier's remark that Priestley was undoubt- 
edly one of the fathers of modern chemistry, but a 
father who never wished to recognize his daughter. 

A most extraordinary man was this Dr. Priestley. 
Davy said of him, a generation later, that no other )ier- 
son ever discovered so many new and curious substances 
as lie ; yet to the last he was only an amateur in science, 
his profession being the ministry. There is hardly an- 
other case in history of a man not a specialist in science 
accomplishing so much in original research as did Joseph 
Priestley, the chemist, physiologist, electrician ; the 
mathematician, logician, and moralist ; the theolo- 
gian, mental philosopher, and political economist. He 
took all knowledge for his field ; but how he found time 
for his numberless researches and multifarious writings, 
along with his every-day duties, must ever remain a 
mystery to ordinary mortals. 

That this marvellously receptive, flexible mind should 
have refused acceptance to the clearly logical doctrines 
of the new chemistry seems cHjually inexplicable. But 
so it was. To the very last, after all his friends had 
capitulated, Priestley kept up the fight. From America, 



iJtber be haAl gone to live in 1794, he sent out the last 
My Up the enemv in 1800, in a brochure entitled ** The 
'^ ^ ine of Ptilogistun Upheld,'" eta In the mind of 
ithor ibis was little less than a paean of victurj ; 
iiU the world besides knew that it was the swan- 
ttg of ibe tli:>ctrineQf phlogiston. Despite the defiance 
! this singlu wiirnor the Uittle was really lost and won^ 
id as ibe century closed, ^^iiitipldugistic'' chemi^itry hatl 
^tical {lossession of the field. 


il causes conspired to niMke exploitation all the 

1.^11011 during the i^losing epoeh of the eighteentli cen- 

iry- New aid to the navigator inid been furnished by 

be perfected compass and quadrant, and by the inv^ention 

ftJiechronomGter; inGdit;aUcieue<3 liad banished scurvy, 

rhirh liitberto had been a perpetual menace to the voy- 

^r; and, aboA'e all, the restless spirit of the age kn- 

the venturesome to seek novelty in fields alto- 

Hber new. Some started for the |Mde, ttthei's trit;d for 

iiorthea-st or northwest passage U> India, yet others 

>!jght lh«^ giviit fictitious antarctic continent told of by 

idition, AH these of course failed of their immediate 

irpo^e. but they adtled much to the world's store of 

fitnvJedge and its fiuul of travellers' tales. 

ong all tliese inlm uont? was more remarkable 
Ithofie which told of strange living creatures found 
aittipo<laI lands. And here, as did not hapfwa in 
rery field, the narratives were often substantiated by 
exhibition of specimens that admitted no question, 
Djr a company of explorers returned more or less 
iritli such trophies fn^m the animal and vegetable 


kingdoms, to the mingled astonishment, delight, and be- 
wilderment of the closet naturalists. The followers of 
Linnieus in the ** golden age of natural history," a few 
decades before, had increased the number of known spe- 
cies of lishes to about 400, of birds to 1000, of insects to 
3000, and of plants to 10,000. But now these sadden 
accessions from new territories doubled the ligure for 
plants, tripled it for iisi] and birds, and brought the 
number of described insects above 20,000. 

Naturally enough, this wealth of new material was 
sorely puzzling to the classifiers. The more discerning 
began to see that the artilicial system of Linnaeus, won- 
derful and useful as it had been, must be advanced upon 
before the new material could b(^ satisfactorily disiK)sed 
of. The way to a mon* nntural system, basetl on less 
arbitrary signs, had been ]>()inted out by Jussieu in 
botany, but the Z(M)l(>gists were not prepared to make 
headway towards such a system until they should gain a 
wider understandiMi; of the organisms with which they 
had to deal tlirouirli comprehensivt?! studies of anatomy. 
Such studi(»s of iiuiividujd forms in their relations to the 
entire scale of or^-anu; lieings were pursued in these last 
decades of tlu^ ceutiny, but though two or three most 
imi)ortant generalizations were achieved (notably Kaspar 
Woltrs conception of the c(»ll as the basis of organic life, 
and (ioethe's all-importaut doctrine of metamorphosis 
of parts), yet, as a whoh\ the work of the anatomists of 
the period was germinativcj rather than fruit-bearing. 
Bichat's volumes, telling of the recognition of the fun- 
damental tissues <»f the body, did not begin to appear 
till the last year of the c(»nturv. The announc<3ment by 
Cuvier of the doctrine of correlation of parts bears the 
same date, but in general the studies of this great nat- 


PUBLIC UB>^'vr-V, I 



umlist, which in due time were to stamp bitn as the 
jcessor of Linnaeus, were as yet only fairly begua. 
In ihe tield of [jbysiology^ on tlie other bantl, two 
most important works wore fairly consummated in this 
epitch^ — the long-standing problems of digestion and 
respiration vver*e solved, almost coincidentlv. Two very 
[iMtmguisbed physiologists share tiie main honors of dis- 
ootery in regard to the function of digestion— the Abbe 
Sjialkinziini, of the University of Pa via, Italy, and John 
Hunter, of England, Working independently, these inves- 
Ugators showeil at about tlie same time that digestion is 
pnmaj'ily a chemical rather than a mechanical process, 
ll ta a curious couiraentary on the crude notions of me- 
duiDJGS of previous generations that it should have been 
ieoeeaarj lo prove by experiment that the thin, almoet 
r * nous stomach of a mammal has not the power to 
} „. , ^. .„j, by mereattritioo, the foods that are taken into 
it However, the proof was now for the first time forth- 
coming, and the question of the general character of the 
function of digestion wiis forever set at rest. 
To clear up the mysteries of respiration was a task that 
I to the lot of chemistry. The solution of the problem 
flowed almost as a matter of cmirse upon the advances 
t that science in the latter part of the century. Hitherto 
noooc* &tDoe Mayow, of the previous century, whose flash 
■ t luid been strangely overlooked and forgotten, 
L. a vaguely surmised the true function of the lungs* 

1 M -^n^il Boerhaave had supposed that respiration is 
' ih.lly iniportitnt as an aid to the circulation of the 
liiHtd ; btft great pupil, llaller, had believed to the day of 
lii$idi^th in 1777 tliat the main purpose of the function 
to form the voice. No genius could hope to fathom 
\ oiyslefy of the lungs so long as air was supposed to 


be a simple element, serving a mere mechanical purpose 
in the economy of the earth. 

But the (hscovery of oxygen gave the clew, and very 
soon all the chemists were testing the air that came 
from the lungs — Dr. Priestley, as usual, being in the 
van. His initial experiments were nuule in 1777, and 
from the outset the problem was as good as solved. 
Other experimenters confirmed his results in all their 
essentials— notably Scheeleand Lavoisier juul Spallauzani 
and I )avy. It was clearly established that there is chem- 
ical action in the contact of thi> air with the tissue of the 
lungs; that some of the oxyg(»n of the air disapiiears, 
and that carbonic acid gas is added to the inspired air. 
It was shown, too, that tlie (>lood, having come in con- 
tact with the air, is changed from black to red in color. 
These essentials were not in dispute from the fii*st. Bat 
as to just what chemical changes caused these results 
was the subject of controvem'. Whether, for exaraplCi 
oxygen is actually absorbed into the blood, or whether 
it merely unites with carbon given off fnmi the blood, 
was long in dispute. 

Each of the main disputants was biassed by his own 
particular vi(»ws as to the moot ])oints of chemistry. 
Lavoisier, for example, believed oxygen gas to be com- 
posed of a nu'tal oxygen combiniHl with the alleged ele- 
ment heat; Dr. Tric^slley thought it a compound of pos- 
itive electricity and phlo^r'ston ; aiul Humphry Dav}', 
when he entered the lists, a litllt* later, supposed it to be 
a compound of o.xygen and light. Such mistaken no- 
tions naturally compli(?at(»d matters,and delayed a com- 
plete understanding of the chemical ]>roc(»sses of respi- 
ration. It was some tinu», too, before the idea gained 
acceptance that the most important chemical changes 



ilo not occur in the luiiij^ theinselvt.'s» Ijiit in tlie ultiinate 
tissues, lodeeil, the mEitter was not clearly settled at 
the close of the century. Nevertheless, the problem of 
respiration hail been liolved in its essentials. Moreover, 
the vastly iiniK>rttint fuct had been esttil^lislied that u 
prtK'ess essentiidly identical with res|)iratiun is necessary 
to the e^Kistenoe not only of all creaturohi supplied witij 
lungs, but tu lislies; insects, and even vegetables — in 
short, to ev*sry kind id* living organiam. 

Froni ihP paliitHigbjr SirTlK'nuu^ r,iii*f«nr« 


All advances in science have a bearing, near or re- 
mote, on the welfare of our race; but it remains to 
credit to the closing decade of the eighteenth century a 
discovery which, in its power of direct and immediate 
benefit to humanity, surpasses any other discovery of 
this or any previous epoch. Needless to say I refer to 
Jenner's discovery of the method of preventing small- 
1K)X by inoculation with the virus of cow-pox. It de- 
tracts nothing from the merit of this discovery to say 
that the preventive i><)wer of accidental inoculation had 
long been rumored among the peasantry of England. 
Such vague, unavailing half-knowledge is often the fore- 
runner of fruitful discovery. To all intents .and purposes 
Jenner's discovery was original and unique. Neither, 
considered as a perfected method, was it in any sense an 
accident. It was a triumph of experimental science; 
how great a triumph it is difficult now to understand, for 
we of to-day can only vaguely realize what a ruthless and 
ever-present scourge small-])ox had been to all previous 
generations of men since history began. Despite all 
efforts to check it by medication and by direct inocula- 
tion, it swept now and then over the earth as an all- 
devastating pestilence, and j'ear by year it claimed one- 
tenth of all the beings in Christendom by death as its 
average (juota of victims. " From small-])ox and love 
but few remain free,'' ran the old saw. A pitted face 
was almost as much a matter of course a hundred years 
ago as a smooth one is to-day. 

Little wonder, then, that the world gave eager ac- 
ceptance to Jenner's discovery. The first vaccination 
was made in 17l>0. Before the close of the century the 
method was practised everywhere in Christendom. No 
urging was needed to induce the majority to give it 



trial; passengers on a burning ship do not hold aloof 
from the life-boats. Eich and poor, high and low, 
sought succor in vaccination, and blessed the name of 
their deliverer. Of all the great names that were be- 
fore the world in the closing days of the century, 
there was perhaps no other one at once so widely 
known and so uniformly reverenced as that of the Eng- 
hsh physician Edward Jenner. Surely there was no 
other one that should be recalled with greater gratitude 
by posterity. 


TiiK Iii'st (Iny of our century was fittingly signalized 
by the discovery of a new world. On the evening of 
.lanuarv 1, 1S(M, an Italian astronomer, Pia/^i, observed 
an apparent star <»f aljout the eighth magnitude (hence, 
of course, (juite invisibli^ to the unaided eye), which later 
on was seen to have moved, and was thus shown to be 
vastly nearer the earth than any true star. lie at first 
supposed, as Ilerschel had <lone when he first saw 
Cranus, that the unfamiliar body was a comet; but 
laitM* obstM'vation ])rov<»d it a tiny planet, occupying a 
positit)n in spac<» l)etween ^lars and Jupiter. It was 
ciiristen<Ml Ceres, after the tutelary g^nMess of Sicily. 

Tliough unpremeditate*!, this discovery was not un- 
t^xpected, for astrononuM's had lonof surmiseil the exist- 
«Mice <^f a planet in the wi<le irap bt^tween Mars and 
.Iupit(T. IndetMl, they were even preparing to make 
conc(M'te<l searcOi for it, d(»s]>ite the protests of philoso- 
phei*s, who arirueil that the planets couUl not pos.siWy 
exetVil the mairie numl>er seven, when Piazzi forestalled 
their t^tTorts. Put a surprise came with tlie sequel: for 
the very next year Dr. Olbers, tht* wondtM-ful ])hysician- 
asironomer of Pixuuen, while fijllowing up the course of 


FKiKimicii WILHELM uesski* 


hiip|>enecl on another tiny moving star, simikrly 
JiR^tecl, wliich soon revealed itself as ]>lanetary* Thus 
two plaat*U were found wliere oi>ly one was expected. 

The existence of the siiperntimerary was a puzzle, but 
0\\)QT% s^filve*i it for the moment by suggesting that 
Ceres and PaUas^ as he called his captive, miyht be frag- 
ments of a quondam planet, shattered by internal ex- 
^iosien, or by the impact of a comet. Other similar 
"Ots^be ventured to predict, would be found wln-n 
r.u. tied for, WJlliani Hei*schel sanctioned this theory, 
untl suggested the name aKtemitls for the tiny planets. 
Th« explosion theory was sujiportetl by the discovery of 
'■I'T asteroid, by Harding, of Lilienthuljn 18o4, and 
I lied chncbed svhen Gibers bi myself found a fourth 
in ISf>7. The new-comers were named Juno and Vesta 
4,,Lre the case rested till 1S45, when a Prussian 
tear astronomer named Ilencke found another aste- 
Tif«d, after long searching, and opened a new e{H>ch of 
diicovery. Fi-om tiien on the finding of asteroids be- 
cjune a commonplace^ Latterly, with the aid of pho- 
tijfjmphy, the list has been extended to above four hun- 
tnd as yet ttien? seems no deartli in the snyiply, 
_ I doubtless ah the larger memliers have been re- 
f Even these are but a few hundreds of miles in 
r,*r^ while the smaller ones are too tiny for raeas- 
The combined bulk of these minor planets is 
► Ixt hut a fraction of that of the earth. 
[tUbem's explosion theory, long accepted by astront> 
beon proven open to fatal objections, Tlie 
ts are now believed to represent a ring of 
Mntical matter, cast off from the solar nebula like the 
Hngitliat went t^ form the major planets, but prevented 



from becoming aggregated iato a single bmly b}' the 
perturbing mass of Jupiter. 

As we Jjave seen, the discover}^ of the first asteroid 
confirmed a conjecture ; the other imporUmt planetary 
(h'scovery of onr century fulfilled a prediction. Nep- 
tune wjis found through scientific prophecy. No one 
suspected the existcMice of a trans-Uranian planet till 
Uranus itself, by hair^breadth departures from its pre- 
dicted orbit, gave out the secret. Xo one saw the dis- 
turbing planet till the pencil of the mathematician, with 
almost occult divinaiion, had pointed out its place in 
the heavens. The general predication of a trans- 
Uranian planet was made by n<»ssel, the great Konigs- 
berg astronomer, in 1.S40; the analysis that revealed its 
exact location was undertaken, half a decade later, by 
two independent workei's — John Couch Adams, just 
graduated senior wrangler at Cambridge, England, and 
U. »I. J. Leverrier, th(^ leading French mathematician of 
his g(Miera.tion. 

Adams's calculation was fiiNt begun and first com- 
pleted. J>ut it had one radical deft»ct — it was the work 
of a young and untried man. So it found lodgment in a 
pigeon-hole of the desk of England's Astronomer Royal, 
and an opportunity was lost which English astronomers 
hav(>. never ceased to mourn. Had the sejirch been 
made, an actual planet would have been seen shining 
there, close to the spot where the pencil of the mathe- 
matician had placed its hy]X)thetical counterpart. But 
the search was not made, and while the ])ro|)hecy of 
Adams gathertnl dust in that regrettable ])igeon-hole, 
Leverrier's calculation wtus coming on, his tentative 
results meeting full encouragement from Arago and 
other French savants. At last the laborious calculations 



proved satbfucUiry. and, confick'snt of the result, Ix'verrier 
M lit the lieiim ohservatorVj requesting that seiirch be 
'^^4^ for the iliHturljer of ITmnus ia a (mrticuUr sjHjt of 
.*^veiis. Div Galle received tlio request September 
,l?v40. That very night he turned his telescope to the 
itM rejj^Ton. and there, within a snigle degree of 
Hggestetl spot, he saw a seeming stur, invisiblo to 
uttiiiilt*d eje, wWcb proved to be the long-sought 
henceforth to be known as Neptune. To the 
je miml, which tinib sou^ething n Huge t her nivsti- 
jrifij^ alHHit abstract mathematics, this was a feat 
of the nil racu Ions. 
.Utcd by this success. Leverrier Ciiieulated un 
bit for an interior planet from perturbations of Mer- 
cury, bat ihough prematurely christened Yulcan, this 
^ *' Meal Tjurseling of the sun still haunts the realm 
iruliscovored, along with certain equally hypo- 
tlictical Inins-Xeptunian planets whose existence has 
hitii sjQgcf*^sted by "residual perturbatirins" of ITraTins. 
hv the movement!^ of comets. No other veritable 
JilianH t*> the sun-s planetary family have Ijeen made 
in oil r century, Ixn-ond the finding of seven small moons, 
-' - fiiefly fittest the advance in telescopic powers, 
, ibe t*ny attendants of our Martian neighbor, 
t1e8cx}vered by Professor Hall witli the great Washington 
nrfmctor* are of greatest interest, because of their small 
jd extremely rapid flighU One of them is |Joised 
k;0 miks from Mars, and whirls about him almost 
bm*^ as fast as he revolves, seeming thus, as viewed 
itaiiian, to rise in the W(*st and set in the east, ami 
Bg the month only one-fonrth as long as the day. 
'Till! disoovcn* of the inner or crape ring of Saturn, 
le sitnuIUneouftlv in 1S50 by William C\ Bond, at 


the Harvard observatory, in America, and the Rev. 
W. R. Dawes in England, was another interesting op- 
tical achievement; but our most important advances 
in knowledge of Saturn's unique system are due to the 
mathematician. Laplace, like his predecessors, supposed 
these rings to be solid, and explained their stability as 
due to certain irregularities of contour which Ilerschel 
had pointed out. But about 1S51 Professor Peirce of 
Harvard showed the untenability of this conclusion, 
proving that were the rings such as Laplace thought 
them, they must fall of their own weight. Then Pro- 
fessor J. Clerk Maxwell of Cambridge took the matter 
in hand, and his analysis reduced the puzzling rings to a 
cloud of meteoric particles — a " shower of brickbats " — 
each fragment of which circulates exactly as if it were 
an independent planet, though of course perturbed and 
jostled more or less by its fellows. Mutual perturbations, 
.and the disturbing pulls of Sfiturn's orthodox satellites, 
as investigated by Max-well, explain nearly all the phe- 
nomena of the rings in a manner highly satisfactory. 

But perhaps the most interesting accomplishments of 
mathematical astronomy — from a mundane stand-|)oint, 
at any rate — are those that refer to the earth's own 
satellite. That seemingly staid body was long ago 
discovered to have a propensity to gain a little on the 
(narth, appearing at eclipses an infinitesimal moment 
ahead of time. Astronomera were sorely puzzled by 
this act of insubordination ; but at last Laplace and 
Lagrange explained it as due to an oscillatory change in 
the earth's orbit, thus fully exonerating the moon, and 
seeming to demonstrate the absolute stability and per- 
manence of our planetary system, which the moon's 
misbehavior had appeared to threaten. 



"nils bigli) y salisfaciary tx^ncloston xrm um orthodox 
Inlkf of celestial meebaoics until l$^3, when Professor 
Adams of X* n fame, with whom complex analyses 

were a pasti:^--, - itnieti Ltipluees calctilution, and dis- 
oorerBd an em>r, %Tbi€b, when correotad^ left about hulf 
tbe mooti's acoeleratioo unac^^ounted fun Tliis was a 
DOiiieiiioa& diderepanc>% which at first no one could 
iplaiiu But present iy ProfesiStjr Heliuhultz^ the great 
Scntuin physicist, su;^gesteti that a ke}" might be fuimd 
riction, irhich, acting as a perpetual brake on 
i^B rotation, and atTectitig not mei'ely the waters 
Bi lli6 entire substaneo of our planet^ must in the long 
iif lime har« changed its rate of rotation. Thus 
ling acceleration of the moon might l>e account- 
actual retardation of the earth's rotation^ — a 
ngthening of the day instead of a shortening ol the 

Agaio the earth iras shown to be at fault, hut this 

ime tbe moon cx>uld not be exonerated, while the esti* 

ited stability of our system, instead of being re-estab* 

shed, was quite upset. For the tidal retanlation is not 

oscillatory t^liange which will presently correct itself, 

Ilk© the orbital wobble, but a perjietual change, acting 

alirays in one direction. Unless fully counteracted by 

wome oppising reaction, therefom (as it seems not to be), 

the effect must be cumulative, the ultimate consequences 

disaiitroas* The exact character of these consequences 

j^jrai flrsi estimated by Professor G, II. Darwin, in 1S79, 

^Be showed that tidal friction in retarding the earth 

^nuat also push tlie moon out from the parent planet on 

^^ ipiraJ arbiL Plainly, then, the moon must formerly 

hife bean Eeftter the earth than at present. At some 

fery remote period it mast have actually touched the 



«\u I h ; musi, in other woiils, have been thrown oflf from 
iiw liifii pliisiiL- mass of the earth, as a polyp buds out 
\i\nn iiN parent poly|). At that lime the earth was spin- 
Miiii; atK»uL in a ilay oi from two to four houi^s. 

Now I ho ihiy has been lengthened to twenty-four 
lioiiis, and ilie nKK)n has been thrust out to a distance 
i'l a »j.iarh'riiiillion miles; but the end is not yet. The 
^»i!iu' |n\»i;ivss of events must continue, till, at some re- 
•iu»ie iviit>d in the future, the day has come to e(jual 
Ilk- iiU'Miii, lunar tidal action lias ceased, and one face of 
liio iM! til looks i>ut always at the moon, with that same 
i\\K\{ Slate wliieh even now the moon has been brought 
!i« .i.vsUMU' lowai'ds her parent ori). Slj«)uld we choose to 
'.i\r k-M'u i;tvater liberties with the future, it may be 
iiuidv :o a|»i>ear uhough some astronomers dissent from 
\i\.:^ |»u'div'iioin that, as sohir tidal action still continues, 
-.K- Kiax must tlnally i?xceed the month, and lengthen 
K'.a liiile l»y little towards coincidence with the year; 
riA '.\\A\ [he moon nieantime must patise in its outward 
li-ii:. isid eome sAvinging back on a descending spiral, 
; .;:: uiially, aflerftlie lapse of untold aM)ns, it ])loughs 
I :.[ ! .. o^ lii'is along the surface of tin? earth, and plunges 
.• , rv»|»!Me th'st.ruction. 

'.1';'. I'M-ii though imagination paus(> far short of this 

li'v -ti. I iilniination, it still is clear that m<Mh»rn calcula 

■ :;., Im.mhI k>]\ inexorable tidal friction, sutlice to revo- 

.. ..'T.-o I hr views formerly current as to the stability 

■ I." }»hi!k'iary system. The eighteenth-century math- 

.:.i .v.a'i looked upon this system as a vast celestial 

.. .1 !k' \\ liivh had been in existence about six thousiind 

w\. ., I'ld v\hieh was destined to run on forever. The 

..i \..;. oj today computes both the past and the future 

. A M MjbAioiu iu millions instead of thousands of years, 


K jusTKsomr 

off«ffS BO 

ft the ■■■■nWe order of 

fcrrcled oat the secret, it 
br aov one ciut 

vU while fire bden. 
edl tie 

eodd be piolting iDJorr to her pareDt orb. But there 
b another inhabitaBt ot the skies vliose ]nirpo6es haw 
not been similailr free from popular siis{>ieii.>n. Xee^: !ess 
to nj I refer to the Uack sheep of the siJer^il fain ; v, 
that "^celestial Tagmbond ^ the comet. 

Time oat of mind these wanderers have neen sii;^ 
poted to presage war. famine, pestilence. |terha|>s tiio 
destruction of the world. And little wontier. Ht-re is 
a body which comes flashing out of lK>un<]Ie$s s|\:kv xwu^ 
oar sjstem. shooting out a pyrotechnic tail some hun- 
dreds of millions of miles in lennih : whiriini: |vrhaps 
tbroogli the very atmosphere of the sun at a sj>eeil of 
three or foor hundred miles a second : then dartlnir otT 
(41 a hyperbolic orbit tluit forhi«ls it ever t«> return, or 
an elliptical one that cannot be cIose«l f«>r humlreils or 
thousands of years ; the tail meantime ]>ointin(; always 
away from the son, and fading to nothinirness as tlie 
weird royager recedes into the spacial void whence it 
came. Not many times need the advent of such an ap- 
parition coincide with the outbreak of a ]>estilence. or 
the death ot a Csesar, to stamp the race of comets as an 



ominous clan in the minds of all snperstitious genera- 

It is true a hard blow was struck at the prestige of 
these alleged supernatural agents when Newton proved 
that the great comet of 1G80 obeyed Kepler's laws in its 
flight about the sun ; and an even harder one when the 
same visitant came back in 1758, obedient to Halley's 
prediction, after its three-quarters of a century of voy- 
aging out in the abyss of space. Proved thus to bow to 
natural law, the celestial messenger could no longer 
fully sustain its role. But long-standing notoriety can- 
not be lived down in a day, and the comet, though 
proved a " natural " object, was still regarded as a very 
menacing one for anotlier hundred years or so. It re- 
mained for our own centur}'^ to completely unmask the 
pretender, and show how egregiously our forebears had 
been deceived. 

The unmasking began early in the century, when Dr. 
Olbers, then the highest authority on the subject, ex- 
pressed the opinion that the spectacular tail, which had 
all along been the comet's chief stock in trade as an 
earth - threatener, is in reality composed of the most 
filmy of vapors, repelled from the cometary body by the 
sun, presumably through electrical action, with a veloc- 
ity comparable to that of light. This luminous sug- 
gestion was held more or less in abeyance for half a cen- 
tury. Then it was elaborated by ZoUner, and particu- 
larly by Bredichin, of the Moscow observatory, into 
what has since been regarded as the most plausible of 
cometary theories. It is held that comets and the sun 
are similarly electrified, and hence mutualW repulsive. 
Gravitation vastly outmatches this repulsion in the 
body of the comet, but yields to it in the case of gases, 






itise electrical force vurios with Lbo surface, while 
^vitatioB varies only with the muss. From sludy of 

inic weights, ami estijiiates of the velocity of thrust 

c^>ineUiry Uuh^ liretl icliin canctuded that the chief 
c4Nnpi)neut^ of the vanuuH kiuds of tails are hydj'oycn, 
liydrocarbotis, and the vaiior of iron ; and spectroscopic 

lysis goes far towards sustaining these assumptions. 

But, thi^ories aside, the unsuhsUintialness of the corn- 
et's Uul has been put to a conclusive test. Twice during 
our cefitnrv the cart I j baa actual !y plunged tlirectly 
thruugh one of tfiese tlireatening uppenduges, in 1S19, 
and again in 1801, once being imfuersed to a ilepth of 
mmi' 300, OOH miles in its substance. Yet nothing dread- 
f.i 1. -. -.iiriiHl to us. There was a peculiar glow in the 
're, st» the nion? imuginativ^u ol^serv^ei^s tiiouglit, 
md that was all. After such ila^eoes, the cometary 
tiuia ctiuld never again pose as a u^urUl-destroyer 

Btti ibe full measure of ttie comet\s huniiUatiun is not 

uriil. The pyrotechnic tail, composed as it is of por- 
Unns ctf the comet'i^ actual substance, m tribute paid the 
fan, and can never be reeoveretl. Should the obeisance to 
ttiosun b*^ many times repeated, tlie train-forming mate- 
rial will be exhausted, and the comet's ohfefest glory will 
I ' irted, Sucli a fate has actually befallen a mid- 
r i:omets, which Jupiter and the other outlying 

pbifieU have dragged into our system, and helped the 
ittn to hold ca|>tive here, Many of these tailless comets 
irere known to the eighteenth-century astronomers, but 
iK>on«* at that time susj>oeted the true meaning of their 
condiiion. It was not even known bow closely some of 
' hained, until the German astronomer Encke, 

ed thiit one which he had rediscovered^ and 
fb ha« since borne his name, was moving in an orbit 


so contracted that it must complete its circuit in about 
three and a half years. Shortly afterwards another 
comet, revolving in a period of about six years, was dis- 
covered by liiela, and given his name. Only two more 
of these sliort-period comets were discovered during our 
first half-century, but latterly they have been shown to 
be a numerous family. Nearly twenty are known which 
the giant Jupiter holds so close that the utmost reach of 
their ellipticiil tether does not let them go beyond the 
orbit of Saturn. These aforetime wanderers have adapt- 
ed themselves wonderfully to planetary customs, for all 
of them revolve in the same direction with the planets, 
and in planes not wide of the ecliptic. 

Checked in their proud hyperbolic sweep, made cap- 
tive in a planetary net, deprived of their trains, these 
quondam free lances of the heavens are now mere 
shadows of their former selves. Considered as to mere 
bulk, they are very substantial shadows, their extent be- 
ing measured in hundreds of thousands of miles ; but 
their actual mass is so slight that they are quite at the 
mercy of the gravitation pulls of their captors. And 
worse is in store for them. So persistently do sun and 
planets tug at them that they are doomed presently to 
be torn into slireds. 

Such a fate has already overtaken one of them, under 
the very eyes of the astronomers, within the relatively 
short period during which these ill-fated comets have 
been observed. In 1832 Biela's comet passed quite near 
the earth, as astronomers measure distance, and in doing 
so created a panic on our planet. It did no greater barm 
than that, of course, and passed on its way as usual. 
The very next time it came within telescopic hail it was 
seen to have broken into two fragments. Six years later 



fragments were separated by many millions of 
: unci in 1852, when the comet was due again, as- 
rners looked for it in vain. It had been completely 

What had become of the fragments J At that time 
no one positively knew. But the question was to be 
aiisnreried presently. It chanced that just at tliis period 
aUrcinomens were paying much atteiuion to a class uf 
hmiiefi which they had hitherto somewhat neglected, the 
familiar shooting-stars or nieteors. The studies of Pro- 
r Newton of Yale and Professor Adams of Cam* 
idg© with particnlar reference to tlie great meteor- 
shower of November, 1866, which Professor Newton 
had predicted, and shown to be recurrent at intervals of 
thirty three years, showed that meteoi-s are not mere 
spomdic swarms of matter flying at random^ but exist 
ialed swarms, and sweep about the sun in regular 
cii.|iucal orbits. 

Presently it was shown by the Italian astronomer 
Schtapiirelli that one of these meteor swarms moves 
in Ihe orbit of a previously observed comet, and other 
eoiiteidenoes of the kind were soon forthcoming; The 
CQiiTiciion grew that meteor swmrms are really the 
debm of comets; and this conviction became a prac- 
Udil certainty when, in November, 1872, the earth 
erased ihe orbit of the ill-starred Biehi, and a shower 
of meteofg came whizzing into our atmosphere in lieu of 
lo«t c*imet* 

I so at last the full secret was out. The awe-inspir- 

f comet, instead of being the planetary body it had all 

»ng bi>en regarded, is really nothing more nor less 

a great at^gregation of meteoric particles, which 

ibecome cl«stere<l together out in space somewhere. 


and which by jostling one another or through electrical 
action lioconie liuninous. So widely are the individual 
particles separated that the cometary body as a whole 
has been estiniateil to be thousands of times less dense 
than the earth's atniospliero at sea-level. Hence the 
ease with which the comet may be dismembered and its 
particles strung out into streaming swarms. 

So thickly is the space we travei-se strewn with this 
comt^tary dust that the earth sweeps up, according to 
Professor Newcoml/s estimate, a million tons of it each 
day. Each individual |)article, perhaps no larger than 
a mill(»t se(»d, hrcomos a shooting-star or meteor as it 
burns to vapnr in the earth's upper atmosphere. And 
if one liny plant*! sweeps up such masst^s of this cosmic 
matl(M\ the amount of it in tht* (Mitire stretch of our sys- 
tem must ho i)eyond all estimate. What a story it tells 
of lh(» myriads of cometary victims tliat have fallen prey 
to the sun since iirst he stretcheil his planetary net across 
the heavens. 


When Ih'rla's comet gavi* tin? inhabitants of the earth 
such a fright in Ix'Ml, it really did not come within 
lifty millions of mili»s of us. Kv(mi the great comet 
through whose tilmy tail the i»arth passed in lSr»l was 
itself fourt«MMi millions of miles away. The ordi- 
nary minti, schoi.h'tl to measun* space by the tiny 
stnMclHv*; <>f a pvirmy planet, cannot grasp the import of 
such distant-es; yet thest* an» mere units of measure 
compartMl with tlu* vast stnMches of sidiTeal $|)ace. 
Were the comet which luirtle> past us at a s]>eed of, 
say, a hundriul miles a sccjhkI ii> continue its nuul flight 
unchecked straight out intt> the vi»id i»f space, it must fly 

Fffw Cbe p«mtiiig ^S H, W. PIclcfiTBgltl, K. A Ju St Jobn'i Collegfi, CftmbridgQ 






frigid way eiglit tliousatid years before it could 
^h the very nearest of our iieighbur stai's; and evtm 
liien it wuudd have penetmted but u luere arm's-length 
I II to the vistas where lie the duzaii or so of sidereal resi- 
dents that aro next beyond. Even to the traiued mind 
such distances are only vagnely imaginable* Yet the 
aistronumer of our century has reached out across this 
uotbinkable void and brought back many a secret 
iliicli our predecessors thuaglit forever beyond human 

A tentative Jissault upon this strongholil of the stars 
was being made by Herschel at the beginning of the 
century- In 1802 that greatest of observing astrono- 
meii announced to the Koyal Society his discovery that 
certain double stars bad changed their relative positions 
towards one another since he first carefully charted 
tbom twenty years before. Hitherto it had been sup- 
pofied that double sta»*s were mere optical effects. Now 
it liacama clear that some of them, at any rate, are true 
**binarj^ systems/' linked together presumably l>y gravi- 
tation, and revolving about one another, Ilidley had 
bown, three<]uarters of a century before, that the stars 

fcve an actual or ** proper" motion in space; Herschel 

himself had proved that the sun shares this motion with 

lie father stars. Here was another slilft of place, hith- 

A) quitt^ unstjspected, to l>o reckoned witli by the as- 

jnomor in fathoming sidereal secrets. 

When John Herschel, the only son and the worthy 
>r of the great iiRtronomer, began starga?:ing in 
_«trfiest, after grailuating senior wrangler at Cambridge, 
Bd making two or three tentative professional starts in 

ber direct ions to which his versatile genius impelled 
,his first extended work was the observation of his 


father's double stai*s. His studies, in which at first he had 
the collaboration of Mr. James South, brought to light 
scores of hitherto unrecognized pairs, and gave fi-csh 
data for the calculation of the orbits of those longer 
known. So also did the independent researches of F. 
(i. W. Struve, the entiiusiastic observer of the famous 
ilussian observatory at the university of Dor]>at, and 
subsequentl}'^ at Pulkowa. Utilizing data gathered by 
these observers, M. Savary of Paris showed in lS27that 
the observed elliptical orbits of the double stars are ex- 
plicable by the ordinary laws of gravitation, thus con- 
firming the assumi)tion that Newton's laws apply to 
these sidereal bodies. Henceforth there could be no 
reason to doubt that the same force which holds terres- 
trial objects on our globe pulls at each and every par- 
ticle of matter throughout the visible universe. 

The pioneer oxplorei's of the double stars early found 
that the systems into which the stars are linked are by 
no means confined to single ])airs. Often three or four 
stare are found thus closely connected into gravitation 
systems; indeed, there are all gradatioiis between bi- 
nary systems and great clusters containing hundreds or 
even thousands of membei's. It is known, for example, 
that the familiar cluster of the Pleiades is not merely 
an optical grouping, as was formerly supposed, but an 
actual federation of associated stars, some :J500 in num- 
ber, only a few of which are visible to the unaided eye. 
And the more carefully the motions c»t the stars are 
studied, the more evident it becomes that widely sepa- 
rated stars are linked together into infinitely complex 
systems, as yet but little undei'stood. At the s;\me time 
all instrumental advances tend to resolve more and more 
seemingly single stare into close piire and minor clus- 


ters. The two Ilerschels between them discovered 
soma thonsands of these close multiple systems; Struve 
ftnd others increased the list to above ten thousand ; 
and Mr. S. W. Burnhara, of late years the most enthusi- 
astic and successful of double -star pursuers, added a 
thousand new ilisico varies wliile he was still an amateur 
ia astronomy, and by pmfession the stenographer of a 
Chicago LUiurt. Clearly the actual number of multiple 
stars is beyond all present estimate. 

Tlie elder llei'schers early studies of double stars 
were andertaken in the hope that these objects might 
aid him in ascertaining the actual ilistance of a star, 
through axeasurement of its annual parallax; that is to 
ay, of the angle which the diameter of the earth's orbit 
would suht<^nd its seen from the star. The expectation 
rjis not fulflltetb The apparent shift of position of a 
star M viewed from opposite sides of the earth's orbit, 
from which the parallax might be estimated^ is so ex- 
U^»iiie}jr minute tbat it proved utterly inappreciable, 
»T€ii to the almost preternatu rally acute vision of Her- 
schei, with the aid of any instrumental means then at 
eonuiMind. So the problem of star distance allured and 
dllded htm to the end, and he died in 1822 without see- 
ing tt even in prospect of solution. His estimate of the 

limum disUtnc^ of the nearest star, based though it 
MOO the fallacious test of apparent brilliancy, was a 
riy sagacious one, but it was at best a scientific 
gvietti, not n scientific measurement. 

Jojt about this time, however, a great optician came 
totbeiiid of the Jistronomers. Joseph Fraunhofer per- 
fect^ the refracting telescope, as Herschel had perfected 
tor, and in vcntinl a wonderfully accurate **he- 
ar sun-ineasarer. With the aid of these in- 


struments the old and almost infinitely difficult problem 
of star distance was solved. In 1838 Bessel announced 
from the Konigsberg observatory that he had succeeded, 
after months of effort, in detecting and measuring the 
parallax of a star. Similar claims had been made often 
enough before, always to prove fallacious when put to 
further test; but this time the announcement carried 
the autliority of one of the greatest astronomers of the 
age, and scepticism was silenced. 

Nor did Besscrs achievement long await corrobora- 
tion. Indeed, as so often happens in fields of discov- 
ery, two other workers had almost simultaneously 
solved the same i)roblem — Struve at Pulkow^a, where 
the great Russian observatory, wliich so long held the 
palm over all others, had now been established; and 
Thomas Henderson, then working at the Cape of Good 
Hope, but afterwards the Astronomer Royal of Scotland. 
Hendei*Sfm's observations had actual precedence in point 
of time, but Rossers measurements were so much more 
numerous and authoritative that he has been uniformly 
considered as deserving the chief credit of the discovery, 
which priority of publication secured him. 

J>y an odd chance, the star on which Henderson's ob- 
servations werc! made, and coiis(M]uont]y the first star the 
])arallax of which was (»V(M' measnred, is our nearest 
neighbor in sidereal si)ace, being, indeed, some ten bill- 
ions of miles nearer than the one next beyond. Yet 
even this nearest star is more than 200,000 times as re- 
mote from us as the sun. The sun's light flashes to the 
earth in eight minutes, and to Xeptune in about three 
and a half hours, but it requires three and a half years 
to signal Alpha Ceiitauri. And as for the great major- 
ity of the stars, had they been blotted out of existence 









eforB the Christiafi era, we of to-day should still re- 
ei?e their VtgUl and seem to see them Just as we do. 
ff lien we look up to the sky, we study Hticient liistory ; 
»e (to not see tlie stai-s as they art\ but as they were 
ars, centaries, even millennia ago. 
The information deriv^**d from the parallax of a star 
^y no means lialts with the disclosure of tiio distance of 
hat IkkIv. Distance knowoj the proper motion of the 
ftr^ hitherto only to 1*6 reckoned as so many seconds of 
c. may reailily be translateil into actual speed of prog- 
i; relative brightnesj^becomes absolute lustre, aacom- 
aml with the mm f and in the case of the double stars 
b(5aWiliite mass of the components may be computed 
urn tbi* la^^'s of gravitation* It i^ found that stars 
liffer enormously among themseh'^es in all these regards. 
^i to *i{K>ed, sotne, like our sun, barely creep through 
B— compassing ten or twenty miJes a second^ it is 
yet even at that rate only passing through the 
ftyiratent of their own diameter in a day. At the 
lljer (*xtn3me, among measured stars, is one that 
i>ve5 two homlred miles a second ; yet even this "fly< 
star;* as seen from the earth, seems to change its 
by only almut three and a half lunar diameters 
Pthousand years. In brightness, some stars yield to 
^un, while fitfiers surpass bim as the arc-light sur- 
I a camlle. Arcturus, the brightest measured Btar, 
men like two hundred suns; and even this giant orb 
fdiin b**side those other stars which are so distant that 
lir {mniUax cannot be measured, yet which greet our 
It h'rst magnitude. As to actual bulk, of which 
Bot lustre furnishes no attequate test, some stars 
aregmailer tlian the sun, while others exceed bira bun- 
Ms 4*r jiorhaps thousands uf times. Yet one and all, 


so distant are they, remain mere diskless points of light 
before the utmost powers of tlie modern telescope. 

All this seems wonderful enough, but even greater 
things were in store. In 1859 the spectroscope came 
upon the scene, perfected by Kirchhoff and Bunsen, 
along lines pointed out by Fraunhofer almost half a 
century before. That marvellous instrument, by reveal- 
ing the telltale lines sprinkled across a prismatic spec- 
trum, discloses the chemical nature and physical condi- 
tion of any substance whose light is submitted to it, 
telling its story equally well, provided the light be 
strong enough, whether the luminous substance be near 
or far — in the same room or at the confines of space. 
Clearly such an instrument must prove a veritable magic 
wand in the hands of the astronomer. 

Very soon eager justronomers all over the world were 
putting the spectroscope to the test. Kii*chhoff himself 
led tlie way, and Donati and Father Secchi in Italy, 
IFuggins and Miller in England, and Rutherfurd in 
America, u^ere the chief of his immediate followers. 
Tlie results excocded the dreams of the most visionary. 
At the very outset, in 18G0, it was shown that such 
common terrestrial substances as sodium, iron, calcium, 
magnesium, nickel, barium, copper, and zinc exist in the 
form of glowing vapors in the sun, and very soon the 
stars gave up a corresponding secret. Since then the 
work of solar and sidereal analysis has gone on steadily 
in the hands of a multitude of workers (prominent 
among whom, in this country, are Professor Young of 
Princeton, Professor Langley of Washington, and Pro- 
fesvsor Pickering of Harvard), and more than half the 
known terrestrial elements have been definitely located 
in the sun, while fresh discoveries are in prospect. 



It is true the snn also contains some seeming elements 
are unknown on the eartli. but this is no matter for 

WSti, The modern chemist makes no claim far bis 


tttmtg except that tbey have thus far resisted all 
&Q efforts to ilissociate them; it would be nothing 
Bge if some of ttiem, when stihjected to the erucible 



of the sun, which is seen to vaporize iron^ nickelj silicon, 
should fail to withstaud the test But again, chemistry 
has by no means exhausted the resources of the earth's | 
supply of raw niaterialj and the substance which sends 
lis message from a star may exist undiscovered in the 
dust we tread or in the air we breathe. Only last year 
two new terrestrial elements were discovered ; but one 
of these bad for years been known to the astronomer as 
a solar and suspected as a stellar element, and named 
helium because of its abundance in the sun. The spec- 
troscope had reached out millions of miles into space 
and brought back this new element, and it took the 
chemist a score of yeai's to discover that he had all 
along had samples of the same substance unrecognized 
in his sublunary laboratory. There is hardly a more 
picturesque fact than that in the entire history of 

But the identity in substance of earth and sun and 
stars was not more clearly shown than the diversity of 
their existing physical conditions* It was seen that sun 
and stars, far from being the cool, earthlike, habitable 
bodies that Ilerschel thouglit them (surrounded by 
glowing clouds, and protected from undue heat by other 
clouds), are in truth seething caldrons of fiery liquid, or 
gas made viscid by condensation, with lurid envelopes 
of belching flames. It was soon made clear, also, par- 
ticularly by the studies of Rutherfurd and of Seech i, 
that stars differ among themselves in exact constitution 
or condition* There are white or Sirian stars, whose 
spectrum revels in the lines of hydrogen ; yellow or 
solar stars (our sun being the type)^ showing various 
metallic vapors; and sundry red stars, with banded 
spectra indicative of carbon compounds; besides, the 



arely gaseous stars of more recent discovery, which 
Professor Pickering had speciixlly ntudied. Zollner's 
interpret at ion of these diversitieSj as indicative 



f ' • I 

- , ' ' S HI « 

I ill I '^ ' 

grucrmA of stabs or carina 

rying stages of et^oling^ has been called in question 
u lo the exact sequence it postnlates, but the general 
pfopositioti that stars exist under widely varying condi- 
iioQiof temperature is hardly in dispute. 


The assumption that different star types mark vary- 
ing stages of cooling has the further support of modern 
physics, which has been unable to demonstrate any way 
in which the sun's radiated energy may be restored, or 
otherwise made perpetual, since meteoric impact has 
been shown to be — under existing conditions at any 
rate — inadequate. In accordance with the theory of 
Uelmholtz, the chief supply of solar energy is held to 
be contraction of the solar mass itself, and plainly this 
must have its limits. Therefore, unless some means as 
yet unrecognized is restoring the lost energy to the 
stellar bodies, each of them must gradually lose its lus- 
tre, and come to a condition of solidification, seeming 
sterility, and frigid darkness. In the case of our own 
particular star, according to the estimate of Lord Kel- 
vin, such a culmination appears likely to occur within a 
period of five or six million years. 

But by far the strongest support of such a forecast as 
this is furnished by those stellar b<5dies which even now 
appear to have cooled to the final stage of star develop- 
ment and ceased to shine. Of this class examples in 
miniature are furnished by the earth and the smaller of 
its companion planets. But there are larger bodies of 
the same type out in stellar space — veritable "dark 
stars " — invisible, of course, yet nowadays clearly recog- 

The opening up of this " astronomy of the invisible " 
is another of the great achievements of our century, and 
again it is Bessel to whom the honor of discovery is due. 
While testing his stars for parallax, that astute observer 
was led to infer, from certain unexplained aberrations of 
motion, that various stars, Sirius himself among the 
number, are accompanied by invisible companions, and 



flSW he definitely predicated the existence of such 
krk stars.*- The correctness of the inference was 
mvn twenty years later^ when Alvan Clarkj Jun., the 



ST A it Sl'^:<. IHA 

inion of Sinus, whieh proved thus to be faintly 
Iraifloim, Since then the existence of other and quite 
Iniisibie star companions has been proved inconteatubly^ 



not merely by renewed telescopic observations, but by 
the curious testimony of the ubiqtritous spectroscope. 

One of the most surprising accomplishments of that 
instrument is the power to record the flight of a luminous 
object directly in the line of vision. If the luminous 
body approaches swiftly, its Fraunhofer lines are shifted 
from their normal position towards the violet end of the 
spectrum; if it recedes, the lines shift in the opposite 
direction. The actual motion of stars whose distance is 
unknown may be measured in this way. But in certain 
cases the light lines are seen to oscillate on the spectrum 
at regular intervals. Obviously the star sending such 
light is alternately approaching and receding, and the 
inference that it is revolving about a companion is una- 
voidable. From this extraordinary test the orbital dis- 
tance, relative mass, and actual speed of revolution of 
the absolutely invisible body may be determined. Thus 
the spectrosco[)e, which deals only with light, makes 
paradoxical excursions into the realm of the invisible. 
What secrets may the stars hope to conceal when ques- 
tioned by an instrument of such necromantic power? 

But the spectroscope is not alone in this audacious 
assault upon the strongholds of nature. It has a worthy 
companion and assistant in the photographic film, whose 
efficient aid has been invoked by the astronomer even 
more recently. Pioneer work in celestial photography 
was, indeed, done by Arago in France and by the elder 
Draper in America in 1830, but the results then achieved 
were only tentative, and it was not till forty j^'ears later 
that the method assumed really important proportions. 






lt%0 Dn Henry Draper, at Hastings-oQ-the-Hudson, 
\ the first successful pliotograph of a nebula. Soori 
^, Dr. David Gill, at the Cape observatory; made line 
Ipbotographs of a cornet^ and the flecks of starlight on 
\ plates first suggested the possibilities of this method 
I charting the heavens. 

Since then star-charting with the film has come to 

irtually suiwrsede the old method. A concerted effort is 

e'mg made by astronoinei^s in various parts of the world 

make a completa chart of the heavens, and before 

? close of our century this work vvill be accomplished^ 

fifty or sixty millions of visible stars being placed 

>rd with a degree of accunicy hitherto unapproach- 

ble. Moreover, other millions of stara are brought to 

light by the negative which are too distant or dim to be 

mihle with any telescopic powders yet attained— a fact 

phich wholly discredits all previous inferences £is to the 

ait« of our sidere(d system. Hence, notwithstanding 

lie wondcrfnl instrumental advances of our century, 

Dowledge of the exact form and extent of our universe 

snift more unattainable than it seemed a century ago. 

Tet the new instruments, while leaving so much 

atold^ have revealed some vastly im|K>rtaut secrets of 

smic structure* In particular, they have set at rest 

lu* long-sLinding doubts as to the real structure and 

sition of the raysterious nebula— those hazy masses, 

sly two or ttiree of tliem visible to the nnaided eye, 

rhidi the telescope reveals in almost limitless abundance, 

ottered everywhere among the stars, but grouped in 

tioQlar about the poles of the stellar stream or disk 

Ihich we call the Milky Way, 

sbersi later view\ which held that some at least 
nebuL'B are composed of a *' shining flnid,'' in 


process of condensation to form stars, was generally 
accepted for almost half a century. But in 1844, when 
Lord Rosse's great six-foot reflector — the largest tele- 
scope ever yet constructed — was turned on the nebulae, 
it made this hypothesis seem very doubtful. Just as 
Galileo's first lens had resolved the Milky Way into 
stars, just as Ilerschel had resolved nebulae that resisted 
all instruments but his own, so Lord Rosse's even greater 
reflector resolved others that would not yield to Her- 
schel's largest mirror. It seemed a fair inference that 
with sufficient power, perhaps some day to be attained, 
all nebiiUo would yield, hence that all are in reality 
what Ilorschel had at first thought them — vastly distant 
" island universes," composed of aggregations of stars, 
comparable to our own galactic sj^stem. 

But the inference was wrong; for when the spectro- 
scope was first applied to a nebula in 1864:, by Dr. Hug- 
gins, it clearly showed the spectrum not of discrete stars, 
but of a great mass of glowing gases, hydrogen among 
others. More extended studies showed, it is true, that 
some nebula? give the continuous spectrum of solids or 
liquids, but tlie different types intermingle and grade 
into one another. Also, the closest affinity is shown be- 
tween nebula? and stars. Some nebulae are found to 
contain stars, singly or in groups, in their actual midst; 
certain condensed ** planetary " nebulae are scarcely to 
l>e distinguished from stars of the gaseous type; and re- 
cently the photographic film has shown the presence of 
nebulous matter about stars that to telescopic vision dif- 
fer in no respect from the generality of their fellows in 
the galaxy. Tlie familiar stars of the Pleiades cluster, 
for example, appear on the negative immersed in a hazy 
blur of light. All in all, the accumulated impressions of 






the pliDtogmphic Sim reveal a prodigality of nebulous 
malter in the stellar system not hitherto even eon- 

And so, of course^ all question of '' island universes " 
Iratii&hea, and the nebulie are relegated to their true po- 
pitjon as component parts of the one stellar system — the 
&ne universe — that is open to present human inspection, 
Ud these vast clouds of world-stuff have been found 
by Professor Keeler, of the Lick Observatory, to be 
ating tlirougti spiKse at the starlike speed of from ten 
Hhirty*eight miles per second. 
The linking of nebulas with stars, so clearly evi- 
nced by all these modern observations, is, after all, 
ily tlie scientific corroboration of wliat the elder Pler- 
hcPis later theories affirmed. But the nebula have 
ber affinities not until recently sns})ected ; for tlie 
ctra of some of tbera are practically identical with 
be s|)Betra of certain comets. The conclusion seems 
rrantod that comets are in point of fact minor nebu- 
Hhat are drawn into our system ; or, puttmg itother- 
le, that the telescopic nebulse are simply gigantic dis- 
ftt oomets. 

Following lip the suprising clews thus suggested, Mr< 
r Nyrman Lockyer, of London, has in recent years 
iited what is perphaps the most comprehensive 
"Sfciogunic gness that has ever been attempted. His 
Heofv, known as the ''meteoric hypothesis,'' probably 
at? the same relation to the speculative thought of 
time that the nebular hypothesis of Laplace bore to 
hat of the eighteenth century. Outlined in a few 
^tinb, it is an attempt to explain all the major phe- 
^'mmB, of the universe as dne, directly or indimctly, to 
ivitational impact of such meteoric particles, or 



specks of cosmic dust, as comets are composed of. Neb- 
ulae are vast cometary clouds, with particles more or 
less widely separated, giving off gases through meteoric 
collisions, internal or external, and perhaps glowing also 
with electrical or pliosphorescent light. Gravity eventu- 
ally brings the nebular particles into closer aggregations, 
and increased collisions finally vaporize the entire mass, 
forming planetary nebulae and gjiseous stars. Contin- 
ued condensiition may make the stellar mass hotter and 
more luminous for a time, but eventually leads to its 
li(]uefaction, and ultimate consolidation — the aforetime 
nebuhe becoming in the end a dark or planetary star. 

The exact correlation which Mr. Lockyer attempts to 
point out between successive stages of meteoric con- 
densation and the various types of observed stellar bod- 
ies <loes not meet with unanimous acceptance. Mr. 
lianyard, for example, suggests that the visible nebulsB 
may not be nascent stars, but emanations from stars, 
and that the true pre-stellar nebula} are invisible until 
condensed to stellar proportions. But such details aside, 
tlie broad general hypothesis that all the bodies of the 
universe are, so to speak, of a single species — that neb- 
uhe (including comets), stars of all types, and planets, 
are but varying stages in the lifi* history of a single 
race or type of cosmic organisms— is acce])ted by the 
dominant thought of our time as having the highest war- 
rant of scritmtific probability. 

All this, clearly, is but an amplification of that neba- 
lar hypothesis which, long before the si>ectroscope gave 
us warrant to accurately judge our sidereal neighbors, 
had boldly imagined the development of stars out of 
nebular and of planets out of stars.' But ^Iv. Lockyer^s 
hypothesis does not stop with this. Having traced the 



daFeJopmeiital process froin the nebula to the dark star, 
it sees nu U* abantlon this dark star to its fate by 
^timing, as the original speculatitm assumed, that this 
is a culminating and tinal stage uf cosmic existence* 
Frir the dark star, though its molecular activities have 
come Irj ruhitive stability and impotence, still retains the 
eiKinnouB [>otentialities of molar motion; and clearly, 



where motion is, stasis is not. Sooner or later, in its 
ceaseless flight through space, the dark star must col- 
lide with some other stellar body, as Dr. Croll imagines 
of the dark bodies which his " pre-nebular theory " pos- 
tulates. Such collision may be long delayed ; the dark 
star may be drawn in cometlike circuit about thousands 
of other stellar masses, and be hurtled on thousands of 
diverse parabolic or elliptical orbits, before it chances to 
collide — but that matters not : '^ billions are the units 
in the arithmetic of eternity," and sooner or later, we 
can hardly doubt, a collision must occur. Then without 
question the mutual impact must shatter both colliding 
bodies into vapor, or vapor combined with meteoric 
fragments ; in short, into a veritable nebula, the matrix 
of future worlds. Thus the dark star, which is the last 
term of one series of cosmic changes, becomes the first 
term of another series — at once a post-nebular and a pre- 
nebular condition ; and the nebular hypothesis, thus am- 
plified, ceases to be a mere linear scale, and is rounded 
out to connote an unending series of cosmic cycles, more 
nearly satisfying the imagination. 

In this extended view, nebulae and luminous stars are 
but the infantile and adolescent stages of the life his- 
tory of the cosmic individual; the dark star, its adult 
stage, or time of true virility. Or we may think of the 
shrunken dark star as the germ-cell, the pollen-grain, of 
the cosmic organism. Reduced in size, as becomes a 
germ-cell, to a mere fraction of the nebular body from 
which it sprang, it yet retains within its seemingly non- 
vital body all the potentialities of the original organism, 
and requires only to blend with a fellow-cell to bring a 
new generation into being. Thus may the cosmic race, 
whose aggregate census makes up the stellar universe, 



be peq)etiiated — individaal solar systems, such as ours, 
being bom, and growing old, and dying to live again in 
their descendants, while the universe as a whole main- 
tuns its unified integrity throughout all these internal 
mntations — passing on, it may be, by infinitesimal stages, 
to a colmination hopelessly beyond human compre- 


Ever since Leonardo da Vinci first recognized the 
true character of fossils, there had been here and there 
a man who realized that the earth's rocky crust is one 
gigantic mausoleum. Here and there a dilettante had 
filled his cabinets with relics from this monster crj'pt; 
here and there a philosopher had pondered over them— 
questioning whether perchance they had once been alive, 
or whether they were not mere abortive souvenirs of 
that time when the fertile matrix of the earth was sup- 
posed to have 

''teemed at a birth 

Innumerous living creatures, perfect forms, 

Limbed and fuH-grown." 

Some few of these philosophers — as Robert Hooke and 
Steno in the seventeenth century, and Moro, Leibnitz, 
Buffon, Whitehurst, Werner, Button, and others in the 
eighteenth — had vaguely conceived the importance of 
fossils as records of the earth's ancient history, but the 
wisest of them no more suspected the full import of the 
story written in the rocks than the average stroller in a 
modem museum suspects the meaning of the hieroglyphs 
on the case of a mummy. 



It wiis not tliat the rudiments of this story are so very 

I It) decipher— though in truth they are hani enough 

Ut father that the men who made the attempt had all 

abng viewed the suliject through an atmosphere of pre* 

oonception^ which gJive ii distorted image. Before this 

[linage could be corrected it was necessary that a man 

, «hoQld appear who could see without prejudice, and 

apply sound common-sense to what he saw. And such 

, a man d'n\ ap|iear towards the close of the century in the 

[person of Wilhum Smith, the English surveyor* He 

[was a self*Uught man, and perhaps the more indepen* 

Ident for that, and he had the gift, besides his sharp eyes 

receptive mind, of a most tenacious memory. By 

ciisnig tliese faculties, rare as they are homely^ he 

the way to a science which was destined, in its 

liter dt*ve!opments, to shake tlie structure of estabhsbed 

jlimni^ht to its foundations. 

Little enough did William Smith snspect^ however, 

hi any nuch dire cotiseqnences were to come of his act 

^hm Ik* firat began noticing the fossil shells that here 

ml there are to be found in the stratificil rocks and soils 

pf the regions over which his surveyor's duties led him, 

W» indeed, was them anything of such apparent revo- 

jBtionary character in the facts which he unearthed ; 

et in tb«ir implications these facts were the most dis- 

oncerting of any that had been revealed since the day 

bf Copernicus and Galileo, In its bald essence Smith's 

piscfivery wuh simply this; that the fossils in the rocks, 

stead of being scattered haphazard, are arranged in 

fegular syjitcms, so that any gi^^en stratum of rock is 

lied by its fossil pnpidation; and that the order of 

Bion of such grou[JS of fossils is always the same in 

BT"ter!icol series of strata in which they occur. That 



is to say, if fossil A underlies fossil B in any given region, 
it never overlies it in any other series; though a kind of 
fossils found in one set of strata rafiy be quite omitted 
in another. Moreover, a fossil once having disappeared 
never reappears in any later stratum. 

From these novel facts Smith drew the common-sense 
inference that the earth had hsid successive populations 
of creatures, each of which in its turn had become extinct. 
He partially verified this inference by comparing the 
fossil shells with existing species of similar orders, and 
found tlhat such as occur in older strata of the rocks had 
no counterparts among living species. But on the whole, 
being eminently a practical man. Smith troubled himself 
but little about the inferences that might be drawn from 
his facts. He was chiefly concerned in using the key he 
had discovered as an aid to the construction of the first 
geological map of England ever attempted, and he left 
to others the untangling of any snarls of thought that 
might seem to arise from his discovery of the succession 
of varying forms of life on the globe. 

He disseminated his views far and wide, however, in 
the course of his journey ings — quite disregarding the 
fact that peripatetics went out of fashion when the 
printing-press came in — and by the beginning of our 
century he had begun to have a following among the 
geologists of England. It must not for a moment be 
supposed, however, that his contention regarding the 
succession of strata met with immediate or general ac- 
ceptance. On the contrary, it was most bitterly an- 
tagonized. For a long generation after the discovery 
was made, the generality of men, prone as always to 
strain at gnats and swallow camels, preferred to believe 
that the fossils, instead of being deposited in successive 



agQ8« had been swept all at once into their present po§!> 

^oos by the current of a mighty liood--and that Hood, 

'needless to say, the Noacljiaa deluge. Just ho^v the 

i numberless successive strata could have been laid down 
n orderly sequence to the depth of several mil^ in one 
;uch fell aitaelysm was indeed puzzling, especially after 
t came to be admitted that ibo heaviest fossils were not 
uuncl ahvaj's at the bottom ; but to doubt that this had 
Deen ilone in some way was rank heresy in the early 
days of our centurv. 

Bill once discovered, William Smith's unique facts as 

the succession of forms in the rocks would not down. 

mere was one most viUU point, however, regarding 

rbich the inferences that seem to follow from these 

facts needed vcriliaation— the question, namely, whether 

!ie disapiiearance of a fauna from the register in the 

[TTK^ks really implies the extinction of that fauna- Every- 

[thing really de|>ended upon the answer to that question, 

|iml mme but an accomplished naturalist could answer it 

I with authority. Fortunately the most authoritative nat- 

aralist of the time, Georges Ciivier, took the question in 

band'— not, indeeil, with the idea of verifying any sug- 

I gestion of Smith's, but in the course of his own original 

«tmiies— at the very beginning of the century, when 

Smith's views were attracting general attention, 

Cuvier and Smith were exact contemporaries, both 
mm having been born in 1769, that '* fertile year" 
gave the world also Chateaubriand, Von Hum- 
Wellington, ana Napoleon, But the Fmnch nat- 
t wag of very different antecedents from the Eng- 




^^^^^^^^^^M ^^m ^^^^H 


ish siirveyofp He was brilliantly educated, had early 
jaintMl recotfiiition as :i scientist, and wliile yet a young 
nrin hud come Ui h*:* known astiie furcuio.nt comparative 
inatomiat of It is time!. It was the anatomical studies. 
Imt lofl fuin int*j tlie realm nf fossils. Some hones dug 
>ut of tlie rocks by workmen in n quarry were Ij rough t 
,o his notice* and at onee Im trained eye toiti him that 
,hey were different from anylJimg ho Jiad seen before. 

L. _. _* 

p ^ni 

^niE cKxruRV^s progress in paleontology 

{ilherto such bones, when not entirely ignoroJ, had 
;for the most partaacribed to giants of former days, 
re?eil to fallen angels. Cuvier soon showed that 
either giants nor angels were in question, but ele* 
|»haula of an nnrecognizuil species* Continuing his 
Rmiies, particularly with material gathered from gyp- 
U near Paris, he had accumulated, by the begin- 
nur century, bone^i of about twenty live species 
D[ AOtmalii tijat he believed to be different from any now 
on the globo. 

fame of these studies went abroad, and presently 
U«Qes [Miured iu hum all sides, and Cuvier's con- 
rtkiionft that t^xtinct forms of animals are represented 
|r ' "i^sjiils was suBtained by the evidence of many 
. ._ , 1 anonuilous forms, some of them of gigantic 
l¥iii. In ll^l^J the fumong Os&emenU ^€?m/tr^j describing 
[liiRse novel objectii, was published, and vertebrate paleon- 
"^'MTUj a science. Among other things of great 
rest tlie liook coutaiued the first authorita- 
t*ri» desenption of the hairy ele[ihant, named by Cuvier 
I ►th. the remains of which hud been found 
11 a mass of ice in Siberia in 1802, so wonder- 
fully preserved thiit the dogs of the Tungusian tisher- 
V ate its flesh. Bones of the same sj)ecies 
i. i.rund in Siboria several years before by the 
I fiatumli^il Pallas, who had also found the carcass of a 
rbinocitrod there, frozen in a mud hank ; but no one then 
mpixted that these were members of an extinct popula- 
lioo—they w*ere supposed to be merely trans].>or ted relics 

d lltfi fluotl 

CllvkT,on the otlior hand, asserted that these and the 
^4W creatures he described had lived and dted in the 
«g?iwi where their remains were found, and that most 



of them have no living representatives upon the globe* 
This^ to be sure, was nothing more than William Smith 
had tried all along to establish regarding lower forms of 
life ; but great monsters appeal to the imagination In a 


way quite beyond the power of mere shells ; so the an* 
noimeemenfc of Cuvier's discoveries aroused the interest 
of the entire world, and the Oifj^enumU Ffmihf^ was 
accorded a popular reception seldom given a work of 
technical science— a reception in which the enthusiastic 
approval of progressive geologists wa^ mingled with the i 
bitter protests of the conservatives* 


In Eogland the inksr^t thus aroused was sent to ferer- 

it ID 1821 by the discovery of abundant beds of fossil 

^nt's in the stalagmite-covered floor of a cave at Kirk- 

le, Yorkshire, which went to show that England tou 

d ouoe iiad her share of gigantic beasts. Dr. Bnck- 

, tbe ineuriibent of the recently estabhshed chair of 

at Oxfordj and the most authoritative English 

ologUt of the day^took these finds hi hand and showed 

It Uie bones belonged to a number of species, including 

I alien formsaselejihants, rhinoceroses, bipi>opotanii, 

nil byonas. lie maintained that all of these creatures 

ul aetaiilly lived in Britain, and that the caves in which 

bones were found had been the dens of hyenas, 

be claim was hotly disputed as a matter of course- 

lAaliite a« 1827 books were publislied denouncing Buck- 

[Und, I>octor of Divinity though he was, as one who had 

I in an ** unhallowed cause," and reiterating the old 

liiAt tbe fossils were only remains of tropical species 

^Tadied ihitber by the deluge. That they were found 

10 njhil rocks or in caves offered no difficulty, at least 

Hijt to the fertile imagination of Granville Penn, the 

Wer of the conservatives, who clung to the old idea 

l<«IWiiodwanl andCattcut that the deluged ha dissolved 

'ike entire cruist of tbe earth to a paste, into which tlie 

wUw BOW called fossils ha*i settletL The caves, said 

Hi. Penn, are merely the result of gases given off by 

li« eamasses during decom posit ion —great air-bubbles, 

*> to speak, in the pivsty m.iss becoming caverns when 

tte iraterH rectHfetl and the paste hardened to rocky 


Boi these and such like fanciful views were doomed 

I «*Bii in tbe da\" of tlieir utterance* Already in 1S23 utfier 

PgWic crealunes, christened ichthyosaurus and plesio- 



saurus by Con j bear©, had been found in deeper strata uf 
Britisb rocks; and these, as well as other monstei's whose 
remains were unearthed in vurious parts of the world, 
bore such strange forms that even the most sceptical 
could scarcely hope to find their counterparts among 
living creatures. Cuvier's contention that all the larger 


vertebrates of the existing age are known to naturalists 
was borne out by recent explorations, and there seemed 
no refuge from the conclusion that the fossil records 
tell of populations actually extinct. But if this were 



adiaitteiU then Smith's view that there have been suc- 
cessive rotations uf popuktioii could no longer be denied. 
Nor could it be in doubt that the successive faunas, whose 
individual remains have been pr*eserved in niyriads, rep- 
resenting extinct species by tlumsunds and tens of thou- 
s^inds, must have requii'ed vast periods of time for the 
productioit and growth of their countless generations. 

As these facts came to be generally knowu, and as it 
came to be umlerstotHl in addition that the very matrix 
of the rock in which fossils are embcddetl is in many 
cases itself one gigantic fossil, CMm[)osed of tiie remairm 
of niieruseopic forms of life, common-sense, which, after 
all, is tlio Hnal tribunal, came to the aid of belabored 
scieoce. It wius concedetl that the only tenable inter- 
pretation of the record in the nx?ka is that numerous 
|>opulatiDns of ci^eatures, distinct from one another and 
from present forms, have risen and passed away; and 
that the geologic ages in which these creatures livetl 
were of jnctjnceivable length. The rank and file carae 
ibas, with lh<! aid of fossil records, to realize the import 
of an idiia which James Huttou, and here an<l thert^ 
another tliinker, had conceived with the swift intuition 
of genius long before the science of paleontology came 
into existence. The Ilnttonian proposition that time is 
long bml l>*3en abundantly estal)]ished, and by about the 
dose of tile first thirti of our century geologists had 
''^L'nn to speak of "ages'* and "untold reons of time'' 
villi a familiarity which their predecessors had reserved 
for davs and decades. 



i And now a new question pressed for solution. If the 
eJiith hftB been inhabited by successive populations of 
a 97 


beings now extinct, how have all these creatures been 
destroyed I That question, however, seemed to present 
no difficulties. It was answered out of hand by the 
application of an old idea. All down the centuries, 
whatever their varying phases of cosmogonic thought, 
there had been ever present the idea that past times 
were not as recent times; that in remote epochs the 
earth had been the scene of awful catastrophes that 
have no parallel in "these degenerate days." Naturally 
enough this thought, embalmed in every cosmogonic 
speculation of whatever origin, was appealed to in 
explanation of the destruction of these hitherto unim- 
agined hosts, which now, thanks to science, rose from 
their abysmal slumber as incontestable, but also as silent 
and as thought -provocative as Sphinx or pyramid. 
These ancient hosts, it was said, have been exterminated 
at intervals of odd millions of years by the recurrence 
of catastrophes of which the Mosaic deluge is the latest, 
but perhaps not the last. 

This explanation had fullest warrant of scientific au- 
thority. Cuvier had prefaced Iiis classical work with a 
speculative disquisition whose very title {DUcours sur les 
Revolutionn du Ghhe) is ominous of catastrophism, and 
whose text fully sustains the augury. And Buckland, 
Cuvier's foremost follower across the Channel, had gone 
even beyond the master, naming the work in which he 
described the Kirkdale fossils, Reliqitm DUuviance^ or 
Proofs of a Univerml Deluge. 

Both these authorities supposed the creatures whose 
remains they studied to have perished suddenly in the 
mighty flood w^hose awful current, as they supposed, 
gouged out the modern valleys, and hurled great blocks 
of granite broadcast over the land. And they invoked 



t^imil&r floods for the exterminatioQ of previous popuia- 


" It lii true these scientific citations had met with only 

elied approval at the time of their utterance, because 
the conservative majority of mankind did not con- 
that there ha<l been a plunihty of popnlations or 
ytions; hut now that the belief in past geologic 
ages had cetisetl lo be a lieresj^ the recurring catasti^o- 
plied of the great paleontologists were accepted with 
cclauiL For the moment science and tradition were at 
Emet&nd there ivas a truce to controversy, except indeed 
those outlying skirmish-lines of thought whither news 
from headquarters does not permeate till it has become 
mcient history at its source. 
The truce, however, was not for long. Hai^dly had 
ontemporary thought begun to adjust itself to the^ 
Lt>nception of past ages of incomprehensible extent, 
I each terminated hy a catastrophe of the Noachian 
type, wlien a man appeared who made the utterly be- 
^tfilderinir assertion tbat the geological record, instead 
of proving numerous catastrophic revolutions in the 
earthV past history, gives no warrant to the pieten- 
ftona of any universal catastrophe whatever, near or 

B Tlii* iiHrnoclast was Charles Lyell, the Scotchman, who 
■ wjisttKin to be famous as the greatest geologist of his 
tiinfli As a young man he had become imbued with the 
- furw iif the Iluttonian proposition, that present causes 
Htm OHO with those that proiluced the past changes of 
» tJif giobe, and he carried that idea to what he conceived 
*^ he it* logical conclusion. To his mind this excluded 
IfctUiofight of catastrophic changes in either inorganic 
•rofginic worlds. 




But to deny catastrophism was to suggest a revolu- 
tion in current thought. Needless to say such revolu- 
tion could not be effected without a long contest. For 
a score of years the matter was argued pro and con, 
often with most unscientific ardor. A mere outline of 
the controverey would fill a volume ; yet the essential 
facts with which Lyell at last established his proposi- 
tion, in its bearings on the organic world, may be epito- 
mized in few words. The evidence which seems to tell 
of past revolutions is the apparently sudden change of 
fossils from one stratum to another of the rocks. Bat 
Lj^ell showed that this change is not always com- 
plete. Some species live on from one alleged epoch 
into the next. By no means all the contemporarieB 
of the mammoth are extinct, and numerous marine 
forms vastly more ancient still have living represent- 

Moreover, the blanks between strata in any particular 
vertical series are amply filled in with records in the 
form of thick strata in some geographically distant 
series. For example, in some regions Silurian rocks are 
directly overlaid by the coal measures; but elsewhere 
this sudden break is filled in with the Devonian rocks 
that tell of a great " age of fishes." So commonly are 
breaks in the strata in one region filled up in another, 
that we are forced to conclude that the record shown 
by any single vertical series is of but local significance — 
telling, perhaps, of a time when that particular sea-bed 
oscillated above the water-line, aiid so ceased to receive 
sediment until some future age when it had oscillated 
back again. But if this be the real significance of the 
seemingly sudden change from stratum to stratum, then 
the whole case for catastrophism is hopelessly lost ; for 



leb breaks in the strata furrnsli the only BUggestion 
>Iog^- can offer of sudden aod catastrophic changes of 
ide estifOL 

When evidence from widely separated regions is 
gathered, ^d Lyeli, it becomes clear that the niimber- 
■i i ^ I bat have been externiinated in the past 


Wve died out one by ojio, jtmt ns indi viihials of a species 

,not in vtiEi shoals; if xvhole |W|>uliitions have passed 

ray. it has bf^en not by instantnnerjus extemii nation, 

It by the elimination of a species now horn, now there, 

luch as one generation succeeds nnother in the hfe his- 

>ry of any single species. The causes which have 

cmg^ht about such gradual exterminations, and in the 

•-■i* uf asrfs hare resnUed in rotations of popula- 

• the same natural causes that are still in opera* 

Species haTe died out in the past as they are 

fing out in the present, under influence of changed 


THE sTouv OF mnp:tp:entii-century science 

surroundings, such as altered climate, or the migration 
into their territory of more masterful species. Past and 
present causes are one — natural law is changeless and 

Such was the essence of the Huttonian doctrine, which 
Lyell adopted and extended, and with which his name 
will always be associated. Largely through his efforts, 
though of course not without the aid of many other 
workers after a time, this idea — the doctrine of uniform- 
itarianism, it came to be called — became the accepted 
dogma of the geologic world not long after the middle 
of our century. The catastrophists, after clinging madly 
to their phantom for a generation, at last capitulated 
without terms: the old heresy became the new ortho- 
doxy, and tlie way was paved for a fresh controversy. 


The fresh controversy followed quite as a matter of 
course. For the idea of catastrophism had not con- 
cerned the destruction of species merely, but their intro- 
duction as well. If whole faunas had been extirpated 
suddenly, new faunas had presumably been introduced 
with ecjual suddenness by sj)ecial creation ; but if species 
die out gradually, the introduction of new species may 
be presumed to be correspondin^^ly gradual. Then may 
not the new species of a later geological epoch be the 
modified lineal descendants of the extinct population of 
an earlier epoch? 

The idea that such might be the case was not new. 
It had been suggested when fossils first began to attract 
conspicuous attention; and such sagacious thinkera as 
Euffon and Eant and Goethe and Erasmus Darwin had 


TBI CK^riM^ 


Imq dopoBi lo aeetft if a the doaag dajs of the 
isrj. Tben^ m ISOd, it had beea coo* 
for bf ooe of the euij worbers ia systematic 
r^ JeftA Bftpbsle lamarck, who had studied 
Ibft Iksil fhells mbtmk Fkm whOe Curier studied the 
T^stebtaletf aod wbo hid been led by these studies to 
medafe that thei^ had been not merely a mtatioii bm 
« pfogRBBOQ of life on the globe. He foaod the fo^il 
•htih the fonls of t]iferlebimte% as he himself bad 
chMeDed them — ttt deeper strata than Curier s verte- 
Intei; and be beliered that there had beeu loug age^ 


armAcaTVi^ o« at^sortso aRievocEHOfl, from socftsbrn wroMisva 

wlien no higher forms than these were in existence, and 
that in successiire ages iishes, and then reptiles, had Keen 
j^the highest of anfmato creatures, liefore inamtnals, in- 
Heading miin, appeared* I^okin^ beynnd the pale of his 
^^he facta, as genius sometimes w ill, he had insisted thut 
Bfflpir progressiire popalatioits had developed one from 


another, under influence of changed surroundings, in 

unbroken series. 

Of course such a thought as tbis was hopelessly mis- 
placed in a generation that doubted tbe existence of ex- 
tinct species, and hardly less so in the ge nenition tbat 
accepted ca last roph ism; but it had been kept alive by 
liere and there au advocate like Geoffrey Bt.41tlaire, 
and now the banisliuient of catEvstrophism opened the 
way for its more respectful consideration, Resj>ectful 
consideration wtts given it by Lyell in each recurring 
edition of his Principle^^ but such consideration led to 
its unqualilietl rejection. In its place Lyell put forward 
a modi lied hypothesis of special creatioti. He assumed 
that from time to time, as the extirpation of a species 
had left room, so to speak, for a new si>eoies, such new ■ 
s})ecies had been created de novo * and he supposed that 
sucli intermittent, spasmodic impulses of creation mani- 
fest themseU'cs nowadays quite as fiNsquently as at Rny 
time in the past He did not say in so many words I 
that no one need be surprised to -day were he to see a 
new species of deer, f<:>r example, come up out of the 
ground before hi 171, " pawing to get free,-' like Milton^s 
lion, hut his theory implietl as much* And that theory, 
let it be noted, was not the theory of Lyell alone, but 
of nearlv all his associates in the Molo^ic world. There 
is perhaps no other fact that will bring home to one so A 
vividly the advance in thought of our own generation ' 
as the recollection that so crude, so almost unthinkable a 
conception could have been the current doctrine of sci- 
ence less than half a century ago. 

This theory of special creation, moreoverj exclnded 
the current doctrine of uniformitarianism as night ex- 
cludes day, though most thinkers of the time did not 




em to be aware of tb© incompatibLlity of the two 
It may be tloubted whether even Lyell bimself 
If ally realised iL if lie didj he saw no escape from tlie 
diteraum, for it seemed to Iiub thut the record in the 
cb clearly litspnjvetl the alternative Laituirckian hy- 
,\ivm. And ill most with one accurd the paleontolo- 
ftsUof the time sustained the verdict. Ovveu> Agassiz, 
ilconer, liarnuide, Pictet^ Forbes, repudiated the idea 
uinjuiililiedly as tlieir great predecessor Cuvier hud 
bm* ill the earlier generation. Some of them did, in- 
Bitcome to believe that there is evidence of a pro- 
siv'e ilitvelopuufnt of life in the successive ages, but 
graded series of fossils had been discovered as 
hM give countenance to tlie idea that one species had 
fer \)mn transformed int«j another. And to nearly 
very one this objection seeme<l insuperable. 
^^ But now in 18511 appeai'ed a book wbich^ though not 
^■e&litig primarily w*itli paleontology, yet contained a 
^■baptitr that revenle<] the geological record in an alto- 
^fc^her new light. The book was Charles Darwin's Orl- 
^^n (f Sj^^^ies^ the chapter that wonderful citation of 
^lhL>'-Imj)*.Tfections of the Geological Ilecord/' In this 
ejHjcbniaking chapter Darwin shows what conditions 
U^st prevail in any given phice in order that fossils 
bail be formed, how unusual such conditions are, and 
Eprohahle it is that fossils once embedded in sedi* 
Lofasea-beil will be destroyed by metamorphosis 
pf llie rockfk, or by ilenudation when the strata are 
}ve the water-ltM'el. Add to this the fact that 
ll torritories of the earth have been explored 
pcally, he says, and it becomes clear that the 
itologieal record as ive now possess it shows but a 
I fiHgment of the paat history of organisms on the 



earth, it is a history *^ imperfectly kept and written in 
a changing dialect. Of this history w© possess the last 
\^olume alone, relating only to two or three countries, 
Of this volume only here and there a short chapter hi 


been preserved, and of each page on 13^ here and there a] 
few lines," For a paleontologist to dogmatize from ' 
such a record would be as rash, he thinks, as '* for a nat- 
uratlst to land for five minutes on a barren point of 



Lustralia and then discuss the number and range of its 

Tills ciUition of observationSj which when once point- 
id out seeuietl almost seifevridentj eame as a revelation 
ihe geological world. In the clariiied view now pos- 
'I facts took on a new meaning. It was I'ccuUed 
1 ' ler bad been < obliged to establish a new order 
»r wme of the firnt fossil creatures he examined, and 
iliuckland had noted that the nondescript forms were 
iieiliate in structure between allied existing ordei-s* 
lore rveentiy such intermediate forms liad been disco v- 
over aud over; so that, to name but one example, 
had bien ahle^ with the aid of extinct species, to 
jlve by gradations the ap|>arently wide interval 
?iwi^n ihe pig and the cameL'* Owen, moreover, had 
Ltn li^<1 to speak repeatedly of the *' generalized forms'' 
extinct animals, and Agassiz had called them ^'syn- 
belie or prophetic types,'* those terms clearly implying 
[tfuii anch forms are in fact intermediate or connecting 
iks," Darwin himself had shown some years before 
tko fossil aninmls uf any continent are closely re- 
to the existing animals of that continent— eden- 
pneilominati ng, for example, in South America, 
iar%y|»iji!s in Austndia. Many observers had noted 
recent i^trata everywhere show a fossil fauna more 
iy Hko the existing one than do more ancient strata; 
! that foi^sits from any two consecutive strata are far 
^Mnt* closely related to each other than are the fossils 
two remote formations, the fauna of each geological 
latton Iming, indeful, in a wide view, intermediate 
tween preceding amJ succeeding faunas. 
So sugjgestive were all these observations that Lyell, 
the admitted leader of the geological world, after read- 



ing Darwin's citations, felt able to drop his own crass 
explanation of the introduction of species, and adopt 
the transmutation hypothesis, thus rounding out the 
doctrine of uniformitarianism to the full proportions in 
which Lamarck had conceived it half a century before. 
Not all paleontologists could follow him at once, of 
course ; tlie proof was not j'^et sufficiently demonstative 
for that ; but all were shaken in the seeming security 
of their former position, which is always a necessary 
stage in the progress of thought. And popular inter- 
est in the matter was raised to white heat in a twin- 

So, for tlie tliird time in this first century of its ex- 
istence, paleontology was called upon to play a leading 
role in a controvei'sy whose interest extended far be- 
yond the bounds of staid truth-seeking science. And 
the controversy waged over the age of the earth had 
not been more bitter, that over catastrophism not more 
acrimonious, than that which now raged over the ques- 
tion of the transmutation of species. The question had 
implications far beyond the bounds of paleontology, of 
course. The main evidence yet presented 'had been 
drawn from quite other fields, but by common consent 
the record in the rocks might furnish a crucial test of 
the truth or falsity of the hypothesis. " He who rejects 
this view of the imperfections of the geological rec- 
ord," said Darwin, " will rightly reject the whole 

With something more than mere scientific zeal, there- 
fore, paleontologists turned anew to the records in the 
rocks, to inquire what evidence in proof or refutation 
might be found in unread pages of the " great stone 
book." And as might have been expected, many minds 


\mng thus prepared to receive new eTideoce^ auch evi- 
dence was not long wlthBeld. 

I ut the moment of Darwin's writing a new 
'^^instructive clnipter of the geologic record was 
presented to the puljlic^ — a chapter which for the 
Hnit time brought tuaii into the story. In 1859 Dr, 
jfftlconer, the distiilguisheil British paleontologist, made 
1 visit to Abbeville, in tlic valley of the Soiimio, incited 
by rejTorts that for a decade before had been sent out 
from thei-C! by U. Boucher des Perthes, Tliese reports 
liiwi to do with the alleged finJing of Hint inipleraents, 
dearly the work of man, m undisturbed gravel lieds, in 
»e midst of fossil remains of the mammoth and other 
tinct animals. Dr. Falconer was so much impressed 
irilh what b© saw that he iir|i:ed his countrymen Pro* 
or Prestwicli to go to Abbeville and thoroughly in* 
V«»tigat** the subject. Professor Prestwich complied, 
^th th*^ C4>ltahoration of Air, John Evans, and the re- 
ttrt which these paleontoh agists made of their investi- 
^tioa brought the subject of the very significant human 
ills at Abl>eviile prominently Jxjfore the public; 
^hemts the publications of the original disco verer^ 
oacher des Perthes, bearing date of 1847, had been al- 
tier ignored. A new aspect was thus given to the 
fit controversy. 
A« Dr. Falconer remarked, geology wm now passing 
^lin^njjh the same ordeal that astronumy passed in the 
kg^ 'if (laliteo. But the times wen3 changed since the 
at nhtm the atithor of the Diatogues was humbled be* 
the Congregation of the Index, and now no Index 



Prohibitorum could avail to hide from eager humaa 
eyes such pages of the geologic story as Nature herself 
had spared. Eager searchei's wei'e turtiing the leaves 
with renewed zeal everywhere, and with no small meas- 
ure of success. In particular, interest attached just at 
this time to a human skull which Dr. Fublrott had dis- 

FROrrOKOttlPPUS, the ancestral FOUH'TOKD nORSK 
Height ftt akouldcr, 16 itLehvs. Fruin the TJ1g Huro ^^rntiiiUltUi 

covered in a cave ^ Neanderthal two or three yeara b&^ 
fore — a cranium which has ever since been famous as 
the Neanderthal slcuU, the type specimen of what mod- 1 
ern zoologists are disposed to regard as a distinct spe-j 
cies of man. Homo nmn*Ierthalenm^. Like others of the 
same type since discovered at Spy, it is singularly Simian 
in character — low-arched, with receding forehead andfl 
enormous protuberant eyebrows. When it was first ex- 
hibited to the scientists at Berlin by Dr, Fuhlrott, in 
1857, its human character was doubted by some of the 
witnesses j of that, however, there is no present question. 



This interefiting find served to recall with f i*esh signifl- 

Icancesome observations that had been made in France 

find Belgium a long generation earlier, but whose bear- 

^ings had hitherto been ignored. In 1S26 MM. Tournal 

nd Cbristol had made indei^endent discoveries of what 

httjr believed to be human fossils io the caves of the 

onth of France; and in liy'27 Dn Schnierling had 

build iu the cave of Eiigis, in Westphalia, fossil bones 

f erua greater tsigniBcance. Schinerling's explorations 

a<l i)een made with the utmost care and patieDce. At 

hj^i ha had found hninan bones, incluilmg skulls^ in- 

termiTigIe<l with those of extinct mamraals of the mara- 

moih [terioti in a way that left no doubt in his mind 

''■ ' ril! datetl from the same geological etx>ch. He had 

iH-cl a full at*couut of his discoveries in an elaborate 

mriQogniph iHSued in 1833. 

But at Uiat time, as it chanced, human fossils were un* 

Mf a ton as effectual as any ever pronounced by canonical 

Hbx, ihougli of far different origin. The oracular voice 

^f Cuvier had declareti against the authenticity of all hu^ 

m fossils. Some of the bones brought him for exam- 

ilinu i\w great anattniiist had pettishly pitclietJ out of 

llto tvindow, deckring them tit only for a cemetery, and 

*' ' ' * ^'If'd the matter for a generation : the evi- 

(1 by lesser workers could avail nothing 

LJnsl the decision rendered at the Delphi of Science. 

on ban, scientific or canonioiil, can long resist the 

inative jiower of a fact, and so now, after three 

dMsdo of suppression, the truth which Cuvier had 

iried beneath the weight of his ridicule burst its 

Bfls, and fossil man stood revealetl^ if not as a flesh 

Dd blrM>cl, at leajt as a skeletal entity. 

Th<j reception now accorded our prehistoric ancestor 



by the progressive portion of the scientific world amouuli 
eel to an ovation ; but the unscientific masses, on tbe otbc^ 
hand, notwithstanding their usnal fondness for tracing 
remote genealogiesj still gave the men of Engis and 

pBOPEaaaii o. c. MAjiHii 

Neanderthal the cold shoulder. Nor were all of the geol 
oghtB qtiite agreed that the conteraporaneity of these hn-l 
man fossils with Uie animals whose remains bad been I 
mingled with tlvem bad been fully estiihlished, Thol 
bare |)4>ssibiUty tliat tlie bones of man and of animalij 



ihal loog preceded hini had been swept together into 
ibe cavea in successive ages, and in some mysterious 
way interiuitigled therej was clung to by the conserva- 

Ki as a kst refuge. But even tbis small measure of 
rily wm soon to be denied them, for in 1805 two as- 
%tAid workers, M. Edouard I^artet and Mr. Henry 
Christy, in exploring tlje caves cif Dordogne, unearthed 
a bit of evidence against wbici) no such objection could 
■^ urged. This momentous exhibit was a bit of ivory^ 
BBlragmcnt uf the tusk of a nuLiamothj on which was 
sttrutched a nido but unmistakable outline portrait of 
tbi* mammoth itself. If all the evidence as to man's 
tiquity before presented was suggestive merely, Iiei*e 
\^l wi\s ili^niMnstnition ; for the cave-d welling man 
could not well have drawn the picture of the mammoth 
unless he had seen that animal, and to admit that man 
and the mammoth had been conteiuporaries was to con- 
cde the entire case. Ro soon, therefore, as the full im- 
rt of this most instructive work of art came to be 
ilixed, scepticism as to man^s antiquity was silenced 
Tali lime to come. 

hi the generation that has elapsed since the first draw- 

ig of the C4ive-dweller artist was discovered, evidences 

the witle-spread existence of man in an early eprich 

have multiptied indeiinitely, and to-day the paleont^ilo- 

Ifist traces the history of our race back beyond the iron 

I hronz«: ages, through a neolithic or polished -stone 

to a paleolithic or rough-stone age, with confidence 

of unequivocal knowledge. And he looks confi- 

ntly Uylhe future explorer of the earth's fossil records 

^m^und the iiistory l>*iek into vastly more remote 

Sf for it is h'ttle doubted that paleolithic man, the 

icieiU of our recogni/*ed progenitors, is a modern 



compared to those generations that represented the real 
childhood of our race. 


Coincidently with the discovery of these highly sug- 
gestive pages of the geologic story, other still more in- 
structive chapters were being brought to light in Amer- 
ica. It was found that in the Rocky Mountain region, 
in strata found in ancient lake beds, records of the 
tertiary period, or age of mammals, had been made and 
preserved with fulness not approached in any other 
region hitherto geologically exfAored. These records 
were made known mainly b}*^ Professors Joseph Leidy, 
O. C. Marsh, and E. D. Cope, working independently, 
and more recently by numerous younger paleontolo- 

The profusion of vertebrate remains thus brought to 
light quite beggars all previous exhibits in point of mere 
numbers. Professor Marsh, for example, who was first 
in tlie field, found 300 new tertiary species between the 
veal's ISTo and 1S70. Meanwhile, in cretaceous strata, 
he unearthed remains of about 200 birds with teeth, 600 
pterodactyls, or Hying dragons, some with a spread of 
win<j:s of twenty-live feet, and 1500 mosiisaurs of the 
sea-ser|)ent type, some of them sixty feet or more in 
length. In a single bed of Jurassic rock, not larger 
than a good-sized lecture-room, he found the remains 
of 100 individuals of mammals, representing twenty 
species and nine genera ; while beds of the same age 
have yielded 30o reptiles, varying from the size of a 
rabbit to sixtv or eiofhtv feet in lenffth. 

But the chief interest of these fossils from the West is 








not their number but their nature ; for among them are 
numerous illustrations of just such intermediate typeBof 
organisms as must have existed in the past if the suc- 
cession of life on the globe has been an unbroken lineal 
succession* Here are reptiles with bat-like vvings^ and 
otliers with liird^like i>elves and legs adapted ft>r bipedal 
locomotion* Hero are birds with teeth and other rep- 
tilian characters. In short, what with reptilinn birds 
and bird-Hkc refitiles, the gap between moilern reptiles 
imtl btnls is quite liridged over* In a similar way, vaH- 
cius diverse niamtualian forms, as the tapir, the rhinoc- 
eros, and the horse, are linked together by fossil pro- 
genitors. And most imiKirtant of all, Professor Jfai^h 
\ins discoveral a series of mammalian remains^ occurring 
in successive geological epochs, which are held to repi^- 
sent beyond cavil the actual line of descent of the modern 
]*f)rse; tracing the lineage (jf our one-toed species back 
throogh two and three toed forms, to an ancestor in the 
ecx^ene or early tertiary that had four functional toes 
and the rnditnent of a fifth. 

Those and such like revelations have come to light in 
nur own time; are, indeed, still being disclosed. Need- 
la^ to say, no Index of any sort now attempts to con* 
oaal them; yet something has been accomplished towards 
the same end by the publication of the discoveries in 
Smithsonian bulletins, and in technical memoirs of 
government surveys. Fortunately, however, the results 
have been rescued from that partial <diUvion by such 
interpreters as Professors Huxley and Co|3e, so the un- 
leienlinc public has been allowed to gain at least an 
inkling of the wonderful progress of paleontology in our 

The writings of Huxley in particular epitomize the 



recoixi. In 1862 ho admittetl candidly that the p 
tological record as then kiiown, so far as it bears on the 
doctrine of progr*3Ssive development, negatives that doc-fl 
trine. In 18 7h he was able to ** soften somewhat the 4! 
Brutus-like severity" of his furmer verdict, and to assert^ 
that the results of recent researches seem ^' to leave 
clear balance in favor of the doctrine of the evolution of 
living forms one from another.*' Six years later, when 
reviewing the work of Marsh in America and of Gaudry 
in Pikenni, he declared that, ** on the evidence of paleon- 
tology, the evolution of many existing forms of animal 
life from their pretlecessors is no longer an hypothesrsj 

frt J 



but an historical fact." In 1881 he asserted that th 
evidence gathered in the previous deeatle had been 
imequi vocal that, had the transmutation hypothesis not 
existed. *'the paleontologist would liave had to invent it.'" 
Since then the del vers after fos*^ils have piled proof 
on proof in bewildering profusion. The fossil beds in 




the '*bad lauds'* of western America seem itiexliauBtible. 
And in the Connecticut Eiver Valley near relatives of 
I be great reptiles vrhich Professor Marsh and others 
hare found in such profusion in the West left their 
iraeks on the mud flats — since turned to sandstone; and 
a few gkeletons also have been found. The hodios of a 
nM» of greal reptile that were tbe lords of creation of 
ibetr day hare been di^ipated to their elements, while 
the chance indentations of their feet as they raced along 
the shores^ mere footprints ou the sands, have been pre- 
serfed among the most impensimble of the memory- 
tablets of the world* 

Of the other vertebrate fossils that have been found 
in the eastern portions of America, among the must 
ahundafit and interesting are the skeletons of masto- 
ilnns. Of these one of the largest and mosit complete is 
that which was unearthed in the bed of a drained lake 
near New burg. New York, in 1845. This specimen was 
lugfir than the existing elephants, and had tusks eleven 
'- • tn length. It was mounte«l and described by i>r. 
. C- Warren, of Boston, and has been famous for 
hair a ©entury as the ^^ Warren mastodon.'^ 

' ■" student of racial development as recorded 
I : , all these sporadic timh have but incidental 

interest aa compared with the rich Western fossil beds 

Rwhich we have already referred. From records here 
mrlb^d the racial evolution of many mammals has in 
ibe past few years been made out in greater or less 
iletaiL Professor Cope has traced the ancestry of the 
oameU (which, like the rhinoceroses, hippopotami, and 
wmiry other forms now spoken of as '*Old World," 
Mcm to have had their origin here) with much com- 



A lenmroid fomi of mammal, believed to be of the 
type from wliicli man bus descenritH], has also been foimdl 
in these l>«ds. It is tljought that the ilescetidants of tht^ 
creatuiT, and of the other ''(JkUWorUl** forms abovei 
referi*eJ to, found their way to Asia, probably, as sng-l 



gested by Professor Marsh, aorosa a bridge at Bering 
Straitj to continue their evolution on the other hemi- 
sphere, becoming extinct in the land of their nativity, i 
The ape-man fossil found in the tertiary strata of thw 
island of Java two years ago by the Dutch surgeon T>n~ 
Eugene Dubois, and named PUkf'mnthrojniii erect m^ may 
have l>een a direct descendant of the American tr 
primitive lemurs, thoiigb this is only a conjecture. 


Not all the strange beasts %vh!ch have left their re- 
maias m our " bad lands" are represented by living de- 
9ceiiflanta. The titanotheres, or brontotheridae, for ex- 
ample, a gigimtic tribe, offshoots of the same stock 
Iwhick pro<hiced the horse and rhinocerosj represented 
I be culmination of a line of descent. They developed 
rapidly in a geological 8ens<% and flourished about tbo 
liddle of the tertiary perioil; then, to use Agassizs 
l^hmse, " time fought iigainst them/' The story of their 
* ' -n has been worked out by Professors Leidy^ 
i'ope, and IL F. Osborne. 
Tho very latest bit of paleontological evidence bear^ 
^ng on the question of the introduction of species is that 
t>res»ented by Dr. J. 1.. Wortman in connection with the 
il lineage of the edentates. It was suggested by 
iwh, in 1877, tliat these creatureSj whose modern rep- 
tatives are all South American, originated in North 
irica lung before the two continents had any land 
inection. The stages of degeneration by which these 
^nitlually lost the enamel from their teeth, coin- 
.Uly to the unique condition of their modern de- 
soendanu of the sloth tribOj are illustrated by strikingly 
graded specimens now preserved in the American Mn- 
teom of Natural History, as shown by Dr. Wortraan. 

All thc*se and a multitude of other recent observations 

I flat cannot be even outlined here toll the same story 

With one accord paleontologists of our time regard the 

I question of the introduction of new species as solved. 

Ait Professor Marsh has said, ^* to doubt evolution to- 

\ diy is to donbt science ; and science is only another 

ntune for truth.-' 

Thus the third great battle over the meaning of the 
UmB records lias come to a conclusion. Again there 



is a trace to controversy, and it may seem to the casnal 
observer that the present stand of the science of fossils 
is final and impregnable. Bat does this really mean 
that a full synopsis of the story of paleontology has 
been told? Or do we only await the coming of the 
twentieth-centary Lamarck or Darwin, who shall attack 
the fortified knowledge of to-day with the batteries of 
a new generalization ? 


Jame!4 Hrrropc's theory that continents wear away 

nl are replaced by voloanic upheaval had gained com- 

(iiratively few adherents at the beginning of our can* 

ary. Even the lucid fllustratimw of the IIuMmuan 

f>ry^ which Play fair, the pupil and friend of the 

It Scotcliman, published in 1802, did not at once 

>Ye convincing. The world had beconae enamoured 

the rival theory of Ilutton's famous contemporary, 

r<!rner of Saxony— the theory which taught that **in 

tie Ijeginning^' all the solids of the earth^s present 

&t were dissolved in the heated waters of a universal 

pirn. Werner affirmed that all rocks, of whatever char- 

|iict#»r, had lx*on formed by precipitation from this sea, 

laitbi* waters cooleil; that t?veu veins have originated 

I m this way ; and that mountains are gigantic crystals^ 

not nplieavei^l masses. In a word, he practically ignored 

vdcanic iietion, and dented in toto the theory of meta- 

"^^^rptioeis of rocks through tho agency of heat. 

Th« followers of Werner came to l>e known as Nap- 
*ttnistj»; the Iluttonians as PUitonists. The history of 
geology during our first quarter-century is mainly a re- 
cital of the intempenite controversy between these op- 



posing schools ; though it should not be forgotten that, 
meantime, the members of the Geological Society of 
London were making an effort to hunt for facts and 
avoid compromising theories. Fact and theory, how- 
ever, were too closely linked to be thus divorced. 

The brunt of the controversy settled about the un- 
stratified rocks — granites and their allies — which the 
Plutonists claimed as of igneous origin. This contention 
had the theoretical support of the nebular hypothesis, 
then gaining ground, which supposed the earth to be a 
cooling globe. The Plutonists laid great stress, too, on 
the observed fact that the temperature of the earth in- 
creases at a pretty constant ratio as descent towards its 
centre is made in mines. But in particular they ap- 
pealed to the phenomena of volcanoes. 

The evidence from this source was gathered and 
elaborated by Mr. G. Poulett Scrope, secretary of the 
Geological Society of England, who, in 1823, published 
a classical work on volcanoes, in which he claimed that 
volcanic mountains, including some of the highest 
known peaks, are merely accumulated masses of lava 
belched forth from a crevice in the earth's crust. The 
Xeptunists stoutly contended for the aqueous origin of 
volcanic as of other mountains. 

But the facts were with Scrope, and as time went on it 
came to be admitted that not merely volcanoes, but many 
" trap " formations not taking the form of craters had 
been made by the obtrusion of molten rock through fis- 
sures in overlying strata. Such, for example, to cite 
familiar illustrations, are Mount Holyoke, in Massachu- 
setts, and the well-known formation of the Palisades 
along the Hudson. 

But to admit the "Plutonic" origin of such wide- 



[>read formations was practically to abandon the Nep- 
tunian hypothesis. So gradoally the Huttonian expla- 
natiori of the origin of granites and other ** igneous^' rocks, 
whether rnasdeti or in veins, oarae to be accepted. Mo3t 
geologists then came to think of the earth as a molten 
mass, on which the crust rests as a mere film. Some, 
indeed, with Lyellj preferred to believe that the mnlten 
areas exist only as lakes in a solid crust, heated to 
melting, perhaps, by electrical or chemical action, as 
Davy suggested. More recently a popular theory at* 
lampla to reconcile geologiail fact^ with the claim of the 
physicists^ that the earth's entire mass is at least as 
igid Gbs steel, by sup|>osing that a molten film rests be- 

reen the observed solid crust and the alleged solid 
|lQcl6Qs. But be that as it may, the theory that subter* 

ineao heat has been instrumental in determining the 

>ndition of "primary-' rocks, and in producing many 
»ther phenomena of the earth*s crust, has never been in 

iispute since the long controversy between the Neptu- 
and the Plutonists led to its establishment. 


If molten matter exists beneath the crust of the earth, 
it mia»t contract an cooling, and in bo doing it must dis- 
turb the level of the portion of the crust already solidi- 
flel. So a plausible explanation of the uplieaval of 
Mitiiietits and mountains was sup[)lied by the Plutonian 
tbeory^ m Button had from the tirst alleged. But 
Un important difference of opinion arose as to the 
ct rationale of such upheavals. Hutton himself, and 
pniriically every one else who accepted his theory ^ had 
SQpfwmi that there are long periods of relative repose, 



during which the level of the crust is undisturbed, fol- 
lowed by short periods of active stress, when continents 
are thrown up with volcanic suddenness, as by the throes 
of a gigantic earthquake. But now came Charles Lyell 
with his famous extension of the " uniformitarian " doc- 
trine, claiming that past changes of the earth's surface 
have been like present changes in degree as well as in 
kind. The making of continents and mountains, he said, 
is going on as rapidly to-day as at an}' time in the past. 
There have been no gigantic cataclysmic upheavals at any 
time, but all changes in level of the strata as a whole have 
been gradual, by slow oscillation, or at most by repeated 
earthquake shocks sucli as are still often experienced. 

In support of tliis very startling contention Lyell 
gathered a mass of evidence of the recent changes in 
level of continental areas. He corroborated by personal 
inspection the claim wliich had been made by Playfair 
in 1802, and by von Buch in 1807, that the coast-line of 
Sweden is rising at the rate of from a few inches to sev- 
eral feet in a century. He cited Darwin's observations 
going to prove that Patagonia is similarly rising, and 
PingoPs claim that Greenland is slowiy sinking. Proof 
as to sudden changes of level of several feet, over large 
areas, duo to earthquakes, was brought forward in 
abundance. Cumulative evidence left it no longer open 
to question that such oscillatory changes of level, either 
upward or downward, are quite the rule, and it could 
not be denied that these observed changes, if continued 
long enough in one direction, would produce the highest 
elevations. The possibility that the making of even the 
highest ranges of mountains had been accomplished 
without exaggerated catastrophic action came to be 
freely admitted. 




tfV/ Y 

. cnO« 



It became clear that the soppoeedlj stable land sor- 
bees are in reftlity modi more TaiiaUe iban tlie sorfuse 
it the ** shifting sea ^ ; that ooa tinea tal mMsam^ seeming- 
I? so filed, are really risitig and failing in billoirs tboa- 
of feet in hdghl, ag^ instead of moments being 
in tb€ sireep between cre^t aod hollow. 
Tbesd dow oscillatioiis of land siirlaoes being onder- 
Lmany geological enigtnas were made clear — such 
alternation of marine and fresh-water formations 
eal series^ wfaicfa Cavier and Bmngniart had 
ibs&n'ed near Paris; or the sandwiching of layers of 
^l of jvnbaerial fcMmation, between layers of sabaqne- 
)m clay or sandstone, which may be Dteerved every- 
rWe in the coal measures. In particnlar, the extreme 
lidknass of the sedimentary strata as a whole, Q3any 
mei exceeding the depth of the dee[>est known sea, 
ras fur ibe first time ejEplicable when it was under- 
low! that such strala had formed in slowly sinking 

fit as to the mode of origin of strati fie^l rocks 
ing Uius reraoTed, the way was ojieniMl for a more 
Toniblf? coDsuieraiiou of that other Uuttonian doo- 
ne uf the extremely slow denudation of land surfaces, 
e enormous amotint of land efijsion will be patent to 
» who Ui^s his eyes intelligently in a mountain 
It will l>e evident in any region where the 
are tilte<i^-as, for examplej the AUeghanies — 
great folds of strata which must once have risen 
«• in height have in many case^ been worn entirely 
ay^so that now a valley mat*ks the lrK5ation of the 
eminence. Where the strata are level, as in the 
mountains of Sicily^ the Scotch Highlands, 
iliar Catskills, the evidence of denudation is, 
1 im 


if possible, even more marked ; for here it is clear that 
elevation and valley have been carved by the elements 
out of land that rose from the sea as level plateaus. 

But that this herculean labor of land-sculpturing could 
liave been accomplished by the slow action of wind and 
frost and shower was an idea few men could grasp 
within the first half-century after Button proi>ounded 
it; nor did it begin to gain general currency until 
LyelFs crusade against catastrophism, begun about 1830, 
liad for a quarter of a century accustomed geologists to 
the thought of slow continuous changes producing final 
results of colossal proportions. And even long after 
that, it was combated by such men as Murchison, Di- 
rector-General of the Geological Survey of Great Brit- 
ain, then accounted the foremost field-geologist of his 
time, who continued to believe that the existing valleys 
owe their main features to subterranean forces of up- 
heaval. Even Murcliison, however, made some recession 
from the belief of the Continental authorities, filie de 
Beaumont and Leopold von Buch, who contended that 
the mountains had sprung up like veritable jacks-in-the- 
box. Yon Buch, whom his friend and fellow-pupil von 
Humboldt considered the foremost geologist of the time, 
died in 185*^, still firm in his early faith that the erratic 
bowlders found high on the Jura had been hurled there, 
like cannon-balls, across th(^ valley of Geneva by the 
sudden upheaval of a neighboring mountain range. 


The bowlders whose presence on the crags of the Jura 
the old German accounted for in a manner so theatrical 
had long been a source of contention among geologists. 



They are found not merely on tbe Jura, but on number- 
les^ other mountains in all north temperate latitudes, 
and often far out in the ojien coimtrj, as many a farmer 
who has broken his plough against them might testify. 
The earlj' geologists accouuted for thera, as for nearly 
erery thing else, with their supposititious Deluge. Brong- 

imrtand Cuvierand Buckland and their contemporaries 
&P|»6ared to have no diffieulty in conceiving that masses 
rf ^tiite weighing hundreds of tons had been swept 
liythis current scores or hundreds of miles from their 

I source. But of course the uniform itarian faith permit- 

^ Qo sQch explanation, nor could it countenance the 

p^jectioo idea; so Lyell was bound to find some other 

Jtonf of transportation for the puzding erratics. 

The only available medium was ice, but fortunately 



this one seemed quite sufficient. Icebergs, said Lyell, 
arc observed to carry all manner of debris, and deposit 
it in the seii-bottoms. Present land surfaces have often 
been submerged beneath the sea. During the latest of 
these submergences icebergs deiK)sited the bowlders now 
scattered here and there over the land. Nothing could 
be simpler or more clearly uniformitarian. And even 
the (NitJistrophists, though they met Lyell amicably on 
ahnost no other theoretical ground, were inclined to ad- 
mit the plausibility of his theory of erratics. Indeed, of 
all Lyeirs non-conformist doctrines, this seemed the one 
most likely to meet with general acceptance. 

Yet, even as this iceberg theory loomed large and 
larg(5r before the geological world, observations were 
making in a dilferent liekl that were destined to show 
its falhicy. As early as 1815 a sharp-eyed chamois-hunt- 
er of the Alps, Perraudin by name, had noted the ex- 
istence of the erratics, and, unlike most of his companion 
liuntei*s, had puzzled his he^id as to how the bowlden 
got where he saw them. lie knew nothing of sub- 
merged continents or of icebergs, still less of upheaving 
mountains; and though he doubtless had heard of the 
Flood, he had no experience of heavy rocks floating like 
corks in water. Moreover, he had never observed stones 
rolling up hill and perching themselves on mountain- 
tops, an<l ho was a good enough uniformitarian (though 
he would have been puzzled indeed had any one told 
him so) to disbelieve that stones in past times had dis- 
porte<l themselves differently in this regard from stones 
of the present. Yet there the stones are. How did they 
get there i 

The mountaineer thought that he could answer that 
question. He saw about him those gigantic serpent-like 



of ice ealled glaciers, '* from their far fountain^^ 
sloir mlltfig on/' caiTving with them blocks of granite 
odior debris to form inomine deposits. If these 
iers had once been much more extensive than they 
|ir are, thej might have carried the bowldei's and left 
wliere we find them. On the other hand, no other 
agency within the sphere of the chamoia-hunt- 


ft kiiofrlf?dge coiihi have accomi>lished this, ergo the 
efs miast once have been more extensive. Ferraudiii 

woolil |m»biibly have saitl that common-sense drove him 
,k> iLis ctfmi^iiisiiHi ; hut be that i\s it may, lie had con- 
fbtk^ one of the hw im\y original and novel ideas of 

•hichciur century can boast 


Perraudin announced his idea to the greatest scientist 
in his little world — Jean de Charpentier, director of the 
mines at Bex, a skilled geologist who had been a fellow- 
pupil of von Buch and von Humboldt under Werner at 
the Freiberg School of Mines. Charpentier laughed at 
the mountaineer's grotesque idea, and thought no more 
about it. And ten years elapsed before Perraudin could 
find any one who treated his notion with greater re- 
si)ect. Then he found a listener in M. Venetz, a civil 
engineer, who read a paper on the novel glacial theory 
before a local society in 1823. This brought the matter 
once more to the attention of de Charpentier, who now 
felt that there might be something in it worth investi- 

A survey of the field in the light of the new theory 
soon convinced Charpentier that the chamois-hunter had 
all along been right. He became an enthusijistic sup- 
porter of the idea that the Alps had once been embed- 
ded in a mass of ice, and in 1830 he brought the notion 
to the attention of Louis Agassiz, who was spending the 
summer in the Alps. Agassiz was sceptical at first, but 
soon became a convert. Then he saw that the implica- 
tions of the theory extended far beyond the Alps. If 
the Alps had been covered with an ice sheet, so had 
many other regions of the northern hemisphere. Cast- 
ing abroad for evidences of glacial action, Agassiz found 
them everywhere, in the form of transported erratios, 
scratched and polished outcropping rocks, and moraine- 
like deposits. Presently he became convinced that the 
ice sheet which covered the Alps had spread over the 
whole of the higher latitudes of the northern hemi- 
sphere, forming an ice cap over the globe. Thus the 
common -sense induction of the chamois - hunter blos- 



tAj[nn JKAK Krjpiiii 

samed in the mind of Ag- 
Bmiz into the conception 
of a universal Ice Age. 

In 1S5T Agassix intro- 
duced his theory to the 
world, in a pa[>er read 
at Neuchatel, and three 
years later he published 
his famous MuJe^ mtr I^es 
Olmuer^, Never did idea 
make a mOre profound 
disturbance in the scien- 
tific world. Von Buch 
treateil it with alternate 
ridicule, contempt^ and 
rage; Murchison opposed it with customary vigor; even 
Lyellj whose most i^emarkable niental endowment was 
an unfailing receptivene.^.^ to new truths, could not at* 

once discaixl his ice- 
berg theory in favor of 
the new chiiniant. Dr, 
Buckland, however, af- 
ter Agassiz had shown 
him evidence of for- 
mer glacial action in 
his own Scotland, be- 
came a convert — the 
more readily, |)erhaps, 
as it seemed to him to 
oppose the uniformita- 
rian idea* Gradually 
others fell in line, and 
after the usual embit- 




tered controversy and the inevitable full generation of 
probation, the idea of an Ice Age took its place among 
the accepted tenets of geology. All manner of moot 
points still demanded attention — the cause of the Ice 
Age, the exact extent of the ice sheet, the precise 
manner in which it produced its effects, and the exact 
nature of these effects ; and not all of these have even 
yet been determined. But, details aside, the Ice Age 
now has full recognition from geologists as an historical 
period. There may have been many Ice Ages, as Dr. 
CroU contends; there was surely one; and the concep- 
tion of such a period is one of the very few ideas of our 
century that no previous century had even so much as 
faintly adumbrated. 


But, for that matter, the entire subject of historical 
geology is one that had but the barest beginning before 
our century. Until the paleontologist found out the 
key to the earth's chronology, no one— not even Hutton 
— could have any definite idea as to the true story of the 
earth's past. The only conspicuous attempt to classify 
the strata was that made by Werner, who divided the 
rocks into three systems, based on their supiK>sed order 
of deposition, and called primary, transition, and sec- 

Though AVerner's observations were confined to the 
small province of Saxony, he did not hesitate to affirm 
that all over the world the succession of strata would be 
found the same as there, the concentric layers, aooord- 
ing to this conception, being arranged about the earth 
with the regularity of layers on an onion. But in this 
Werner was as mistaken as in his theoretical explana- 



iXtttJi IIWmilT UAH A 

tion uf the origin of the 
prioiary " n>cks. It re- 
]oirefl but little observa- 
tion to show til lit the ex* 
let soccossiuu of strata 
never precisely the 
in any widely sep- 
_th€less^ llH*re w;is a ^erm 
if truth in Werners eys- 
li contairifHl tlie 
however faultily in- 
erpreleit, of u cbmnoJug- 
il jiftuect^ssioti of strata ; 
it furnii^lied a work- 
ag outlino for the observei'S who were to make out the 
»e gtory of geulogical development. But the correct 
intiTpri'tatioii of tlio observed facts could only l>e made 

after the Iluttonian view 
MS to the origin of strata 
haii gained complete ac- 

When William Smith, 
having found the true key 
to this storj", attempted 
to a|*ply it, the territory 
with which he had to 
tleal clianced to be one 
where the surface rocks 
are of that later series 
which Werner termed sec- 
ondary. He made numer- 
rous subdivisions within 

m% »*inM)irB. tvVKX wi KniiNrj^ 


this system, based mainly on the fossils. Meantime it 
was found that, judged by the fossils, the strata that 
Brongniart and Cuvier studied near Paris were of a still 
more recent period (presumed at first to be due to the 
latest deluge), which came to be spoken of as tertiary. 
It was in these beds, some of which seemed to have been 
formed in fresh- water lakes, that many of the strange 
mammals which Cuvier first described were found. 

But the *' transition " rocks, underlying the " second- 
ary " system that Smith studied, were still practically 
unexplored when, along in the thirties, they were taken 
in hand by Roderick Impey Murchison, the reformed 
fox-hunter and ex-captain who had turned geologist to 
such notable advantage, and Adam Sedgwick, the brill- 
iant AVoodwardian professor at Cambridge. 

Working together, these two friends classified the 
transition rocks into chronological groups, since familiar 
to every one in the larger outlines as the Silurian system 
(ago of invertebrates) and the Devonian system (age of 
fishes) — names derived respectively from the country of 
the ancient Silures, in Wales, and Devonshire, England. 
It was subsequently discovered that these systems of 
strata, which crop out from beneath newer rocks in re- 
stricted areas in Britain, are spread out into broad un- 
disturbed sheets over thousands of miles in continental 
Europe and in America. Later on Murchison studied 
them in llussia, and described them, conjointly with 
Verneuil and von Kerserling, in a ponderous and classi- 
cal work. In America they were studied by Hall, New- 
berry, AVhitney, Dana, Whitfield, and other pioneer 
geologists, who all but anticipated their English contem- 

The rocks that are of still older formation than those 


adied by Miircbison and Sedgwick (corresponding ia 
ion to the " primary '' i*ooks of Werner's conc^p* 
a) are Urn surface feature of vast ai'eas in Canada, 
aad were first proniinciitly studiecl there by William L 


tjo^an, of the Canadian Government Survey, as early aa 
I IW*, and later on by Sir William Dawson. These rocks 
I— comprising theLaureutian system — were formerly sop- 

^m\ to represent parts of the original crust of the earth. 




formed on first cooling from a molten state ; but they 
are now more generally regartled as once-stratified de- 
posits metamorpliosed by the action of heat. 

Whetlier " primitive " or metamorphic, however, these 
Canadian rocks, and analogous ones beneath the fossil- 
iferous strata of other countries, are the oldest portions 
of the earth's crust of which geology has any present 
knowledge. Mountains of this formation, as the Adi- 
rondacks, and the Storm King range overlooking the 
Hudson near West Point, are the patriarchs of their 
kind, beside which AUeghanies and Sierra Nevadas are 
recent upstarts, and Rockies, Alps, and Andes are mere 
parvenus of yesterday. 

The Laurentian rocks were at first spoken of as repre- 
senting '* Azoic" time; but in 1846 Dawson found a 
formation deep in their midst which was believed to be 
the fossil relic of a very low form of life, and after that 
it became customary to speak of the system as " Eozoic." 
Still more recently the title of Dawson's supposed fossil 
to rank as such has been questioned, and Dana's sug- 
gestion that the early rocks be termed merely Archaean 
lias miit with general favor. Murchison and Sedgwick's 
iSilurian, Devonian, and Carboniferous groups (the ages 
of invertebrates, of fishes, and of coal plants respective- 
ly) are together spoken of as representing Paleozoic time. 
William Smith's system of strata, next above these, onoe 
called "secondary," represents IMesozoic time, or the age 
of reptiles. Still higher, or more recent, are Cuvier 
and Brongniart's Tertiary rocks, representing the age of 
mammals. Lastly, the most recent formations, dating 
back, however, to a j>eriod far enough from recent in 
any but a geological sense, are classed as Quaternary, 
representing the age of man. 



It must not be sup- 
however, that 
successive '*ages" 
IhiJ geologist are 
bat off from one an* 
ther in any such ar* 
itrarv way as this rer* 
cl lissi ii ca t i o n m igh t 
3111 to suggest. In 
loint of fact, these 
5 ' ' have no better 
for existence 
have the **c6n' 
i" and the** weeks'' 
every-day coinpata- gi. -i i lur; 

:>n. They are convenient, and they may even stand 
local divisions in the stmta, hut they are bounded by 
uictuid gaps in the sweejj of terrestrial events. 

Moreover, it must be 
un tiers toot I iliat the 

"ages'* of d liferent 
continents, though de- 
seril><?d nndor the same 
namo, are not neces- 
sarily of exact contem- 
porant^ity. Tliere is no 
sure test avaikdjlt; by 
which it could be 
shown that the Devo- 
nian age* for instance, 
as outlined in the 
strata of Europe, did 
not begin millions of 


years earlier or later than the period whose records are 
said to represent the Devonian age in America. In at- 
tempting to decide such details as this, mineralogical 
data fail us utterly. Even in rocks of adjoining regions 
identity of structure is no proof of contemporaneous 
origin ; for the veritable substance of the rock of one 
age is ground up to build the rocks of subsequent ages. 
Furthermore, in seas where conditions change but little 
the same form of rock may be made age after age. It 
is believed that chalk beds still forming in some of our 
])resent seas may form one continuous mass dating back 
to earliest geologic ages. On the other hand, rocks dif- 
ferent in character may be formed at the same time in 
regions not far apart — say a sandstone along shore, a 
coral limestone farther seaward, and a chalk bed be- 
yond. This continuous stratum, broken in the process 
of upheaval, might seem the record of three different 

Paleontology, of course, supplies far better chrono- 
logical tests, but even these have their limitations. 
There has been no time since rocks now in existence 
were formed, if ever, when the earth had a uniform 
climate and a single undiversilied fauna over its entire 
land surface, as the early paleontologists supposed. 
Speaking broadly, the same general stages have attend- 
ed the evolution of organic forms everywhere, but there 
is nothing to show that equal periods of time witnessed 
corresponding changes in diverse regions, but quite the 
contrary. To cite but a single illustration, the marsupial 
order, which is the dominant mammalian type of the 
living fauna of Australia to-day, existed in Europe and 
died out there in the Tertiary age. Hence a future 
geologist might think the Australia of to-day contempo- 






mnmn with a period in Europe vrhich in reality ante- 
dalecl it by perhaps millions of year 

All these puzzling features unite to render the subject 
of hbtfincal geolagy anything but tlie simple matter the 
fathers of the science esteemed it* No one would nou' 
I attempt to trace the exact sequence of formation of all 
I llio mountains of the gluhe, as £lie tie Beaumont did a 
half-centary ago. Even within the limits of a single 
fsontmenu tho geologist must proceed with much caution 
iMdiaptiiig to chronicle the order in whicii its variuus 
from the matirix of tl!e sea. The key to this 
f Btonr k found in the identitlcation of the strata that are 
imrface feature in each territory. If Devonian rocks 
the surface in any i^iren region^ for example, it 
would ap|)ear that this region i^eeame a land surface in 
the Doronian age, or just afterwards- But a moment's 
oonsideraticm shows that there is an element of uncer- 
Urnty about this, due to the steady denudation that all 
ilaod surfiices undergo. The Devonian rocks may lie at 
IthMjurface simply because the thousands of feet of car- 
fkotiifermis strata tliat once lay above them have been 
^<m away. All that the cautious geologist dare assert, 
j therefore, is that the region in question did not become 
L permatient land surface earlier than the Devonian age. 
^M But to know even this is much — sufficient, indeed, to 
^■Hdijih the chronological order of elevation^ if not its 
^^Bl perifxf, for all parts of any continent that have 
btt?ii geologicitlly explored-— understanding always that 
^Ihere mtii*t be no scrupHng about a latitude of a few mill- 
lor perhaps tens of millions of years here and there. 


Begarding our own continent, for example, we learr 
through the researches of a multitude of workers thai 
in the earl}^ day it was a mere archipelago. Its chiel 
island — the backbone of the future continent — was a 
great V-shaped area surrounding what is now Hudson 
Bay, an area built up, perhaps, through denudation of a 
yet more ancient polar continent, whose existence is only 
conjectured. To the southeast an island that is now the 
Adirondack Mountains, and another that is now the 
Jersey Highlands, rose above the waste of waters ; and 
far to the south stretched probably a line of islands now 
represented by the Blue Kidge Mountains. Far oflf to 
the westward another line of islands foreshadowed our 
present Pacific border. A few minor islands in the in- 
terior completed the archipelago. 

From this bare skeleton the continent grew, partly by 
the deposit of sediment from the denudation of the orig- 
inal islands (which once towered miles, perhaps, where 
now they rise thousands of feet), but largely also by the 
deposit of organic remains, especially in the interior sea, 
which teemed with life. In the Silurian ages, inverte- 
brates — bracliiopods and crinoids,and cephalopods — were 
the dominant types. But very early — no one knows just 
when — there came fishes of many strange forms, some 
of the early ones enclosed in turtlelike shells. Later 
yet, large spaces within the interior sea having risen to 
the surface, great marshes or forests of strange types of 
vegetation grew and deposited their remains to form 
coal beds. Many times over such forests were formed, 
only to be destroyed by the oscillations of the land sur- 
face. All told, the strata of this Paleozoic period aggre- 
gate several miles in thickness, and the time consumed 
in their formation stands to all later time up to the 






iilj aocorditig to Professor Bana-s estimate, as tkree 
to one. 

TrHViirtIs tiie close of this Paleozoic era the Appalachian 
Hounlaitis wen? slowly upheaved in great convoluted 
folds, some of them prohably reaching three or four 
I miles above the si3a-level, thougli tlio tooth of time has 
I «ioc{*gna\v<*«l thf:^ni dosvn to coiiipuratively puny limits. 
T be coil U II e u tal a reas 1 1 j u s en 1 arged vv ere peop 1 ed d u r- 
Lrn^ tbo ensniog Meaozoic time with multitudes of 
[itmng^ repliles, manj^ of them gigantic in size. The 
pvattTs, Um>^ stiil teeming with inverteiirates and Bshes, 
j had their quota of reptilian monsters; and in the air 
jwerc flying reptiles, some of which measured twenty-Gve 
Ifwt from tip to tip of their bat-like wings. During this 
imthe Sierm Nevada Mountains rose, Ne^ar the east- 
1 tMjrcterof the forming continent the strata were per- 
haps now too thick and stiff to bend into mountain 
fiAih, for they were rent into great iissures, letting out 
\ of molieD lava, remnants of which are still in evi- 
ence after ages of denudation, as the Palisades along 
Uadson, and such elevations as Mount Holyoke in 
Stiil there romained a vast interior sea, which, later 
^^n, in the Tertiary age, was to be divided by the slow 
_aprising of the land, which only yestert lay —that is to 
Ay^a million, or three or five or ten million years ago — 
06 the Ri-)cky Mountains, High and erect these 
^'JOiiQg mountains stand to this day. their sharp angles 
wul rocky contours vouching for their youth, in strange 
QontTiyit with the shrunken forms of tlie old Ad iron- 
Green Mountains, and Appalachians, whose low* 
faaads and rounde<l shoulders attest the weight of 
In the vast lakes which still remained on either 


side of the Rocky range, Tertiary strata were slowly 
formed to the ultimate depth of two or three miles, en- 
closing here and there those vertebrate remains which 
were to be exposed again to view by denudation when 
the land rose still higher, and then, in our own time, to 
tell so wonderful a story to the paleontologist. 

Finally the interior seas were filled, and the shore 
lines of the continent assumed nearly their present out- 

Then came the long winter of the glacial epoch — per- 
haps of a succession of glacial epochs. The ice sheet 
extended southward to about the fortieth parallel, driv- 
ing some animals before it, and destroying those that 
were unable to migrate. At its fulness, the great ice 
mass lay almost a mile in depth over New England, as 
attested by tiie scratched and polished rock surfaces and 
deposited erratics in the White Mountains. Such amass 
presses down with a weight of about one hundred and 
twenty-five tons to tiie scjuare foot, according to Dr. 
CrolKs estimate. It crushed and ground everything be- 
neath it more or less, and in some regions planed oflf 
hilly surfaces into prairies. Creeping slowly forward, it 
earned all manner of debris with it. When it melted 
away its terminal moraine built up the nucleus of the 
land masses now known as Long Island and SUiten Isl- 
and ; other of its deposits formed the " drumlins " about 
l»oston famous as Danker and Dreeds hills; and it left a 
loiii,^ irregular line of ridges of '' till " or bowlder clay 
and scattei'ed erratics clear across the country at about 
the latitude of Xew York City. 

As the ice shivt slowly receded it left minor moraines 
all along its course. Sometimes its deposits dammed up 
river courses or ineipialities in the surface, to form the 





TILOLN F'-v.i'::.\ri .»■, ^ 



which everywhere abound over NortherD territo- 
ries. Some gUicialists even bold the view fir-st suggested 
^^ Ramsey, of the British Geological Survey, that the 
^■nrat gliiciul sheet scooped out the basins of many lakes, 
^Bcluiling thesysteui that feeds the Saint Lawrence. At 
^%a events, it left tnices of its* presence aJl along the line 
^of its retreat, and its remnants exist to this day as 
Hb<ninUdn glaciers and the polar ice cap. Indeed, we 
^live im the U>rder of tlie last glacial epoch, for with the 
clusiQg of tins period the long geologic past merges into 
^^ the present. 

^H And the present, no less than the past, is a time of 
^Belmnga That is the thought which James Hut ton oon- 
^ceiml more than a century ago, hut which his contem- 
|M>rdriea and successors were so very slow to appi^eciate. 
NVw, however, it has become axiomatic— one can hardly 
fcalize that it mis ever doubted. Every new scientiBc 
trnth, says Agassiz, must pass through three stages — 
Bmt,(nen say it is not true; tlien tliey declare it hostile 
til religion; finally, they assert that every one has 
kiuiwn it always. IIutton*s truth that natural law is 
Hmuj^'eless and eternal has reached this final stage. No- 
^^here now could you find a scientist who would dispute 
ilie truth of that text which Lyelh finoting from P!ay- 
h[f% IUtiHiraiit>n» of the Ifuffonian Theory, printed on 
tke title-page of his Prlnclpkii: '' Amid all the revolu- 
tions of the gloJ>e the economy of Nature has been uni- 
Wm,and lier laws are the only things that have resisted 
ihff general mf>vement, Tfje rivei^ and the rocks, the 
«Mii»d the continents, have been changed in all tlieir 
pwte; but the laws which dfreet those changes, and the 



rules to which they are subject, have remained invaria- 
bly the same." 

But, on the other hand, Hutton and Playfair, and in 
particular Lyell, drew inferences from this principle 
which the modern physicist can by no means admit. 
To them it implied that the changes on the surface of 
the earth have always been the same in degree as well 
as in kind, and must so continue while present forces 
hold their sway. In other words, they thought of the 
world as a great per|^tual-motion machine. But the 
modern physicist, given truer mechanical insight by the 
doctrines of the conservation and the dissipation of en- 
ergy, will have none of tiiat. Lord Kelvin, in particular, 
has urged that in the periods of our earth's infancy and 
adolescence its developmental changes must have been, 
like those of any otiier infant organism, vastly more 
rapid and i)ronounced than those of a later day ; and 
to every clear thinker this truth also must now seem 

Whoever thinks of the earth as a cooling globe can 
hardly doubt that its crust, when thinner, may have 
heaved under strain of the moon's tidal pull — whether 
or not that body was nearer — into great billows, daily 
rising and fidling, like waves of the present seas vastly 

Under stress of that same lateral pressure from con- 
traction whicii now produces the slow depression of the 
Jersey coast, the slow rise of Sweden, the occasional 
belching of an insignificant volcano, the jetting of a 
geyser, or the trembling of an earthquake, once large 
areas were rent in twain, and vast floods of lava flowed 
over thousands of square miles of the earth's surface 
perhaps at a single jet ; and, for aught we know to the 



itmry, gigantic mountains may have heaj>etl np their 
ilorted heailB in cataclysms as spasmodic as even the 
ciHt anient cataslrophist of the elder day of geology 
luld Ijuve iniagined. 

[The atmuHphiire of that early day, filled with vast 
Vhmies uf carbon, oxygen, and other chemicals that 
^ve since been stored m beds of coal, limestone, and 


. unites, may have worn down the rocks, on the one 
liJtml, and Imilt np organic f^rms on tlie other, with a 
iipidity that wouUl now seem hardly conceivable. 
And yet whiht all these anomalous things wsBt on, 


the same laws held that now are operative; and a trae 
doctrine of uniforraitarianism would make no unwonted 
concession in conceding them all— though most of the 
embittered geological controversies of the middle of our 
century were due to the failure of both parties to realize 
that simple fact. 

And as of the past and present, so of the future. The 
same forces will continue to operate; and under oper- 
ation of these unchanging forces each day will differ 
from every one that has preceded it. If it be true, as 
every physicist believes, that the earth is a cooling 
globe, then, whatever its present stage of refrigeration, 
the time must come when its surface contour will assume 
a rigidity of level not yet attained. Then, just as sure- 
ly, the slow action of the elements will continue to wear 
away the land surfaces, particle by particle, and trans- 
port them to the ocean, as it does to-day, until, compen- 
sation no longer being aflForded by the upheaval of the 
continents, the hist foot of dry land will sink for the 
last time beneath the water, the last mountain -peak 
melting away, and our globe, lapsing like any other 
organism into its second childhood, will be on the sur- 
face — as presumably it was before the first continent 
rose — one vast '' waste of waters." As puny man con- 
ceives time and things, an awful cycle will have lapsed; 
in the sweep of the cosmic life, a pulse-beat will have 


•* Ajs astonishing miracle has just occurred in out dis- 
wrot« M. Marais, a worthy if tintlistinguished 
ItiEeii uf Fraiieej from his home at L'Aigle^ under date 
** the 13th Fioreal, year 11" — a date which outside 
France would be interpreted as meaning May 3, 
IW^. This *Moinichi'' was the appearance of a ''lire- 
ImJI^* 15 broad daylight— '^'^ perhaps it was wildfire,*' 
njE the naive chronicle — which '* hnng over the 
meftdow/* being seen by many people, and then ex- 
plodexl witli a h>ud sound, scattering thousands of 
«tooy fragments over the surface of a territory some 
mflea in extent. 

Socb a '* niiniole" could not have been announced at 
imon5 opportune time. For some years the scientific 
I^otM had been agog over the question whether such a 
[form of tight ning us tlutt refKirterl— appearing in a clear 
«ky,aiHl hurling literal tliunder-l)olts — had real existence- 
Sycl) aises had been reported often enough^ it is true. 
[Ttif* ^^tlmniier-bolts'' themselves were exhibited as sa- 
cral relics before many an altar, and those who doubted 
^ihm authenticity had been chided as having *'an evil 
haait of unbelief/* But scientific scepticism had ques- 



tioned the evidence, and late in the eighteenth century 
a consensus of opinion in the French Academy had de- 
clined to admit that such stones had been ^^ conveyed to 
the earth by lightning," let alone any more miraculous 

In 1802, however, Edward Howard had read a paper 
before the lloyal Society in which, after reviewing the 
evidence recently i)ut forward, he had reached the con- 
clusion that the fall of stones from the sky, sometimes 
or always accompanied by lightning, must be admitted 
as an actual phenomenon, however inexplicable. So 
now, when the great stone-fall at L'Aigle was an- 
nounced, the French Academy made haste to send the 
brilliant young physicist Jean Baptiste Biot to investi- 
gate it, that the matter might, if possible, be set finally 
at rest. The investigation was in all respects successful, 
and Hint's report transferred the stony or metallic light- 
ning-bolt—the ac^rolite or meteorite — from the realm of 
tradition and conjecture to that of accepted science. 

But how explain this strange phenomenon? At once 
speculation was rife. One theory contended that the 
stony masses had not actually fallen, but had been 
f<)rnie<l from the earth by the action of the lightning; 
but this contention was early abandoned. The chemists 
were disposed to believe that the aerolites had been 
formed by the combination of elements floating in the 
upper atmosphere. Geologists, on the other hand, 
thought them of terrestrial origin, urging that they 
might have been thrown up by volcanoes. The astron- 
omers, as represented l)v Olbers and Laplace, modified 
this theory by suggesting that the stones might, indeed, 
have been cast out by volcanoes, but by volcanoes sit- 
uated not on the earth, but on the moon. 



And one speculator of the time took a step even more 
^ving, urging tbat the aerolites were neither of telluric 
^Vtieleiiic origin^ nor yet chiklren of the sun, as the old 


^■isekR had, many of them, contended, but that they 
^Bb visilatits from the depths of cosmic space. This 
^■U «{>ecuktur %vas the distinguished German physicist 
^ftiist F. F. Chladni, a man of no small repute in his 
^Mt As early as 1704 he urged his cosraical theory 
^P inetoontir*,<, when the rery existence of meteorites 
was denied by most scientists. And he did more : he 


declared his belief that these falling stones were really 
one in origin and kind with those flashing meteors of 
the upper atmosphere which are familiar everywhere as 
*' shooting-stars." 

Each of these coruscating meteors, he affirmed, must 
tell of the ignition of a bit of cosmic matter entering 
the earth's atmosphere. Such wandering bits of mat- 
ter might 1x3 the fragments of shattered worlds, or, as 
Chladni thought more probable, merely aggregations 
of "world stuff" never hitherto connected with any 
large planetary mass. 

Naturally enough, so unique a view met with very 
scant favor. Astronomers at that time saw little to jus- 
tify it; and the non-scientific world rejected it with 
fervor as being ''atheistic and heretical," because its 
acceptance wouhl seem to imply that the universe is not 
a perfect mechanism. 

Some light was thrown on the moot point presently 
by the observations of Brandes and Benzenberg, which 
tended to show that falling-stars travel at an actual 
speed of from fifteen to ninety miles a second. This 
observation tended to discredit the selenic theory, since 
an object, in order to acquire such speed in falling mere- 
ly fi'oni the moon, must have been projected with an in- 
itial velocity not conceivably to be given by any lunar 
volcanic inij)ulse. Moreover, there was a growing con- 
viction that tliere are no active volcanoes on the moon, 
and other considerations of the same tenor led to the 
complete abandonment of the selenic theory. 

But the theorv of telluric orimn of aerolites was bv 
no means so easily disposeil of. This was an epoch 
when electrical phenomena were exciting unbounded 
and universjil interest, and there was a not unnatural 



ideney to appeal to electricity in explanation of every 

cure |ih©noineri*jn ; and in this case the seeming sim- 

tty between a ligUtoing-llash and t!ie fltish of an 

lite lent color to the explanation* So we tind 

las Foistep^ a meteorologist of repute, still adher- 

ifig U^ the atmospheric theory of formation of aerolites 

^n his book published in 1823 ; and, indeed, the prevail- 

ng opiuiou of the time seemed divided between various 

telluric theories, to the neglect of any cosmical theory 


Bat in 1833 occurred a phenomenon which set the 
natter Hnally at rest. A great meteoric shower Dc- 
arrcd in November of that year, and in observing it 
professor Denison Olmsted, of Yale, noted that all the 
itar* uf the shovrer appeared to come from a single 
entre or vanishing- point in the heavens, and that 
bit centre shifted its position with the stars, and hence 
iras not telluric. The full signiticance of this obser- 
Ivation was at once recognized by tistronamers ; it de- 
tratiM] bcyonfl all cavil the cosmical origin of the 
iing-stars. Some conservative meteorologists kept 
I op the argument for the telluric origin for some decades 
tooomrr US a matter of coui-se — such a band trails always 
in the rear of [>r*>*>ress. But even these doubters were 
iilenoeil when tlic great shower of shooting-stars ai> 
|p«ari?clagain in ISGO, aa predicted bj^ Olbers and New- 
tan, nidiating from the same jwint of the heavens as 
f More. 

Since then the spectroscope has added its confirmatory 

|9?id$iioe as to the identity of meteorite and shooting- 

[itir, and, moreover, has linked these atmospheric meteors 

J ^ithgueh distant cosmic residents as cojnets and nobulae. 

Tljiasitfippears that Chludni*s daring hypothesis of 1T04 


has been more than verified, and that the fragments of 
matter dissociated from planetary connection — which he 
postulated and was declared atheistic for postulating — 
have been sliown to be billions of times more numerous 
than any larger cosmic bodies of which we have cog- 
nizance — so widely does the existing universe differ from 
man's preconceived notions as to what it should be. 

Thus also the " miracle" of the falling stone, against 
which the scientific scepticism of yesterday presented 
" an evil heart of unbelief," turns out to be the most 
natural of phenomena, inasmuch as it is repeated in our 
atmosphere some millions of times each day. 


If fire-balls were thought miraculous and portentous 
in days of yore, what interpretation must needs have 
been put upon that vastly more picturesque phenom- 
enon, the aurora? "Through all the city," says the 
Book of Maccabees, " for the space of almost forty days, 
there were seen horsemen running in the air, in cloth 
of gold, armed with lances, like a band of soldiers : and 
troops of horsemen in array encountering and running 
one against another, with shaking of shields and multi- 
tude of pikes, and drawing of swords, and casting of 
darts, and glittering of golden ornaments and harness." 
Dire omens tliese ; and hardly less ominous the aurora 
seemed to all succeeding generations that observed it 
down till well into the eighteenth century — as witness 
the popular excitement in England in 1716 over the 
brilliant aurora of that year, which became famous 
through Ilalley's description. 

But after 1752, when Franklin dethroned the light- 


ling, all spectacular meteors came to be regarded as 
itnml phenometia, the aurora aiiiung the resL Frank- 
In explained the aurora— which was seen commoDlj 
mugh in the eighteenth eentur}^ though only recorded 

cmBUs cLouns 

^Scein the seventeenth— as due to the accumulation of 
wleclricity on the surface of polar snows, atid its dis- 
cliarg«i lo the equator through the up[»er atmosphere. 
Krasimus Darwin suggested tJiat the luminosity might be 
<lueUj the ignition of hydrogen, which was supposed by 
Hiany phihisophers to form the upper atmosphere. Dal- 
^ft, who firat measureil the height of the aurora, esti- 
Alng it at aliout one hundred niil*^s, thought the phe- 
aenon due to magnetism acting on ferruginous 
particles in the air, and his explanation was perhaps 
themoit popular one at the beginning of the century, 



Sinoe then a multitude of observers have studied the 
aurora, but the scientitic grasp has found it as elusive in 
fact as it seems to casual observation, and its exact nat- 
ure is as undetermined today as it was a hundred years 
ago. There has been no dearth of theories concerning 
it, however. Biot, who studied it in the Shetland Isl- 
ands in 1817, tliought it due to electriiied ferruginous 
dust, the origin of which he ascribed to Icelandic vol- 
canoes. Much more recently the idea of ferruginous 
particles has been revived, their presence being ascribed 
not to volcanoes, but to the meteorites constantly being 
dissipated in the upper atmosphere. Ferruginous dust, 
presumably of such origin, has been found on the polar 
snows, as well as on the snows of mountain-tops, but 
whether it could produce the plienomena of auroras is 
at least an open question. 

Otlier theorists have explained the aurora as due to 
the accumulation of electricity on clouds or on spicules 
of ice in the upper air. Yet others think it due merely 
to the passage of electricity through rarefied air itself. 
Ilinnboldt considered the matter settled in yet another 
way when Faraday showed, in 1831, that magnetism 
may produce luminous effects. But perhaps the pre- 
vailing theory of to-day assumes that the aurora is due 
to a current of electricity generated at the eijuator, and 
])assing through u|)i)er regions of space, to enter the 
earth at the magnetic poles — simply reversing the course 
Avhich Franklin assumed. 

The similarity of the auroral light to that generated 
in a vacuum hull) by the passage of electricity lends 
support to the long-standing supposition that the aurora 
is of electrical oi'igin, but the subject still awaits oom- 
])lete elucidation. For once even that mystery-solver 



specti-oscoi^e has been baffled, for the Hue it sifts 
I Ibe aurora ia not matched by that of any r^cog- 
I subetance. A Uke line is found in the zodiacal 
Itghl, it is true, but this is of tittle aid^ for tlie zodtacai 
iight, ifaougb tbutight by some astronoraet's to be due to 
ttcteur swaruiii abuut the sun, is held to bSj on the 
rbolo, as mysterious as the aurora itself. 
Whatever the exact nature of the aurora, it has long 
known to be intimately associated with the (>be- 
ftyaicna of terreatrial magnetism. Whenever a briUiant 


ira is visible, the worUl is sure to be visited with 
It liunibfildt called a miignetie storm — a *' storm*- 
^Uob manifests itself to human senses in no way what- 
except by deflecting the magnetic needle and 



conjuring with the electric wire. Such magnetic storms 
are curiously associated also with spots on the sun — ^just 
how no one has explained, though the fact itself is un- 
questioned. Sun-spots, too, seem directly linked with 
auroras, each of these phenomena passing through peri- 
ods of greatest and least frequency in corresponding 
cycles of about eleven years' duration. 

It was suspected a full century ago by Herschel that 
the variations in the number of sun-spots had a direct 
effect upon terrestrial weather, and he attempted to 
demonstrate it by using the price of wheat as a criterion 
of climatic conditions, meantime making careful observa- 
tion of the sun-spots. Nothing very definite came of his 
efforts in this direction, the subject being far too complex 
to be determined without long periods of observation. 
Latterly, however, meteorologists, particularly in the 
tropics, are disposed to think they find evidence of some 
such connection between sun-spots and the weather as 
Herschel suspected. Indeed, Mr. Meldrum declares that 
there is a positive coincidence between periods of numer- 
ous sun-spots and seasons of excessive rain in India. 

That some such connection does exist seems intrinsi- 
cally probable. But the modern msteorologist, learning 
wisdom of the past, is extremely cautious about ascribing 
casual effects to astronomical phenomena. He finds it 
liard to forgot that until recently all manner of climatic 
conditions were associated with phases of the moon; 
that not so very long ago showers of falling-stars were 
considered *' prognostic " of certain kinds of weather; 
and that the "equinoctial storm" had been accepted as 
a verity by every one, until the unfeeling hand of statis- 
tics banished it from the earth. 

Yet, on the other hand, it is easily within the possi- 




^Fbilitii^ that the science of the futiirt^ may revual iissocia- 
' tions IjcLwcuii tlie weather and smi sjKjts, iiurunis, and 
t^rreBtrial tuagnetisoi that as yet aro hardly ilrearned of, 
HX^ntjl »uch time, however^ these phetiuinena nnist feel 
^^tliems«.*Ives very grudgingly admitted to the inner circle 
I i>f meteorology. More and more thiss science concerns 
^fetsielf, in our age of eoueentmtion and siiecialimtioji, 
' with weutlier and climate. Its votaries no longer con- 
j_cern tlieniselvcs with stai'S or planets or comets or shoot* 
Qg-stars— once thought the very essence of giiidi^s to 
thor wisdom ; and they are even looking askance at 
tn*>«>n, and asking bor to show cause why she ako 
PsheuUl not \}e excluded from their domain. Equally 
ittle do they care for the interior of the earth, since 
Ltiiey have learned that the central envanations of heat 
[tvliich Mairan imagined as a main source of aerial 
'Warmth can claim no such distinction. Even snch prob- 
e^ms as why the magnetic pole does not coincide with 
Jthcj geogra|)hical, and w^hy the force of terrestrial mag- 
Qetism <lecreases from tlie magnetic poles to the mag- 
luetic equator, as Humboldt first discovered that it does, 
UxcitL' tbcni only ti> lukewarm intiTOSt; for niagnotiam, 
Itliey say, is not known to have any connection whatever 
[With elinnaie or weather- 

Thert^ is at least one form of meteor, however, of those 
that interested onr forebears, whose meteorological im- 
portance they ditl not overestimate. Tbis is the vapor 
m water. How great w^ns the interest in this faniiHar 
meteor at the beginning of the century is attested by the 
btimber of theories then extant regarding it; and these 
^coa&ictiog theories bear witness also to the difficulty 




with which the familiar phenomenon of the evaporation 
of wat^r was exphiined. 

Franklin had suggested that air dissolves water much 
as water dissolves salt, and this theory was still popular. 


thouf^h Dt^luc had disproved it by showing that water 
evji])()rates cvimi more rapidly in a vacuum than in air. 
Deluc's own theory, borrowed from earlier chemists, 
was that evjiporation is tlie chemical union of particles 
of wat(jr with p:uli<-lesof the supposititious element heat. 
Erasmus Darwin combine<l the two theories, su*rgesting 
that the air mijrlit hold a vnriabh* (juantity of vapor in 
mere solution, and in addition a permanent moiety in 
chemical combinati<m with c^aloric. 

Undisturbed by those conflicting views, that strangely 
original genius, John Dalton, afterwards to be known as 

ruB c;entijky\s i^roohess [n meteouulogy 

paps the gi-ealest of theoretical cliemiBts, tcK>k the 
*tion ill Uaml, and solved it by sliowiiig that water 
^i^ ill the air as an utterly indeperulent gas. He 
3ht.H| a partuil insight into tlje matter In 1793^ when 
lirst volume of meteoi*Dlogical essays was published; 

the full eluui<laliun of the [irahleni came to him in 
)1. The merit of his studies was at once recognized. 

the tetiability of his hypothesis was long and arilently 

While the nature of evaporation was in dispute, ;is a 

|tt«r of course tlic question of precipitation must l>e 

loatly ondotorniioed. The tuost famous tlieory of the 

riuii was that formulatetl by Dw Iliitton in a paper 

ftd before the R4}yal Society of Etiinl)urgh, and pub- 

in the volutins of tninsactions whicti contained 

tie same authors epoch-making pnper on geology, 

bid "the*>ry of rain" explained precipitation as due to 

he cooling of a current of saturated air by cr>ntact with 

I t'olJtsr current, the assumption being that the surplus- 

•u^ !if moi^tuE*e was precipitateil in a chemical sense, 

ju&i jij* (he excess of mlt dissolved in hot water is pre- 

li t im.hI when tlie water cools. The idea that the cool- 

: '*f the Katurateil air causes the precipitation of its 
njwstore is the germ of truth that renders this [)a|>er of 
^^^?'>Trs important. All correct later theories buihl on 

! > I'lUndntion. 

The next ambitious attempt to explain the phenomena 

"f aijiieouf* meteoi's was made by Luke llmvard, in his 

iftnimrkable paper on clouds, published in the PhUompk- 

rM Mii^a^im^ in ISnB— ^the paper in whicli the names 

turni*, cumulus, stnitus, etc., afterwards so universally 

i'.'M Wire first pro[>osed. In this pajjcr Howard 
idgi.s his indebted uess to Dalton for the theory 


of evai>oration, yet he still clings to the idea that the 
vapor, though independent of the air, is combined with 
particles of caloric. He holds that clouds are composed 
of vapor that has previously risen from the earth, com- 
bating the opinions of those wlio believe that they are 
formed by the union of hydrogen and oxygen existing 
independently in the air; though he agrees with these 
theorists that electricity has entered largely into the 
mod as operandi of cloud formation. He opposes the 
opinion of Deluc and de Saussure that clouds are com- 
{)osed of particles of water in the form of hollow vesicles 
(miniature balloons, in short, perhaps filled with hydro- 
gen), which untenable opinion was a revival of the theory 
as to the formation of all vapor which Dr. llalley had 
advocated early in the eighteenth century. 

Of particular interest are Howard's views as to the 
formation of dew, which he explains as caused by the 
particles of caloric forsaking the vapor to enter the cool 
body, leaving the water on the surface. This comes as 
near the truth perhaps as could be expected while the 
old idea as to the materiality of heat held sway. How- 
ard believed, however, that dew is usually formed in 
the air at some height, and that it settles to the surface, 
opposing the opinion, which had gained vogue in France 
and in America (where Noah Webster prominently ad- 
vocated it), that dew ascends from the earth. 

The complete solution of the problem of dew forma- 
tion— Avhich really involved also the entire question of 
precipitation of watery vapor in any form — was made 
by Dr. C. W. Wells, a man of American birth, whose life, 
however, after boyhood, was spent in Scotland (where 
as a young man he enjoyed the friendship of David 
Hume) and in London. Inspired no doubt by the re- 



searches of Black, Hutton, and their conMres of that 
Edinburgh school, Wells made observations on evapora- 
tion and precipitiitioii as early as 1784, but other things 
claimed his attention; and though he asserts tbat the 
subject was often in his mind, he did not take it up 
again in earnest until about 1812. 

Meantime the observations on lieat of Rumford and 
Davy and Leslie had cleared the way for a proper in* 
terpretation of the facts — about the facts themselves 
there had long been praxjtical unanimity of opinion. Dr, 
Black, with his lateat-lieat observations, had really given 
the clew to all subsequent discuiisions of the subject of 
precipitation of vapor; and from his time on it had been 
known that beat is taken up when water evajxirates^ 
and given out again when it condenses. Dr, Darwin 
had shown in 178S, in a paper before the Royal Society, 
that air gives off beat on contracting, and takes it up on 
expanding; and Dalton in his essiiy of IT^Kl had ex- 
plained tliis phenomenon as due to the condensation and 
vajiorimtion of the water contained in tlii^ air. 

But some curious and puz/Jing observations which 
Professor Patrick Wilson, Professor of Astronomy in 
the University of Glasgow, had communicated to the 
Royal Hociet}^ of Edinburgh in 1784, and some similar 
ones mado by Mr. Six of Canterbury a few years later, 
had remained unexplained. Both these gentlemen ob- 
served that the air is cooler where dew is forming than 
the air a few feet higher, and they inferred that the dew 
in forming had taken up heat, in apparent violation of 
established physical principles. 

It remained for Wei Is ^ in his memorable paper of 
1816^ to show that these observers had simply gotten 
the cart liefore the horse. He made it clear that the 



air is not cooler because the dew is formed, but that the 
dew is formed because the air is cooler — having 
so through radiation of heat from the solids oa wl 
tlie dew forms. The dew itself, in forming, gives 
its latent heat, and so tends to equalize the tempenf 
This explanation made it plain why dew forms:' 
clear night, when there are no clouds to reflect the ] 
iint heat. Combined with Dalton's theory that 
is an independent gas, limited in quantity in any gijj 
space by the tem)>erature of that space, it solved - 
problem of the formation of clouds, rain, snofv, 
hoar-frost. Thus this pa))er of Wells^s closed the e| 
of s|M^culation regarding this field of meteorologji 
Ilutton's paper of 17Si had opened it. The fact 
the volume containing Ilutton's paper contained 
his epoch-making paper on Geology, finds curioasljj 
(Inplicatiou in the fact that Wells^s volume oontaii] 
also his essay on Albinism, in which the doctrine 
natural selection was for the first time formulated, i 
(Charles Darwin freely admitted after his own effc 
had made the doctrine famous. 


IV j 

The very next year after Dr. Wells's paper was pall-V 
lished, there appeared in France the third volume of the-^ 
Wmoirrs th: J^/if/sffjifr ct ijr Cli'ntiie fh la Soeiite cPAt'' 
ritrtl^ and a new epoch in meteorology was inaugurated. 
The society in question was numerically an inconse- 
((uontial band, listing only a dozen members. But every 
name was a famous one: Arago, Berard, IJerthoUet, 
niot, Ghaptal, de CandoUe, Diilong, (iay-Lussac, Hum- 
boldt, Laplace, Poisson, and Thenard — rare spirits every 





^B. Little danger that the memoirs of such a band 
^Buld be relegated to the diistj shelves where most 
pmoeediTigs of sacieties Ixslong — no inilk*for*babes fare 
»ald be served to such a company, 
e particular paper which here interests us closes 
third and last Tolume of memoir's. It isentitled2?e« 
\^ m4/tenn^'i( tt th' lu distrihutimi de la chalmir stir le 
The author is Alexander UumbohiL Needless 
.\% the topic is handled in a masterly manner. The 
ribution of heat on the surface of the globe, on the 
iniUain sjiies, in the interior of the earth ; the causes 
1 regulate such distribution; 'the climatic results — 
the topi cs d iscussed , B u t w h at g i ves e poe h al 
er to the pa|5er is the introduction of those iso* 
rmal bnes, circling the earth in irregular course^ join- 
together places having the same mean annual tem- 
uture, an«l thus laying the foundation for a science of 
jmrative climatology. 
It is true the attempt to study climates comparatively 
Dot new. Mairan had attempted it in those papers 
which he develojied his bizarre ideas as to central 
enianatioHs of heat. Euler hail bruugkt his profound 
iuathf*rnatic.!al genius to beiir on the topic, evolving the 
'"^:^riordinary conclusion that under the equator at 
^Ijt the coltl ought to be more rigorous than at 
I ibe pole*i in winter" And in particular Richard Kir- 
"" ■ tht! EnglisElj chemist, had combined the matheraat* 
nil the empirical methods, and calculated teraper- 
for all latitudes. But Iluraboldt differs from all 
iredecessors in that he gras]}s the idea that the 
all such computations should be not theory, but 
Ue drew his isothermal lines not where some oe- 
ii calculation would locate them on an ideal globe, 



but where practical tests with the thermometer locate 
them on our globe as it is. London, for example, lies in 
the same latitude as the southern extremity of Hudson 
Bay ; but the isotherm of London, as Humboldt outlines 
it, passes through Cincinnati. 

Of course such deviations of climatic conditions be- 
tween places in the same latitude had long been known. 
As I[uinl)oldt liimself observes, the earliest settlers of 
America wore astonished to find themselves subjected 
to rigors of climate for which their European experience 
had not at all prepared them. Moreover, sagacious 
travellers, in particuhir Cook's companion on his second 
voyage, j'oung George Forster, had noted as a general 
principle that the western borders of continents in tem- 
perate regions are always warmer than corresponding 
hititudcs of their eastern borders; and of course the 
general truth of temperatures being milder in the vicin- 
ity of the sea than in the interior of continents had long 
been familiar. Hut Humboldt's isothermal lines for the 
first time gave tangibility to these ideas, and made prac- 
ticable a truly scientific study of comparative climatol- 

In studying these lines, particularly as elaborated by 
further ol)servati()ns, it became clear that they are by 
no means liai)hazard in arrangement, but are dependent 
upon geographical conditions which in most cases arenot> 
(lilHcult to determine. Humboldt himself pointed out 
very clearly the main causes that tend to produce de^ 
via t ions from the average — or, as Dove later on callecl 
it, the normal— temperature of any given latitude. Foi* 
example, the mean annual temperature of a region (re- 
ferring mainly to the northern hemisphere) is raised bjT 
the {)roximity of a western coast ; by a divided config*- 



ttoiiaf ihe continent into peninsulas ; by the existence 

tif open aeas to the north or of radiating continental 

ftu ' To the south; by mountain I'anges to shield 

ft' 'I winds; by the infrequeney of swamps to be- 

come congeiiletl ; by the absence of woods in a dry, 

idr soil ; ami by the serenity of sky in the summer 

ntbs, and the vicinity of an ocean current bringing 

water which is of a higher tempernture than that of the 

I] ltd in;; ^a. 

^' 'editions opposite to these tend^ of course, corre- 

ngly to lower tlie teinperatum. In a word, Hum* 

btildt 9ays the climatic distribution of heat depends on 

the relative distribution of hind and sea, and on the 

**hyf«Himeiricnl conHgiirutiun of the continents''; and 

be urged that '* i^recit meteorological phenomena cannot 

W ©omjii*ehended when considered independently of 

googooiitii' rcdatiuns ■'— a truth which, like most other 

genemt principles, seems simple enough once it is 

pr>inted out. 

Witli that broad sweep of imagination which charac- 
lerixe^l him, Humboldt speaks of the atmosphere as the 
•* aerial ocean, in the lower strata and on the shoals of 
tiiich vre live^*' and he studies tlie atmospheric phe* 
oomena always in relation to those of that other ocean 
4 water. In each of these oceans there are vast per- 
imneni currents, flowing always in determinate direc* 
iirms, tvliicli enormonsly modify the climatic conditions 
_ijlL*verv zone. The ocean of air is a vast niaelstrom, 
Wling up always under the influence of the sun's heat 
mator, and ttowiiig as an upper current towards 
, 1l% \vh\\v an un(h:?r current fn>m the poles, wliicli 
ib«»in«i the tradi>winds, flows towards the equator to 
wipply Jts place, 

M 177 

CB ^ 


Bat the superheated equatorial aiTj becoming chilled, 
descends to the surface in temperate latitudes, and con- 
tinues its iioleward journey as the anti-trade winds?. 
The trade- wi nils are deflected towainds the west, because 
in approaching the equator they constantly pass over 
surfaces of the ciirth haviufj a greater and greater veloc- 
ity of rotation, and so, as it were, tend to lag behind — 
an exphmatton which lladley pointal out in 17^5, but 
which was not accepted »ntil Dalton independently 
worked it out and promulgated it in 1793. Fcjr the 
opposite reason, the anti-trades are deflected towartls 
rlie east ; hence it is that the western borders of con- f 
tinents in temperate zonc^ are bathed in moist sea* 
breezes, while their eastern bordera lack this cohidis* 
[Jelling influence. 

In the ocean of water the main currents run as more 
sharply circumscribed streams — veritablerlvci*s in the sea, 
()t these the best known and most sharply circumscribed 
is the familiar Gulf Stream, wljich has its origin in an 
equatorial current^ impelled westward by trade-winds, 
which is deflected northward in the main at Caj^e St. 
Koque, entering the Caribbean Sea ancf Onlf of Mexico, 
to emerge (inally through the Strait of Florida, and 
journey olF across the Atlantic to warm the shores of 

Such, at least, is the Gulf Stream as Humboldt under- 
stood it. Since his tinie^ howev^er, ocean currents in 
general, and this one in particular, hare been the subject 
of no end of controversy-, it being hotl}^ disputed w^hether 
either causes or effects of the Gulf Stream are just what 
Humboldt, in common with others of his time, con* 
ceived them to be. About the middle of the century, 
Lieutenant M. F. Maury, the distinguished American 





liydrognipher and meteorologist, advocated a theory of 

graritatioD as the cbief cause of the curr-ents, claiming 
that difference in densh}^ duti to difference in temper- 
ature aod sultness, would sufflciently account for the 


oceanic circulation. This theory gained great ixipularity 
through the wide circulation of Maury's Phpnail Genf/- 
raphy of the Sea^ which is said to have passed through 
more editions than any other scientitic book of the 


period ; but it was ably and vigorously combated by Dr. 
James Croll, the Scottish geologist, in his Climate and 
Time^ and latterly the old theory that ocean currents 
are due to the tiude-winds has again come into favor. 
Indeed, very recently a model has been constructed, with 
the aid of which it is said to have been demonstrated 
that prevailing winds in the direction of the actual trade- 
winds would produce such a current as the Gulf Stream. 

Meantime, however, it is by no means sure that gravi- 
tation does not enter into the case to the extent of pro- 
ducing an insensible general oceanic circulation, inde- 
jHjndent of the Gulf Stream and similar marked currents, 
and similar in its larger outlines to the polar-equatorial 
circulation of the air. The idea of such oceanic circula- 
tion was fii'st suggested in detail by Professor Lenz of 
St. Petersburg, in 1845, but it was not genendly recog- 
nizxnl until Dr. Carpenter independently hit upon the 
idea more than twenty years later. The plausibility of 
the ooncc^ption is obvious; yet the alleged fact of such 
circulation has been hotly disputed, and the question is 
still .si(h jinUce. 

I>ut wii(»ther or not such general circulation of ocean 
water takes place, it is beyond dispute that the recog- 
nized euirents carry an enormous quantity of heat from 
the tropics towai'ds tlu^ poles. Dr. CroU, who has per- 
haps given more atttMition to the i)hysics of the subject 
than almost any other person, computes that the Gulf 
Stream conveys to the North Atlantic one-fourth as 
much heat as that body receives directly from the sun, 
and he arguc^s that were it not for the transportation of 
heat by this and similar Pacific currents, only a narrow 
tropical region of the globe would be warm enough for 
habitation by the existing faunas. Dr. CroU argues that 



li^^lit cliange m the relative values of northern and 
Itfaem Irade^ winds (eiich as he believes has taken 
nt various periods in the past) would suffice to so 
MiUiT the etjoa tonal current which now feeds^ the Gull" 

tteam that its main bi^lk would be deflected southward 
letid or north wikril, l*y tlie angle of Cape St. Roque. 
fus the Gulf 8treiim would be nipped in the bud, and, 
Hording U> Dr. Croll's estimates, the results would be 
ftfitroys for the northern hemisphere. The auti-trades, 
l^ieh now nm warrnetl by the Gulf Stream, would then 
^^^p>^r as cokl winds across the shonis of we^^tem Europe, 
gild in all pmbabdity a glacial epoch would su[>6rvene 
>tighout the northern hemisphere, 
The same congcquentvs* so far as Europe is con- 
aed at least, would ap|iarantly ensue were the Isth- 
[IS of Panama to settle into tlie sea, allowing the Car 
^bean current Up pass into the Pacific, But the geoU 
hst tells us that this isthmus rose at a comparatively 
!fnt gt^ologicai period, though it is hinted that there 
bi bt*en some tirne previously a temporary land con- 
ctiuri between the two continents. Are we to infer, 
m^ that the two Americas in their unions aad dis- 
liocis have juggled with the climate of the other bem^ 
pkref Apparently so, if the estimates made of the 
mfluence of the Gulf Htream be tenable. It is a far cry 
frm Piiminia to Russia. Yet it seems within the possi- 
Liiiii*si that the meteorf>logist may learn from thegeolo- 
atuf Central America something that will enable him 
explain to tlie paleonti>logist of Europe how it 
lat at one tiine the niammoth and rhinoceros 
^r^j6s northern Siberia, while at another time 
? reindeer and musk-ox browsed along the shores of 



Possibilities, I said, not probabilities. Yet even the 
faint glimmer of so alluring a possibility brings home to 
one with vividness the truth of Humboldt's perspicuous 
observation that meteorology can be properly compre- 
hended only when studied in connection with the com- 
panion sciences. There are no isolated phenomena in 

Yet, aftor all, it is not to be denied that the chief 
concern of the meteorologist must bo with that other 
medium, the *' ocean of air, on the shoals of which we 
live.'' For whatever may be accomplished by water 
cuiTonts in the way of conveying heat, it is the wind 
currents that effect the final distribution of that heat 
As Dr. Croll lias urged, the watere of the Gulf Stream 
do not warm the shores of Europe by direct contact, 
but by warming the anti-trade-winds, which subsequent- 
ly blow across the continent. And everywhere the 
heat ac(uimulated l)y water becomes effectual in modi- 
fying climate*, not so much by direct radiation as by dif- 
fusion througli the mtjdiuin of the air. 

This very obvious importance of aerial currents led 
to tluMr pi'actioa.l study long before meteorology had 
any till(^ to tin* rank of s(;i<MK*(\ and Dalton's explana- 
tion of th(i trade winds had laid the foundation for a 
sfi(Mico of wind dynamics hofore our century began. 
I>nt no substantial further advance in this direction was 
effected until about IS'27, when lleinrich W. Dove, of 
lvr>nigsborg, aftoi'wards to be known as perhaps the fore- 
most meteorologist of his generation, included the winds 
among the subjects of his elaborate statistical studies in 



jxe classified the winds sris permanent^ perioflical, 

rariable. His great discuvery was that i\ll wiuds^ 

>f whatever charact*?r, and not inemlj the permanent 

rinds, come ittider the iritttiencu of the eartlrs rotation 

isach a wny as to im detiected from their coui'se, and 

^imOQ to take on a gyratory motion — that, in short, all 


local winds are minor eddies in the gvmt polar^cfpmtori^ 
d whirl, and tend to reproduce in miniature the cliar- 
acter of that vast niaelstronu For thtj lirst time, then, 
tera|K>rary or variable winds were seen to lie within the 
prerinc4.^ of hiw* 
A generation later. Professor William Ferrel, the 

m nil 


Aniericiin meteomlogist, who had been led to take up 
the subject by a i perusal of Maury ^s discourse on ocean 
winds, formuhited a gcnend mathematical hiw, to the 
effect that any body moving in a right line along the 
surface of the eartli in any direction tends to have its 
C(nii*se deflected, owhig to the earth's rotation, to the 
right hand in the northern and to the left hanil in tlie 
southern henussphcres» This law had indeed ijeen stated 
as early as 1885 by tlie French pliysicist Poiss^jn, Init no 
one then thought of it as other tfjan a mathematical 
curiosity ; its true significance was only untler-stood after 
Professor For rel hail itnlqiendently rediscovered it (just as 
Dal ton rciiisctovered Had ley's forgotten law of the trade- 
winds) and applied it to the motion of wind currents. 

Then it became clear that here is a key to the phe- 
nomena of atmosplieric circulation, from th e great ]x>lar- 
equatorial maelstnim which manifests itself in the trade- 
winds, to the most circumscribetl rifHe which is an- 
nounced as a local stonn. And the more the phenoni* 
ena were studied, the more striking seemed the parallel 
between the greater maelstrom and these lesser eddies. 
Just as the entire atmospheric mass of each hemisphere 
is seeUj when viewed its a whole, to be carried in a great 
whirl about the pole of that hemisphere, so the local dis- 
turbances within til is great tide are found always to M 
take the form of wliirls alKmt a local storm* centre^ " 
which storm^entre, meantime, is carried along in the 
major current, as one often sees a little whirl|K>ol in the 
water swept along with the main currtmt of the streK^m* 
Sometimes, indeed, the local eddy, caught as it were in 
an ancillary current of the great polar stream, is de- 
flected from its normal course and may seem to travel 
against the stream; but such deviations are departures 




tfuw the rule. In the great majority of cases, for ex- 
ample, in the north- temperate zone, a storm-centre (with 


its attendant local vrJiirl) travels to the northeast, along 

Ih*; main current of the anti-trade^wind, of which it is a 



part ; and though exceptionally its course may be to the 
southeast instead, it almost never departs so widely 
from the main channel as to progress to the westward. 
Thus it is that storms sweeping over the United States 
can be announced, as a rule, at the seaboard in advance 
of their coming by telegmphic communication from the 
interior, while similar storms come to Europe oflf the 
ocean unannounced. Hence the more practical availa- 
bility of the forecasts of weather bureaus in the former 

But these local whirls, it must be understood, are local 
only in a very general sense of the word, inasmuch as a 
single one may be more than a thousand miles in diam- 
eler, and a small one is two or three hundred miles 
across. But quite without regard to the size of the 
whirl, the air composing it conducts itself always in one 
of two ways. It never whirls in concentric circles ; it 
always either rushes in towards the centre in a de- 
scending spiral, in which case it is called a cyclone, 
or it spreads out from the centre in a widening spiral, 
in which case it is called an anti-cyclone. The word 
cyclone is associated in popular phraseology ^vith a 
terrific storm, but it has no such restriction in techni- 
cal usag(\ A gentle zephyr flowing towards a "storm- 
centre'' is just as much a cyclone to the meteorologist 
as is tlie whirl constituting a West- Indian hurricane. 
Indeed, it is not properly tiie wind itself that is called 
the cyclone in eitlier case, but the entire system of 
whirls — including the storm-centre itself, where there 
may be no wind at all. 

What, then, is this storm-centre? Merely an area of 
low barometric pressure — an area where the air has be- 
come lighter than the air of surrounding regions. Under 





linilfldQee af gmritation the air seeks its level just as 

[water does; so the heavy air coraes flowing in from all 

I sides towards the low-pressure area, which thus becomes 

** storm 'Centre/' But tbe inrusbing currents never 

>iiie atmight to their miirk. In accoitlance ivith Fer- 

er« biw, they are deflcetetl to tbe right, and tbe result, 

as will readily be seen, mast be a vortex curi*ent, wbicb 

vrbirls always in one direction — narauly, from left to 

[fight, or in the direction o|j[>osite t^) iliat of tbe hatids 

[jL watch held with its face upwan!. The velocity of 

^cyclonic currents will dep^snd largely upon tbe dif- 

fen^nce in baruinetric pressure between the storm-centre 

land the confines n( tlie cyclone system. And the veloo- 

Ifty of tbe currents will determine to some extent the 

«gree of dt?fiection, ami hence the exact path of the 

Ntjgcending spiral in which the wind approaches the 

l^entre. But in every case and in every part of the 

|py clone system it is true, as Buys Biiliot's famous rule 

pointed out, that a person standing with his back 

the wind has the storm-centre at his lefL 

Tbe primary cau^e of tlie low barometrio pressui^e 

which marks tbe storm-centre «ind establishes the 

sy clone is expansion of the air tli rough excess of tern- 

?rature. Tbe heated air, rising into cold upjier regions, 

laa a portion of its vapor condensed into clouds, and 

low a new dynatJiic factor is a<ld*.*d, for each particle of 

rapor, in condensing, gives up its modicum of latent 

tieat* Each pound of va[>or thus liberates, according to 

'rofessor TyndalTs estimate, enough heat to melt live 

3unds of cast iron ; so the amount given out where 

^arge masses of cloud are forming ntust enormously add 

the convection current® of the air, and hence to the 

itorm- developing power of tbe forming cyclone. In- 



deed, one schcK>l of meteorologists, of whom Professor 
Espy was the leader, has held that without such added 
increment of energy constantly augmenting the dynamic 
effects, no storm could long continue in violent action. 
And it is doubted whether any storm could ever attain, 
much less continue, the terrific force of that most dread- 
ed of winds of temperate zones, the tornado — a storm 
which obeys all the laws of cyclones, but dffers from 
ordinary cyclones in having a vortex core only a few 
feet or yards in diameter — without the aid of those 
groat masses of condensing vapor which always accom- 
pany it in the form of storm-clouds. 

The anti-cyclone simply reverses the conditions of the 
cyclone. Its centre is an area of high pressure, and the 
air rushes out from it in all directions towards surround- 
ing regions of low pressure. As before, all parts of the 
current will be deflected towards the right, and the re- 
sult, clearly, is a whirl opposite in direction to that of 
the cyclone. But here there is a tendency to dissipa- 
tion rather than to concentration of energy, hence, con- 
sidered as a storm-generator, the anti-cyclone is of rela- 
tive insignificance. 

In particular the professional meteorologist who con- 
ducts a '' weather bureau" — as, for example. Sergeant 
Dunn, of the United States signal-service station in New 
York — is so i)reoccupied with the observation of this 
phenomenon that cyclone-hunting might be said to be 
his chief pursuit. It is for this purpose, in the main, 
that government weather bureaus or signal-service de- 
partments have been established all over the world. 
Their chief work is to follow up cyclones, with the aid 
of telegrapliic reports, mapping their course, and record- 
ing the attendant meteorological conditions. Their so- 


I called predictions or forecasts are essentidly preclica- 
lions, gaining locally the effect of predictioBS because 
the Idagraph outstrips the wind* 
At only one place on the globe has it been possible as 
yet for the ineteorologist to make long-time forecasts 
meriting the titto of predictions. This is in the middle 

I'^' ' VaUey of northern India* In this country the 
c r conditions are largely dependent iii>on the peri* 

bdical winds called monsoonSj which blow steadily land- 
ward from April to October, and seawaixl from October 
to ApriL The summer monsoons bring the all-essential 
mins ; if they are delayed or restricted in extent, there 

iirill be <1 fought and eonseqaent famine. And such re- 
striction of the monsoon is likely to result when there 
has« iieen an unusually deep or very fate snowfall on the 
Himalayas^ Ixscause of the lowering of spring tempera- 
lure by the melting snow. Thus here it is possible, by 
observing the snowfall in the mountains, to pretlict with 
mme measure of success the average rainfall of the fol- 

I lowing sumraen The drought of 189(5, with the conse- 
quent famine and plague that *levastated India last win- 
ter, was thus predicted some months in advance. 

This is the greatest present triumph of practical me- 
Amrolot^y. IS'otbing like it is yet possible anywhere in 
leinpemtu zones. But no one can say v^^hat may not l>e 
))0«iaible in times to come, when the data now being 
I gathered all over the world shall at last he co-ordinated, 
cla»8ifieil» and made the basis of broad inductions. Me- 
teorology is pre*eminenttj' a science of the future- 



There were giants abroad in the world of science in 
the early days of our century. Herschel, Lagrange, 
and Laplace ; Cuvier, Brongniart, and Lamarck ; Hum- 
boldt, Goethe, Priestley — what need to extend the list? 
— the names crowd upon us. But among them all there 
was no taller intellectual figure than that of a young 
Quaker who came to settle in London and practise the 
profession of medicine in the year 1801. The name of 
this young aspirant to medical honors and emoluments 
was Thomas Young. He came fresh from professional 
studies at Edinburgh and on the Continent, and he had 
the theory of medicine at his tongue's end; yet his 
medical knowledge, compared with the mental treasures 
of his capacious intellect as a whole, was but as a drop 
of water in the ocean. 

For it chanced that this young Quaker physician was 
one of those prodigies who come but few times in a cen- 
tury, and the full list of whom in the records of history 
could be told on one's thumbs and Angel's. His biogra- 
phers tell us tilings about him that read like the most 
patent fairy-tales. As a mere infant in arms he had 



een able to read fluently. Before his fourtli birtlitlay 

lEoe he huJ roul the Bible twice througli, as well as 

ratifies //}//?i/i^— poor cliikl !— iuhI wIjou seven or eight 

had shown a projieiisity ta abisorb hmguages uiucli 

other children absorb nui'sery tattle and Mother 

hyose rhymes. When he wiis fourti^en, a young hul y 

risiting the hotisehuld of iiis tutor patruuizeil the pretty 

oy by a.'^king tu see a sj>eciuien of Ins peninauyfiip* 

The prolty boy complie*! reiwlily onuuf^ii, and mildly re- 

d his inteiToiifator by ra|ndly wrilir^g soiue sen- 

for her in fourteen languages, including such iis 

diian, Persian, and Ethiopia. 

Mi*-nntimc languages ha<1 been but an incipient in the 

Khicatirm of the hui* He seems to tiavo entereil every 

raiklde field of thought— mathematics, physics, bot- 

ny, liteniture, music, painting, hinguages* philosophy, 

inch:? - , imd mi on to tiresome lengths- anil nnce he 

lad 1 any field he seldinii turueil aside until he 

bad reached tlie con lines of tin* subject as then known, 

and ailded scunetiiing new froui tfie recesses of his own 

^l^nius. lie was as vorsuitile as Priestley, as profouml 

iXewt^m liimseir lie had the range of a mere dilot- 

[tante, but everywhere tlie full grasp of the master. He 

ltfM>k early for his motto the saying that wliat one man 

Iwii done, another man raay do, rtranting that the 

I Hbr msin has the brain of a Thomas Young, it is a true 


Stlch then wi\s the young Quaker who came to London 
to fallow out the humdrum lifo of a practitioner of medi- 
ant* in the year 1801 , But incidentally the young phy si- 
was prevailed upon to occupy the interims of early 

ticoby fulJllbng the duties of thecbair of Natural Phi* 

"itophy at the Royal Institution, which Count Runiford 




had founded, and of which Davy was then Professor ol 
Chemistry — the institution whose glories have been per 
})etuated by such names as Faraday and Tyndall, and 
which the liriton of to-day speaks of as the *' Pantheon 
of Science/' llci*e it was that Thomas Young made 
tliose studies which have insured him a niche in the 
temple of fame not far i*emoved from that of Isaao 

As early as 1703, when he was only twentj'', Young 
had begun to communicate pai)ers to the Iloyal Society 
of ]A>iidon, which were adjudged worthy to be printed 
in full in the Philosophical Transactions; so it is not 
strange that he should have been asked to deliver tile 
JJakeriuii lecture before that learned body the very fint 
year after he came to J^ondon. The lecture was deliv- 
(mhmI November 1-2, ISol. Its subject was ''The Theory 
of Light and C-olors/' and its reading marks an eiKKsb in 
physical science; for here was brought forward for the 
first time convincing proof of that undulatory theory of 
light witli whicli (iverv student of modern physics is far 
miliar — the tli(M>rv which holds tliat light is not a cor- 
\)(>voi\\ iMitity, but a mere pulsation in the substance of 
an all-)><M'vading ether, just as sound is a pulsation in the 
air, or in licpiitls or snlids. 

Young had, indeed, advocated this theory at an earii- 
(T date, hut it was not until ISOl that he hit upon the 
idea whicli enabled him to bring it to anything ap- 
]>n.)aching a demonstration. It was while pondering 
over th(^ familiar but puz/ling phenomena of colored 
rings into whieh white light is broken when reflected 
fi'om thin films -X(;wton's rings, so called — that an ex- 
planation occurred to him whic^h at once put the entire 
undulatory tlu^ory on a new footing. With that sagac- 


I £4fit qf Timnif, bf periiii«(op ef John Mnrmy, Ptjbllihen London 





of insight whicU we call genius, he saw of a sudderi 
pat the plictiomena could bt; explained by supposing 
Imt when rays of light fail on a tbiii ylu^s, jxirt of the 
i\B being retlticLed from tim upper surface, other rays, 
iected from the lower surface, might be so retarded 
their coai^e through tin* glass that the two sets would 
llerfere vvitli one another, the forward pulsjition of one 
iV corresjKHidiiig to the backward |jnLsation of another, 
Itis quite neutralising the effect. Some of the com- 
m^ni pulsations uf the light being thus effaced by 
Hual interference, the remaining rays wouhl no longer 
re the optieal effect of white light; imnce the puz^ 
Ing colors, 

[By following up this elew with mathematical preci- 
3n, measuring the exnct thickriei>rt ut ifm plate and the 
epsice between th© diffomnt rings of color. Young was 
We ti> hIiow mathemnttcally what must be the leni,rth 
' pulsation for each of the difft^rent colors of ttie spec- 
am, lie estimated that the undidiitions of re<l light, 
the extreme lower end of the visible spectrum, must 
d>er about 37,*i40 to the inch, ami puss any given 
ot at a rate of MV^ millions of millions of undulations 
a Sf3eond, while the extreme violet numbers 59,750 
nhilMti^m'i to the inch, or TM'i millions of millions to 
Ijf lieeond. 

Young similarly examined the colors that are pro- 
by scratches on a smooth surface, in particular 
the light from ** Mr. Coventry's exquisite mi- 
et«?r»,'* which consist of Hues scratched on glass at 
mertsur^l intervals, Theie microscopic tests brought 
the Jilts as the other experiments. The colors 

wer- ^ tl at certain definite and measurable angles, 

I And the theory of interference of undulations explainetl 


1 I ^r^ 


them perfectly, while, as Young affirmed with confi- 
dence, no other theory hitherto advanced could explain 
them at all. Taking all the evidence together, Young 
declared that he considered the argument he had set 
forth in favor of the undulatory theory of light to be 
"sufficient and decisive." 

This doctrine of interference of undulations was the 
absolutely novel ])art of Young's theory. The all- 
compjissing genius of Robert llooke had, indeed, very 
nearly api)relionded it more than a century before, as 
Young himself points out, but no one else had so much 
as vaguely conceived it ; and even with the sagacious 
Ilooko it was only a happy guess, never distinctly out- 
lined in his own mind, and utterly ignored by all others. 
Young (lid not know of llooke's guess until he himself 
had fully fonnnlated the theory, but he hastened then 
to give his predecessor all the credit that could possibly 
be a(lju(lir(Ml his due by the most disinterested observer. 
To llooke's contemporary, Iluyghens, who was the orig- 
inator of tli(» general doctrine of undulation as the ex- 
planation of li«;ht. Young renders full justice also. For 
hiniseir luM-lainis only tlie merit of having demonstrated 
llui theorv wliicli these and a few othei*s of his prede- 
cessors had advocated without full proof. 

TIh^ following year Dr. Young detailed before the 
Itoyal Society other experiments, which threw addi- 
tional light on th(* doctrine of interference; and in 1S03 
ho (!it(Ml still others, which, lie affirmed, brought the 
<loctrin(» to comph^te demonstration. In applying this 
demonstration to the general theory of light, he made 
the striking suggestion that " the luminiferous ether 
pervades the substance of all material bodies with little 
or no resistance, as freely, perhaps, as the wind passes 




roogli a grove of trees/' He asserted his lielief also 
at th© chemical rays whicli Rittor had discovered 
^yond the violet end of the visible spectrum ai'e but 
Idl more mpid undulations of the same character as 
lose ivhich prmluce light. In his eariier lecture ho 
ud affirmed a like afTinity between the light rays and 
he mys of radiant heat which llei'schel detected below 
the red end of the spectrum, suggesting that *Might 
ffers from heat only in the frequency of its undii* 
lions or vibrations^ those unchilations wduch are 
itliin certain limits with respect to frequency affect- 
g the optic nerve and constituting liglit, and those 
hich are slow^er and probably stronger constituting 
eitt only,*' From the very outset he iiad recognijsed 
le affinity between sound and light; indeed, it had 
n this affinity that led hirn on to an appreciation 
f the undnlatory theory of light. 
But while all these affinities seemed so clear to the 
*M co-ordinating brain of Youngs they made no such 
ion on the minds of his cuntemtK)raries> The 
i riality of light had been substantially demon- 

strated, but practically no one save its author accepted 
e demonstration, Newton's doctrine of the emission 
t corpuscles was too firmly routeti to be I'eadil}^ dis- 
lodged^ and Dr. Young had too many other interests to 
Gontintie the assault unceasingly. He occasionally wrote 
mvetliing touching on his theory, mostly papers con- 
ibuled to the QmirUrly Remew and similar period- 
^ anonymously or under a pseudonym, for be had 
iitcaiFed the notion that too great conspicunusnesB in 
OQtside of medicine would injure his practice as a 
Lfkbjsician. His Tiews regarding light (including the 
original papers from the PhUompkuHd Trmuaction^ of 



the Rmjal Society) were agaiti given publicity in full in 
liis celebrutt^d volume on natural philosophy, consisting 
iu part of I lis lectures before the Royal Institution^ pnb- 
lislied in 1807; but even then they failed to bring con- 
viction to the philosophic world* Indeed, they did not 
even arouse a controversial spirit, as his first papers had 

So it chanced that when, in 1S15, a young Fi'^nch 
military engineer, named Augustin Jean Fresnel, re- A 
turning from the Nnpoieonic wiu'^, beeaine interested in 
the iihenoniena of light, and made some experiments 
concerning diffraction, which seemed to him to contro- 
vert the accepted notions of tlie maicriality of light, he 
was quite unaware that his experiments had been an- 
ticipated by a philosopher across the Channel. He 
communicated hisexjieriinents and results to the French 
Institute, su]>posing them to be absolutely novel That 
body referred them to a committee, of which, as good 
fortune woidd have it^ the dominating member was 
T)omini(|ue Frani;ois Arago, anian as versatile as Young 
himself, and hardly less profound, if perhapii not quite so 
original Arago at once recognized the merit of Fres- 
iiefs worl%, and soon became a convert to the theory, 
lie told Fresnel that Youug had anticipate*! him as re- 
gards the general tiieorj^ but that much remained to be 
done^ and he offered to associate htm self with FresTiel 
in prosecuting tlie investigation* Fresnel was not a 
little dashed to learn that his original ideas had been 
worked out by another while he was a lad, but he 
bowed gracefully to the situation, and went ahead with 
unabated zeah 

The championship of Arago insured the undulatory 
theory a hearing before the Froncli Institute, but by no 


^ alMTlCti 



, n.K«^ M^***^^"^ 





■ tni 

^^^kis t» u ill eoil to b r i n g a bo u t i ts gen e ral accept a n ce . On 

^^TO contrary, a bitter feud ensued, m which Arago was 

oppose*] by the ^vJupiter Olympius of the Academy/' 

Laplace, by the only less famous Poisson, and by the 

IrouRi^^er but hardly less abl« Biot. iSo bitterly raged the 
peud tliat a life- long friendsliip between Arago and Biol 
|r;i£t ruptur*?d forever. The opposition managed to delay 
Ihe piiblicatioa of FresnePs pajiei"S, liut Anigo continued 
\u light with his custoimiry enthusiasm and pertinacity, 
and at last, in 1823, the Academy yielded, and voted 
Fresnel into ity ranks, thus implicitly admitting the 
value of his work: 

It is a h mil i lifting thought that such controvei*sies as 
this must mar the progress of scientific truth ; but fort- 
ly the story of the introduction of the undulatory 
ry has a more |>leasant side. Three men, great both 
iadianicterand In intollect, were concerned in pressing 
its claims — Young, Fresnfel and Arago — ^and the rela- 
tions of these men form a picture un marred by any 
of those petty jealousies that so often dim the lustre 
of great names. Fresnel freely acknowletiged Young's 
priority so soon as his attention w*as called to it ; and 
YtMing ap|)hLuded the v^^ork of the Frencliman, and 
sii'lod with his counsel in the application of the undnla- 
^m tlH:H>ry to the problems of polarization of light, 
which still dcmandetl explanation, and whicli Fresnel's 
ff^itiltty of experimental resource and ))rofimdity of 
it*3tlb(*matical insight sutticed in the end to conquer. 

After Fresnefs admission to the Institute in 1823 the 

oppffsition weakened, and gradually the philosophers 

cami* to realize the merits of a the<irv which Younsr 

vainly called to th<*ir attention a fnll quarter- 

iirv before, ^ow, thanks largely to Arago, both 


Young and Fresnel received their full meed of apprecia- 
tion. Fresnel was given the Rumford medal of the 
Royal Society of England in 1825, and chosen one of the 
foreign members of the Society two years later, while 
Young in turn was elected one of the eight foreign 
members of the French Academy. As a fitting culmi- 
nation of the chapter of felicities between the three 
friends, it fell to the lot of Young, as Foreign Secretary 
of the Royal Society, to notify Fresnel of the honors 
shown him by England's representative body of sci- 
entists; while Arago, as Perpetual Secretary of the 
French Institute, conveyed to Young in the same year 
the notification that he had been similarly honored by 
the savants of France. 

A few months later Fresnel was dead, and Young 
survived him only two years. Both died premature- 
ly ; but their great work was done, and the world will 
remember always and link together these two names in 
connection with a theory which in its implications and 
importaneo ranks little below the theory of universal 


The full importance of Young's studies of light might 
perhaps have gained earhcr recognition had it not 
clianced that, at tlie time when they were made, the 
attention of the philosophic world was turned with the 
lixity and fascination of a hypnotic stare upon another 
Held, which for a time brooked no rival. How could 
the old familiar phenomenon light interest any one 
when the new ag(mt galvanism was in view? As well 
ask one to fix attention on a star while a meteorite 
blazes across the sky. 




The t|uestioti of the hour was wliether in galvuDisin 
[le world hail to do with a new force, or wiiether it is 
Wt^ntical with electricity, iiia.sking under a new form. 
V*>ry t^arlir in the century the profountl, if rather cap 
^Hi>fis^ Dr. Wollaston made experiments which seemed to 
^Biow that the two are identieul ; and bv l!SU7 Dr, Young 
^BDuhJ write in his published lectures : '' The Identity of 
^B>e general causes of electrical and of galvanic effects is 
^Bow doubted by few," To be entirely accumte, he 
^^h«iuld have added, ** by few of the leaders of scieiitilie 
I Ihougbl/* for the lesser lights were by no means so fully 
^A^greed as tbo sentence cited might seem to imply « 
^^ I5ut ineantiine an even nic^re striking uttinity had been 
found for ilm new agent galvanism. From tije lii'st it 
id \}^en the cliemists rather^ than the natural pbiloso* 
phers— the woi'd physicist was not then in vogue — who 
4 clnetly experimented witli \"olUfs battery ; uTid the 
cute mind of Humphry Davy at once recognised the 
clijse ivlalionshi]^ between chemical decom] Position and 
Ihe appearance of the now '* imponderable/' The great 
ISwc^iisli cheniiat Berzelius also had an inkling of the 
fiwne thing. But it was Davy who fii^st gave the 
thought full expression, in a Baker ian lecture before 
i\m lUtyai Society in 1800 — the lecture which gained 
bim nut only the plaudits of bis own countrymen, but 
die Xtipoleohic pri?^ of the French Academy at a time 
wlten the political bodies of the two countries were in 
llitj midst of a sanguinary war, '' Scit^nce knows no 
c<miitry,'' said the young Englishman, in accepting the 
Freijcli testimonial, against tlie wishes of some of the 
mo(^ imrrovv*minded nf his friends. '* If the two conn- 
Wcior governments are at wan tlie men of science are 
»ftt That would, indeed, be a civil war of the worst 



description. We should rather, through the instro- 
mentality of men of science, soften the asperities of 
national hostility." 

Here it was that Davy explicitly stated his belief 
that "chemical and electrical attraction are produced 
by the same cause, acting in one case on particles, in 
the other on masses," and that "the same property, 
under different mollifications, is the cause of ail the 
phenomena exhibited by different voltaic combinations." 
The phenomena of galvanism were thus linked with 
chemical action on the one hand, and with frictional 
electricity on the other, in the first decade of the cen- 
tury, showing that electricity is by no means the iso- 
lated " fluid '' that it had been thought. But there the 
matter rested for another decade. The imaginative 
Davy, whose penetrative genius must have carried him 
further had it not been diverted, became more and more 
absorbed in the chemical side of the problem ; and 
Young, having severed his connection with the Royal 
Institution, was devoting himself to developing his med- 
ical practice, and in intervals of duty to deciphering 
Egyptian hieroglyphics. Parenthetically it may be 
a<hled tliat Young was far too much in advance of his 
time to make a great success as a practitioner (people 
demand sopliistrv rather than pliilosophy of their fam- 
ily physician), hut that his success with the hiero- 
glyphics was no less novel and epoch-making than his 
work in pliilosophy. 

For a time no master-generalizer came to take the place 
of these men in the study of the ''imponderables "as such, 
and the phenomena of electricity occupied an isolated cor- 
ner in the realm of science, linked, as has been said rather 
to chemistry than to the field we now term physics. 



But in the year 1819 there flashed before the philo^ 
sophic world, like lightning from u clear sk}^ the report 
that Hans Christian OersteJ, the Danish philosopher, 
had discovered that the magnetic needle may be deflect- 
by the passage near it of a onrrent of electricity. 
Mie exiwrimont was t^penteel everywhere. Its validity 
rsiB Un'ond quest ion J its importance beyond estimate* 
my men had vaguely dreamed that thei*e might be 
)me CKinnection between electricity and magnetism — - 
liofly IjeoiiUSLt e^ich shows phenomena of seeming at- 
;tiofi and repulsion — ^but here was the first exi>eri- 
Hental evidence that any such connection iictaally ex- 
iU. The wan tiering eye of science was recalled to elec- 
picity as sudilerdy anil as irresistibly as it had been in 
S0O by the discovery of the voltaic pile. But now it 
^as the ptiysieal rather than the chemical side of the 
Bbjeet that chiefly demanded attention. 
At once Andre Marie Ampere, whom the French love 
call the Newton of electricity, appreciated the far* 
?hing importance of the newly disclosed relationships 
tid, combining mathematical and experimental studies, 
liowed how close is the link between electricity and 
aetism, and suggested the possibility of signalling 
^distance by means of electric wires assoeiatetl with 
ma^etic needles. Gauss, the great mathematician, and 
JWeber, the physicist, put this idea to a practical test by 
rnnmnntcating with one another at a distance of sev- 
f^nil roods, in Gottingen, long liefore ^'practicaP' teleg- 
n[ihy grew out of Oersted's discovery. 

A new jmpetns thus being given to the investigators^ 
iin epoch of electrical discovery naturally followed. For 
^Miini^ intereat centred on the French investigators, in 
licBlar upon the experiments of the ever^receptive 

2Q7 • 


Arago, who discovered in 1825 that magnets may be 
produced at will by electrical induction. But about 
1830 the scene shifted to London ; for then the protege 
of Davy, and his successor in the Royal Institution, 
Michael Faraday, the '' man who added to the powers 
of his intellect all the graces of the human heiirt," began 
that series of electrical exi)eriments at the Royal Insti- 
tution which wei*e destined to attract the dazed atten- 
tion of the philoso|)hic world, and stamp their originator 
as *' the greatest experimental philosopher the world 
has ever seen." Nor does the rank of prince of experi- 
mentei-s do Faraday full justice, for he was far more 
than a mere experimenter. He had not, i)erhaps, quite 
the intuitive insiglit of Davy, and he utterly lacked the 
profound mathematical training of Young. None the 
l(»ss was lie a num who could dream dreams on occasion, 
and, as Maxwell has insisted, think in mathematical 
clianni^ls if not with technical symbols. Only his wagon 
must always traverse earth though hitched to a star. 
His dn»ams gui<l(?(l him onward, but ever the hand of 
experiment k(*pt clieek over the dreams. 

It was in ls:U that Faraday opened up the field of 
magneto-electricity. Reversing the experiments of his 
prechM't^ssois, who liad found tliat electric currents may 
g<Mierate magn<'tism, he showed that magnets have 
power under ciM'tain circumstances to generate electric- 
ity ; he ])rov(»(I, indeed, the interccmvertibility of elec- 
tricity and magn(»tism. Then he showed that all bodies 
an* more or less subject to tlie influence of magnetism, 
and that even light may Ix* affected by magnetism as to 
its phenomena, of polarization. He satisfied himself 
conipletc^ly of the true identity of all the various forms 
of electricity, and of the convertibility of electricity and 



bemical action. Ttiiis he linked together ligfit, cliemi- 
cjil ufiinity* magnetism, and electricitj; And, moreover, 
he knevv full well tliat no one of these can bu produced 
11 iiKlrfinite supply fvoni another. No\vherej he say^, 
there a pure creation or proiluction of power with- 
it a corresponding exhaustion of something to supply 

When Faraday wrote those words in 1840 he was 
idiug on the very heels of a gi'eater generalization 

bin any which he actually formu luted ; nay, lie had it 
fairly within Itts reach. He saw a great truth witiiout 
fully realizing its import; it was left for others, ap- 

^laching the same truth along another path, to point 

It its full signifleunce. 


JThe great generalimtion which Faraday so narrowly 
Issed 13 the truth wldch since then has become familiar 
the doctrine of the conservation of energy — the law 
in transforming energy from one condition to an- 
we can never secure more than an equivalent 
ijuantity ; that, in short, '* to create or annihilate ener- 
£jy i.^ as imjKissible as to create or annihilate matter; 
^ml that all the phenomena of ttie material universe 
Diisi&t in transformations of energy alone/' Some phi- 
lers think this the greatest generalization ever 
ivtMl by the mind of man, Be that as it Tnay, it is 
amly one of the great intellectual landniarks of our 
otury. It stands apart, so stupendous and so f ar- 
ching in its implications that tlie generation which 
saw the law developr3d could little a))prpciate it; 
uly now, ihnnigh the vista of half a century, do we 
h'^n to see it in its true proi>ortions. 




A vast generalization such as this is never a miub- 
rooni growth, nor dues it usually spring full grow^n from 
the mind of any single man. Ahvaiys a namber of 
minds ai*e very near a truth before any one mind fully 
grasps it. Pre-eminently true is this of the doctrine of 
conservation of energy, ^'ot Faraday alone, but half a 
dozen ditl'erent men had an inkling of it before it gained 
full expression; indeed, every man who advocated the 
undulatory theory of light and heat was verging towaids 
tlu: g(»al. The doctrine of Young and Fresnel waa as a 
highway leading surely on to the wide plain of oo^8e^ 
vation. The ])henomona of olectro-magnetiam fnmisbed 
another sneh highway. Hut there was 3'et another roaid 
which led just as surely and even more readily' to the 
same gojil. This was the road furnished by the phe- 
nomeiiM of<l the men who travelled it were des- 
tiiird to outstrip their fellow-workei's ; though, as ire 
imve seen, wayfjirers on other roads were within hailing 
distance when the l(»ad(M*s passed the mark. 

In order to do <*ven approximate justice to the men 
who eiilenMl into tln^ gi'tNit achievement, we must recall 
that jiisl nt tlie close of tlu^ last, century Count Rumford 
aiiil Ilnniplu'v Davy inde])eiidently showed that labor 
may he Iransfoi-mtMl into heat : and correctly interpreted 
this fact as nuNining the transformation of molar into 
molecular motion. We can hardly doubt that each of 
th(»se men of genius realized, vaguely, at any rate, that 
tlnTe must he a. close corres])ondence between the 
amount of the molar and the molecular motions; hence 
tliat each of them was in siglit of the law of the nie- 
clianical eipiivalent of heat. I^ut neither of them quite 
gras])(»d or explicitly stated what each must vaguely 
have seen; and for just, a (jna]i<'r of a century no one 






else even came abreast their line of tliouglit, lei alone 
passing it. 

But tben, in 1824r, a French philosopher, Badi Carnot, 

E'^"f^ht step ivitli the great Eiigliabrnun, ami look a long 
ahead by explicitly stilting his belief that a definite 
itily of work coukl be traiisforrncd into a delinite 
Bantity of iieat, no more, no less. Carnot did not, ia- 
ifif rtiacb the clear view of his pretlecessors as to tht^ 
fmturu of heat, for \m still thought it a form of ** impon^ 
dentble" flakl ; but he reasoned none the less clearly as 
to its mutual convertibility svith niechanrcal work. But 
iatix>rtant as his conclusions seem now that we look 
kck u(»on ttieni with clearer vision, tfjey made no im- 
preasiou wlmtever upon bis conlompuraries. Carnors 
work ill this line was an isolated phenomenon of histori- 
cal inten^st, but it tbd not enter into tlie scheme of the 
Cf>m{>leted narrative in any such way as did the work of 
ItEtnford atid Davy. 

The man w*ho really took up tlie broken thread where 

liforel and Davy had dropped it, and wove it into a 

iph'ted texture, came njion tije scene in 1840. His 

El© was in Manchester, England ; his occupation that 

manufacturer. He was a friend antl pupil of the 

It Dr. Dalion* His name was James pj'r.ncutt Joule. 

ben posterity has done its final juggling with the 

im of our century* it ts not unlikely that ihe name of 

Manchester philosopher will be a household word 

p: Uic names of Aristotle, Copernicus, and Newton. 

[For Joule's work it was, done in the fifth decade of our 

.which demonstrated beyond all cjivil that there 

else and alisolute equivalence between mechani- 

trork and heat ; that whatever the form of mani- 

Atalion of molar motion, it can generate a definite and 



measurable amoant of heat, and no more. Joule found, 
for example, that at the searlevel in Manchester a poond 
weight falling through seven hundred and seventy-two 
feet could generate enough heat to raise the temperatare 
of a pound of water one degree Fahrenheit. There was 
nothing haphazard, nothing accidental, about this; it 
bore the stamp of unalterable law. And Joule himself 
saw, what others in time were made to see, that this 
truth is merely a particular case within a more general 
law. If heat cannot be in any sense created, but only 
made manifest as a transformation of another kind of 
motion, then must not the same thing be true of all 
those other forms of *' force " — light, electricity, magnet- 
ism — which had been shown to be so closely associated, 
so mutually convertible, with heat? All analogy seemed 
to urge the truth of this inference ; all exi)eriment tend- 
«.m1 to confirm it. The law of the mechanical equivalent 
of heat then became the main corner-stone of the greater 
law of the conservation of energy. 

But while this citation is fresh in mind, we must turn 
our attention with all haste to a country across the 
Channel — to Denmark, in short— and learn that even as 
Joule experimented with the transformation of heat, a 
philosopher of Copenhagen, Colding by name, had hit 
upon the same idea, and carried it far towards a demon- 
stration. And then, without pausing, we must shift yet 
again, this time to Germany, and consider the work of 
tiiree other men, who independently were on the track 
of the same truth, and two of whom, it must be admit- 
ted, reached it earlier than either Joule or Colding, 
if neither brought it to quite so clear a demonstra- 
tion. The names of these three Germans are Mohr, 
Mayer, and Helmholtz. Their share in establishing 



the great doctrine of conservation must now claim our 

As to Karl Friedrich Molir, it may be said that his 
statement of the doctrine preceded tiiat of any of his 
fellows, yet that otherwise it was fmrhups least iinpor- 
int. In 1837 this thoughtful Oennan had grasped the 
lin truth, and given it expression in an article pub- 
shed in the ZeiUehn/ifar /^fit/ml\ etc. But the article 
ttmcted no attention whatever, even iVora Mohr's own 
motrymen. Still, Molir's title to rank as one wbo 
lide{iendently conceived the great truth, and perhaps 
|i"st conceiveci it beforw tiny oilier man in the world 
iw it as clearly* even though he did not demonstrate 
validity, is not to bo disputed. 

It was jnst live yeoi'ii later, in 184!2, that Dr, Julius 
jbert Mayer, praetiging pliysician in the little German 
>wu of Ileilbrcmn, pul>lisliet] a ])aper in T.iebigs A uualt^n 
'The Forces of Inorganic Nature," in which not 
lierely the mechanical theory of heat, but the entire 
Iriclrine of the conservation of energy, is explicitly if 
iefly stated. Two years earlier Dr. Mayer, while 
argeon to a Dutch India vessel cruising in the tropics, 
iad observed that the venous blood of a patient seemed 
reilder tJjan venous blood usually is observed to be in 
temperate climates. He pondered over this seemingly 
IpisigniHcant fact^ and at last reached the conclusion 
hat thi) cause must be the lesser amount of oxidation 
|uired to keep up the body temperature in the tropics* 
kI by this reflection to consider the body as a machine 
adent on outside forces for its capacity to aet^ he 
on into a novel re;dm of thought, which brought 
Rm At last to indejiendant discovery of the mechanical 
beory of heat, and to the first full and comprehensive 



appreciation of the great law of conservation. Blood- 
letting, the mo\lern physician holds, was a practice of 
very doubtful benefit, as a rule, to the subject ; but once, 
at least, it led to marvellous results. No straw is so small 
that it may not point the receptive mind of genius to 
new and wonderful truths. 

Here, then, was this obscure German ph3'sician, lead- 
ing the humdrum life of a village practitioner, yet seeing 
such visions as no human being in the world had ever 
seen before. 

The great principle he had discovered became the 
dominating thought of his life, and filled all his leisure 
hours, lie applied it far and wide, amidst all the phe- 
nomena of the inorganic and organic worlds. It taught 
him that both vegetables and animals are machines, 
bound by the same laws that hold sway over inorgan- 
ic matter, transforming energy, but creating nothing. 
Then his mind reached out into space and met a universe 
made up of questions. Each star that blinked down at 
him as he rode in answer to a night call seemed an inter- 
rogation-point asking. How do I exist? Why have I 
not long since burned out if your theory of conservation 
he true i No one hitherto had even tried to answer that 
([uestion; few had so much as realized that it demanded 
an answer. l>ut the Ileilbronn physician understood 
tiie question and found an answer. His meteoric hy- 
pothesis, published in 18-1^8, gave for the first time a 
tiMiabhj explanation of the persistent light and heat of 
our sun and the myriad other suns — an explanation to 
which we shall recur in another connection. 

All this time our isolated philosopher, his brain aflame 
with the glow of creative thought, was quite unaware 
that any one else in the world was working along the 



same lines. And the outside world wns eqiially lieedless 

(of th*_* work of tbe IleilbroTm jiliyisician. There wa3 no 
friead to inspire etithusrusiii and give couragtf, no kindred 
spirit to react on this masterful but lonely mind. And 
is is the more remarkable liecause tliere are few other 
wbere a master -origins tor in science has cume 
tUd scene except as the pupil or friend of some 
[>tlier rnasteroriginatun Of the men we have noticed 
fin the pi'esenl connection, Young was the friend and 
'confrere of Davy ; Davy, the protege of Rum ford ; Far- 
raday, the pupil of Davy ; BYesnel, the co-worker with 
Lmgo; Colding, the confrere of ( Jersted ; Joule, the 
^pupil of Dalton, But Mayer is an isolated phenomenon 
— one of the lone ninuntair^peak intellects of the century, 

ITImt osttmate may be exaggerated wliich has called him 
the Galileo of the nineteenth century, but surely no luke- 
wann pnuse can do him justice. 
Yel for a long time his work attracted no attention 
whatever. In 1847, whe^ another German physician, 
^Hermann von Uelmlioltz, one of the most massive and 
^towering intellects of any age, had been independently 
ltd to c*>m prehension of the dcK!trine of conservation of 
lenergy, and published his treatise on the subject, he had 
bardty heard of his ci>untryman Mayer. Wiicn lie did 
of bim, how evar^ he hastened to renounce all claim 
' Uit* doctrine of conservation, though the world at 
gc gives him credit of independent even tliough sub- 
jucnt discovery* 

Meantime in England Joule wjis going on from one 

Experimental demonstration to another, oblivious of [tis 

Iterman competitors and ahnost as little noticcil by his 

country men* lie read his first paper before the 

lioat section of the British Association for the 



Advancement of Science in 184:3, and no one heeded it 
in the least. Two years later he wished to read another 
l)a})er, but the chairman hinted that time was limited, 
and asked him to confine himself to a brief verbal synop- 
sis of the results of his experiments. Had the chair 
man but known it, he was curtailing a paper vastly more 
im])ortant than all the other papers of the meeting pot 
together. However, the s3'nopsis was given, and one 
man was there to hear it who had the genius to appre- 
ciate its importance. This was William Thomson, the 
present Lord Kelvin, now known to all the world as 
among the gi^eatest of natural philosophers, but then 
only a novitiate in science. He came to Joule's aid, 
started I'olliiig the hall of controverev, and subsequently 
associated liiinself with the Manchester experimenter in 
pursuing his investigations. 

l»ut miNintinie tlie acknowledged leaders of British 
science viewed the new (hx^trine askance. Faraday, 
l»iH»wster, llersi»hel those were the great names in 
physics at that iU\\\ and no one of them could quite 
accept the new viiMvs regarding energy. For several 
y^Niis no older |)hysicist, s|H.»aking with recognizeil 
authority, came forwanl in support of the doctrine of 
ci>nstM*vation. This culminating thought of our first 
half-ceniury i*anie silently into the world, unheralded 
and unop]>oscd. The lifth decade of the century had 
seen it elahi»rale<l and substantially demonstrated in at 
least three ilitTtMvnt countries, yet even the leaders of 
thonglit dill m>t so much as know of its existence. In 
1 ^:»:» W hewelK t he historian of the inductive sciences, pub- 
lisheil a second inlitiim of his history, and, as Huxley has 
pi>inteil out, he did not so much as n^fer to the revolution- 
izing thought which even then was a full decade old. 



A«sTOR, LtNCX ^f^O 


By this time, howeverj the battle was brewing. The 
fmng generation saw the imi>orUince of a law whicii 
"tlieir eldf?rs could not appreciate, and soon it was noised 
abrmni that there were mure titan one chiirnant to the 
honor of discoverv* Chiefly through the effijrts of Pm- 
^lessor Tyndall, ttie work of Mayer became known U) ihe 
^KritiHli public, and a most reji^rettahle controversy ensued 
^Hictween the partisans of Mayer and those of Joule — a 
Hbitter controversy^ in wliich Davy's contention that 
^Bcienee knows no country was not always regarded, and 
^k'hlch left its ^ai*^ upon the hearts and minds uf the 
Hpreat men whose pei^onal interests were involved. 

And so to this day the question who is the clilef dis- 

Icoverer of the law of conservation of energy is not sus- 
^ptihle of a categorical answer that would satisfy all 
|ihilo$>ophers. It is generally held that the lii^t choice 
lies between Joule and Mayer, Professor Tyndall has 
expressed the belief that in future each of these men 
will be cNpially remembered in connection with this 
work, Bnt history gives us no warrant for such a hope, 
'l^tisterity in the long run demands always that its liercjies 
^kiull stand alone. Who remembers now that Robert 
^Hooke contested with Newton the discovery of tlie dw- 
^^rino of universal gravitation J The judgment of pos- 
terity is unjust, but it is inexorable. And so we can 
little doubt tliat a century from now one name will Ije 
lentioneil as tliat of tiie originator of the great doctrine 
: cxmservation of energy. Tlie man whose name is thus 
fmemberecl will perhaps be spoken of iis the Galileo, 
jibe Newton, of the nineteentli eif^ntiiry; but whether 
lie name thus dignilied by the final verdict of history 
rill be that of Cokling, Mohr, Mayer, Hehnholtz, or 
lonle, it is not for our century to decide. 





The gradual permeation of the field by the great 
doctrine of conservation simply repeated the history 
of the introduction of every novel and revolutionary 
thought. Necessarily the elder generation, to whom 
all forms of energy were imponderable fluids, must pass 
away before the new conception could claim the field. 
Even the word energy, though Young had introduced 
it in 1807, did not come into general use till some time 
after the middle of the century. To the generality of 
philosophers (the word physicist was even less in favor 
at this time) the various forms of energy were still 
subtle fluids, and never was idea relinquished with 
greater unwillingness than this. The experiments of 
Young and Fresnel had convinced a large number of 
philosoi)hers tliat light is a vibration and not a sub- 
stance; but so great an authority as Biot clung to the 
old emission idea to the end of his life, in 1802, and held 
a following. 

Meantime, however, the company of brilliant young 
men who had just served their apprenticeship when the 
doctrine of conservation came u[)on the scene had grown 
into authoritative positions, and were battling actively 
for the new ideas. (Confirmatory evidence that energy 
is a molecular motion and not an "imponderable'' form 
of matter accumulated day by day. The experiments of 
two Frenchmen, ITippolyte L. Fizeau and Leon Foucault, 
served finally to convince the last lingering sceptics that 
light is an undulation ; and by implication brought heat 
into the same category, since James David Forbes, the 
Scotch physicist, had shown in 1837 that radiant heat 
conforms to the same laws of polarization and double 



L^fraetjon that govern ligbt. Eut, for that matter^ the 
tperiments that bad established the mechanical equiva- 
Tent of beat lianlly left room for doubt as to the iniina- 
iality uf tliis " jraponderable/' Doubters had, imJeedj 
rpressed sceptioisra as to the yalidity of Joule's exper- 
Eieiits« but the further researches, .experimental and 
iiitbefnatiad, of such workers as Thomson (Lord Kel* 
!n>, Kankine, and Tyi^dall in Great Britain, of Ilelra- 
liolu and Clausius in Germany, and of Regnauit in 
France, deahng with various raanifestations of heat, 
iced the evidcnc<> beyond tlie reach of criticism. 
Out of these studies^ just at the middle of tbe cen- 
to wbielj tbe experiments of Mayer and Joule bad 
^greiv tbe new science of thernio-dynamics. Out of 
titem also grew in tbe mind of one of the investigators 
mew generaliscation, only second in importance to the 
ine of c*>nservation itself. Professor William 
ason(Lonl Kelvin) in his studies in thernio-dynam- 
mns early impressed with the fact that whereas all 
"ihe HKilar motion ilevelo[>etl through labor or gravity 
ouuld be converted into beat, the process is not fully re- 
femible. Ueat can, indeed, be converted into molar 
action Of tvork, but in the pi*ocess a certain amount of 
heat is nidialetl into spac.^e and lost. The same 
tlving happens whenever any other form of energy is 
[djofert^l into molar motion. Indeed, every transmuta- 
hm of energy, of whatt.vver character, seems com)>H- 
|a»od by a tendency to develop heat» jiart of which is 
IkiL Till* observation led Professor Thomson to bia 
Mioctririf; of tbe dissipation of energy, which he formu* 
k'foro tbe Royal 8r>ciety of EUinlnn^gh in 1S52, 
imbliabeil also in the PhUomtphieal Jffftjagme the 
iirne vear, ttie litle borne b<?ing, "(hi a Universid Ten- 



dency in Nature to the Dissipation of Mechanical En- 

From the principle here expressed Professor Thomson 
drew the startling conclusion that, " since any restora- 
tion of this mechanical energy without more than an 
equivalent dissipation is impossible," the universe, as 
known to us, must be in the condition of a machine 
gradually running down ; and in particular that the 
world we live on has been within a finite time unfit for 
human habitation, and must again become so within a 
finite future. This thought seems such a commonplace 
to-day that it is difficult to realize how startling it ap 
peared half a century ago. A generation trained, as 
ours has been, in the doctrines of conservation and dis- 
sipation of encTgy as the very alphabet of physical sci- 
ence can but ill appreciate the mental attitude of a gen- 
oration which for the most part had not even thought it 
problematical whether the sun could continue to give 
out heat and light forever. But those advance thinkers 
who had grasped the import of the doctrine of conser- 
vation could at once appreciate the force of Thomson's 
doctrine of dissipation, *and realize the complementary 
character of the two conceptions. 

Here and there a thinker like Rankine did, indeed, at- 
tempt to fancy conditions under which the energy lost 
through dissipation might be restored to availability, 
but no such effort has met with success, and in time 
Professor Thomson's generalization and his conclusions 
as to the consecpiences of the law involved came to be 
universally accejited. 

The introducticm of the new views regarding the nat- 
ure of energy followed, as I have said, the course of 
every other growth of new ideas. Young and imagina- 



re men cnuki ticccpt the new point of viev^ ; older phi- 
>phers, tlieir minds ctiantielled by preconceptions, 
mill not ^t into the new groove. So strikingly true 
is ill is in tb*i particular case tiow before us that it is 
^Vorth while to note the ages at the time of the re^olu- 
^BDttary exj>erinient.s of tiie men whose work has been 
^■entioned ti& entering into the scheme of evolutioJi of 
^Ke idea that energy k merely a manifestation of matter 
^B motion. 8ueli a list will tall the story batter than a 
^MDlnitte of connnentary. 

^P Oljserve, tht»n, that Davy made his epochal experi- 
ment of melting ic^ by friction when he was a youth of 
twenty. Young was no older when he rna^le his first 
^pmmunication to the Itoyal Society^ and was in iiis 
^wenty seventh year when he first actively espi^used the 
^niftutatory theory. Fresnel was twenty six wiien he 
^%aile his first inijiortant discoveries in the same Held; 
and Arago, who at once Ijecame his champion, was then 
hut two yejxrs his senior, though for a decade he had 
jn so famous that one invohintarily thinks of him as 
Blonging to an elder generation, 

Forbes was under thirty when be discovered the po- 

^rimtion of lieat, w^iiich pointed thn way to Mohr, then 

lirty-one, to the mechanical equivalent. Joule was 

renty^two in 1840, when his great work was begun ; 

id Mayer, whose discoveries date from the same year, 

then twenty-six. which was also the age of Helm- 

OlUt when he published his iiulepenilent discovery of 

pe same law, William Thomson was a youth just past 

js majority when he came to the aid of Joule before 

be British Society, and but seven 3 ears older when he 

lalateil his own doctrine of dissipation of energy. 

And Claoiiias and Kankine, w^ho are usually mentioned 



with Thomson as the great developers of thermo-dynam- 
ics, were both far advanced with their novel studies 
before they were thirty. We may well agree with the 
father of inductive science that ^' the man who is young 
in years may be old in hours." 

Yet we must not forget that the shield has a reverse 
side. For was not the greatest of observing astrono- 
mers, Ilerschel, past thirty-five before he ever saw a 
telescoi>e, and past fifty before he discovered the heat 
rays of the spectrum ? And had not Faraday reached 
middle life before he turned his attention especially to 
electricity 2 Clearly, then, to make his phrase complete, 
Bacon must have added that "the man who is old in 
veal's may be young in imagination.'" Here, however, 
even more appropriate than in the other case — more's 
the pity — would have been the application of his quali- 
fying clause : "but that happeneth rarely." 


There are only a few great generalizations as yet 
thought out in any single field of science. Naturally, 
then, after a great generalization has found definitive 
exi)ression, there is a period of lull before another for- 
ward move. In the case of the doctrines of energy, the 
lull has lasted half a century. Throughout this period, 
it is true, a multitude of workers have been delving in 
tlu» field, and to the casual observer it might seem as if 
their activity had been boundless, while the practical 
applications of their ideas — as exemplified, for example, 
in the telephone, phonograph, electric light, and so on — 
have been little less than revolutionary. Yet the most 
competent of living authorities. Lord Kelvin, could as- 



^rt in 1895 llml in titty years he had learned nothing 
^ow regarding thi; nature of energy. 

This, however, miHt nut be interpreted as meaning 
that the world lias stood still during these two genera- 
jons* It means rather that the rank and file have been 
loring forward along the roacl the leaders hud aireaily 
ravel letK Only a few men in the world had the range 
if thought reganling the new ductrine of energy that 
iftl Kelvin had at the middle of the century. The 
few leaders then saw clearly enough that if one form of 
energy h in iH3ality merely an undulation or vibration 
imong the [mrticlesuf ''pondi^rable'' matter or of ether^ 
11 other manifestations of energy must be of the same 
ilure. But the rank and Hie were not even within 
^Iglit of this truth for a long time after they liad partly 
ftspetl the meaning of the doctrina of conservation. 
^When, late in the fifties, that nmrveUous young Scotch- 
man, Jitmes Clerk Maxwell, furniulating in other words 
jflim of Faniday's, ex(>ress6il his belief that eleetricu 
anil magnettsniare but manifestations of various con- 
itions of stress and motion in the ethereal medium 
jectrieity a displacement of strain, magnetism a whirl 
tti the ether), the idea met with no iinmetUate populari- 
And even less cordial was tho reception given the 
^me lhinker*s theory, put forward in 1808. that tlie 
kbereal undulations prmlucing the phenomenon we call 
rUi tliffer in no respect exct-pt in their w^ave-length 
>m the pulsations of eleetriMnagnetism, 
At about the same time Jlelmholtz formulated a 
:>raowhat similar electro-magnetic theory of light ; but 
ren tlie wciglit of this combined authority could not 
^ve the iloclritie vogue until very recently, when the 
artmoiits of Heinrich Uertz, the pupil of Ilelmholtz^ 


have shown that a condition of electrical strain may be 
developed into a wave S3^stem by recurrent interruptions 
of the electric state in the generator, and that such 
waves travel through the ether with the rapidity of 
light. Since then the electro-magnetic theory of light 
has been enthusiastically referred to as the greatest gen- 
eralization of the century; but the sober thinker must 
see that it is really only what Hertz himself called it- 
one pier beneath the great arch of conservation. It is 
an interesting detail of the architecture, but the part 
cannot equal the size of the whole. 

More than that, this particular pier is as yet by no 
means a very lirm one. It has, indeed, been demon- 
strated that waves of electro-magnetism pass througli 
space witii the speed of light, but as yet no one has de- 
velo])ed electric waves even remotely a])proximating the 
sliortness of the visual rays. The most that c<an ]K>si- 
tively be asserted, therefore, is that all the known forms 
of radiant energy — heat, light, electro - magnetism- 
travel througli spnce at the same rate of speed, and con- 
sist of traverse vibrations — "lateral quivers," as Fresnel 
said of light — known to differ in length, and not posi- 
tively known to differ otherwise. It has, indeed, been 
suggested that tin* newest form of radiant energy, the 
famous X ray of Pi'ofessor Rontgen's discovery, is a 
longitudinal vibration, but this is a mere surmise. I>e 
that as it may, there is no one now to question that all 
forms of radiant energy, whatever their exact affinities, 
consist essentially of undulatory motions of one uniform 

A full century of experiment, calculation, and con- 
trovei*sy has thus sufficed to correlate the '' impondera- 
ble fluids " of our forebears, and reduce them all to man- 



stations of motion amoog particles of matter. At 

It glim|)S8 that seems an etiormoug change of view. 

id yet, wLien clusely considered^ that change in 

iboogbt is not so riulical as the chauge in phrase might 

am to imply. For the nineteenth-century physicist, in 

{tsplacing the ** imponderable fluids'' of many kinds — 

uiicli for Hgbi^ heat, electricitVj magnetism — has 

obliged to substitute for them one all-pervading 

ltd, whose various quiverts, waves, ripples, whirls, or 

rains produce the manifestations which in popular 

irhince are Lerined forms of force. This all-pervading 

fluid the physicist terms the ether, and he thinks of it 

^■b having no weight In effect, then, the physicist has 

^Rspoascjiisetl the many imponderables in favor of a single 

imiKindorable — though the word imjTonderable has been 

^ loisbed from his vocabulary. In this view the ether — 

lich, cunsitlereif as a recognized scientific verity, is es- 

itially a nineteenth-century discovery-— is about the 

lost intere»iing thing in the nnivei*se. Something more 

to its properties, real or assumed, we shall have oc- 

bion tci examine iis we turn to the obverse side of 

bystica, ivhich oemands our attention m the next chap- 


" Whatever difficulties we may have in forming a 
consistent idea of the constitution of the ether, there 
can be no doubt that the interplanetary and interstellar 
spaces are not empty, but are occupied by a material 
substance or body which is certainly the largest and 
probably the most uniform body of which we have any 

Such was the verdict pronounced some twenty years 
ago by James Clerk Maxwell, one of the very greatest 
of nineteentli-century physicists, regarding the existence 
of an all-pervading ])lenum in the universe, in which 
every particle of tangible matter is iqimersed. And this 
verdict may be said to express the attitude of the entire 
philosophical world of our day. Without exception, the 
authoritative physicists of our time accept this plenum 
as a veritv, and reason about it with somethinfir of the 
same confidence they manifest in speaking of "pondera- 
ble " matter or of energy. It is true there are those among 
them who are disposed to deny that this all-pervading" 
plenum merits the name of matter. But that it is a 
samethiruj^ and a vastly important something at that, all 
are agreed. Without it, they allege, we should know^ 



thing of light, of radistnt heat, of electricity, or mag- 
iielLsm ; without it there woulJ probably be no such 
^nng aa gmvitatiun ; nay, they even hint that without 
^k ^tningi! soinethnig« ether, there would be no auch 
thing as matter in the universe. If these contentions of 
the iiHxlern physicist are justified, then ibis intangible 
eihcr is incomjmnibly the most important as well as the 
irgt^st and most uniform substance or body" in the 
kTefseu Its discovery may well be looked upon as the 
It important feat of our century,- 
Tor a discovery of our century it suinsly is, in the 
that all the known evidences of its existence have 
511 gathered in this epoch. True, dreamers of all ages 
re, for metapliysical reasons, imagined the existence 
of intangible fluids in space— they had, indeedj peopled 
space several times over with diiferent kinds of ethers. 
Maxwell remarks— but such vitgue drcamings no nioi'e 
nstituted the discovery of the modern ether than the 
im of some pre-Columbian visionary that land might 
[h4?yond the unknown waters constituted the discov- 
of America. In justice it must be admitted that 
nyghtms, the seventeenth-century originator of the un- 
^latory theory of light, caught a glimpse of the true 
imr\ but his contemporaries and some eight genera- 
K^nsof his successors were utterly deaf to his claims; 
1 bean^ practicallj^ tlie same relation to the nine- 
b^^entury diacoverei-s of ether tluit the Norseman 
an to Columbus, 

The tm© Columbus of the ether was Thomas Young. 

lis iliacoverv was consummated in the early days of the 

eat century, when ho brought forward the first con- 

Wfe proofs of the undulatory theory of light. To 

i*y tliat light consists of undulations is to postulate 



K'irnething which undulates ; and this something oouU 
not lie air, for air exists only in infinitesimal quantity, if 
at all, in the interstellar spsices, through ivhich light 
fnj^Jy [lenetrates. But if not air, what then i Why, 
clearly, s^>mething more intangible than air; something 
Hii|H;rsi^nBible, evading all direct efforts to detect it, vet 
existing everywhere in seemingly vacant space, and also 
iriter|M;netniting the substance of all transparent liquids 
and Kolids, if not, indeeil, of all tangible substances. 
TliiH intangible something Young rechristened the La- 
niinif<;rou8 Ether. 

In the early days of his discovery Young thought of 
the undulations wliich produce light and radiant heat as 
JMiing longitudinal — a forward and backward pulsation, 
coiTcisponding to the pulsations of souml — and as such 
pulsations (;an bo transmitted by a fluid medium with 
llip prop(»rtios of ordinary fluids, he was justified in 
tliinking of I lie ether as being like a fluid in its proper- 
ties, «»x('(»pl. for its «^\trenie intangibility. But al)out 
ISIS thr exptM-inuMits of Fresnel and Arago with |X)lar- 
i/.atii»n «»f light made it. .seiMii very doubtful whether the 
tluMiry «»f loiiLTitudinal vibrations is sutticient, and it was 
suy:i4:i»sttHl l)v Young, and indop(»ndently eonceiveil and 
ilemonsl rated l)y Fresnel, that the luniiniferous undula- 
tions are ma loni^itudinal, but transverse; and all the 
\\\ow riHvnl experiments iiave tendtnl to confirm this 
view. lUit it happens tiiai i>rdinary fluiils — g:ises and 
liipiids eannoi transmit lateral vibnuions; only rigid 
Innlies aiv eajKible of sueh a vibration. So it became 
luvessiiry ii> assume that the luminifen»usether isa body 
possessinsr elaslie rigidity a familiar pn>jH?riy of tangi- 
ble solids, but v>ne quite unknown among fluids. 

The idea oi iransvei*se vibrations oarrieii with it an- 


ther puzzle* Why does not the etber; when set uquiver 
rith the nbration which gives us the sensiition we call 
jht, have produced in its substance subordinate quiv- 
s, setting out at right angles from the path of the 
igitial qiHYer? Soch perpenJicuJar vibrations seem 
>t to exiHt, else we might see aruund a corner; how 
cplain tlieir absence? The physicists could think of 
It one way: they must assume that the ether is in- 
:>nipressible. It must Jill all space — at any rate^ all 

Ipace with which human knowledge deals — perfectly 
These properties of the ether, incom press ibility and 

elastic rigidity^ are quite conceivable by themselves; 

>ut difficulties of thought appear when we reflect upon 

lot her quality which ttie ether clearly must possess^ 

mielVj frictionlessness. Per hyp*jtliesis this rigid, in- 

^topressible body pervailes all space, imbedding every 

irticleof tangible matter; yet it seems not to retard the 

of this matter in the slightest degree. This 

timloubtedly the most difficult to comprehend of the 

leged properties of the ether. The physicist explains 

as du(> to the perfect elasticity of the ether, in virtue 

W which it ehist*s in behind a moving particle with a 

push exactly couu tor balancing the stress required to 
enotrato it in front. 

To a person unaccustomed to think of seemingly 
lliil matter as really c<mqMised of particles relatively 
ride ii()art, it is hard to understand the claim that 
ther penetrates the substance of solids— of glass, for 
impli*^and, to use Young's expression, which we 
ive previously quoted, moves among them as freely 
rind moves through a gr-ove of trees. TIjis 
however, prusunLs few difficulties to the mind 


accustomed to philosophical speculation. But the ques- 
tion early arose in the mind of Fresnel wliether the 
ether is not considerably aflFected by contact with the 
particles of solids. Some of his experiments led him to 
believe that a portion of the ether which penetrates 
among the molecules of tangible matter is held captive, 
so to speak, and made to move along with these par- 
ticles, lie spoke of such portions of the ether as 
" bound " ether, in contradistinction to the great mass 
of '* free" ether. Half a century after Fresnel's death, 
when the ether hypothesis had become an accepted ten- 
et of science, experiments were undertaken by Fizeau 
in France, and by Maxwell in England, to ascertain 
whether any portion of ether is really thus bound to 
particles of matter; but the results of the experiments 
were negative, and the question is still undetermined. 

While the undulatory theory of light was still fighting 
its way, another kind of evidence favoring the existence 
of an ether was put forward by Michael Farada\% who, 
in the course of his experiments in electrical and mag- 
netic induction, was led more and more, to perceive def- 
inite lines or channels of force in the medium subject to 
electro-magnetic influence. Faraday's mind, like that 
of Newton and many other philosophers, rejected the 
idea of action at a distance, and ho felt convinced that 
the phenomena of magnetism and of electric induction 
told strongly for the existence of an invisible plenum 
everywhere in space, which might very probably be 
the same plenum that carried the undulations of light 
and radiant heat. 

Then, about the middle of the century, came that final 
revolution of thought regarding the nature of energy 
which we have already outlined in the preceding chap- 



r, and with that the case for ether was considered to 
fully established- The idea that enert^y is merely a 
I *' mode of niotiuii " (to adopt TyndalTs faniiHar plirase), 
combined with the univ^ersal rejection of the notion of 

t3tion at a distance, made the acceptance of a plenum 
jroughoat space a necessity of thought^ so, at any 
ite, it lias seemed to most physicists of recent decades, 
'he proof tliat all known forms of radiant energy move 
a rough space at tiio same rate of speed is regarded as 
ractjcally a dcunonst ration that bnt one plenum — one 
ether— is concerned in their tmnsmission. It lias, in* 
eed, been tentatively suggested, by Professor J, Oliver 
[>tlge, tliat there may \m two etliers, representing the 
ft'o upp*>site kinds of electricity, but even the author 
this hypothesis would haiilly claim for it a high de- 

of prtihahility. 

The most recent s{»eculations regarding the properties 

of the ether have departed but little from the early ideas 

of Vonng and Fresneh It is assumed on all sides that 

J© ether is a continuous, incompressible bod 3% posscss- 

Bg rigidity anil ehistrcity. Lord Kelvin has even cal- 

"calated the prulmble density of this ether, and its coefll- 

uient of rigidity. As might be sup|)osed, it is all but 

ifjnitely teaunus ;is compared with any tangible solid^ 

and its rigidity is but infinitesimal as compared with 

tiat of steeh In a word, it cond^ines properties of 

ingiblo matter in a way not known in any tangible 

ilistanre. Therefore we cannot possibly conceive its 

je condiiifm eorrt^etly, Tlie neirrest opproximation, 

c?ording to fAml Kelvin, is furnished by a mould of 

insparent jelly* It is a crude, inaccurate analogy, of 

choree, the ilensity and resistance of jelly in particular 

eing utterly dilTerent from those of the ether; but tlie 



quivers that run through the jelly when it is shaken, 
and the elastic tension under which it is placed when its 
mass is twisted about, furnish some analogy to the quiv- 
ers and strains in the ether, which are held to constitute 
radiant energy, magnetism, and electricity. 

The great physicists of the day being at one regarding 
the existence of this all- pervading ether, it would be a 
manifest presumption for any one standing without the 
pale to challenge so firmly rooted a belief. And, in- 
deed, in any event, there seems little ground on whioh 
to base such a challenge. Yet it may not be altogether 
amiss to reflect that the physicist of to-day is no more 
certain of his ether than was his predecessor of the 
eighteenth century of the existence of certain alleged 
substances which he called phlogiston, caloric, corpuscles 
of light, and magnetic and electric fluids. It would be 
but the repetition of history should it chance that be- 
fore the close of another century the ether should have 
taken its place along with these discarded creations of 
the scientific imagination of earlier generations. The 
philosopher of to-day feels very sure that an ether ex- 
ists ; but when he says there is *' no doubt " of its exist- 
ence he si)eaks incautiously, and steps beyond the bounds 
of demonstration. lie does not himo that action cannot 
take place at a distance ; he does not know that empty 
space itself may not perform the functions which he 
ascribes to his space-lilling ether. 

Meantime, however, the ether, be it substance or be 
it only (InNun-stulT, is serving an admirable purpose in 
furnishing a fulcrum for modern physics. Not alone 


ruK mnvAi a\u ponderable maiter 

the student of energy hiifi it provLti invaluable, but to 
student of matter itself as well Out of its hy\H> 


Fpdid « pbot<3fni|>h bjT Lrtejicrhnr and PutB^h, Berlin 



tiietical mistiness has been reared the most tenable 
theory of the constitution of ponderable matter which 
has yet been suggested — or, at any rate, the one that 
will stand as the definitive nineteenth-century guess at 
this " riddle of the ages." I mean, of course, the vortex 
theory of atoms— that profound and fascinating doctrine 
which suggests that matter, in all its multiform phases, 
is nothing more or less than ether in motion. 

The author of this wonderful conception is Lord Kel- 
vin. The idea was born in his mind of a haj)py union 
of mathematical calculations with concrete experiments. 
The mathematical calcuhitions were largely the work of 
Hermann von Ilelmholtz, who, about the year 185S, had 
undertaken to solve some unique problems in vortex 
motions. Ilelmholtz found that a vortex whirl, once es- 
tablished in a frictionless medium, must go on, theoret- 
ically, unchanged forever. In a h'mited medium such a 
whirl may be V-shapod, with its ends at the surface of 
the medium. We mav imitate such a vortex bv drawing 
the bowl of a spoon quickly through a cup of water. 
Hut in a limitless medium the vortex whirl must always 
be a closed ring, which may take the simple form of a 
hoop or circle, or which may bo indefinitely contorted, 
looped, or, so to speak, knotted. Whether simple or 
contorted, this endless chain of whirling matter (the 
particles revolving about the axis of the loop as the par- 
ticles of a string revolve when the string is rolled be- 
tween the fingers) must, in a frictionless medium, retain 
its form, and whirl on with undiminished speed forever. 

While these theoretical calculations of Helmholtz were 
fresh in his mind. Lord Kelvin (then Sir William Thom- 
son) was shown by Professor P. G. Tait, of Edinburgh, 
an apparatus constructed for the purpose of creating 



Irortex rings in air. The ap[mraliis^ which nuy ooe may 

"duplicai4), c(>nsisted simply of a box with a hole boreJ 

in i>Off side, and a iiicoe **f canviiji siretcbed acr<MS I he 

i)ppf:»iite side io lieu of boanls. Fufiies of eliloride of 

tnittKmk ai-e genenitecl withia the box, taerely to render 

h^ air visible. By tapping iviih the hand on the eanras 

^ideuf thu box, vortex rings of the clouded air aredriren 

^at, prt^cisel^' sltntliir in it]i{>e«intnoe to those smoke^ring^ 

pbicii ^mm expert tobacci>sf Tinkers can prod nee by tap- 

»iug on their cheeks, or to tliuse iat^r onets which we 

ir>metiines see bh>wn out from ibe funnel of h iocomo- 


The advantage of Professor Tail's apparatus Is its 
ianageableness, and the cert4iinty witb wbicb the de- 
siretl result ean Ije pro<bic*HK Before Ij^rd Kelvin's in- 
[?rest4>d observation it threw out rings of various si^es, 
diicfi moved stniight acri>ss the room at varying rates 
>f s|>eed» according to this initial impulse, and which l>e- 
iVGii very stmngely when coming in contact with one 
mother. If, for example, a mpidly moving ring over- 
i>ok am>ther moving in the same path, the one in ad- 
sce aeemeil to pause, and to spread out its |>eriphery 
Bkt! an t4:i>itic hand, whik^ the pursuer seemed to oon- 
2t, till it actually slid through the oritice of the other, 
which each ring rcisrimed its original size^and oon- 
Tinued its course as if nothing had happened. When, on 
^^e other hand, two rings moving in slightly different di- 
^■ections cara« near each other, tliey seemed to have an 
^Kttraction for each other; yet if th**y imi>tnged, they 
^MMlldeil away, quivering like elastic solids. If an effort 
^^Ipb made to gnisp or to cut one of these rings, the subtle 
thing shrunk from the contitct,and slipped away as if it 
rere alive. 


And «ill the while the body which thus conducted 
itself consisted simply of a whirl in the air, made visi- 
ble, but not otherwise influenced, by smoky fumes. 
Presently the friction of the surrounding air wore the 
ring away, and it faded into the general atmosphere— 
often, however, not until it had persisted for many sec- 
onds, and passed clear across a large room. Clearly, if 
there were no friction, the ring's inertia must make it a 
permanent structure. Only the frictionless medium was 
hicking to fulfil all the conditions of Helmholtz's inde- 
structible vortices. And at once Lord Kelvin bethought 
him of the frictionless medium which physicists had now 
begun to accept — the all-pervading ether. What if vor- 
tex rinsrs were started in this ether, must thev not have 
the properties which the vortex rings in air hjul exhib- 
ited — inertia, attraction, elasticity? And are not these 
the properties of ordinary tangible matter? Is it not 
probable, then, that what we call matter consists merely 
of afrofrefcations of infinitesimal vortex rin^i^s in the 

Thus the vortex theory of atoms took form in Lord 
Kelvin's mind, and its expression gave the world what 
many philosophers of our time regard as the plausible 
conception of the constitution of matter hitherto formu- 
lated. It is only a theory, to be sure ; its author would 
be the last person to claim finality for it. "It is only a 
dream," Lord Kelvin said to me, in referring to it not long 
ajro. But it has a basis in mathematical calculation and 
in analogical experiment such as no other theory of mat- 
tor can lay claim to, and it has a unifying or monistic 
tendency that makes it, for the philosophical mind, little 
less than fascinating. True or false, it is the definitive 
theory of matter of the nineteenth century. 




Quite aside from tho question of the exact constitu- 
tion of the ultimate particles of matter, questions as to 
be distribution of such particles, their mutual relations, 
properties, and actions, have come in for a full share of 
Itlertttun during our century, though the foundations 
>r the raoilarn speculations were furnished in a pre- 
rioEs epoch. The most popular eighteenth -century 
peculation as to the ultimate constitution of matter 
ras that of the learn eiil Italian priest, Roger Joseph 
>vich, published in 1758, in his Tftf^on'a Philoso- 
&Mb ^aturallfi, ^' In this theory/* accor<ling to an 
ly commentator, *Hhe whole mass of which the 
lK)die^ of the universe are comfXisoil is sup[>osed to con- 

iiRt of an exeeodingly great yet finite number of simple, 
Eidivisible, inextended atoms. Those atoms are endued 
w the Creator with rspuhwe and aUmetive forces, 
rhich vary acording to the distance* At very small 
listances the particles of matter rejicl each other; and 
his repulsive force increases beyond all limits as the 
(iistunces an5 diminislied, and will consequently forever 
prevent actual contact. When the particles of matter 
' are removed to sensible distances, the repulsive is ex- 
changi^d for an attractive force, which decreases in in- 
^Berse ratio with the squares of the distances, and extends 
P^y«nd the spheres of the most remote comets/* 

This conception of the atom as a mere centre of force 

j^bas hardly such as could satisfy any mind other than 

^Bie metaphysical No one made a conspicuous attempt 

^Bu improve upon the idea, however, till just at the close 

of the century, when Humphry Davy was led, in the 

GOurHe of his studies of heat, to speculate as to the 



changes that occur in the intimate substance of matter 
under altered conditions of temperature. Davy, as we 
iiave seen, regarded heat as a manifestation of motion 
among the particles of matter. As all bodies with 
which we come in contact have some temperature, Da\'y 
inferred that the intimate jKirticles of every substance 
must be i>erpetually in a state of vibration. Such vibra- 
tions, he believed, produced the " I'epulsive force" which 
(in common with Boscovich) he admitted as holding the 
particles of matter at a distance from one another. To 
heat a substance means merel}' to increase the rate of 
vibration of its particles ; thus also, plainly, increasing 
the repulsive forces, and expanding the bulk of the mass 
as a whole. If the degree of heat applied be sufficient, 
the repulsive force may become strong enough quite to 
overcome the attractive force, and the particles will sep- 
arate and tend to fly away from one another, the solid 
then becoming a gas. 

Not much attention was paid to these very suggestive 
ideas of Davy, because they were founded on the idea 
that heat is merely a motion, which the scientitic world 
then repuiliated ; but half a century later, when the new 
theories of energy had made their way, there came a 
revival of practically the same ideas of the particles of 
matter (molecules they were now called) which Davy 
had advocated. Then it was that Clausius in Germany 
and Clerk ^[axwoll in England took up the investigation 
of what came to be known as the kinetic theory of giises 
— the now familiar conception that all the phenomena 
of gases are due to the helter-skelter flight of the show- 
ers of widely separated molecules of which they are 
composed. The s}>ecific idea that the pressure or 
'* spring" of gases is due to such molecular impacts was 



le to Daniel Bouraelli, wbci advanced it early in Uie 
^hleenlh centurj. The idea, then little notice], tmd 
m mviveii about a century later by Williaia Ubt^ 
nil, and tigaiu witb sonic sueaens by «L J. WatanHoOf 
Bombay, about 1S4:6; but it gained no dkUnct fcKii- 
kg until taken in band by Ctaii^tiyi in 1857 and by 
lax well in 1851^. 

I The investig»%tions of these great pbyKicij^t« not only 
Starved fuliy to substantintis the doctrine, but lbr€?ir a 
uf light upon the entire i^ubjeel of malcxMibir dy. 
tmics. Soon tbe piiysici&t$ ciirne Ui feel aji certain of 
llie existence of tbese ghowers of flying inoteetltet mftk' 
ig up a gaii afi if tliey could actually noe and tvaUrh 
lleir individual actions. Tbrougii i^tudy of tho \imtmiiy 
gases — that is to stiy^of the d^egnub of frictional opito- 
tion they shoi? to an object moving through tbtjm or 
another current of gits— an idea mm gitint^l, with the 
d of niiitheTnatics^ of the rate of ^H'J^l at tvbicb th« 
particles of the gas are moving, and tbe nutn^K^rof €*A 
siiKis ^vhich each particle muBt oxijerience iii a given 
|m»\ and of the length of the airerage free (latb traf* 
letl by tbe molecule between coUisiotw. TUmti mean^ 
jinen ts were conlirrn*?*] by study of th«^ rattiof rliffujiion 
wliich different gitsos mix together, and aim by tbe 
|te of li iffy don of heat tb rough a gait, b^th thes^j phe^ 
>mena being chieHy due to the helternkelter flight of 
ie mnlecules. 

It is sufRoiently astonishing t<j be told that such 

mea.'inroments lis these have been niaile at all, but the 

Itoninhment grovvs when on*3 lioars tlie results. It ajv 

int from Max weirs calculations that the mean free 

lih, or distance traveDw^d by the molecules between 

>lltsion3 in ordinary air^ is about one half-mjlljonth of 



an inch ; while the speed of the molecules is such that 
each one experiences about eight billions of collisions 
per second ! It would be hard, perhaps, to cite an illus- 
tration showing the refinements of modern physics bet- 
ter than this ; unless, indeed, one other result that fol- 
lowed directly from these calculations be considered 
such — the feat, namely, of measuring the size of the 
molecules themselves. Clausius was the first to point 
out how this might be done from a knowledge of the 
length of free path ; and the calculations were made by 
Loschmidt in Germany, and by Lord Kelvin in England, 

The work is purely mathematical, of course, but the 
results are regarded as unassailable ; indeed. Lord Kelvin 
s|>eaks of them as being absolutely demonstrative within 
certain limits of accuracy. This does not mean, how- 
ever, that they show the exact dimensions of the mole- 
cule ; it means an estimate of the limits of size within 
which the actual size of the molecule may lie. These 
limits, Lord Kelvin estimates, are about the one ten- 
millionth of a centimetre for the maximum, and the one 
one-hundred-millionth of a centimetre for the minimum. 
Such figures convey no particular meaning to our blunt 
senses, but Lord Kelvin has given a tangible illustration 
that aids the imagination to at least a vague comprehen- 
sion of the unthinkable smallness of the molecule. He 
estimates that if a ball, say of water or glass, about " as 
large as a football, were to be magnified up to the size 
of the earth, each constituent molecule being magnified 
in the same proportion, the magnified structure would 
be more coarse-grained than a heap of shot, but proba- 
bly less coarse-grained than a heap of footballs." 

Several other methods have been employed to estimate 



i>r raolecoles. One of these is l>a!$fM] n\mn tlin 
iif ctmtMci electricity ; aiiotlior U[iuii 1 do 
vraire>lbmry of tight; and anoihur ujKjn t!u|)iUm'v til 
tiofi, M sbown in Uie tense film of a aoap-bttblklu I 
fo iJiH* of these ittelhods gives insults ituM» ch^Iinilo tluMi 
liat dae to the kinetic thLH:>ry of gjtHt.i;i, jusl tiutliiirul ; 
iui tilts itii{M>rtuiit thing is tlmt tho msiilts obtiiinml by 
ulifferent methods (atl of them duo ti) Lord Ki^lvin) 
iriUi ono another in fixing tht"; ([iun^nsiruis uf tl«i« 
at s^omewhere about tlio limitK ah*niuly num 
jdckh]. We may feel very suro indootl, thHrnfnn% lUni 
ultimate particles of matter aro not tlin nnnxl<*ri<lHd, 
irmleBs points which Boscuvicli and hin loiliiwi^iM nI i ho 
century thought them* 

Whateirer the exact form of the luolocule, itn outline iu 
Inhject tf> incessant variation; fur notliin^ in nniliitvidur 
sience ii* regarded as more finnly cstuhliHhod than that 
the molecule, under all ordinary cireum«tancm, in In u 
state of intensse but varialilo ribnititnu The fjntirn tui 
ergy at a molecule uf giis, fur example, ie not meamnHul 
by itfi momentum, but by this plu» it« oncrgy of vibm- 
tion and rotation, due to the collisions alreatly ri^forriHl 
to* C'lausina has even esliraated tfio relative iru|itjrtanee 
of these two (pjantities, showing that the tmn«lHtinnal 
motion of a molecule of gas aecountH ftrr (»nly three* 
fifths of its kinetic energy. The toLiil energy of the 
jnoh^onle (which we call **hoaf ) ineludes also another 
ctar, nafnoly, potential energy » or energy of positioRt 
le to the work that has been done on expanrling, in 
rer€oming external pra*ianre, and internal attnu^tion 



between the molecules themselves. This potential en- 
ergy (which will be recovered when the gas contracts) is 
the " latent heat " of Black, which so long puzzled the 
philosophers. It is latent in the same sense that the en- 
ergy of a ball thrown into the air is latent at the mo- 
ment when the ball poises at its greatest height before 
beginning to fall. 

It thus appears that a variety of motions, real and po- 
tential, enter into the production of the condition we 
term heat. It is, however, chiefly the translational mo- 
tion which is measurable as temperature ; and this, too, 
which most obviously determines the physical state of 
the substance that the molecules collectively compose— 
whether, that is to say, it shall appear to our blunt per- 
ceptions as a gas, a liquid, or a solid. In the gaseous 
state, as we have seen, the translational motion of the 
molecules is relatively enormous, the molecules being 
widely separated. It does not follow, as we formerly 
supposed, that this is evidence of a repulsive power act- 
ing between the molecules. The jihysicists of to-day, 
headed by Lord Kelvin, decline to recognize any such 
power. They hold that the molecules of a gas fly in 
straight lines in virtue of their inertia, quite indepen- 
dently of one another, except at times of collision, from 
which they rebound in virtue of their elasticity; or an 
approach to collision, in which latter case, coming with- 
in the range of mutual attraction, two molecules may 
circle about one another, as a comet circles about the 
sun, then rush apart again, as the comet rushes from 
the sun. 

It is obvious that the length of the mean free path of 
the molecules of a gas may be increased indefinitely by 
decreasing the number of the molecules themselves in a 



drcumscrititHJ spac^. It bus been shown by Professors 
Tail and Uenar that a vacuum iii»y be produced aiti* 
ficiaUy of such u de<;ree of rarefaction thai the mean 
ftm path of the remaining moieiCQles Is measurable in 
iuches* The calculation is based on ejcperimeDts made 
with tbe radiometef of Professor Crookes, an instra- 
ment which in itself is held to demonstrate the truth of 
the kinetic tlieory of gases. Such an attenuated gas as 
this is considereti by Professor Crookes as constituting a 
fuurth state of matter, which he terms ultra-gaseoas. 

If, on the other hand, a gas is subjected to pressure, 
its molecules are crowded closer together, and the length 
nt their mean free path is thus lessened. Ultimately, the 
pressure being sufficient, the molecules are practically 
in c*>ntimious cont-uC Meantime the enormously in- 
creased nnudier of collisions has set the molecules more 
ami more actively vibrating, and the temperature of the 
giis lias increase^l, as, indee<U necessarily results in ac- 
cortlanoe with the law of the conservation of energy. 
No amount of pressure, tlierefore. can suffice by itself to 
reduce the gas to a liquid state. It is believed that 
iivi^n at the centre of the jjuu, wliere the pressure is aU 
most inconceivably great, all matter is to lie regarded as 
really gaseous, though the molecules must be so packed 
together that the consistency is probably more like that 
fif a srdid. 

If^ however, coincidently with the application of press- 
ure, op|)ortunity be given for the excess of heat to be 
dissipated to n colder surrounding medium, the mole- 
cules, giving off their i^xoess of energy, become relative- 
ly ijuiescent, and at a certain stage the gm becomes a 
liquid. The exact point at which this tninaformation 
occurs, liowevcr, difft^rs enormously for different sub- 


stances. In the case of water, for example, it is a tern- 
perature more than four hundred degrees above zero, 
Centigrade ; while for atmospheric air it is 194:° Centi- 
grade below zero, or more than a hundred and fifty de- 
grees below the point at which mercury freezes. 

Be it high or low, the temperature above which any 
substance is always a gas, regardless of pressure, is 
called the critical temperature, or absolute boiling-point, 
of that substance. It does not follow, however, that 
below this point the substance is necessarily a liquid. 
This is a matter that will be determined by external 
conditions of pressure. Even far below the critical tem- 
perature the molecules have an enormous degree of ac- 
tivity, and tend to fly asunder, maintaining what ap- 
pears to be a gaseous, but what technically is called a 
vaporous, condition — the distinction being that pressure 
alone suffices to reduce the vapor to the liquid state. 
Thus water may change from the gaseous to the liquid 
state at four hundred degrees above zero, but under 
conditions of ordinary atmospheric pressure it does not 
do so until the temperature is lowered three hundred 
degrees further. Below four hundred degrees, however, 
it is technically a vapor, not a gas; but the sole differ- 
ence, it will be understood, is in the degree of molecular 

It thus appears that the prevalence of water in a 
vaporous and liquid rather than in a "permanently" 
gaseous condition here on the globe is a mere incident 
of telluric evolution. Equally incidental is the fact that 
the air we breathe is " permanently " gaseous and not 
liquid or solid, as it might be were the earth's surface 
temperature to be lowered to a degree which, in the 
larger view, may be regarded as trifling. Between the 



; imere Ifei 
je paint woold bei 
vajior, J 
^mpenUnre of i 
Mir is tha m 
utmiMm of 
of Iheuij* Tkm fkj 
^mdooed aiitfiool 
bim to change the 
bm<t Cfu jr< 

infancTt FanKfaLT ! 
E^thvi the I 

by Claillecei in Switaaiud. br Pfai«i 
Dr Thorns 

Sngkiid, In tlie eemrm of 
imr been liquefied, bat h jA^gm nlm. tlv i 

> and hqjBud mre. na Andrewn Icm^ a^ ■■■fttrii, 
usiani stages uf a long nmei of eoniinneaspiiji- 
1 obangm.^ Of comrm if ibe leoipeMlnie be lowered 
'edn farther, the liquid beoooMS a solid ; and Hus change 
also bos been effected in the cmse of mme of tbe most 
*' permatietit ^ gaaea^ indnding air. 

II Tbe degree of cold— that Is, of afaeeooe of beat — tlins 
produced is enormoos. r&lati%-elj to anything of which 
we have experienee in nature here at the earth now, 
iret the molecules of solidified air, for example, are not 
i^jisoluutly «jui*38eent- In other wofda, they still ha?e a 
?mi>eratur«?, tbongli so vitv low. But ii is cWarly ©on- 

ordinary ^ero. 

A temperature (or absence 
approximating this is believed tc 
ooean of interplanetary und in 
transmits, but is tlioiight not to 
We here on the e£irth's sn efface 
posure to this cold, which wuuk 
thing of life almost instantaneoi 
blanket of atmosphere with whi 
It would seem jvs if this atmosjjl 
tem[)erature at its surface, musi 
liquelied, and thus fall back lilt* 
into gas again while it still is i 
earth's surface. This tnav be the 
ing molecules have not long ago vi 
and left the w^orld without protec 

But whether or not such lique 
occurs in oar outer atmosphere, t! 
as to what must occur in its enti 
raanentlj shut off from the heatir 
as the astronomers threaten that 
age. Each molecule, not alone of 

the i^ntirr mrfliV nuhmi^^^^a^^^ 


ultimately ruiining completely down, as surely as any 
human^made machine whose power is not from time to 
time restored. If then it shall come to pass in some 
future age that the sun*s rays fail us, the temperature 
of the globe must gradually sink towards the absolute 
zero. That is to say, the molecules of gas which now 
fly about at such inconceivable speed must drop helpless 
to the earth; liquids must in turn become solids; and 
solids theraselveSj their molecular quivers utterly stilled, 
may perhaps take on properties the nature of which we 
cannot surmise. 

Yet even then, according to the current hypothesis, 
the lieatless molecule will still be a thing instinct with 
life* Its vortex whirl will still go on, uninfluenced by 
tlie dying out of those subordinate quivers that produced 
the transitory effect which we call temperature. For 
those transitory thrills, though determining the physical 
state of matter as measured by our crude organs of sense, 
were no more than non-essential incidents; but the irortex 
whirl IS the essence ol matter itself. 


Small beginnings have great endings — sometimes. 
As a case in point, note what came of the small original 
eflFort of a self-trained back-country Quaker youth named 
John Dalton, who along towards the close of the last 
century became interested in the weather, and was led 
to construct and use a crude rain-gauge to test the 
amount of the waterfall. The simple experiments thus 
inaugurated led to no fewer than two hundred thousand 
recorded observations regarding the weather, which 
formed the basis for some of the most epochal discov- 
eries in meteorology, as we have seen. But this was 
only a beginning. The simple rain-gauge pointed the 
way to the most important generalization of our century 
in a field of science with which, to the casual observer, 
it might seem to have no alliance whatever. The won- 
derful theory of atoms, on which the whole gigantic 
structure of modern chemistry is founded, was the logical 
outgrowth, in the mind of John Dalton, of those early 
studies in meteorology. 

The way it happened was this : From studying the 
rainfall, Dalton turned naturally to the complementary 
process of evaporation. He was soon led to believe that 



va;>or exists in the atmosphet-e as an indepeodent gas. 
But since two btxlks ci&nnot oocajiy the same space at 

I I lie same time, thia implies that the varioug atmuspheric 
gtisos are really composed of ilii^ret© part teles. These 

ultimate particles are so small that we cannot see them 
J — cannot, indeed, more than %'aguely imagine them — 

jet ciich particle of vapor, for example, is just im much 
portion of water as if it were a drop oat of the ocean, 

ir, for that matter, the ocean itself. But again, water 
Ifs a compound Kub^taiicej for it may be separated, as 

Cavemlij*h had shown, into the two eleinenUry sul> 

Bumces hydmgen and oxygen. Ilence the atom pf 

ivater must be composed of two les^r atoms joinetl 
litigether. Imagine an atom of hydrogen and one of 

oxygen. Unite them, and we have an atom of water; 

sever thera, and the water no longer exists ; but whether 
111 ni ted or separate the atoms of hydrogen and of oxygen 

remain hydi^i^^en and oxygen and nothing else, Ditfer- 

Btttly mixed together or united, atoms produce different 
'gross substances: but the elementary atoms never change 

Ithetr cbemicfd nature— their distinct [jeraonality. 
I It was about the year 1803 that Dal ton first gained a 
full grasp of the conception of the chemical atom. At 
once he saw that the hypothusii^, if true^ furnished a 
marvellous key to secrete of mutter hitherto insoluble^ 
juestlons relating to the relatiw* proportions of the 
lUmm themselves. It is known, for example, tliat a 
pertain bulk of hydrogen gas unites with a certain bulk 
>t oxygen gas to form water. If it be true that this 
combination consists essentially of the union of atom.'^ 
>ne with another (each single atom of hy*lrogen unites! 
a single atom of oxygen), then the relative weights 
&f the original masses of hydrogen and of oxygen must 



bo a!ao the relative weights of each of their respective 
atoms. If one pountl of hydrogen unites with five and 
one-half ]K)unds of oxygen (as, accortling to Dalton^s ' 
exiKsrimeiits, it did), then the weight of the oxygan 

atom must be five and one-half times that of the hydro 
gen atona. Other compounds may plainly he tested in 
the same way. Dalton made numerous^ tests before hiil 
|>nblished his thoory* He found tliat liydrogon enters 
into compounds in smaller proportioni^ than any other 
element known to him, and so, for con ven ion oo, deter- 
mined to take the weight of the hydrogen atom as unityj 



The aloMic weight uf oxygen then becomes (as given in 
Dmltoti's first table of 1S03) 5,5 ; that of water (bytliogen 
plus oxygBUi being of courise *i5. The atomic weiglits 
of about a score of substances are given in Dal ton's firwt 
paper, which was reatl before the Literary and PhilO' 

^sophic^l Society of Manchester, October 21, IH03, J 
Womior if Dalton himself, great anil acute intellect 
though be had, sus]iected, wbeti he read that papofj that 
[he was iaaugu rating inie of the most fertile raoveraent» 
B?er enterod uq in the whole history of science if 

Be that as it may, it is certain enongh that Dalton *s 
conteni|iomries were at first little inipn*ssed witli tite 
Iftovd atomic theory. Just at this time, as it chanced, a 
lispute was waging in the fioUl of chemistry regarding 
matter of empirical fact which must necessarily be 
Bttled before such a theory as that of Dalton con Id 
feven hope for a hearing. This was the question wliL^ther 
or not chemical elements unite with one another always 

kin defuiiu^ proftortions. Berthollet, the great co-workor 
with UiViiisien and now the uujhL authoritative of living 
chemists, contended tfiat substanc<-*-s combine in alnn^Kt 
indefinitely graded proportions between fixed extreruen* 
^lli^ held that solution is really a form of chemical cotn- 
^bination^a po^sition which, if accepted, left no room fur 

Bat this contention of the master was most actively 
^disputed, in particular by Louis Joseph Proust, and all 
chemists of repute were obliged to take sides with one 
>r tho other For a time the authority of Bertliollet 
beld out against the facts, but at last accumalated evi- 




dence told for Proust and his followers, and towards the 
close of the first decade of our century it came to be 
generally conceded that chemical elements combine with 
one another in fi^ed and definite proportions. 

More than that. As the analysts were led to weigh 
carefully the quantities of combining elements, it was 
observed that the proportions are not only definite, but 
that they bear a very curious relation to one another. 
If element A combines with two different proportions of 
element B to form two compounds, it appeared that the 
weight of the larger quantity of B is an exact multiple 
of that of the smaller quantity. This curious relation 
was noticed by Dr. Wollaston, one of the most accurate 
of observers, and a little later it was confirmed by Johan 
Jakob Berzelius, the great Swedish chemist, who was to 
be a dominating influence in the chemical world for a 
generation to come. But this combination of elements 
in numerical proportions was exactly what Dalton had 
noticed as early as 1802, and what had led him directly 
to the atomic weights. So the confirmation of this 
essential point by chemists of such authority gave the 
strongest confirmation to the atomic theory. 

During these same years the rising authority of the 
French chemical world, Joseph Louis Gay-Lussac, was 
conducting experiments with gases, which he had un- 
dertaken at first in conjunction with Humboldt, but 
which later on were conducted independently. In 1809, 
the next year after the publication of the fii'st volume 
of Dal ton's N<'io Si/stem of Chemical Philosophy^ Gay- 
Lussac jmblished the results of his observations, and 
among other things brought out the remarkable fact 
that gases, under the same conditions as to temperature 
and pressure, combine always in definite naraerical 


THE cEvn'Rvs imoGEE^ » cacxisnr 

proportions as to rabme^ Eiactlj two wiIbmi ■ ef 

^vdrogen^ for examfte, ciihiae wiik cmm t^laam of 

pxTgen Ui (orm wmter. Moff«afv, thm ftwuHimg cam- 

ouiid giis ;4hvajt beats a mmfic ffriblks totkeaoM' 

bluing vcitumea^ Id the ctm joBl cted I^smmi ^ |W9 


j<Hi>.ni tstrtn flAV-iXflSM? 

iof hvclrogen and on© of oxygen results in pr©- 

bIv two volames of h siler %'apor 

Naturally enoagh the champions of the atomic theory 
^iied upon these obserY^at ions of GayLussac as lending 
Irong support to tbeir bypi>thf?sb— all of them, that is, 

il the enriotmly self reliant and self-sufficient author nf 
he atotnic theory him^if. nho declined to accept the 



observations of the French chemist as valid. Yet the 
observations of Gay-Lussac were correct, as countless 
chemists since then have demonstrated anew, and his 
theory of combination by volumes became one of the 
foundation-stones of the atomic theory, despite the op- 
position of the author of that theory. 

The true explanation of Gay-Lussac's law of combina- 
tion by volumes was thought out almost immediately by 
an Italian savant, Amadeo Avogadro, and expressed in 
terms of the atomic theory. The fact must be, said 
Avogadro, that under similar pliysical conditions every 
form of gas contains exactly the same number of ulti- 
mate particles in a given volume. Each of these ulti- 
mate physical particles may be composed of two or more 
atoms (as in the case of water vapor), but such a com- 
pound atom conducts itself as if it were a simple and 
indivisible atom, as regards the amount of space that sep- 
arates it from its fellows under given conditions of press- 
ure and temperature. The compound atom, com|>osed 
of two or more elementary atoms, Avogadro proposed 
to distinguish, for purposes of convenience, by the name 
molecule. It is to the molecule, considered as the 
unit of physical structure, that Avogadro's law applies. 

This vastly important distinction between atoms and 
molecules, implied in the law just expressed, was pub- 
lished in 1811. Four years later, the famous French 
physicist Ampere outlined a similar theory, and utilized 
the law in his mathematical calculations. And with that 
the law of Avogadro dropped out of sight for a full gen- 
eration. Little suspecting that it was the very key to 
the inner mysteries of the atoms for which they were 
seeking, the chemists of the time cast it aside, and let 
it fade from the memory of their science. 



H This, however, was not strange, for of course the law 
Bof Avogadro is based on the atoinic theory, and in ISll 
^■ihe atomic theory was itself still being weigbeti in the 
biilanoe. The law of multiple proportions found general 
acceptance as an empirical fact ; but many of tbeletuling 
lights of chemistry still luokeil askance at Dal ton's ex- 
pknaUon of this law. Thus Wollaston, though from 
the first be inclined to acceptance of tlie Daltonian view, 
cantionsly suggested that it would l>e well to use the 
non-committal word '^etiuivulent'- instead of "atom"; 
and Davy^ for a simihir reason, in his book of 1812, 
speaks only of ** proportions,'* binding himself to no 
theory as to what might bo the nature of these propor- 

I At least two great chemists of the time, however, adopt- 
Bil the atomic view with less reservation. One of these 
was Thomas Thomson, professor at Edinburgh, who in 
1807 had given an outline of Dalton's theory iu a widely 
circulated book, which first brought the theory to the 
general attention of the chemical world* The other, 
and even more noted advocate of the atomic theory, 
was Johan Jakob Berzelius. This great Swedish chem- 
ist at once set to work to put the atomic theory to such 
^la^ts as might Ixj applied in the laboratory. lie was an 
inalyst of tbe utmost skill, and for years he devoted 
bimaelf to the determination of the combining weights, 
** equivalents," or '^ jiroiiortions " of tbe different ele- 
men Us. These determinations, in so far as they were 
ac^mrately made, were simple expressions of empirical 
(acts, inde]>endent of any theory ; but gradually it be- 
ime moi**? and more plain that these facts all har- 
mnrm with the at4>mic theory of Dal ton. So by com- 
rtoon consent the proportionate combining weiglits of 



the elements came to be known as atoraic weights— 
the name Dalton had given them i'roiu the first — and 
the tangible conception of the chemical atom as a body 
of definite constitution and weight gained steadily in 

From the outset Llje idt*a liad ]iad the utmost tangibil- 
ity in the mind of Dalton. He liad ail along represented 
the different atoms by geometrical symliola— as a circle 
for oxygen, a circle enclosing a ilot for hydrogen, and 
the like — and had represented coinptHinds by placing 
these symbols of the elements in juxLa position. Ber^^elius 
proposed to im]}r(jve uj)on this methixl by siiU^titutiug 
for the (^eometi'ical symbol the initial of the Latin name 
of the element represented— O for oxygen » II for by- 
drogen, and so on — a numerical coefficient to follow 
the letter as an indication of the number of atoms pres- 
ent in any given compound. Tliis simple system soon 
gained general acceptance, and with slight modifica- 
tions it is still univei'sally employed. Every school* 
boy now is aware that 11/) is tiie chemical way of ex- 
pressing the union of twti atoms of hydrogen with one 
of oxygen to f<»rra a molecule of water. But snch a 
formula would have htui no meaning for the wisest 
cliomist before the day of Bcrzelius. 

The universal fame of the great Swedish authority 
served to give general currency to Ins symbols and 
atomic weights, ami the new pf>int of view thus devel- 
oped led presently to two iutportnnt discoveries which 
removed the last lingering doubts as to the valitlity 
of the atomic theory. In 1810 two French physicists, 
Dillon g and Petit, while experimenting with heat, dis- 
covered that the specific heats of solids (that is to say, 
the amount of heat required to raise the temperature of 




THE cENTUHV^s !n;<>Giiii:ss in chemistuv 

given mass tci a given degree) vnry inversely as their 

"ntomic weights. In the same year Eilhartl ilitscherlich, 

XI German investigator, observed that compouiuis having 

the same number of atoms to the molecule are disposed 

^Bd form the sam^* angles of crystallization — a property 

^^vhich he called isomorphisra. 


Here, then, were two utterly novel and inde|>endeiit 

lets* of empirical facts which harmonize strangely vvilh 

iicsiippisition that substances are cornpos(Hl of chemical 

IS of a determinate weight. Tliis surely could not 

>incidenc«— it tells of law. And so as soon as the 

lims of Dulong and Petit and of Mitscherlich had 

i>en subiLantiated by oMier observers, the laws of the 



specific beat of atoms, and of isomorphism, took their 
place as new levers of chemical science. With the aid 
of these new tools an impregnable breastwork of facts 
was soon piled about the atomic theory. And John 
Dalton, the author of that theory, plain, provincial 
Quaker, working on to the end in semi-retirement, be- 
came known to all the world and for all time as a mas- 
ter of masters. 


During those early years of our century, when Dalton 
was grinding away at chemical fact and theory in his 
obscure Manchester laboratory, another Englishman held 
the attention of the chemical world with a series of the 
most brilliant and widely heralded researches. Hum- 
phry Davy had come to London in 1801, at the instance 
of Count Rumford, to assume the chair of chemical phi- 
losophy in the Royal Institution, which the famous 
American had just founded. 

Here, under D.ivy's direction, the largest voltaic bat- 
tery yet constructed had been put in operation, and with 
its aid the brilliant young experimenter was expected al- 
most to perform miracles. And indeed he scarcely'' disap- 
pointed the expectation, for with the aid of his battery 
he transformed so familiar a substance as common pot- 
ash into a metal \vhich was not only so light that it 
floated on water, but possessed the seemingly mirac- 
ulous property of bursting into flames as soon as it 
came in contact with that fire-quenching liquid. If 
this were not a miracle, it had for the popular eye all 
the appearance of the miraculous. 

What Davy really had done was to decompose the 
potash, which hitherto had been supposed to be elemen- 



tary, liberating its oxygen, and thus isolating its metallic 
bise, which be named putHS.siuin, Thu siune thing was 
done with &oda, and the closely similar metal sodium 
was discovered—metals of a uaique tyjie, possessed of a 
strange avidity for oxygen, and capable of seizing on it 
even when it is bound up in the molecules of water- 
Cbnsiclered as mere curiosities, these discoveries were in- 
teresting, but aside from that thej^ were of great tlieo- 
petiail im|iortauce, because they showed the compound 
tiatore of some familiar chemicals that had been re- 
garded as elements. Several other elementary earths 
met the same fate when subjecteil to the electrical in- 
fluence, the ntetals ImriumjCulciumjaud strontium l>eing 
thus discovered, Therejifter Davy always referred to 
the sup|K)sed elementary substances (including oxygen, 
hydrogen, and tlie rest) as ** undecojnponnded" bodies. 
These resist all present efforts to dectiuipose them, but 
liow can one know what migiit not luipjien were they 
sabjetrted to an influence, perha|>s some (hiy to be dis- 
covereil, which exceeds the battery in |>i>wer as the bat- 
tery exceeds the blow-pi[>e ? 

Another and even more ini|><irtant theoretical result 
that flowed from Davy's ex|>eriim:ints during tfiis first 
dix'ade of tlie century wiis the proof tFiat no elementary 
other than hydrogen and oxygen are produce*! 
"fWre water is decomposed by the electric current. 
It was early noticed by Davy and others that when a 
Strang current is passed through water, alkalies appear 
at one (vole of the battery and acids at the other, and 
Ibis though the water used were absolutely pure. This 
seemingly told of the creation of elements— a transmuta- 
tion but rine step reriioved from the creation of matter 
it«elf — under the influence of the new "force." It was 




one of Davy's greatest triumphs to prove, in the series 
of experiments recorded in his famous Bakerian lecture 
of 1806, that the alleged creation of elements did not 
take place, the substances found at the poles of the bat- 
tery having been dissolved from the walls of the vessels 
in which the water experimented upon had been placed. 
Thus the same implement which had served to give a 
certain philosophical warrant to the fading dreams of 
alchemy banished those dreams peremptorily from the 
domain of present science. 

Though the presence of the alkalies and acids in the 
water was explained, however, their respective migra- 
tions to the negative and ]X)sitive poles of the battery 
remained to be accounted for. Davy's classical expla- 
nation assumed that diflFerent elements differ among 
themselves as to their electrical properties, some being 
positively, othei's negatively, electrified. Electricity 
and "chemical affinity," he said, apparently are mani- 
festations of the same force, acting in the one case on 
masses, in the other on particles. Electro-positive i)ar- 
ticles unite with electro-negative particles to form chem- 
ical compounds, in virtue of the familiar principle that 
opposite electricities attract one another. When com- 
pounds are decomposed by the battery, this mutual at- 
traction is overcome by the stronger attraction of the 
poles of the battery itself. 

This theory of binary composition of all chemical 
compounds, through the union of electro-positive and 
electro-negative atoms or molecules, was extended by 
Berzelius, and made the basis of his famous system of 
theoretical chemistry. This theory held that all inor- 
ganic compounds, however complex their composition, 
are essentially composed of such binary combinations. 




>r many years tins ?ie\v enjoyed almost undisputed 
ray. It receivetl what seemed strong coo tir mat ion 
ivben Famduy showed tlje delinite connection between 
the amount of electricity employed and the iimount of 
(Imrom position produced in tlie so-called electrolyte, 
But iL;5 cliiims were really niucli too couipiehensive, as 
Lsabse<juent discoveries proved* 

r When Beneelins first promulgated his binary theory 
he was careful to restrict its unmodified application to 
the compounds of the inorganic vvorkL At that time, 
and for a long time thereafter, it was sup(>o9ed that sub- 
stances of organic nature harl some properties that kept 
them alc»of from the domain of inorganic chemistry. It 
1 was little doubtc*! that a so-called ** vital force" oper- 
^pted here, replacing or modifying the action of ordinary 
"'chemical aittnity.'' It was, indeed, admitted that or- 
ganic compounds are composed of familiar elements^ 
I chiefly carbon, oxygen, hydrogen, and nitrogen — but 
' these elements were supposed to be united in ways that 
j could not be imitated in the ilomain of the non-living. 
^ It Wiis n^garded almost as an axiom of chemistry that 
no organic compimnd whatever could be put together 
from Its clements-^syntliesized— in the laboratory. To 
iffect the syntliesis of even the simplest organic com- 
and it was thought that the *' vital fortje" must be in 

Til ere fore a veritabl© sensation was crciitetl in tlie 

mical world when, in the year 1828, it was an* 

Trounced that the young German chemist Fried rich 

ohler, formerly pupil of BerzeHus, and already known 





as a coming master, had actually sjiitheiiized the well- 
known organic product urea in liis laburatory at Sacrow. 
The ''exception which prov^ the rule" is something 
never heard of in the domain of logical science. Nair 
ural law knows no exceptions. 80 the synthesis of a 
single organic compoiuul suBiced at a blow to break 
down the chemical barrier which the imagination of tije 
fathei's of the science had erected between animau? and 
inanimate nature. Thenceforth the philosophical chem- 
ist would regard the plant and animal organisms ns 
chemical laboratories in which conditions are peculiarly 
favorable for building up complex compounds of a few 
familiar elements, under tlie oixjration of univei^al 
chemical laws. The chimera ''vital force" could no 
longer gain recognition in the domain of chemistry. 

Now a wave of interest in organic chemistry swept 
over the chemical world, and soon the stntly of carbon 
conii>onnds became as much the fashion as electro-chem- 
istry had been in the preceding generation. 

Foremost among the workers who rendered tliis epoch 
of organic chemistry memorable were Justus Liebig in 
Oermany and Jean Baptist© Andr6 Dumas in France, 
nnd their respective pupils, Charles Fretleric Gerhardt 
and Augustus Laurent. Wohler, too, must l>e named in 
the same breath, as also must Louis Pasteur, who, f 
though somewhat younger than the others, came upon 
the scene in time to take chief part in the most impor- 
tant of the controversies that grew out of their labors. 

Several years earlier than this the way had been 
paved for the study of orphan ic substances by Gay-LuK- 
sac's discovery, made in 1815, that a certain compound 
of carbon and nitrogen, which he named cyanogen, has 
a peculiar degree of stability which enables it to retain 





identity, ami enter into clieniical relations after the 

nanner of a simple bmly, A year later Ampfire discov- 

^ifecl that nitr<>|ft*n and hydrogen, when combined in cer- 

iin jirofx>rtions to form what he oallad ammonium, 


ive the same property. Berxelfus had seized upon this 
jjiscovery of the compoiinfl radical, as it was called, be- 
lt seemed to lend aid to his dualistic theory. He 
jived the idea that all organic com|x»iind3 are bi* 
iry unions of rarious compound radicals with an atom 
"of oxygen* announcing this theory in 1818. Ten years 



later, Liebig and Wohler undertook a joint investigation 
wliich resulted in proving that compound radicals are 
indeed very abundant among organic substances. Thus 
the theory of Berzelius seemed to be substantiated, and 
organic chemistry came to be defined as the chemistry 
of compound radicals. 

But even in the day of its seeming triumph the dual- 
istic theory was destined to receive a rude shock. This 
came about through the investigations of Dumas, who 
proved that in a certain organic substance an atom of 
hydrogen may be removed, and an atom of chlorine 
substituted in its place without destroying the integrity 
of the original compound — much as a child might sub- 
stitute one block for another in its play-house. Such a 
substitution would be quite consistent with the dualistic 
theory, were it not for the very essential fact that hy- 
drogen is a powerfully electro-positive element, while 
chlorine is as strongly electro-negative. Hence the 
compound radical which united successively with these 
two elements must itself be at one time electro-positive, 
at another electro-negative — a seeming inconsistency 
which threw the entire Berzelian theory into disfavor. 

In its place there was elaborated, chiefly through the 
efforts of Laurent and Gerhardt, a conception of the 
molecule as a unitary structure, built up through the 
•iggivtration of various atoms, in accordance with ''elec- 
tive attinities'' whose nature is not yet understood. A 
doctrine of " nuclei " and a doctrine of " types " of molec- 
ular structure were much exploited, and, like the doc- 
trine of compound radicals, became useful as aids to 
memory and guides for the analyst, indicating some of 
the plans of molecular construction, though by no means 
penetrating the mysteries of chemical affinity. They 



are clas^si Heat ions rather than explanations of chemical 
ID ions. Bui at least Lliey served un important purpose 
giving ileliniteuess to the idea of a molecular struct- 
ure built of atoms as the basis of all substances. Noa7 
last the word moleL-ulL* came to have a distinct mean- 
ig, as dtsliiict from '*atom,-' ia the minds of the gener- 
jty of ahemists, as it had had for Avogadro a third of 
I century before. A?ogadro*s hypothesis that there are 
:|ual n limbers of these iiiulocules in ctjual volumes of 
seSj u ruler lixed cijnditionSj was revived by Gerhard t, 
and a tittle later^ under the championship of Caniiizmro^ 
exalted to the plane of a fixed law. Thenceforth 
de concejilion of the molecule was to be as dominant a 
bought in chemistry as the idea of the atom had be- 
Jine in a previous epoch. 

course the atom itself was in no sense dtj^placed, 
It Avogadro's law soon made it plain that the atom hail- 
ften usurpeil territory that did not really belong to it 
In many cases the cliemists had supposed tijemselves 
dealing with atoms as units where thi? true unit was the 
molecule, In tla? ease nf elementary gases, such as hy* 
ogen and oxygen, for example, the law of equal num- 
sn^ of mok^cuies in equal spaces made it clear that the 
:m\H do not exist isolateil, us had been supposed. Since 
?o vi>lumes of hydrogen unit© with one volume of oxy- 
m to form two voiumes of water vapor, the simplest 
baihematios shows, in the light of Avogadro*s law, not 
unly that each molecule of water must contain two hy- 
^fgen atoms (a \xnni previously in dispute), but that 
I ♦ original molecules of hydrogen and oxygen must 



have been composed in each case of two atoms — else 
how could one volume of oxygen supply an atom for 
every molecule of two volumes of water? 

What, then, does this imply ? Why, that the ele- 
mentary atom has an avidity for other atoms, a long- 
ing for companionship, an "affinity " — call it what you 
will — which is bound to be satisfied if other atoms are 
in the neighborhood. Placed solely among atoms of 
its own kind, the oxygen atom seizes on a fellow oxy- 
gen atom, and in all their mad dancings these two 
mates cling together — possibly revolving about one an- 
other in miniature planetary orbits. Precisely the same 
thing occurs among the hydrogen atoms. But now 
suppose the various pairs of oxygen atoms come near 
other pairs of hydrogen atoms (under proper conditions 
which need not detain us here), then each oxygen atom 
loses its attachment for its fellow, and flings itself madly 
into the circuit of one of the hydrogen couplets, and— 
presto ! — there are only two molecules for every three 
there were before, and free oxygen and hydrogen have 
become water. The whole process, stated in chemical 
phraseology, is summed up in the statement that under 
the given conditions the oxygen atoms had a greater 
affinity for the hydrogen atoms than for one another. 

As chemists studied the actions of various kinds of 
atoms, in regard to their unions with one another to 
form molecules, it gradually dawned upon them that 
not all elements are satisfied with the same number of 
companions. Some elements ask only one, and refuse 
to take more ; while others link themselves, when occa- 
sion offers, with two, three, four, or more. Thus we 
saw that oxygen forsook a single atom of its own kind 
and linked itself with two atoms of hydrogen. Clearly, 



ihen, the oxygen atom, like a creature with two hands, 

Hk able to clutch two otiier atoms. Bat we have no 

proof that under anj circumstances it could hold more 

than two. Its atUnities seem satis tied when it has two 

[)o«ds. But, on the other hand^ the atom of nitrogen 

able to hok) three atoms of liydrogen, and does so in 

the molecule of ammonium (NII^^); while the carbon 

itrmi can hold four atoms of hydrogen or two atoms 

>f lixygen. 

Evidently, then, one atom is not always equivalent to 

aother atom of a differt^nt kind in combining powers. 

'A recognition uf this fact by Fninkhtnd aliout 1852, and 

its further investigation by othem (notably A. Kekul^ 

^nd A* S. Couper), led to the introduction of tlie word 

juivalent into chemical terminology in u new sense^ 

jid in particular to an understanding of the altiuities 

^r " valency ^' of different elements, which proved of the 

st fundamental importance. Thus it was shown that, 

fcf the four elements that enter most prominently into 

rgantc compounds, hydrogen can link itself with only 

single Ixmd to any other element^ — it has, so to speak, 

li a singk? liatnl witli which to gi'asp — while oxygen 

hail cafxicity for two bonds, nitrogen for three (possi- 

bly for five), and carbon for four. The words mono- 

ilent, divalent, trivalent, tretmvalent, etc., were coined 

express this most important fact, and the various ele- 

iients f^nne to be known as monads, diads, triads, etc. 

Just why different elements should differ thus in valency 

one as yet knows; it is an empirical fact that they 

IK Ami once the natui*e of any element has been deter- 

lined as regards its valency, a most important insight 

Ito the possible behavior of that element has been 

ffamd. Tims a consideration of the fact that hydro- 



gen is monovalent, while oxygen is divalent, makes it 
plain that we must ex|>ect to find no more than three 
compounds of these two elements, namely, H — 0— 
(written HO by the chemist, and called hydroxy!); 
II— O— H (H^O, or water), and H— O— O— H (II2O2, 
or hydrogen peroxide). It will be observed that in the 
first of these compounds the atom of oxygen stands, so 
to speak, with one of its hands free, eagerly reaching 
out, therefore, for another companion, and hence, in the 
language of chemistry, forming an unstable compound. 
Again, in the third com|>ound, though all hands are 
clasped, yet one pair links oxygen with oxygen ; and 
ihis also must be an unstable union, since the avidity of 
an atom for its own kind is relatively weak. Thus the 
well-known propeities of hydrogen |)eroxide are ex- 
plained, its easy decomposition, and the eagerness with 
which it seizes ui)on the elements of other compounds. 

But th(i molecule of water, on the other hand, has its 
atoms arrnn<;:ed in a state of stable equilibrium, all their 
aHinities bein^i: satisfied. Each hvdrocren atom lias sat- 
islied its own affinity by clutching the oxygen atom; 
and the oxygen atom has both its lionds satisfied by 
clutching back at the two hydro^ren atoms. Therefore 
the trio, linked in this close bond, hav^e no tendency to 
roach out for any other companion, nor, indeed, any 
])()wer to hold another should it thrust itself upon them. 
Th(\v form a ''stable'' compound, which under all onli- 
narv circumstancos will retain its identity as a molecule 
of water, even though the physical mass of which it is 
a part chan^^es its condition from a solid to a gas — from 
ice to vapor. 

But a consideration of this condition of stable equi- 
librium in the molecule at once suggests a new question : 



How can an agtrregation of atoiiis^ having all their 

afflniliea satisfled, take any furtlior part in chemical 

^^^aciionsf Seemingly such a moleciile, wliatever its 

^Bljvsical pro[>erties, must be cbemically inert, incapable 

^■f any atomic readjust men ts. And so in point of fact 

^^t is. SO long as it« corn jjonent atoms cling to one another 

unremittingly. l>ut tins, it appears, is precisely what lIjc 

^Ktotrts a 1*6 little pmne to do. It seems that they are 

^Hckle to the last tlegree in their individual attacliments, 

^■md are us prone to break away from bondage as they are 

^Id enter into it. Thus the oxygen atom which has just 

rtung itself into the circuit of two hytJrogen atoms^ the 

Hfiext moment llings itself free again and seeks new com- 

^^laniuns. U is for all the worki lilie the incessant change 

of partners in a rollicking dance, 
^^ This incessant dissolntion :Hid refonnation of molecides 
^^i a substance whicli as a uhtde remnins nppan:*iitly un- 
change*! was first fully appreciated by Ste.*Cluire Deville, 
and by him named dissociation. It is a process which 
goea on mucli inore actively in ^<ime conij>onnds^ than in 
uther*s, antl very much nwre actively uuiler stnne l>liysi- 
cal conditioni?(sucl» as increase of teni(>eruture) than un- 
der othfrn. But apparently no suljstanees at onHnary 
tem)M*i*atureB, and no tcTuporature above the al)Solute 
zero, are absolutely free from its disturbing inHtience, 
Hence it is that moletmlos having all tlie valency of 
Mar-ir atoms fully satisfied do not lose their chemical 
.uiivitv- since each atom is momentarily free in the 
QXchangf* of partners, and may seiKe upon different 
atuins fnnn its former partneT*s, if those it prefers am 
at liand. 

While, l^o\vever, an appreciation of this ceaseless 
aclivitv <»f the atom is essentrMJ Ui a proper unilerstantl- 


ing of its chemical eflBciency, yet from another point of 
view the " saturated " molecule — that is, the molecule 
whose atoms have their valency all satisfied — may be 
thought of as a relatively fixed or stable organism. 
Even though it may presently be torn down, it is for 
the time being a completed structure ; and a considera- 
tion of the valency of its atoms gives the best clew that 
has hitherto been obtainable as to the character of its 
architecture. How important this matter of architecture 
of the molecule — of space relations of the atoms — may 
be was demonstrated as long ago as 1 S23, when Liebig and 
Wohler proved, to the utter bewilderment of the chem- 
ical world, that two substances may have precisely the 
same chemical constitution — the same number and kind 
of atoms— and yet differ utterly in physical properties. 
The word isomerism was coined by Berzelius to express 
this anomalous condition of things, which seemed to 
negative the most fundamental truths of chemistry. 
Naming the condition by no means explained it, but 
the fact was made clear that something besides the 
mere number and kind of atoms is important in the 
architecture of a molecule. It became certain thaU 
atoms are not thrown together haphazard to build a^ 
molecule, any more than bricks are thrown together 
at random to form a house. 

Ilow delicate may be the gradations of architectural 
design in building a molecule was well illustrated about 
1850, when Pasteur discovered that some carbon cora- 
])ounds — as certain sugars— can only be distinguished 
from one another, when in solution, by the fact of their 
twisting or polarizing a ray of light to the left or to 
the right, respectively. Rut no inkling of an explana- 
tion of these strange variations of molecular structure 



came ootil tlie discovery of the law of valency. Then 

ittncb of the mystery was cleaned away ; for it was 

platB that since each atom iu a molecule can hold to 

itiself unly a fixed number of other atoms, complex 

fi0otecule$ must have their atoms linked in definite 

chains or groups. And it is equally plain that where 

the atoms are numerous, the exact |>lan of grouping 

I may sometimes \)e susceptible of cliange without doing 

violence to the law of valency* It is in such cases that 

isomerism is observed to occur. 

By paying constant heed to this matter of the afBni- 

J ties, chemists are able to make diagrammatic pictures of 

[the plan of architecture of an}' molecule whose cum- 

«>silion is knuwn. In the simple molecule of water 

[H3O), for exatu|)lef the two hydrogen atoms must have 

relt^asml one another before they could join the oxygen^ 

and the manner of linking must appai'ently be that rep- 

nesented in the griiphic formula II — ^O— IL With raole- 

sales composed of a large number of atoms, such graphic 

*prc8entatiun of the scheme of linkiTig is of course in- 

ri^asingly difficult, yet, with the afflnities for a guide, it 

[is always possible. Of course no one supposes that such 

formuhu written in a single plane, can possibly repre- 

Ecnl the true architecture of the molecule : it is at best 

suggest! V0 or diagrammatic rather than pictorial, Never- 

tbeless, it aJfoixIs hints as U> the structure of the raole- 

Icnlo MJcli as the fatliers of chemistry would not have 

Itbought it pussible ever to attain. 


These utterly novel studies of molecular architecture 
[nmy seem at first sight to take from the atom much of 



its former prestige ns iin3 all-iruportant persouago of tUtj 
chemical world. Since so much depends upon the mere 
pDsiLiijii of the iitonis, it may appear that coniparutively 
itltlu depends upon the naturo of the atoms tliumselvos. 
But such a view is incorrect, for on closer consideration 
it will appi?ar that at no time Ims the atom been seen to 
renounce its peculiar [)ersomility. Within certain limits 
the cliaracter of a molecule may be altered by changing 
the positions of its atoms (just as different buildings may 
bo constructed of the same bncks)i but these limits are 
sharply defined, and It would be as impossible to exceed 
them as it would be to build a stone building with bricks. 
From first to last the brick remains a brick, whatevei" 
the stjie of architecturu it helps to construct; it never 
becomes a stone. And just as closely does etich atom 
retain its own peculiar properties, regardless of its sur- 

Thus, for example, the carbon atom may take part in 
the formation at one time of a diamond, again of a piece 
of coal, and yet again of a particle of sugar, of wood 
fibre, of animal tissue, or of a gas in the atmosjihere; 
but from first to last — from glass-cutting gem to in- 
tangible gas— there is no demonstrable change whatever 
in any single property of the atom itself. So far as we 
know, its size, its weight, its capacity for vibration or 
rotation, and its inherent afiinities, remain absolutely 
unchanged tliroughout all those varying fortunes of po- 
sition and association. And the same thing is true of 
every atom of all of the sixty-odd elementary substances ■ 
with which the moiiern cliemist is acquainted. Every 
one appears always to maintain its unique integrity, 
gaining nothing and losing nothing. 

All this being true, it would seem as if the position of 



the Dultcmian atom as a primordial bit of inatterj imle- 

itructible antl nan^Tiiiisinu tabic?, luuf been put to the 

est by tlie cljeniistry of our centur^^ and not found 

anting* Since those early days of the century when 

bt? electric battery porfornned its miracles and seemiLg 

reached its iimitationB in thf* bunds of Davy, mtxi^ 


5 w deinenliiry substances have been discovered, but un 

[ftglo element has been displaced from its position as an 

lUooamposable body. Rather have the analyses of the 

the: story of ninetkentii-ukntury science 

clieniLst seemed to make it more and more certain that 
all elementary atoms are in truth what John Hepschel 
called tliem, '" manufactured articles" — primordial, 
changeless, indestructible. 

And yetj oddly enough^ it has chanced that band in 
hand with the experiments leading to such a goal have 
gone other expenmerits and speculations o( exactly the 
opfK>site tenor. In eacli generation there have been 
chemists among the leaders of their science vyho have ■ 
refused to admit that the so^^alled elements are really 
elements at all in anv final sense, and who have soucrht 
eagerly for proof which might warrant their scepticism. 
The lii*st bit of evidence tending to support tfiis vieiv 
was furnisbed by an English physician. Dr. William 
Pruutj who in 1815 called attention to a curious riilation 
to be observed between the atomic weight of the van 
ons elements* Accepting the fignres given by the au- 
thorities of the time (notably TIjomson and Berzelius), it 
appeared that a strikingly large proportion of the 
atomic weights were exact multiples of the weight of 
liydrogen, and that others differed so slightly that errors 
of observation might exj)lain the discrepancy, Prout 
felt that this could not be accidentaU and he could thtnV ■ 
of no tenable explanation, unless it be that the atoms of 
the various alleged elements are made up of different 
fixed numbers of hydrogen atoms. Could it be that the 
one trne element — the one primal matter— is hydrogeu, 
and that all other forms of matter are but compounds 
of this original substance? 

Prout advanced this startling idea at first tentatively, 
in an anonymous publication ; but after wanls he espouse4i 
it ojienly and urged its tenabiliby. Coming just after 
Davy's dissociation of some supposed elements, the idea 




>ved alluring^ and for a time gaiiieti such popularity 
bat chemists were disposecl to roimd out the observed 
t'linic weights of all elements into whole numbers. 


[But presently renewecl determinations of the atomic 
1 weic^liLs seemed to discountenance this practice, and 
I ProTjt's alleged law fell into disrepute. It was revived, 
iliQrdver^ about 1840, by Dumas, whose great authority 
i^ocQml it a respectful hearing, and whose careful rede- 
I tflrminfition of the weight of carlion, making it exactly 
twclvij times that of hvdrocren, aided the cause. 


Subsequently Stas, the pupil of Duihas, undertook a 
long series of determinations of atomic weights, with 
the expectation of confirming the Proutian hypothesis. 
But his results seemed to disprove the hypothesis, for 
the atomic weights of many elements differed from 
whole numbers by more, it was thought, than the limits 
of error of the exf^riments. It is noteworthy, however, 
that the confidence of Dumas was not shaken, though 
he was led to modify the hypothesis, and, in accordance 
with previous suggestions of Clark and of Marignac, to 
recognize as the primordial element, not hydrogen it- 
self, but an atom half the weight, or even one-fourth 
the weight, of that of hydrogen, of which primordial 
atom the hydrogen atom itself is compounded. But 
even in this modified form tlie hypothesis found great 
opposition from experimental observers. 

In 180i, however, a novel relation between the 
weights of the elements and their other characteristios 
was called to the attention of chemists by Profesaor 
John A. li. Newlands, of London, who had noticed that 
if the eleni(nits are arranged serially in the numerical 
order of their atomic weights, there is a curious recur- 
rence of siniihir properties at intervals of eight elements. 
This so called '' law of octaves" attracted little immedi- 
ate attention, but the facts it connotes soon came under 
th(i observation of other chemists, notably of Professors 
(Justav llinri(;hs in America, Dmitri Mendeleeff in Rus- 
sia, and Lothar \r<»yor in (Germany. Mendeleeff gave 
the discovery fulh^st expression, expositing it in 1869, 
under tlie title of ''])eriodic law." 

Thoiit;h this early exposition of what has since been 
admitted to be a most important discovery was very 
fully outlined, the generality of chemists gave it little 


AliraJwtii BtignnliiB, New Y«fk 

mm n iiof^caslon ol 




\ lieed till a decatlia or so later, when three new eletnetits, 

{gulliuni, seiuidium, and geriuanimn^ were discovered, 

which, on being analyzed, were quite unexpectedly 

found U> fil into three gaps which Mendeleeff had left 

I in his periodic scale. In effect, the j>oriodic law had en- 

ahled Mendeli;efT to predicate the existence of the new 

^^(•ietiient^ years befum they were discovered. Surely a 

^bystetn that \muls to such results is no mere vagary. So 

^prary soon the [jeriodic law took its place as one of the 

tiio8t imjKjrtant generalizations of clieinicul science, 

Thi8 law uf periodicity waa put fur wan I as an expres- 
sion of observed i*elations independent of hypothesis; 
l^>ut of course tfje theoretical beanngs of these facts 
^^(»ald not lie overlooked. As Professor »T. H* Ghiflstone 
^lias said, it forceH upon us ^* the conviction that the ele, 
iiients are not separate bodies created without reference 
to one anothcrt hut that they have been originally fash- 
^t>nt*d, or have been built up, from one another, accord- 
ing to Si>me geneiid plan.'* It is but a short step from 
that pro|iositin!i to the Proutian hypothesis. 

But the atomic weights are not alone in suggesting 
khi5 compound nature of the alleged elements. Evi- 
dence of a totally dilferent kind has contributed to the 
\me end, from a souree that could hardly liave been 
Imagined when the Proutian liypotiiesis was formulated, 
through the addition of a novel weapon to the arraa- 
tTnenfarium of the chemist— the spectroscope. The per- 
[ftictiun of this instrument, in the handsi of twr> German 
Iscientists, Gnstav Rolx^rt KirohiiolTand Roliert Wilhclm 
IRuniw^n, came about through the investigation, towards 
tlm middle of the century, of the meaning of the dark 
'linu* which had been observed \n the solar spectrum b}^ 
Pmunhofer as early jis 1315, and by WoUiiston a decade 



'54*.--rr I: -Ti.4 •.--:»ci.-:c»i ov <:.>ie> an-1 by Fox Tall»t 
.:. f>.j..i-:..iL >-: -r-: >• .-::^: tv »:r:2i'>!i>:ra:i->c bv Kircb- 
i-'>i*f i'«: i^jri^', 'LaZ ZLrs^ lln^is. Allien :vere kaowm to 
'>y:j;»v «;T!i' .:•;• >.«5:: >Ti^ :n i^e speeiranu are neallv in- 
•j -it.vr- •»: :• *•►: :i. i- ^.-rnir-^jirT satfStarc^rsL Bv means 
o* • .-r ^•9'*.:\rr^: jV*'. '*v:J.::^ > c&seni.aiiv a maOTifjing 
l-rr.-i a'.: i.:.i»^I t*i * }»r.^:n of glass, il is [possible to locate 
ifj*r i;n»r» viiij irivi: ;ii>*'jraej. aaJ it was soon shown 
tfj;ii ii'rr'T v. IS a ri- v la-^iTis ••: chemical analysis of the 
uvrii ex'j'i:si:'? •l»ri;«jacy. It -.vas foun*K for example, 
tiiut ill*: -p--c:rTv:'iif' c«>'ii-I <kteoT the presence of a 
#jijantiiy of s«>li'i:ii <*» infinitesimal as the one two- 
)jiin*ln-«I-iijoj^iinliij •/ a irrain. IJut what was even raar« 
i!ii|K>ftaJit. lii- >! K*e I r »><:'> j»e pal no limit upon the dis- 
Uiiu: : of of tli»' suiistance it tested, providt3^ 
orjiy tiiat >'iffic.Vnt liiriit came fr«»m it. The ex|>ei"i- 
rri'mrs it. re^vni»f«l ini^ht 'oe ]>?rforme<l in the sun, or i" 
tlj*' THo-t ilisTiiit sta!*s or nel)uke: indeetl, one of tli« 
**;irli<'sr f^Mts of the instrument was to wrench from the 
sun tin- s«M-n»t of his ch«Mnical constitution. 

To r<*rMl«T th»* utility of the spectroscoi)e complete, 
ho.vf'v*-?'. it was nfH'essary to link with it another new 
r-h*MMi^iI :\iri^n('\\ naiUL'ly, i>hi>togniphy. Tills now fa- 
niihar |>nK!<'ss is hasrd on tlie property of light to de- 
(:oiii|)os(* (!<*itain unstMl)le couipoimds of silver, and thus 
alt<'r t,hcir chcruif^al (composition. We have seen that 
Davy ;ni<l W«Mlir\v<»o(| barely escaped the discovery of 
\.\n'. v;ihi<* of th«; pliotoirraphic method. Their successors 
(jiiit<(; ov«-i'lorik(Ml it until al)out iJ^'iO, when Louis J. M. 
I);ii^ni(Mrc. th<' French (;homist, took the matter in hand, 
and afliM- many years of oxp(^rimentation brought it to 
n^lativc pcji-fcction in Is^O. in which year the famous 
(hi^niriTcotypjj first brought the matter to popular at- 



itioiK In the same year Mr, FoxTalix>t rend a paper 
the subject befom the Royal Society, and soon after, 

Jfartis the elTorts of nersdiol and numerous other natu- 
phihHophers ooutributed to tbc advaaueuit^in of the 

Bw methfxl* 


In 1843 Dr. John W. Di-upor. the famous English- 
^fnvricun clicinist and physiologist, showed that by 
f»hr>Ujgrapliy the Fraunhofer lines in the solar spectrum 

l^iight he mapped witii absohite accuracy ; also proving 
limt the sil Venn! film revealed many lines invisible to 

|lt(e unaided eye* The value of this method 4*f observa- 
tion WM recognized at once, and, as soon as the spectro 



scope was perfected, the photographic method, in con- 
junction with its use, became invaluable to the chemist. 
B}' this means comparisons of spectra may be made 
with a degree of accuracy not otherwise obtainable; 
and in case of the stars, whole clusters of spectra may 
be placed on record at a single observation. 

As the examination of the sun and stars proceeded, 
chemists were amazed or delighted, according to their 
v.arious preconceptions, to witness the proof that many 
familiar terrestrial elements are to be found in the ce- 
lestial bodies. But what perhaps surprised them most 
was to observe the enormous preponderance in the si- 
deral bodies of the element hydrogen. Not only are 
there vast quantities of this element in the sun's atmos- 
phere, but some other suns appeared to show hydrogen 
lines almost exclusively in their spectra. Presently it 
appeared that the stars of which this is true are those 
white stars, such as Sirius, whicli had been conjectured 
to be the hottest; whereas stars that are only red-hot, 
like our sun, show also the vapors of many other ele- 
ments, including iron and other metals. 

In 187S ^^r. J. Norman Lockyer, in a paper before 
the Royal Society, called attention to the possible sig- 
nilicance of this seric^s of observations. He urged that 
the fact of tho sun showing fewer elements than are ob- 
served here on the cool earth, while stars much hotter 
than the sun show chiefly one element, and that one 
hydrogen, the lightest of known elements, seemed to give 
color to the possibility that our alleged elements are 
really compounds, which at the temperature of the hot- 
tc^st stars may be decom]>osed into hydrogen, the latter 
'* element " itself being also doubtless a compound, which 
might be resolved under yet more trying conditions. 



Here, then, was what might be termed direct experi- 

tlietilal evidenci? fur tljc hypotliesis uf Prout. Unfurtu- 

atelv, however, it is evidence of a kind which only a 

w experts are competent to discuss— so very delicate a 

"matter is the sjx*ctnd analysis of the stai's. What is 

|!*lill more ini fortunate, the exi)erts do not agree among 
themselves as to the validity of Mr, Lockyer's conclu- 
^<>ns. Soraet like Professor Crookes, have accepted 
ibem with acclaim, hailing Lookyer as '*the Darwin of 
tlie inorgaaic world," while utheis have songht a differ- 
ent explanation of the facts he brings forward* As yet 
i t ca a no t be sa id that i h e co n t ro ve rs y h as be en br on g 1 1 1 
to final settlt*inent. Still, it is hiirdly Lu bo doubted 
tbttt now, since the periodic law has seemed to join 
ands with the spectroscope, a belief in tiie compound 
tare of the so-called elements is rapidly gaining 
>und among chemists. More and mure geueml he- 
mes the belief that the Dal Ionian atom is really a 
'omipound radical, antl that back of the seeming di- 
versity of the alleged elements is a single unique form 
f primonlial matter. But it should not be forgotten 
that this view, whatever its attractiveness, still lurks in 
ihe domain of theory. There is no proof that the Dal- 
tonian atom has yet been divided in the labomtory. 




WoF»r Coleridge a;ii<l of lliiniphry Davy tbat he mign 
have been tlie greatest poet of his time had he not _ 
chosen rather to be the greatest chemist, it is possible f 
that the enthusiasm of the frieml outweighed the caa- 
tion of tlie critic. But however that may be, it is be- 
yond dispnte that tlte man who actually was the great- 
est poet of that time migfit easily have taken the very ■ 
highest rank as a scientist had not the Muse distracteil 
his attention. Indeed, tles[)i to these distraetionK, Jobann 
Wolfgang von Goethe achieved successes in the field of I 
pure science tbat would insure permanent recognition 
for his name had lie never written a stanxa of poetry. 
Snch is the versatility that marks the highest genius. 

It was in 1700 that Goethe published the work tbat 
laid the foundations of his scientific rpputation— the 
work on the Mftffmorjfffoses of PJftnU^ in which be ad- 
vanced the novel doctrine tbat all parld nf the flower am 
mmlified or metamorphostHl leaves. This was folio wchI 
presently by an extension of the doctrine of metamor- 




phosis to the animal kingdom, in the doctrine which 
Goethe and Oken advanced independently, that the ver- 
lebrate skull is essentially a modified and developed ver- 
tebra. These were conceptions worthy of a poet; im- 
pj&sible, indeed, for any mind that had not the poetic 
facidty of correhition. Hut in this case the poet'g vision 
was pniphetic of a futut\i view of the must prosaic sci- 
ence. The doctrine of metamorphosis of parts soon 
came to be regarded as a fundamental feature In tho 
science of living tilings. 

But the doctrine had implications that few of its 
early advocates realized. If all the [mrts of a ttovver' — 
sepal, petal, stamen, pistil, with their countless devia- 
tions of contour and color^are but modilicatiuns of the 
leaf, such moditiciiliun implies a marvellous differentia- 
tion and developiuent. To assert that a stamen is a 
metarnurphosed leaf means, if it menns anything, that in 
the long swL»ep of lime the leaf has by sh*w or sudden 
gmdatftuis chanc:ed its character through successive 
genenitions* until tho offspring, so to speak, of a true 
leaf luis bccoiiu^ a stamen. I'ut if such a metamorphosis 
as this is poftsilile — if the seemingly wide gaj) between 
leiif and stamen may be spanned by llie m^Hlification of 
a line of organisms — where iloes the possibility of modi- 
fication of organic type find its bounds'^ Why may 
not tho modification of parts go on along devious lines 
nntil the remote descendants of an organism are utterly 
unlike that organism ? Why may we not thus account 
for the development of various species of beings all 
sprung from one parent stock? That too is a poet's 
dream; but is it only a dream? Goethe thought not. 
Out of hiss studies of metamorphosis of parts there grew 
in his mind the belief that the multitudinous species of 

T 289 


plants and animals about 11$ hare been evolved from 
^ewer and fewer earlier parent tvpes, like twigs af li 
jiant tree drawing their nurture fmm the same primal 


root It was a bold and rev(4utionarv thought- and 
the worlil reji^ni'iied it ns but ti*e vagorv of a poet* 

Just at the time when this thought was takings form 
in Goethe's brain, the same idea was germinating in the 
mind of iinother philosopher, an Englishnmn of interna* 
tional fame, T>r. Erasmus Darwin, who, while he lived, 
enjoyed tlie widest popiilaritv as a poet, the rhynie<l 
couplets of his Bohime /Jtrrffen being q noted every- 





where with admiiation, AjuI [lo^sterity, repudiating the 
Verne whirh makes the body of the book, yet grants 

Hpermanfint value to the book itself, because, fofsc»oth, 

^Ets copious uxphinatory rootnott*s furnish an out Hue of 

Htlie &tatu!£ of almost every department of science of 

Htlie time. 

^ But. even though he lacked the highest art of the versi- 
lier, Darwin had, beyond peradv'enture, the imagination 

^bif u [>oet coupled with profound scientific knowltKlge ; 

^atid it was his poetic insight, correlating urganisms seem- 
ingly diverse in structure, and imbuing the lowliest 
flower with a vital personality, which led him to sus- 
5ct that there are no lines of demarcation in nature. 
Can it be," he queries, *Hhat one form of organism 
has develojiod from another ; that different species are 
really but modified descendants of one parent stcx^k?" 

■The alluring thought nestleil in his mind and was nurt- 
ured there, and grew into a fixed belief, which was 
given fuller expression in liis Zfxhmmm^ and in the 

I]Kjst.hamous Temph' of Nature, But there was little 
pro4*f of its validity forthcoming that could satisfy any 
one biit a poet, and when Erasmus Darwin died, in 1802, 
the idea of transmutation of species was still but an un- 
aubstuDiiated dream. 

It was a dream, however, wbich was not confined to 

kvoethe and Darwin, Even earlier the idea had come 

linore or less vaguely to anotlier great dreamer — and 

[worker— of Germaity, Immanuel Kant, and to several 

It Frenchmen, including De Maillet, Maupertuts, 

lobinet, and the famous naturalist Buffon— a man who 

IWl tlie imagination of a |K)et, though his message was 

cixiched in most artistic prose. Not long afk»r tlie mid- 

jdte of the eighteenth century Buffon had put forward 



the idea of transmutation of species, and he reiterated 
it from time to time from then on till his death in 1788. 
But the time was not yet ripe for the idea of transmu- 
tation of si>ecies to burst its bonds. 

And yet this idea, in a modified or undeveloped form, 
had taken strange hold upon the generation that was 
upon the scene at the close of the eighteenth century. 
Vast numbers of hitherto unknown species of animals 
had been recently discovered in previously unexplored 
regions of the globe, and the wise men were sorely puz- 
zled to account for the disposal of all of these at the 
time of the Deluge. It simplified matters greatly to 
suppose that many existing species had been developed 
since the episode of the Ark by modification of the 
original paii-s. The remoter bearings of such a theory 
were overlooked for the time, and the idea that Amer- 
ican animals and birds, for example, were modified 
descendants of Old World forms — the jaguar of the 
leopard, the puma of the lion, and so on — became a cur- 
rent belief with that chiss of humanity who accept al- 
most any statement as true tliat harmonizes with their 
prejudices, without realizing its implications. 

Tlius it is recorded witli eclat that the discovery of 
the close proximity of America at the northwest with 
Asia removes all dilficulties as to the origin of the 
Occidental faunas and Horas, since Oriental sj^cies 
might easily have found their way to America on the 
ice, and have been modified as we find them by '* the 
well-known inttuence of climate." And the persons who 
gave expression to tiiis idea never dreamed of its real 
sitrnificance. In truth, here was the doctrine of evolu- 
tion in a nutshell, and, because its ultimate bearings 
were not clear, it seemed the most natural of doctrines. 



Bat most of the persoas who advanced it would have 
turned from it aghast could they have idealized its ira- 
[K>rt, As it wiis, Imwev^er, only here and there a man 
like Buff on reasoned far enough to inqaire what might 
I be the limits of such assumed transniutation; and only 
here and there a Darwin or a Goethe reached the coa- 
victioQ that there are no limits. 


Lnd even Goethe and Darwin had scarcely passed be- 
yond that tentative stage of ctrnviction in which they 

^hehi the thought of transmutation of species as an ancil- 

llary belief, not yet reaily for full eX|K>sitiou There 

]wa8 one of tfietr contemporaries, however^ who, holding 
the sfiine c^jnception* was moved to give it full explica- 
tion. This was the friend antl diseiplc of Bnjfon, Juan 
liapti^te de Lamarck, Possessed of the spii'it of a pL>et 

land philosopher, ttds great Frenchman had also the widest 
raiigo of feclinieal knowledge, eovering the entire field 

I of animate nature. The first half of his long life was 
devoted cliielly to botan3% in which he attained high 

I distinction. Then, just at the beginning of our cen- 
tor\\ he turned to zoology, in particufar to the lower 
fornix* of animal life. Studying tliese lowly organisms, 

leiasling iind fossil, he was more and more impressed 
with the gradations of form everywhere to be seen ; 
the linking of diverse families tlm>agh interinoiiiate 
imm; and in particular witli the predominance of low 
types of life in the earlier geological strata. Called njmn 
ponntantly to classify the various forms uf life in the 
ooQnsc of his systematic writings, lie found it more and 
dKHcult to ilniw sharp lines of demarcation, and at 



last the guspicton long harlxjitnl grew into asetlletl con 
viytion that tiurrr* in really no sueh thing as a specie-s d 
orgiinisrii in natum; that '* species*' 13 a ligmeot of im 



mman imagination, wheroas in nature there ar©^ 

Til fit c^ortain sets of indivitluab are more like one i 
other than like other sets is of course patent^ but 




otily means, said I^iinarck, that tbese similar groupB 
have hud comparuLiveLj recent tioiuinou aiicestuiis^ whUci 

tfiis^iiiiilur seis uf boiiigs uru muro reraotely related in 
cjunsaaguiiuty. But trace back the lines of descent far 
Esnougli, and aJl wjU calmiaaty in one original stock. 
All forms of life whatsoever are nii^diiied desutjiidants 
>f uu ongioal organ ism. From lowest to liighest, then, 
^bere is but one race, one species, just as all the mul- 
titudinous branches and twigs from one root are but 
ne tree. For [inr poses of convenience of descHptionj 
ive may divide organ isnm into oi-der-s, fanilUeSj genera^ 
:speeies, just as we divide a tree into root, trunk, 
■branches, twigs, leaves ; but in the one ease, as in the 
^^ther, the dii'tsion is arbitrary and artificial. 

In Pkilttmp/iiti Ztt/f/^tfji*jn6 (1800), liamai-ck first ex- 
plicitly forinntateil his ideas as to the transmutation of 
species, tliuiigb he had outlined them as early as 1801, 

tin this nieniuruble publication not only did ho state Ida 
belief mure explicitly and in fuller detail than the idea 
had been expnss(*d by any ]>redecessor, but he took an- 
other kiTig forward step, carrying him far beyond all his 
forerunnei^ except Darwin, in that he nnnle an attempt 

IUMtxplain l]w wny in which the transmutation of spe* 
cic^ had been brought about The citanges have been 
wrought, he said, through tlie nnceasing efforts of each 
organism to meet the needs imposed upon it by ita envi- 
ronment Constant striving means the constant use of 
^H ^Tftain organs, and such use lends to tlie development 
^t at thi>se orirans* Thus a bird running by the seashore 
f is constantly tempted tu wade deeper qnd deeper in 
K pnrKuit of food; its incessant efforts tend to develop 
Wm itu lei:^, in accorclanc^ with the observed principle that 
Ifie use of any organ tends to strengthen and develop it. 



But such slightly increased development of the legs is 
transmitted to the offspring of the bird, which in turn 
develops its already improved legs by its individual ef- 
forts, and transmits the improved tendency. Generation 
after generation this is repeated, until the sura of the 
infinitesimal variations, all in the same direction, results 
in the production of the long-legged wading-bird. In 
a similar way, through individual eflFort and transmitted 
tendency, all the diversified organs of all creatures have 
been developed — the fin of the fish, the wing of the bird, 
the hand of man ; nay, more, the fish itself, the bird, the 
man, even. Collectively the organs make up the entire 
organism; and what is true of the individual organs 
must be true also of their ensemhle^ the living being. 

Whatever might be thought of Lamarck's explanation 
of the cause of transmutation — which really was that 
already suggested by Erasmus Darwin — the idea of the 
evolution for which he contended was but the logical 
extension of the conception that American animals are 
the modified and degenerated descendants of European 
aninijils. l^ut people as a rule are little prone to follow 
ideas to their logical conclusions, and in this case the 
conclusions were so utterly opposed to the proximal 
hearings of the idea that the whole thinking world 
repudiated them with acclaim. The very persons w^ho 
had most eagerly accepted the idea of transmutation of 
European species into American species, and similar hm- 
itod variations through changed environment, because 
of the relief thus given the otherwise overcrowded Ark, 
were now foremost in dcniouncing such an extension of 
the doctrine of transmutation as Lamarck proposed. 

And, for that matter, X\w leaders of the scientific world 
were equally antagonistic to the Lamarckian hypothesis. 




Cuvier in particular, once the pupil of Lamurck, but now 
ills colleague, and in uuttiority more tlian liis [leer, stood 
oat zii^iirist the transmutation doctrine with all bis force. 
lie a rgu eil f o r t h ♦.? a bsol u t e fi x i Ly of s pec i es , hviu g\ ng to 
bear the resources of a raind u^hichj as a mere rej>ository 
of faictBf perhaps never was excelled. As a iinal and 
tiuigible pmof of Ida posit ion^ he brouglit forward the 
Ixjdtes of ibises that liad been erabahiiB<.l by the ancient 
Egyptians, and showed by comparison that tliese do not 
ditFer in the aliglitest particular from the ibises that visit 
the Nile today. Lamarck replied that this proved noth^ 
ing except that the ibis hud become perfectly adaptesi 
to its Egyptian surroundings iti an early day, historically 
speaking, and tliat the climatic and otlier conditions of 
the Nile Valley IkuI not since tlien changed. His the- 
ory, he allegetl, provided for the stability of species 
under Rxal conditions quite as well as for transmuta- 
tion nntler %^arying conditions. 

But, neetlless to say, the popular venlict lay with Cu 
vier: udent won for the time ag«unst genius, and La- 
nmrck was Imjked npon iis as impious visionary* His 
faitli UL^vor wavennl, however. He believed tliat he hail 
^uneil a trae insiglit into the processes of animate nat- 
un.% and lie reiterated his hypotheses over and over, par- 
ticularly in the introduction to his JliMoire naturdk fhm 
Animanj* mng Vertrhrm^ in 1815, and in liis Stjatime deH 
CoHUiiimant'teit pimtheif th riiomme^ in 1820. He lived 
m till 1820, rnspt^cted as a naturalist, but almost unreo 
Ionized as a [>rophet. 

While the names of Darwin and Goethe, and in par- 
ticular that of Lamarek, must always stand out in high 



relief in this generation as the exponents of the idea of 
transmutation of species, there are a few others which 
must not be altogether overlooked in this connection. 
Of tliese the most conspicuous is that of Gottfried Rein- 
hold Treviranus, a German naturalist physician, profess- 
or of mathematics in the lyceum at Bremen. 

It was an interesting coincidence that Treviranus 
should have published the first volume of his Biolvgie, 
oder Philoi<o2)hie der lehenden Natur^ in which his views 
on the transmutation of species were expounded, in 1802, 
the same twelvemonth in which Lamarck's first exposi- 
tion of the same doctrine appeared in his Recfierches sut 
rO/yatilfifftiofi des Corps Vivants. It is singular, too, 
that Lamarck, in his Ibjdnnjeoloijie of the same date, 
should independently have suggested "biology" as an 
appropriate word to express the general science of living 
things. It is significant of the tendenc}' of thought of 
the time that the need of such a unifying word should 
have presented itself simultaneously to independent 
thinkers in different countries. 

That same memorable year, Lorenz Oken, another 
philosopiiical naturalist, professor in the University of 
Zurich, published the preliminary outlines of his Plu- 
hfsojdiir (h r Xafu/\ which, as developed through later 
))iibli('ati()ns, outlined a theory of spontaneous generation 
and of evolution of species. Thus it appears that this 
idea was germinating in the minds of several of the 
ablest men of the time during the first decade of our 
century. J>nt thc^ singular result of their various expli- 
cations was to give sudden check to that undercurrent 
of thought which for some time had been setting tow- 
ards this conception. As soon as it was made clear 
whither the concession that animals ma\' be changed by 



their environment must logically trend j the recoil from 
the idea was instantaneous and fervid. Then for a gen- 
eration Cuvier was ahuost ahsolutely dominant, and his 
verdict was generally considered final 

There was, indeed, one naturalist of authority in 
France who had the hardiliood to stand out against 
Cuvier and his school, and who was in a position to 
gain a hearing, though hy no means to divide the foh 



lowing. This was ^fetienne Geoffrey Saint-Hilaire, the 
famous author of the PMlomphie Anatamiqiie^ and for 
many years tlie colleague of Lamarck at the Jardin des 
Plantes. Like Goethe, Geoffrey was pre-eminently an 
anatomist, and, like the great German, he had early 
been impressed with the resemblances between the anal- 
ogous organs of different classes of beings. He con- 
ceiveil the idea that an absolute unity of tyj>e prevails 
throughout organic nature as regards each set of organs. 
Out of this idea grew his gradually formed belief that 
similarity of structure might imply identity of origin— 
that, in short, one species of animal might have devel- 
oped from another. 

Geoffroy's grasp of this idea of transmutation was by 
no mejins so complete as that of Lamarck, and he seems 
never to have fully determined in his own mind just 
what might be the limits of such development of species. 
Certainly he nowhere includes all organic creatures in 
one line of descent, as Lamarck had done; nevertheless 
he held tenaciously to the truth as he saw it, in open op- 
position to Cuvier, with wMiom he held a memorable de- 
bate at the Academy of Sciences in 1830 — the debate 
which so aroused the interest and enthusiasm of Goethe, 
but which, in tiie opinion of nearly ever}'^ one else, re- 
sulted in crushing defeat for Geoffroy, and brilliant, 
seemingly linaK victory for the advocate of special cre- 
ation and the fixity of species. 

With that all ardent controversy" over the subject 
seemed to end, and for just a quarter of a century to 
conio there was published but a single argument for 
transmutation of species which attracted any general at- 
tention whatever. This oasis in a desert generation was 
a little book called Vestujeft of the Natural History of 




iafwii,, which appeared anonymously in England in 
jl644, and which passed through numerous ediLiuns, and 

ras the suhject of no end uf abusive ami derisive com- 
jneiil. The auth<*j*hhi|» ut this iK>nk reiuained for forty 
irs a secret, but it is now coneede*! to have been the 
'w<»rk (jf Robert Chambors, the well -known English 
L^ailH>r and pubbsher. The book itiielf is reauirkableas 
^Blt^ing fin avowed and ini equivocal exposition of a gener- 
^h1 docirintt of evolutioiu its view being as ratlicai artd 
^Comprt?ber»sive as llnit of Laniai-ck himself. But it was 
I a r^jtiiui*' of earlier efforts rather tluin a new departure, 
Hto Stiv nothing of itR technicjil sliortcomings, and, while 
^■1 aroust'rl bitter uniinadversions, and cannot have been 
HEritbuut etfect in creaung an undeixjurrent of thought in 
r opfioftitton to Lbe main ti*end of opinion «)f the time, it 
can hardly Im said to have done more than that. lu* 
I ileed, M^me criLies have dt^nied it even ibis merit. After 
iLh jHililjfation, as before, the conce[>tion of transnmta- 
on of s|>ecie8 remained in the |K*puiHr estimation, both 
ly arid wientlHe, an almost forgottet^ '" lieresy." 
It is true that Imvv antl tliere a scientist of greater or 
repute — as Von Buch, Meckel, and Yon Baer in 
lemiany, Kory Saint Vincent in France, Wells, Grant, 
m\ Mnlthcvv in Engbind, and Lcidy in America— had 
tpivs^eil more or less tentative dissent from the doc- 
ine of 8[)ecial creation and immutability of sj>ec»es, but 
beir nna^^m^sisive suggestions, usually put forward in 
jibncnre pubbcations, and incidentally, were utterly over- 
oked and ignored* And so, despite the scientific ad- 
mces along many lines Ht the middle of the centm'y^ 
in* i(ieii of tlie transmutability of orgsinic nices had no 
leb prominence, either in scientific or unscientific oir- 
leu, as it liad acquiretl fifty years before. Special cre- 


.1-:^-. Li'- 

uj.: : i: 

1. *.<=«« 

> > • :y ,..: :y[v 

T T. - < . ::•;• r»-:::o!i. 

r :::.'.z: rT .:: ^^:.:eil 


c© one another as lie proc^seded southward over the 

'continent; and "'by the South American character of 

mck^t uf tlie productions of the Galapagos Archipelago, 

itntl mi>n3 especially by the manoer in which they differ 

slightly on each island of the gmup, none of the islands 

^B^pearing to be Yery aocient in a geological sense/' 

^" At first the full force of these observations did not 

S strike him; for, under sway of Lyell's geologieal con- 
ptions. he tentatively explained tlie relative absence 
life on OHL* of the Galapagos Islands by suggesting 
tlisit j>erhaps no species had been created since that isl- 
il arose, T?nt gradually it dawned upon him that 
keh facts as lie had observed '^couUl only be explained 
the supposition that species gradualh^ become mmli- 
d.*' From then on, as he afterwards asserted, the sub- 
ct haunied him ; hence the journal of 1837* 
It will thus be seen that the iilea of the variability of 
cies came to Cliarles Darwin as an inference from 
irsonal observations in the linUI, not as a thought bor- 
}wtH] from books. He had, of course, read the works 
his grand father much earlier in life, but the argu- 
m&nts of the Zotmomia and Tenipk of Nature had not 
Hprved in the least to weaken his acce|itance of the cur- 
^«it Ijelief in fixity of species. Nor had he been more 
^^pres^'d with the doctrine of Lamarck, so closely sim- 
ilar to that of his grandfather. Indeed, even after his 
auth American experience* had aroused him to a new 
^int of view he was still unable to see anything of 
Ine in these earlier attempts at an explanation of the 
iriatioti of species. In opening his journal, therefore, 
I Jiad no preconceived notion of upholding the views of 
or JUiy other makers of liyptHheses, nor at the 
I had he formulated any hypothesis of his own. His 


inintl wus oiH'n anrl mceptive; he was eager anly fn? ■ 
facU wbjcli might leail liiin to an undet-siatiiling ut 

problem which geeiiitid utterly nlwcuro. It was some- 
thing to feel mire that s|iedes liave varied ; but ho\v 
have siicii vjiriations been brini«;bl ulHiutf 

It wus ru*t lijri*:: l)t^fnr<* Durwiii (tmnd a chnv whidi he ' 
thought ini^lit Ivatl to tli*^ anRWt*r he sou^liL In ax^t- 
iog about for facts he luui mmn discoverefl that ihu 



most available field for observation lay among doraesti- 
eiited animals, whose numerous variations within specific 
lines are familiar to every one. Thus under domestica- 
tion creatures so tangibly different as a mastiff and a 
terrier have sprung from ti common stock. So have the 
Sbelland poi^y, the thoroughbmd, tmd the draught- 
horse. In short, there m no domesticaLed animal that 
has n0t dGvelo|)ed varieties deviating more or less wide- 
ly friHii the parent stock. Now huw Ijas this lieen fic- 
cuin|ih&bed i Wln% clearly, by tlie preservution, thiough 
elective breeding, of seemingly accidental variations. 
us one horseman, by ctmstantly selecting animals 
at ^* chance " to liave the riglit f)uiltl ami stamina, 
Itnally develops a race of running-liorscs; while another 
homeman, by selecting a ilifferent series of progenitors, 

Iia develo[)ed a race of slow, heavy draiiglit-aninials. 
80 far HO good; the preservation of '* accidental'* va- 
pttions through selective breeding is plainly a means by 
liich races may \w developed that are very different 
DUi their original parent form. Out this is under 
an's su(iervisiuri an<l direction. By what process could 
guch selection be bixjiight about among creatures in a 
state of nature ? Ilore surely was a piiitzle, aiKl one that 
tnust Iwj solved before another ste]* could be Uikeu in 
Hfcis dircctiont 

H The key to the solution of this jmzzle came into Dar^ 
HbiQ^s mind through a chimce reading of the famous 
[Hni^on '* Population" which Thomas Robert Malthus 
bad pablisbed*almost half a century bef<jn3. This essay, 
L^positing ideas by no means exclusively original with 
^■althus, emjihasizes the fact that organisms tend to 
increase at a geometrical ratio tlirough successive gen* 
iions, and hence would overpopulate tlie earth if not 



somehow kept in check. Cogitating this thought, Dar 
win gained a new insiglil into the processes of nature. 
IIo saw that in virtue of this tendency of each race of 
boings to overpopulate the earth, the entire organic 
world, anitnal and vegetable^ must be in a state of 
perpetual carnage and strife, individual against Indi- 
vid ual, fighting for sustenance and life. 

That idea fully imagined, it becomes plain that a select- 
ive inliuence is all the time at work in nature, since only 
a few individuats, relatively, of each generation can come 
to maturit}^ and these few must, naturally, be those 
best fitted to battle with the particular circumstcmccs 
in the midst of wbich they are placed. In other words, 
the individuals best adapted to their surroundings will, 
on the average, be those that grow to maturity and 
produce offspring. To these offspring will be trans- 
mitted the favorable peculiarities. Thus these pecul- 
iarities will become permanent, and nature will hare 
accomplished precisely what the human breetler is seen 
to accomplish. Grant that organisms in a state of 
nature vary, however slightly, one from another (which 
is indubitable), and that such variations will be trans- 
mitte*l by a parent to its offspring (which no one then 
doubted); gmnt, further, that there is incessant strife 
among the various organisms, so that only a small pro* 
portion can come to maturity — grant these things, said 
Darwin, and we have an explanation of the preservation 
of variations which leads on to the tra^nsrautation of 
species themselves. 

This wonderful coign of vantage Darwin had reached 
by 1839. Here w;ls the full outline of his theory ; here 
were tlie ideas whicli afterwards eamt; to be embalmed] 
in familiar speech in tlie phrases *' spontaneous varia* 










ion,'' and the '* survival of the titLesl;^ tiiruugh *' nat- 
tui seltjctian," After suob a discovery aay ordinary 
man wouUl at once have run through the streets of 
science, so to speak, screaming " Eureka !*' Not so Dar- 
win, He tilaced tlie man user ijit outline of his theory iu 
is portfolio, and went on gathering facts bearing on his 
discovery. In 1844 he made an abstract in u uianuscript 
book of tlie mass of facts by tbat time accnnmlated. 
He showed it to his friend Hooker, made earefal provi- 
iou for its publication in the event of his sudden <leath, 
then stored it away in bis desk, and sveut aliead with 
the gathering of more data. This was the unexploded 
ivder-mine to which I have just referred. 
Twelve years more elapsed; veal's during which the 
lent worker gat lie red a [n'odigious rajiss of factSj an- 
swered a multitude of objections that arose in his own 
iod, vastly fortified his theory. All this time the toiler 
as an invalid, never knowinj^ a day free from illness 
nd discomfort, obbged to husband his strength, never 
able to work more tlian an hour and a half at a stretch ; 
et he accomplished what would have been vastachieve- 
i**iits for half a dtmm men of robust liealth. Two 
friends among the eminent scientists of the day knew of 
hh Jailors— Sir J(>sef»h Hooker, the botanist, and Sir 
Cliarles Lyelb the geologist. Gradually Hooker had 
me to be more than half a convert to Darwin's views. 
[lyell was still sceptical, yet he urged Darwin to publish 
is theory witliout further delay, lest he be forestalled, 
yit last the patient worker decided tocom^jly with tfjis 
lulvice, and in 1856 he set to work to make another and 
ller alu^tract of the mass of data he had gathereth 
And then a strange thing happened. After Darwin 
been at work on his ** abstract'' about two years, 



ArchipeIag<L lie read the psiper, and, to his atnax&j 
lout, foutitl thai il conUiini^J an ixitlino of the same 



theory of ''natural selection^* which he himself hail 

Ri gin a ted and for twenty years had worked upon. 
orking independently, on opposite sides of the gloije, 
nrvvin and Wallace had hit upon tlie same explanation 
i>t the cause of transmutation of species* ** Were Wal- 
^are^'i pa(>er an abstract of my unpublished nianuscH[?t 
^Hf 1^44," said Darwin, '* it could not better express my 

^ Mere Wiis a dilemma. To publisli this paper with no 
roftl from D*rrwin would give Wallace priority, and 
rrest from Darwin the credit of a discovery which he 
id made yean* btifora \m co-discoverer entered the 
M, Yet, on ilie other hand, conld Darwin honorably 
otherwise than publish lii^s tVit^rnrs paper and himself 
Imain silent ? It Wits a ooniplical ion well calcuhite<:I to 
a man's souL Darwin's was ix^nal to the test. 
Leenly aliro to tlie delicacy of tin? ponition, he placed 
be whole matter l>efore his friends Ilfjoker and Lyell, 
and left the decision as to a course of action absolutely 
h|0 them. Needless to say, these great men did the one 
^ning which inHUh3d fidl justice to all con(a*raed. They 
^■Dunselled a joint publication, to include on the one 
^■find Wallace's \y*i\^v. and on the other an abstract of 
^Vlarwin^a idcJia, in the exact form in which it had been 
outlined by the author in a letter to A&a Gray in the 
■H*eviouH year— an abstract which was in Graves hands 
^^fore Wallace's paper was in existence. Tliis joint 
iinxlnction, togetlier with a full statement <»f the fiicts 
the oaso, was presented to the Linnaean Society of 
rmilon by Hooker and Lvell on tlie evening of July 1, 
B58, this l>eing, by an odd coincidence, the twenty dirst 
miversary of the day on which Darwin had opened 
journal to collect facts bearing on the "species qnes- 


tion/^ Not often l)efore in the history of science has it 
happened that a great theory has been nurtured in its 
author's brain through infancy and adolescence to its 
full logal majority before being sent out into the world. 
Thus the fuse that leil to the great powder-mine had 
been lighted. The explosion itself came more than a 
year later, in November, 1859, when Darwin, after thir- 
teen months of further effort, completed the outline of 
his theory, which was at Urst begun as an abstract for 
the Linnjean Society, but which grew to the size of an 
independent volume despite his efforts at condensation, 
and which was given that ever- to-be-famous title. The 
Or'njiii of S/xrieft htj fruunis of N^atural Selection^ or thr. 
Prf's,rijatiini of Farotrd Races in the Struggle for Lfe. 
And what an explosion it was ! The joint pajier of 1858 
had made* a momentary flare, causing the hearers, as 
IIonktM' said, to "speak of it with bated breath," but be- 
yond that it made no sensation. What the result wjis 
when the Orhj'ni itself appeared, no one of our genera- 
tion n(MMl l)e told. The rumble and roar that it made in 
tluj intclhvtual world have not yet altogether ceased to 
echo after fortv vears of reverberation. 


To tiie Oriffin of Spectra^ then, and to its author, 
Charles Darwin, must always be ascribed chief credit 
for that vast revolution in the fundamental beliefs of 
our race which has come about since 1S59, and made 
the sf^cond half of the century memorable. But it must 
not he overlooked that no such sudden metamorphosis 
could have been effected had it not been for the aid of a 
few notabh^ lieutenants, who rallied to the standards of 




TtlT5' V r • •, . ■ » T .,(sjs 




e leader imjuediately after the publication of the Orir 

n, Darwin had all along felt the utmost contidence 

the ultimate triumpli of his ideas* ''Our posterity,*' 

declared in a letter to 1 looker, *^ will marvel as much 

about the current belief [in s|)ecial creation] as we do 

about fossil shells having Ijeen thought to be created as 

we now see thenu" But he fully realized tliat for the 

^sent success of his theory of transmutation the cbam- 

ionship of a few leaders of science was all-essential, 

e felt that if he could make converts of Hooker and 

Lyell and of Thomas Monry Huxley at once, all would 

be well, 

Hjs success in this regard j as in others, exceeded his 
expectations. Hooker was an ardent diseiple from reath 
^ing the proof -sheets before the book was published ; 
^B^ell renounced his former beliefs and fell into line a 
^H^^^hths later; while Huxley, so soon as he had mas- 
^^roProe central itlea of natural select ion j marvelled 
that so simple yet all-poLcnt a thouglit had escaped him 
m long, and then rushed eagerly into the fray, wielding 
tbe keenest dialectic blade that was drawn during the 
efitire controvei^y. Then, too, unexpected recruits were 
fotind in Sir John Lubbock and John Tyndall, who car- 
nal tbe w^ar eagerly into tlieir resjiective territories; 
while Flerbert Spencer, who had advocated a doctrine 
transmutation on pliibsophic grounds some years be- 
re Darwin published the key to the mystery — and who 
im»elf had barely escaped independent discovery of 
tliat key --lent his nmsterful influence to the cause. In 
America, the famous lx>tanist Asa Gray, who bad long 
n a correspondent uf Darwin's, but whose advocacy 
new theory had not been anticipated, became an 
ent propagandist; while in Germany Ernst Heinrich 



ASA "— ^ 1 

tl,B ontMl. r"' „, every r ^ ■„ 


rson «n i"^ 


ing^ of the doetrino of natumL seloctioiK Soon it was 
fieeri timt slioulcl the dootririe of the survival of the 
favoivtl races ihroiiy^h th« struggle for existence win, 
theru must cuiiie witli it as radical a change in man's 
estmialQ of his own (losltion as had come in the day 
whi*ji* tijnjijt^h LJuf t'fTi*rts at Co|K*rnicns ;ind (tahloo, the 
wo r I i i w im 1 1 r i f i n » t 1 1- d f ro in i tK s u [> |>ose< I ce n t ra 1 p osi t i o n 
in the universe* Th« whole conservative majority of 
mankind recoiled Troni this necessity witli horror. And 
ibk^ consicrvjitive majority inclncknl not laynitni merely, 
but a Viiiit |>re[»(Hiderance of tlie leuilers of science also. 

With th« c)|>en-minded minority, on the other hand^ 
the theory of natural selection made its way by leaps 
and bounds. Its delightful sinijihcity^^whioii at llrst 
lit iriade it seem neitlier imw nnr important — coupled 
th the marvel Ions eomprehLnisivtHicHs of its impLica* 
nSt gave it a liold on the imagination, find stniured it 
lieuring wliere other theories of transmutation of E\m' 
had been utterly scorn eih Men who had found 
larckV conception of change through voluntary ef 
rt ndiculons, and the vaporings i*f the Vt&tJye^i alto- 
gether desi>icaljle, men whose scientific cautions held 
Kcm back fnirn Hpenc-er's rled native argument, took 
ger hold of that tangible, ever-present pnncjple of 
itural selection, anil were led on and on to its goal, 
lliiur by hour the attitude of the thinking worltl tow- 
rds thi« new principle changeil ; never before was so 
ftut M revolutioti wrought so suddenly* 
Nor was this merely because ^'the times were ripe'* 
'' nji*n''s minds prepared for evolution/' Darwin 
iimself hears witness that this was not altogether so. 
II tlirongh tin? years in which he brfKided tliis theory 
goynded his acientific fri^rnds, attd could find among 


them not one who acknowledged a doctrine of transmu- 
tation. The reaction from the standpoint of Lamarck 
and Erasmus Darwin and Goethe had been complete, 
and when Charles Darwin avowed his own conviction 
he expected always to have it met with ridicule or 
contempt. In 1857 there was but one man speaking 
with any large degree of authority in the world who 
o|H>nly avowed a belief in transmutation of species— that 
man being Herbert Spencer. But the Origin of Species 
oanu\ as Huxley has said, like a flash in the darkness, en- 
abling the benighted voyager to see the way. The score 
of veal's (hiring which its author had waited and worked 
had Invn yoai^s well spent. Darwin had become, as he 
himself vsjiys, a veritable Croesus, "overwhelmed with 
Ins rirhes in facts" — facts of zoology, of selective artifi- 
rlal bivediiig, of geographical distribution of animals, of 
iMubryology, of paleontology. He had massed his facts 
alnnit his theory, condensed them and recondensed, un- 
til his volume of live hundred pages was an encyclo- 
paniia in seope. During those long years of musing he 
had thoui^lit out almost every conceivable objection to 
his theory, and in his book every such objection was 
stated with fullt»st force and candor, together with such 
reply as tht» faets at command might dictate. It was 
tlu» foret* of tiios(» twenty years of effort of a master 
niiiul tiiat iua(l(* tlie sudden breach in the breastwork of 
current thoui^ht. 

Onee this breach was effected, the work of conquest 
went rapiilly on. Day by day squads of the enemy 
eapituhitiMl and struck their arms. By the time another 
score of years had passed the doctrine of evolution had 
become the working hypothesis of the scientific world. 
The revolution had been effected. 




And from amid the wreckage of opinion and belief 
uuids furth the ii^^ure of Cbariesi Darwin, calm, imper^ 
turbnble, serene; scutbeless to ridiculej contumely, abuse ; 
uris|H>di.'d by ultimate succuss ; nusulliud alike by the 
strife and tUe victory— take liini for all in iill^ for ciiar- 
acter, fur intellect, for what be was and what be didj 
:;rlia|^ tbe most Soeratic tii^urtiuf the century » Wben, 
188^^ be died, friend and foe alike eonoeded that one of 
tbe greatest sons uf inun liad rested from bis labors, and 
^^It tbe wurld felt it lit ting tliat the remains of Charles 
^Darwin should be eu turn bed in Westminster Abbey, 
^Blose beside tbe honoR^d t^rave of Is^tae Newton. Kur 
^Brere there many who would dispute tbe justice of IIux- 
^ny*s estimate of his accomphsliment : 'Mle founil a great 
truth trodden under foot. Reviled by bigots, and ridiculed 

iy all tlje world, he lived Ion ij enough to see it, chiefly by 
is own efforts, irrefragably established in science, in- 
eparably incorporated with tlieeonmmn thoughts of men, 
ml only hated and feared by those who would i-evile, but 
are liut/* 

Wide as an* the imt>lications of the great truth which 
Darwin and liis co-workers established, however, it 
leaves quite untouched the proljlem of the origin of 
those ** favored \^ariattons" ujion which it oi>erates, 
Tbat such variations are due to fixed and determinate 
caases no one understood iietter than Darwin; but in 
l^is original exposition of his doctrine he made no as- 
im|>tion as to what tho9#! causes are. lie accepted the 
bliscrved fact of variation— as constantly witnessed, for 
imple, in the differences between parents and off- 
ring — and went ahead from ibis assumption* 



Tin: :>'[\)\l\ uF MNETKHNTU-(;KXTL'UY scienxe 

lUit US soon as the validity uf the principle of natural \ 
selection came to be acknowledged, speculators began to 
search for the explanation of those variations which, for j 
pur[X)ses of argument, liad been provisionally called 
** s[)ontaneous." Herbert Si>encer had all along dwelt 
on this phase of the subject, expounding the Lamarck- 
ian conceptions of the direct influence of the environ- 
ment (an idea which had especially appealed to Buffon 
and to Geoffroy Saint-IIilaire), and of effort in resi)onse 
to environment and stinmlus as modifvinfr the individu- 
al organism, and thus supplying the biisis for the opern-- 
tion of natural selection. liaeckel also became an advo- 
cate of this idea, and presently there arose a so-calle^ 
school of neo-Lamarckians, which developed particula-^ 
strength and prominence in America, under the leader*' 
ship of Professors A. Hyatt and E. D. Cope. 

But just as the tide of opinion was turning strongly io 
this direction, an utterly unexpected obstacle appeared 
in the form of the theory of Professor August Weis- 
mann, put forward in 1S83, w^hich antagonized the La- 
marckian conception (though not touching the Darwin- 
ian, of which Weismann is a firm upholder) by denying 
that indivithial variations, however ac(]uired by the ma- 
ture organism, are transmissible. The flurry which this 
denial created has not yet altogether subsided, but sub- 
socpient observations seem to show that it was quite dis- 
pn)i)ortionate to the real merits of the case. Notwith- 
standing Professor Weismann's objections, the balance 
of evidence appears to favor tlie view that the Lamarek- 
ian factor of acquired variations stands as the comple- 
ment of the Darwinian factor of natural selection in ef- 
fecting the tininsnmtation of sj^ecies. 

Even though this partial explanation of what Pro- 



ar Cope calls the ** origin of the fittest" be acoeptecl^ 

bere still Pemains one great life problem which the doe- 

^Xrm of evolution does not touch. The oiigin of sjieciesj 

gt!tiera^ ordei*s, aiicl classes of f>eiiigs through endless 

tigmutations is in a sense explained ; but what of the 

first term of tins long seriirs? Whence came that pri- 

i^umrtlial orgsmisrri whose transmuted descendants make 

\[H\iv existing fiiunas and floras of the globe J 


iere was a time, soon after the dftetrine of ev^olution 

»eil a haarmg, whan the answer to that question 

leil to some scteuti^ts cif authority to have baen 


given by experiment. Becurring to a former belief, and 
repeating some earlier experiments, the director of the 
Museum of Natural History at Rouen, M. F. A. Pouchet, 
reached the conclusion that organic beings are sponta- 
neously generated about us constantly, in the faoiiliar 
processes of putrefaction, which were known to be due 
to the agency of microscopic bacteria. But in 18()2 
Louis Pasteur proved that this seeming spontaneous 
generation is in reality due to the existence of germs in 
the air. Notwithstanding the conclusiveness of these 
experiments, the claims of Pouchet were revived in Eng- 
land ten years later by Professor Bastian ; but then the 
experiments of John Tyndall, fully corroborating the 
results of Pasteur, gave a final quietus to the claim of 
'* si>ontaneous generation" as hitherto formulated. 

There for the moment the matter rests. But the end 
is not yet. Fauna and flora are here, and, thanks to 
Lamarck and Wallace and Darwin, their development, 
through the operation of those "secondary cjiuses*' 
which we call laws of nature, has been proximally ex- 
plained. The lowest forms of life have been linked with 
the highest in unbroken chains of descent. Meantime, 
through the efforts of chemists and biologists, the gap 
between the inorganic and the organic worlds, which 
once seemed almost infinite, has been constantly nar- 
rowed. Already i)hilosophy can throw a bridge across 
that gap. But inductive science, which builds its own 
bridges, has not yet spanned the chasm, small though it 
appear. Until it shall have done so, the bridge of or- 
ganic evolution is not quite complete: yet even as it 
stands to-day it is the most stupendous scientific struct- 
ure of our century. 




The focal points of the physiological world towanls 
the close of tiie eighteenth century were Italy and Eng* 
laed^ but when Spallanzaniancl Hunter passed away the 

Bne shifted to France* The time was pecjuliarly pro- 
|t]ou§^ as the recent advances in many lines of science 

d brought fresh data for tlie student of animal life 
^vhich were in need of classitication, and, as several 
minds capable of such a task were in the field, it was 
natural that great generalizations should have come to 
be quite the fashion. Thus it was that Cuvier came for- 
^artl witli a brand-new elassitication of the animal king- 

jTO, establishing four great types of being, which be 

llled vertehrates, moll uses, articulates, and mdiates. 
Lamarck had shortly before established the broad dis- 
tinclion between aninuilft with and those without a back* 

duo; Cuvier^s classilication divided the latter — the in- 

irtebrates— into three minor groups. And this divis- 
Ton, familiar ever since to all students of zoology, has 
mdy in very recent years been sup]>lanted, and then not 
by revolution, but by a further division, which the elab- 
orate recent studies of lower forms of life seemed to 

ike desirable. 


In the coarse of those studies of comparative anato- 
my which led to his new classification, Cuvier's atten- 
tion was called constantly to the peculiar co-ordination 
of parts in each individual organism. Thus an animal 
with sharp talons for catching living prey — as a member 
of the cat tribe — lias also sharp teeth, adapted for tear- 
ing up the llesh of its victim, and a particular type of 
stomach, quite different from that of herbivorous creat- 
ures. This adaptation of all the parts of the animal to 
one another extends to the most diverse parts of the or 
ganism, and enables the skilled anatomist, from the ob- 
servation of a single typical part, to draw inferences as 
to the structure of the entire animal— a fact which was 
of vast aid to Cuvier in his studies of paleontology. It 
did not enable Cuvier, nor does it enable any one else, 
to reconstruct fully the extinct animal from observation 
of a single bone, iis has sometimes been asserted, but 
what it really does establish, in the hands of an expert, 
is suificiently astonishing. 

Of course this entire principle, in its broad outlines, is 
something with which every student of anatomy had 
been familiar from the time when anatomy was first 
studied, but the full expression of the " law of co-ordina- 
tion,'' as Cuvier called it, had never been explicitly made 
before; and notwithstanding its seeming obviousness, the 
exposition which Cuvier made of it in the introduction 
to his classical work on comparative anatomy, which 
was published during the first decade of the century, 
ranks as a great discovery. It is one of those general- 
izations which serve as guide-posts to other disco ver- 

Much the same thing may be said of another general- 
ization regarding the animal body, which the brilliant 


f rrUHUiESS in anatomy and niYSIOLOGY 

Voung French physician Marie Franyois Bichat made in 
ptlling attention to tlie fact that each vertebrate organ- 
ism, including man, has really two quite different sets of 

From A iti$4iiUlci[) b; David d' Angers 

ins— one set under vohttonal control, and senring the 

snd of locomotion^ the other remolded from volitional 

control, and serving the ends uf the '* vital processes" of 

Jigestion, assimilation, and the like* lie called these 

^iM of organs the animal system and the organic sys- 

&ra, respectively. The division thus pointed ont was 

^ot quite new, for Grimaud, professor of physiology in 

iie nnivemty of Montp(dlier, had earlier made what 

rajs subtilantially the same classification of the functions 

ito "internal or digestive and external or loooraotive ■*; 


but it was Bichat's exposition that gave currency to the 

Far more important, however, was another classifica- 
tion which Bichat put forward in his work on anatomy, 
published just at the beginning of the century. This was 
the division of all animal structures into what Bichat 
called tissues, and the pointing out that there are really 
only a few kinds of these in the body, making up all 
the diverse organs. Thus muscular organs form one 
system; membranous organs another ; glandular organs 
a third ; the vascular mechanism a fourth, and so on. 
The distinction is so obvious that it seems rather diffi- 
cult to conceive that it could have been overlooked by 
the earliest anatomists ; but, in point of fact, it is only 
obvious because now it has been familiarly taught for 
almost a century. It had never been given explicit ex- 
pression before the time of Bichat, though it is said that 
Bichat himself was somewhat indebted for it to his mas- 
ter, the famous alienist, Pinel. 

Iloweverthat may be, it is certain that all subsequent 
anatomists have found Bichat's classification of the tis 
sues of the utmost value in their studies of the animal 
functions. Subsequent advances were to show that the 
distinction between the various tissues is not really so 
fundamental as Bichat supposed, l)ut that takes nothing 
from the practical value of the famous classification. 


At the same time when these broad microscopical dis- 
tinctions were being drawn there were other workers 
who were striving to go even deeper into the intricacies 
of the animal mechanism with the aid of the microscope. 



This unilertaking, bowever, ivas beset with very great 
>ptieal tlirticuliius, and for a long time little advance 
ras made iijjnn llie work of preceding generations. 
Two great upiicai barriers, knowa technically as s[>lier- 
ical and cbromatic aberration — the on© due to a failure 
&f tlieniysof ligbtto fall all in one plane when focalized 
through a leas, the other due to the dispersive action of 
the lens in breaking the white light into prismatic col- 
ors — confronted the makci's of microscopic lenseSj and 
ii.^med all Init inHUi>erabh^ The making of achromatic 
enses for telt?scopes had been accomplished, it is true, 
Dolland in the pm^ious century, by the imioa of 
snses of crown glass with those of flint glass, these two 
jrials having different indices of itif faction and dis- 
>n* But, asiile from the mechanical difficulties 
rliich arise when the lens is of * the minute dimensions 
LnjUired for use with the microscope, other perplexities 
ire intrudueed by tlie fact that the use of a wide pencil 
af Ught is a desideratum, in order to gain sufficient illu- 
'niinalion when large magnification is to be secured. 
In the attempt to overcoino tliesedifiiculties, the fore- 

Imosi pliysicul philost^phem of the time came to the aid 
pf the best opticians. Very early in the century, Dr. 
(afterwards Sir Ihtvid) Brewst^^r, the renowned Scotch 
bhysjcist, &uggeste4 that certain advantages might ac- 
crue from the use of such gems as have high refractive 
knil low dispersive indices, in place of lenses made of 
|tass. Accordingly lenses were made of diamond, of 
mpi»hire^ and so on, and with some measure of success. 
But in 1S12 a nnich more important innovation was intro^ 
diiced by l>r. William Hyde Wollaston, one of the great- 
est and most versatile, and since the death of Cavendish 
' far the most eccentric, of English natural philosophers. 

' — .^'-y •> 


This was the suggestion 
placed at a prescribed dij 
gle doable convex lens j 
tion largely overcame t 
gained immediate fame a 

instead of in front of the 
thus equipped, Dr, Wollits 
scope. Dr, Brewster su| 
same object might be atta 
ing an equatorial groove 
and filling the groove wi 
rangeinent found much h 
be known as aCoddingtc 
laid no claim to being its 
Sir John lierschial, ano 
of the time, also gave a 
proving the microscope, « 



to use two plaQo-ooavex lenses, I 
stance apart, in lieu of the ^n-l 
generally used. This corabina-B 
le spherical aberrutioti^ and iti 
B the *' Wollaston doublet'' 1 
To obviate loss of hght" 
in such a doublet from iu- J 
crease of reflecting surfaces,! 
Dr Brewster suggested fiiul 
ing the interspace between™ 
the two lenses with a oe- i 
nient having the same index 
of refraction as the lenses 
t bemselves — an improve- 
ment ot manifest ad van- 
uige. An improvement yet 
more important was made 
by Dr. Wollaston Ijituself, 
in the introduction of the 
diaphnigni to limit the field 
of vision between tlie lenses, 
anterior lens, A pair of lenses 
5toncidlefl the perlscopic micro- 
^gesteil that in sach a lens the 
ined with greater ease by grind* , 
about a thick or globuhir lens 
th an opaque cement. This ar* 
ivor, and came subsequently to 
m lens, though Mr, Coddington 
I inventor. 

ther of the very great physicists 
ttention to the problem of im- 
ind in 1821 he introduced what 


PR(X;RKSS JN anatomy and PnYSIOLOGY 

ras called an aplanatic combination of lensesj in which^ 
as the Dame implies* the spherieal aberration was largely 
lone aWHj witli. It wub thought that the use of tiiis 
Horschtil aplanutic corabination as an eye -piece, coni- 
Jiueil with the WoUaston doublet for the objective, came 
IS near perfectioa as the compound microscope was like- 
ly SiKJii lu come. But in mality tlie instrunient thus 
jDStructixlj though doubtless su]K»rior to any predeces- 
sr, was ^ defective that for piuctical purposes tlie sim- 
ple microscupe^ such as the doublet or the Coddington, 
i'as preft*rah]e to the more cotnplicuted one. 
Many opticians^ indeed, quite despaired of ever being 
[able to make a satisfactory refracting cotnpound micro- 
y scope, and sotntf of them had taken up anew 8ir Isaac 
I Newton's snggeetion in reference to a reflecting micro- 
I scope. In particular. Professor Giovanni Battista Amici, 
a ver3i^ famous nmtbematician and practical optician of 
Modena» succeetled in constructing a reflecting micro- 

Ifteope which wab said to be sujjenor to any compound 
tnicroscope of the time^ tliough the events of the ensu- 
ing years were destined to rob it of all but historical 
lvalue. For there were others, fortunately, who did not 
di'Kpair of the possibilities of tlie refracting microscope, 
Und their efforts weredt^tined before long to be crowned 
with a degree of success not even dreamed of by any 
preceding generation. 
The man to whom chief credit is due for directing 
[those final steiis that made the compound microscope a 
practical implement instead of a scientific toy was the 
^n^listt amateur optician Joseph Jackson Lister. Com- 
bining mathematical knowledge with mechanical ingenu- 
^T, and having the practical aid of the celebrated opti- 
"cian Tulley, he devised formula* for the oombinntion 



of lenses of crown glass with othere of flint glass, so 
adjusted that the refractive errors of one were corrected 
or compensated by the other, with the result of produc- 
ing lenses of hitherto unequalled powers of definition; 
lenses capable of showing an image highly magnified, 
yet relatively free from those distortions and fringes of 
color that had heretofoi'e been so disastrous to true in- 
terpretation of magnified structures. 

Lister had begun his studies of the lens in 1824, 
but it was not until 1830 that he contributed to the 
Royal Society the famous paper detailing his theories 
and experiments. Soon after this various Continental 
opticians who had long been working along similar lines 
took the matter up, and their expositions, in particular 
that of Aniici, introduced the improved compound mi- 
croscope to the attention of microscopists everywhere. 
And it required but the most casual trial to convince 
the experienced observers that a new implement of sci- 
entific research hud been placed in their hands whicii 
carried tiiem a long step nearer the observation of the 
intimate physical processes v^^hich lie at the foundation 
of vital phenomena. For the physiologist, this perfec- 
tion of the compound microscope had the same signifi- 
cance that the discovery of America had for the fifteenth- 
century geographers ^ — it promised a veritable world of 
utterly novel revt^lations. Nor was the fulfilment of 
that promise long delayed. 

Indeed, so numerous and so important were the dis- 
coveries now made in the realm of minute anatomy that 
the rise of histology to the rank of an independent sci- 





ence may be said to date from this period. Hitiierto, 
evt^r since the dJscov^ery of magnifying -glusses, there 
had beeu here and there a man, such as Leuwenhoek or 
Matpighi, gifted with exceptional vision, and j^erhaps 
unusually iiappy in liis conjectures, who made important 
contributions to the knowletlge of the minute structure 
of organic tissues ; but no^v of a sudden it became pos- 
sible for the veriest tyro to couflrm or refute the la- 
borioii?* observations of these jHoMeers, while the skilled 
observer couhl step e<isily beyuud the barriers of vision 
hitherto quite un passiible. And so, naturally enough, 
the pliysiologists of the fourth decade of our century 
rushed iis eagerly into the new realm of the microscope 
aa, for csamjile, their successoi*s uf to-day ai'e exploring 
the i^enlm of the X ray* 

Lister himself, who tiad become an eager interrogator 
of the instmnient he bad perfected, made many impor- 
tant diBCOverieg, the most notable being his itnal set- 
tlement of tbe hjng-monted question as to the true 
f(»rrn of the red corpuscles of the liuman blood. In 
reality, as every liody knows nownfbiys, these i\m i>icon- 
cave disks, but owing to their peculiar figure it is easily 
jiossiblo to misinterpn^t the a|)|)enrances they ]>rcsent 
when seen through a jKwjr lens, and thougli Dr. Tiiomas 
Young and various other observers had come very near 
the truth rotranling them, unanimity of opinion waspos- 

Iiiihle only after tbe verdict of the perfected microsco|>e 
was given. 
Those blood corpuscles am so inlinitesiraal in size tliat 
Bomething like five millions of them are found in each 
fiuhie millimetre of the blood, yet they are isolated par- 
%iiile% eaeh having, so to speak, its own imrsonality. 
Thi8, of course, had been known to microscopists since 



the days of the earliest 
too^ by hem ami thera an 
af>lid tissues set^med to pr 
texture, as if they too, ii 
were made up of particles 
ter lenses were coustruc 
constantly, ttiougli for a t 
cance. In the ease of vej 
that little particles encase 
md called cells, are the n1 

gervation of the English 
n^ho, in the course of his 
dennU of orchids, discov* 
spot,^' which lie named the 
* SfK>t *' had l>een seen of t^ 
servers, but Brown was 
component part of the 

I - . 


lenses- It had been noticed, 
I observer, that certain of the 
esent iiiomelhiiig of a granular 
1 thair ultimate constitution, 
, And now, as better and bet- 
tetl, this idea gained gn>und 
ime no one saw its full signif- 
letablo tissues, indeed, the fact 
d in a membranous covering, 
tiumte visible units of struct- 
ure had long been known. 
But it was supposed that 
iinimal tissues diflfei-e*! radi- 
cully froiu thisconstruction, 
Tiie elementary jmrticles ot 
vegetables ** were regartied 
to a certain extent as indi- 
viriuals which coini>c5sed the 
entire plant, while, on the 
*»ther lumd, no such view 
was taken of the elementary 
parts of animals," 

In the year 1833 a further 

insigh t in to the nature of the 

ultimate particles of plants 

was gained tlirough the ob- 

microseopist Robert Brown, 

microscopic studies of tho epi- 

jretl in the cells **an oimqun 

1 nucleus* Doubtless the same 

m enough before by other ob- 

the first to recognize it as a 

vegetable cell, and to give it 





a name* That this newly recognized structure must be 
itapartant in the economy of the cell was recognized by 
Brawn himself, and by the celebrated German Mcyen^ 
who dealt witli it in his work on vegetable physiology, 
published not long afterwards ; but it remained for an- 
other German, "the prufci^sur of botany in the univei^ity 
of Jenu, Dr. JL J. i^chleiden^ to bring the nucleus to 
popnlar attention, and to assert its alMraportance in the 
economy of the cell* 

Schleiden freely acknowledged his indebtedness to 
Brown for fi rnt knowledge of the nucleus, but he soon 
mrried his studies of that structure far beyond those of 
its iliscoverer. lie came to believe that the nucleus is 
really the most {injKjrtant portion of the cell, in that it 
is the original structure from which the remainder of 
the coll is developed. Hence he namerj it thecytoblasL 
He outlined his views in an epoelud pai>er published in 
UnHev^s Arehht^s ill 1838, under title of '^Beitrage zur 
Phytogenesis.-* This i»a|)er is in itself of value, yet the 
most iini>ortunt outgrowth of Schleiden's observations of 
the nucleus did not spring from his own laboi^, but from 
tbofld of a friend to whom he mentioned his discoveries 
the year previous to their publication. This friend was 
l)r, Theodor Schwann, professor of physiology in the 
university of Louvain. 

At the moment when these observations were com- 
municated to him Schwann was puzisling over certain 
details of iinlmal histology which he could not clearly 
explain* His great teacher, Johannes MiUler, had called 
attention to the strange resemblance to vegetable cells 
shown by certain cells of the cbortla dorsalis {the em- 
bryonic cord from which the spinal column is deveK 
ope<l), and Schwann himself had discovered a corre- 



spending similarity in the branchial cartilage of a tad- 
pole. Then, too, the researches of Friedrich Henle had 
shown that the particles that make up the epidermis of 
animals are very cell-like in appearance. Indeed, the 
cell-like character of certain animal tissues bad come to 
be matter of common note among students of minute 
anatomy. Schwann felt that this similarity could not 
be mere coincidence, but he had gained no clew to 
further insight until Schleiden called his attention to 
the nucleus. Then at once he reasoned that if there 
really is the correspondence between vegetable and ani- 
mal tissues that he suspected, and if the nucleus is so im- 
portant in the vegetable cell as Schleiden believed, the 
nucleus should also be found in the ultimate particles of 
animal tissues. 

Schwann's researches soon showed the entire correct- 
ness of this assumption. A closer study of animal tis- 
sues under the microscope showed, particularly in the 
case of embryonic tissues, that "opaque spots" such as 
Sclileiden desorilKMl are really to be found there in 
abuudanco — forming, indeed, a most characteristic phase 
of the stnictnro. The location of these nuclei at com- 
parativ(»ly re<^uhir intervals suggested that they are 
found in (Infinite* compartments of the tissue, as Schleiden 
had shown to ho the case with vegetables; indeed, the 
walls that sepai'al ( d such ccll-like compartments one from 
another were in some cases visible. Particularly was 
this found to be tliecase with embryonic tissues, and 
the study of these soon convinced Schwann that his 
original surmise had been correct, and that all animal 
tissues are in their incipiency composed of particles not 
unlike the ultimate particles of vegetables — in short, of 
what the botanists termed cells. Adopting this name, 


HAliL KHSS^I v<>^ liA''" 








Schwann propounded what soon became famous as his 
wll theory, under title of Mikrmkoj}ist:^/ie Uniersuckun* 
f/en Qber die USerelnBtlmmting hi der Structur mul 
dem Wacfmthum der Thiere nnd PJiunzen. So expeditious 
bad been his work, tliat this book was published early 
in 1S31', only a few iiiontiia after the appearance of 
Sehleideii's paper. 

As the title suggests, the main idea that actuated 
Schw^ann was to luufy vegetable anil animal tissues, 
Aocepting cell structure as the basis of all vegetable 

fiii,'s» he sought to show that the same is true of ani- 
mal tissues* all the seeming divei'sities of fibre btung but 
the alteration and development of what were oi'iginally 
sLtnple cells. And liy cell Schwann meant, as did Schlei- 
dcn also, what the word ordinarily implies — ^a cavity 
walled in on all sides. lie conceived that the ultimate 
constituents of all tissues were really such minute cavi- 
ties* the most important part of which w^as the cell wall, 
with its associated luicleus. He knew, indeed, that the 
cell might be filled with fluid contents, but be regarded 
these as relatively subordinate in importance to tiie w^aJI 
itself. Tins, however, ilid not apply to the nucleus, 
which was supposed to lie against the cell w^all, and in the 
beginning to generate it Subsequently the w^all might 
grow so rapidly as to dissociate itself from its contents, 
thus becoming a hollow bubble or true cell ; but the 
nucleus, as long as it lasted, was supijrmed to continue in 
contact with the cell wall, Schleiden bad even supposed 
the nucleus to be a constituent part of the wall, some* 
limes lying enclosed between two layers of its substance, 
and Schwann quoted this view^ with seeming approval. 
Schwann believed, however, that in tlie mature cell the 
nucleus ceased to be functional, and disappeared. 



The main thesis as to the similarity of development 
of vegetable and animal tissues, and the cellular nature 
of the ultimate constitution of both, was supported by a 
mass of carefully gathered evidence which a multitude 
of microscopists at once confirmed, so Schwann's work 
became a classic almost from the moment of its publi- 
cation. Of course various other workers at once dis- 
puted Sch vvann's claim to priority of discovery, in particu- 
lar the English microscopist Valentin, who asserted, not 
without some show of justice, that he was working 
closely along the same lines. But so, for that matter, 
were numerous others, as Ilenle, Turpin, Dumortier, 
Purkinje, and Miiller, all of whom Schwann himself had 
quoted. Moreover, there were various physiologists who 
earlier than any of these had foreshadowed the cell the- 
ory ; notal)ly Kaspar Friedrich Wolff, towards the close 
of the previous century, and Treviranus about 1807. 
But, as we have seen in so many other departments of 
science, it is one thing to foreshadow a discovery, it is 
quite another to give it full expression and make it 
germinal of other discoveries. And when Schwann put 
forward the explicit claim that '* there is one universal 
principle of development for the elementary parts of 
organisms, however different, and this principle is the 
formation of cells/' he enunciated a doctrine which was 
for all practical purposes absolutely new, and opened 
up a novel field for the microscopist to enter. A most 
important era in physiology dates from the publication 
of his book in 18,39. 

That Schwann should have gone to embryonic tissues 
for the establishment of his ideas was no doubt due very 



|largely to the iniltience of the great Russian, Kurl Ernst 
[Von Haer, who about ten years earlier bad published tlie 
I first part of his celebrated wurk on em bryology, uml 


^ose ideas were rapidly gaming ;jround, thanks large- 

y to the advocacy of a few men, notably Johannes ^liil- 

|ler in Germany, and William B* Carpenter in England. 

mi to the fact that the improved microscijpe had made 

minute anatomy popidar. Schwann's researches made 

it plain that the best field for the study of the animal 

is herij, and a host of explorers entered the Sehi 

ha result of their observations was, in the main, to con- 

^it F 


firm the claims of Schwann as to the universal prev- 
alence of the cell. The long-current idea that animal 
tissues grow only as a sort of deposit from the blood- 
vessels was now discarded, and the fact of so-called 
plant-like growth of animal cells, for which Schwann 
contended, was universally accepted. Y'et the full 
measure of the affinity between the two chusses of cells 
was not for some time generally apprehended. 

Indeed, since the substance that composes the cell 
walls of plants is manifestly very different from the 
limiting membrane of the animal cell, it was natural, so 
long as the wall was considered the most essential part 
of the structure, that the divergence between the two 
classes of cells should seem very pronounced. And for 
a time this was the conception of the matter that was 
uniformly accepted. Hut as time went on many olv 
servers had their attention called to the peculiar cliar- 
acleiistics of the contents of the cell, and were led to 
ask tlieniselves whether these might not be more im- 
])(>rtant tlian had been supposed. In particular Dr. 
Hugo von Mohl, professor of botany in the university of 
Tiibin^^Mi, in the course of liis exhaustive studies of the 
V(?^etable cell, was impressed with the peculiar and 
characteristic ap])earance of the cell contents. lie Ab- 
served univei'sally within the cell ** an opaque, viscid 
fluid, havin*^ granules intermingled in it,'' wliich made 
up the main substance of the cell, and which particular- 
ly impressed him because under certain conditions it 
could be se(Mi to be actively in motion, its parts sep- 
arated into Hlanientous streams. 

Von Mohl called attention to the fact that this mo- 
tion of the cell contents had been observed as long ago 
as 1774 l)y r»onaventura Corti, and rediscovered in 1807 


by Treviranus, and that these observers had described 

the phenomenon ander the *' most unsuitable name uf 

* mtaiion of tlie cell sap/ " Von Mohl recognized that 

1 1 1 e s t rea in rn g s n bs t a n ce was 

something quite different 

fnim sap. He assert e<i that 

tlie nuch^us of the cell lies 

within this suljstanee^ and 

not attached to the cell wall 

a^Schloidon Ijnil c<»ntended. 

lie saw, too, timt tlie chlo* 

rophyl granules, and all 

other of the celi contents, 

are incorporateil with the 

"opaque, viscid fluid/' and 

in 1846 he had Iwicome so 

pressecj with the impor- 

iCe of this universal cell ^jlua^ ,.,.:...; oh 

suhst^inee that he gave it 

the name of protf3pIasm. Yet in so iUiiu^f he bad no inten- 
tion of subordinating the cell wall Tire fact that Pay en 
in IH44* had deinonstmted that the cell walls of all vege- 
t4ibles, high or low, are corajwsod largely of one sub- 

Ifitatiee, cellulose, tended to strengthen tfje position of 
tfie cell ivall aa the really essential structure, of wliich 
the protoplasmic contents were only subsidiary prod- 
Meantime, however, the students of animal histology 
WCTO morts and more impressed with the seeming pre- 
pondenince of cell contents over cell walls in the tissues 
they studied. They too found the cell to be filled with 
fk Tiseid, slimy fluid, capable of motion. To this Dli^ 
jiirdtn gave the name of siircode. Presently tt came to 





be known, through the labors of KoUiker, Nageli, Bis 
clioff, and various others, that there are numerous lower 
forms of animal life which seem to be composed of this 
sarcode, without any cell wall whatever. The same 
thing seemed to be true of certain cells of higher organ- 
isms, as the blood corpuscles. Particularly in the case 
of cells that change their shape markedly, moving about 
in consecjuence of the streaming of their sarcode, did it 
seem certain that no cell wall is present ; or that, if pres- 
ent, its role must be insignificant. 

And so histologists came to question whether, after 
all, the cell contents rather than the enclosing wall must 
not be the really essential structure, and the weight of 
increasing observations finally left no escape from the 
conclusion that such is really the case. But attention 
i)eing thus focalized on the cell contents, it was at once 
apparent that tiiero is a far closer similarity between 
the ultimate particles of vegetables and those of ani- 
mals than had been supposed, (-ellulose and animnl 
iiioml)rane Ix^in^j; now regarded as mere by-products, the 
way was clear for the recognition of the fact that veg- 
etable protoplasm and animal sarcode are marvellously 
similar in apptnirarice and general proj)erties. The closer 
the observation tiio more striking seemed this similar- 
ity ; and linaily, about 1800, it was demonstrated by 
lleinrich de l>ary and by ^Fax Schultze that the two are 
to all intents and purposes identical. Even earlier Re- 
niak had nNiclied a similar conclusion, and applied von 
^fohrs word protoplasm to animal cell contents, and 
now this application soon became universal. Thence- 
forth this ])rotoplasm was to assume the utmost impor- 
tance in the physiological world, being recognized as the 
universal "physical basis of life," vegetable and animal 



rut Ni:W YOF<K 


ASTO-«. '-f.NOX AND 


dike* This atnounted to the logical extension and cal- 
Tninatioo of Schwann's doctrine as to the similarity of 
cJevelopraeot of the two animate kingtloms. Yet at the 
same time it was in effect the banishment of the cell 
that Schwanti had defined. The word cell was retained, 

t, is true, but it no longer signified a minute cavity- It 
ow implied^ as Schaltze defined it, ^'a small mass of 
protophism endowed with the attributes of life.*' This 
definition w^as destined presently to meet with yet an- 
)tber modification, as we shall see; but the conception 
^{ the protoplasmic mass as the essential ultimate siruct- 
ire, which might or might not sniTound itself with a 
)rote€ti\'^e covering, was a permanent addition to physi- 
Dlogical knowledge* The earlier idea had, in effect, de- 
plaretl the sliell the most imi>ortant part of the egg; 
^bis developed view assigned to the yolk its true posi- 


In one other im}>ortant regard tlie theory of Schleiden 
ind Schwann now tiecame modified. This referred U^ 
Iho origin of the cell. Sell wan n had regarded cell 
rniwth as a kind of crystallization, beginning with the 
fcpQsit of a nuclf»ns abi>ut a granule in the intercellular 
IftQiKstance — the cvtoblastemn, as Schleiden called iL 
But vtm MohL as f*arly as 1835, had called attention to 
ihe foniiatiort of new vegetable cells through the divis- 
ion of a preexisting celL Ehrenl>erg, another high au- 
I lliunly <if the time, contended that no such division oo 
J ami the matter was still in dispiue when Schleiden 
forward with his discovery of so-called free cell 
|f*>pmation within the parent cell, and this for a long 
titoe dirertet] attention from the process of division 
^ »liich von Mobl had descrilje<L All manner of schemes 
rfcell fonimtioti were pot forward during the ensuing 




years by^a multitude of obst^rvei's, anil gaiiierl cinTfm cj 
notwftlistanding von Mohrs n'iterated conlvulion llr^^ 
there arc? roidly but two wavss in wLich ilie format ic»jff] 
of new cells takes place, namely, *'* first, throiigb Uivi*. 
ion of older eclls; stscondly, thmugb the formatioii o/ 
secondary celk lying free in the cavity of a celL" 

fiUGO VON mmu 

But gradnally the researches of such accurate observ, 
ers as UngLT, Nasreli, KoUiker, Kcichart, and lieuiak 
t^jnded to confirm the o]>ininn of von Mt*hl that cells 
spring only from cells, and finally Rudolf Virchow 
brought tlie matter to demonstration about 18(i0. Urn 



7mnU ceUula e eellula became from that time one of 
Jae ncteptecl t lata of physiologj. This was supplement- 
a liltli? hiUiV by Fleiuing*s (hntds niideu» e nud^o^ 
rheti still more relint^Hl niefbocls uf observation had 
liown that the part of Hie cell which ithvays tirst under- 
goes change preparaton* to new ceil fortnation is thealU 
essential nuel«*uj*. Thus the nucleus was restored to the 

lm{Kirtant position which Schwann and SchleUlen had 
jiven it, but with greatly altered signiticance. Instead 
sf Uiirig' a structure generatetl ih- novo from non-eellular 
lidjstance, ami disa|>|*earin|^ as soon as its function of 
{jUfonnation was accomplished, the nucleus was now 
m^iwn as the central and |iermanont featun? of every 
tjtl, indestructible while the cell lives: itself the divis- 

l<»n-product of a prf>existing nucleus^ and the |>arent, by 
tli vision of its substance, of other generations of nuclei. 
The word cell retreived a tinal detinition as "a small 
njo-s* of protfiphism Hup|)iied with a nticleus/' 
In thiji widened and culminating general view of the 

|l!i4l tho«»ry it Ijetraine clear that every animate org^inism, 

Itnimal or \*egetahk% is but a cluster of nueleateil cells, all 
Df which* in each individual csise.are the direct descendants 
fjf a single priitn^rdial c»-ll of the ovum. In the devel- 
oped individuals of higher organisms the successive gen- 
erations i>f cells become TnarveUously divei-sifieit in form 
anil in siiecific functions; there is a wonderfnl division 

itif labor, special fiinctiona lieing chiefly relegated todefi- 
aito grou()s of cells; but from first to last there is no 
anction davelo]ied that is not present, in a primitive 
•t'ny, in every cell, however isolated ; nor does the de- 
fluped cell, however specialized, ever forget altogether 
av one of its primordial functions or capacities. AJl 
alogy, Ihcn, pro|>eriy interpreted ^ becomes merely 


a study of cellalar aetlvities; and the developTnent of 
the cell theory hikes its place aa the great central gen- 
eralization in physiology of our century- Something of 
the hiter develnpuients of ibis theory u e sball see in aa* 
other connection. 

Just at the time when tht^ microscope was oponing 
up the paths that were to lead to the wonderful cell 
theory, another novel line of interrogation of the liv* 

ing organism was being^ 
put forward by a differ- 
ent set of observers. Two 
great schools of ijhysio- 
lugical chemistry had ariiien 
— one under guidance of 
Liel>ig and Wrdiler in Ger- 


many, tho other duniinated 
by tlie great French master 
Jraji Baiitiste Pujuls. IJ*^ 
big IjmI at one time conteiii- 
phited the study of rut!*licine. 
anil I) n mas had acliieveildiS' 
ti act ion in ('oaiu.*ctiou with 
Prevost at (icneva in the 
Held of pure physiology be- 
fore ha turned his attentioTi eapecially to chemistry. Both 
these masters, therefiirt% and Wuhler m well, fonrjd ah* 
sorbing interest in those phases of chemistry that hav(? 
to do witli the functions of li%*ing tissues; and it was 
largely through their efforts and the lalwra of their fol- 
lowers that the prevah^nt idea tliat vital processes are 
dominated by unicpie laws was discarded and physiology 



&£ brouglit within the recognized province of the 
IchciiUiit* 8u at about the lime when the microscope 
had taught that the cell is the really essential structure 
f the living urgnnisin^ the chemists had come to under- 
stand that every function of the organ ism is really the 
— expression of a chemical change — that each cell is, in 
Hibort, a miniature chemical labonitory. And it was 
Btbis combined point of view of anatomist and chemist, 
Vthis union of bitherto dissociated forces, that made {>os- 
W Bible the inroads into the unexplored lielils of pliysi- 
ology that were effected towards the midtile of our cen- 

H One of the first subjects reinvestigated and brought 
Hto proximal solution was the long-mooted question of 
Hthe digestion of foods. Hgiallanzani and Hunter had 
"shown in the previous century that digestion is in some 
sort a solution of foods; but little advance was made 
Btipon their work until 1824, when Prout detected the 
presence of hydrocldoric acid in the gastric juice. A 
decade later Sprott and Boyd detectetl llie existence of 
|w>culinr glands in the gastric mucous mend>rane; and 
Cagniard lu Tour and Schwann indei>endcntly discov- 
ereii that the really active principle of the gastric juice 
is a substance which was named pepsin, and which was 
shown by Schwann to be active in the presence of hy- 
drochloric acid. 

Almost coincidently, in IBM, it was discovered by 
Purkinje and Pa|»t>enheim that another organ than the 
stomach— the |>ancreas, nainely— has a share in diges^ 
tion, and in the oourHc of the ensuing decade it came to 
be known, throng fi the efforts of Eberle, Valentin, and 
Chiade Bernani, that this organ is all*imix>rtant in the 
digestion of starchy and fatty foods. It was found, too. 


that the liver and the intestinal glands have each an im- 
portant share in the work of preparing foods for absorp- 
tion, as also has the saliva — that, in short, a coalition of 
forces is necessary for the digestion of ail ordinary foods 
taken into the stomach. 

And the chemists soon discovered that in each one of 
the essential digestive juices there is at least one sub- 
stance having certain resemblances to pepsin, though 
acting on different kinds of food. The point of resem- 
blance between all these essential digestive agents is 
that each has the remarkable property of acting on 
relatively enormous quantities of the substance which 
it can digest without itself being destroyed or apparent- 
ly even altered. In virtue of this strange property, 
pepsin and the allied substances were spoken of as fer- 
ments, but more recently it is customary to distingush 
them from such o?*ganized ferments as yeast by desi*!: 
nating them enzymes. The isolation of these enzymes, 
and an appreciation of their mode of action, mark a 
longstep towards the solution of the riddle of digestion, 
but it must l)e added tliat we are still quite in the dark 
as to the real ultimate nature of their strange activity. 

In a comprehensive view, the digestive organs, taken 
as a whole, are a gateway between the outside world 
and the more intimate cells of the organism. Another 
e(pially important gateway is furnished by the lungs, 
and here also there was much obscurity about the exact 
method of functioning at the time of the revival of phys- 
iological cluMuistry. That oxygen is consumed and 
carbonic acid given off during respiration the chemists 
of the age of Priestley and Lavoisier had indeed made 
clear, but the mistaken notion prevailed that it was in 
the lungs themselves that the important burning of fuel 



[jurs^ of which carbonic acid is a chief protlnct. But 
aow I hat attentirm had been calletl to the iinportance of 
tht5 ultimate cell, this miscoiiception could not lon«j iiokl 
its gTOundt and as early as 1842 Liebig, in the course of 
his studies of animal heat^ became convinced that it is 
not in the lungs, but in the ultimate tissues to which 
they are tributary, tbat the true consuinptiun of fuel 
ikes place* lieviving Lavoisier's itleaj with niodifica- 
linns and additions, Liebig conteniled, and in the face 
}{ opposition linally demonstrated, tiiat the source of 
inimal heat is really the consumption of the fuel taken 
in through the stomach and the lungs. lie showed 
.|imt all the activities of life are really the product of 
Energy liberated solely through destructive processes, 
imounting, broadly speaking, to combustion occurring 
^in the ultimate eelk of the organism. 

Further researches showed that the carriers of oxy- 
fen^ from the time of its absorption in the lungs till its 
Tiheration in the ultimate tissues, are the red corpuscles, 
^^whose function hnd been supposed to be the mechanical 
Hone of mixing of the blood. It transfjired that the red 
^■oorpuscles are composed chiefly of a substance which 
iKuhne lii'st isolated in crystalline form in l?!i05, and 

Iirhich was named haemoglobin — a substance which luis 
I inarvidloyg affinity for oxygen, seisciug on it eagerly 
It the hiTJgs, yet giving it up with efjual readiness when 
poursing among the remote celts of the hotly. When 
N^ighlad with oxygen it becomes oxyhaeraoglobin, and 
is rerl in color ; when fix^ed from its oxygen it takes a 
purple hue; hence the witlely different api>earance of 
arterial and venous blood, wliich so puzzled the early 
Thiis proof of the vitally important rdla played by the 




reel blood corpuscles led, naturally, to renewed studies 
of these infinitesimal bodies. It was found that they 
may vary greatly in number at diflPerent jieriods in the 
life of the same individual, proving that they may be 
both devoloped and destroyed in the adult organism. 
Indeed, extended observations left no reason to doubt the process of corpuscle formation and destruction 
may be a perfectly normal one; that, in short, every 
red blood corpuscle runs its course and dies like any 
more elaborate organism. They are formed constantly 
in the md marrow of bones, and are destroyed in the 
liver, where they contribute to the formation of the 
coloring matter of the bile. Whether there are other 
seats of such manufacture and destruction of the cor- 
puscles is not yet fully determined. Nor are histolo- 
gists agreed as to whotJKM' the red blood corpuscles 
themselves are to b(» regarded as true cells, or merely as 
fragments of cells l)U(ld<'(l out from a true cell for a 
sjH'cial jinrpose; but, in either case, there is not the 
slightest (louht that the chief function of the red cor- 
[)uscle is to carry oxygen. 

If the oxygen is taken to the ultimate cells before 
combining with the combustibles it is to consume, it 
goes witiiout saying that these combustibles themselves 
must bo carried there also. Nor could it be in doubt 
tliat till* cliiefest of th(»se ultimate tissues, as regards 
(|uantity of fuel required, are the muscles. A general 
and (u)]npn»liensiv(> view of the organism includes, then, 
digestive appai'atus and lungs as the channels of fuel- 
supply : blood and lym])h channels as the transportation 
system : and musele cells, united into muscle fibres, as 
the consum]>tion furnaces, where fuel is burned and 
energv transformed and rendered available for the pur- 



of the organism, supplemented by a set of ex- 
>ry organsj through which the waste products — 
m ashes— are oljtninated from the system. 
But there remain, broadly 
fS[K^ukiug, two other j^ets of 
[organs wliose size demon- 
Btrateg their importance in 
"the economy of the organ- 
ism, jet whose functions are 

I not accounted for in this 
itynopsis. These are those 
gland like organs, such as the 
Epleeu, which have no duct 
and produce no visible se- 
cretions; and the nervous 
tneohanism, whose central 
organs are the brain and 
Htpinal cord* What offices 
Hdo these sets of organs per- 
■ furui in the great lahor-spocializing aggregation of cells 
which we call a Uving organism ? 

As reganls tlu* tluclless inlands, the first clew to their 
^function was given wiieu tlu* great Frenchman Clautle 
Hl^rnaixl (the man of whom his admirers loved to say, 
Hp^he id not a physiologist merely; ho is physiology it- 
^eelf ^*) discovered what is sp<>ken of as the glycogenic 
function of tlie liver. The liver itself, indeed, is not a 
ductless organ, hut the quantity of its biliary output 
isi^ems utterly disproportionate to its enormous size, par- 
iticuhu'Iy when it is considered that in the cjise of the 
liiman sjjecleK the liver contains normally about one- 
ifth of all the blood in the en tiro body. Bernard dis- 
fcuvered that the blotnl undergoes a change of cimiposi- 


viJkViiH imtiSAiui 


tion in passing through the liver. The liver cells (the 
peculiar forms of which had been described by Parkin je, 
Henle, and Dutrochet about 1838) have the power to 
convert certain of the substances that come to them into 
a starchlike compound called glycogen, and to store this 
substance away till it is needed by the organism. This 
capacity of the liver cells is quite independent of the 
bile-niaking power of the same cells ; hence the discov- 
ery of this glycogenic function showed that an organ 
may have more than one pronounced and important 
specific function. But its chief importance was in giv- 
ing a clew to those intermediate processes between di- 
gestion and final assimilation that are now known to 
be of such vital significance in the economy of the or- 

In the forty-odd years that have elapsed since this 
pioneer observation of Bernard, numerous facts have 
come to light showing the extreme importance of such 
intermediate alterations of food-supplies in the blood as 
that performed by the liver. It has been shown that 
the pancreas, the spleen, the thyroid gland, the supra- 
renal capsules are absoUitely essential, each in its own 
way, to the health of the organism, through metabolic 
changes which they alone seem capable of performing; 
and it is sus[)ected that various other tissues, including 
even the muscles themselves, have somewhat similar 
metabolic capacities in addition to their recognized func- 
tions. But so extremely intricate is the chemistry of 
tlie substances involved that in no single case has the ex- 
act nature of the metabolisms wrought by these organs 
been full\^ made out. Each is in its Avay a chemical 
laboi'atory indispensable to tlie right conduct of the 
organism, but the precise nature of its operations re 



mains inscrutable. The vast importance of the opera- 
tions of these intermediate organs is unquestioned. 

A consideration of the functions of that other set of 
organs known collectively as the nervous system is re- 
served for a later chapter. 


Although Napoleon Bonaparte, First Consul, was not 
lacking in self-appreciation, he probably did not realize 
that in selecting a physician for his own needs he wiis 
markedly influencing the progress of medical science as 
a whole. Yet so strangely are cause and effect ad- 
justed in liuman affairs that this simple act of the Fii*st 
Consul Iiad tliat very unexpected effect. For the man 
chosen was the envoy of a new method in medical prac- 
tice, and the fame which came to him through being 
pliysiciiin to the First Consul, and subsequently to the 
Em[)eror, enabh^d him to promulgate the method in a 
way otherwise impracticable. Hence the indirect but 
telling valui* to nuMlical science of Napoleon's selection. 

The physician in (piostion was Jean Nicolas de Corvi- 
vSart. His novt^l method was nothing more startling 
than the now familiar procedure of tapping the chest of 
a patient to elicit sounds indicative of diseased tissues 
within. Every one has seen this done commonly 
enough in our day, but at the beginning of the century 
Corvisart, and perhaps some of his pupils, were proba- 
bly the only physicians in the world who resorted to 



this simple and useful procedure. Hence Napoleon's 

surprise when, on catling in Corvisart, after becoming 

sutiiewhat dissatisfied with his other physicians, Pi net 

and Portal, liis physical comlition svas tiUermgated m 

this strange manner. With cUaracteristic shrewdness 

Jonaparte saw tlio utility of the method, and the physi- 

leiati who tlms attemjitt^d to substitute scientilic method 

for guess-work in the diagnosis of disease at once found 

favor ID his eyes^ and was installed as his regular medi- 

a adviser. 

For fifteen years before this Corvisart had practised 
ercussion, as the chest-tapping method is called, with- 
out succeeiling in convincing the profession of its value, 
Phe method itself, it should l>e ad<led, had not origi- 
nated witli Corvisart, nor did the Fi-ench physician for a 
mojnent claim it as his own. The true originator of the 
practice vras the German physician Avenbrugger, who 
pabljstied a of>ok about it as early as 17B1. This book 
had even been translated into French^ then the language 
}f international commnnicaLion everywhere, by Rozitire 
la Chassagne, of MontpclHer, in 1T70; but no one 
other than Corvisart appeai-s to have paid any attention 
either original or translation. It was far otherwise, 
iowever, when Corvisart translattMl Avenbrngger's work 
luew, with important adtiitions of his own, in 1S08, By 
this time a reaction had set In against the metaphysictil 
mcthofls in medicine that bad previously been so hIIut- 
ing; the scientific spirit of the time was making itself felt 
Hb medical practice; and this, combined with Corvisart's 
^■ame, brought the metliod of jjercussion into immediate 
^pnd welkieservetl popuhirity. Thus wjls laid the foun* 
^plation for the method of so-called physical diagnosis^ 
which is one of the corner-stones of modern medicine, 




The method of physical diagnosis as practised in oar 
day was by no means completed, however, with the 
work of Corvisart. Percussion alone tells much less 
than half the story that may be elicited from the organs 
of the chest by proper interrogation. The remainder of 
the story can only be learned by applying the ear itself 
to the chest, directly or indirectly. Simple as this 
seems, no one thought of practising it for some years 
after Corvisart had shown the value of percussion. 
Then, in 1815, another Paris physician, Ren6 Theophile 
Ilyacinthe Laonnec, discovered, almost by accident, that 
the sound of the heart-beat could be heard surprisingly 
through a cylinder of paper held to the ear and against 
the patient's chest. Acting on the hint thus received, 
Lciennec substituted a hollow cylinder of wood for the 
paper, and found himself provideil with an instrument 
through which not merely heart sounds, but murmurs 
of the lungs in respiration, could be heard with almost 
startling distinctness. 

The possibility of associating the varying chest sounds 
with diseased conditions of the organs within appealed 
to the fertile mind of Laennec as opening new vistas in 
therapeutics, which he determined to enter to the fullest 
extent ])ractical)le. His connection wMth the hospitals of 
Paris <j:avehini full opportunity in this direction, and his 
labors of tli(^ next few yeai^s served not merely to estab- 
lish tli(^ value of the new method as an aid to diagnosis, 
hut laid the foundation also for the science of morbid 
anatomy. In 1811) Laennec published the results of his 
labors in a work called Traite (F Aiiscultatian Mediate^ 
a work which foi-ms one of the landmarks of scientific 
medicine. \\\ mediate auscultation is meant of coui*se 
the interrogation of the chest with the aid of the little 







instrument already referred to, an instrument which its 
originator thought hardly worth naming until various 
barbarous appeiliitions were applied to it by others, after 
which Latinnec decided to call it the st-ethoscope, a name 
which it has ever since retained. 

In subsequent years the form of the stotlioscope, as 
usually employed, v?as modified, and its value augment- 
ed by a binauricular attacliment; and in very recent 
years a further improv^ement has been made through ap- 
plication of the principle of the telephone; but the es- 
sentials of auscultation with the stethoscope were 6stab> 
lished in much detail by Lai-nnec, and the honor must 
always be his of thus taking one of the longest single 
steps by wbicb practical medicine has in dur century ao- 
quired the right to lie considered a mtional science. 
Im^nnec*3 etforts cost him his life, for he died in 1826 
of a lung disease acquired in the couiise of his hospital 
practice; but even before this his fame was universal, 
and the value of bis method hud been recognized all 
over the world. Not long after, in IS*28, yet anotlier 
French physician, Piorry, jierfected the method of per- 
cussion by introducing the custom of tapping, not the 
chest directly, but the linger or a small metal or hard 
, rubber plate held against the chest— mediate percussion, 
Bin short. This perfected the methods of physical diag- 
Hnosis of diseases of the chest in all essentials; and from 
■ that day till this percussion and auscultation have helil 
Han uEiquestioned place in the regular armamentarium of 
T^the physician. 

Coupled with the new method of physical diagnosis 

in the effort to substitute knowledge for guess-work 

eame the studies of the experimental physiologists^ in 

mrticular, Marshall Hall in England, and Franfois Ma- 


gendie in France ; and the joint efforts of these various 
workers led presently to the abandonment of those se- 
vere and often irrational depletive methods — blood-let- 
ting and the like — that had previously dominated med- 
ical practice. To this end also the " statistical method," 
introduced by Louis and his followers, largely contrib- 
uted ; and by the close of the first third of our century 
the idea was gaining ground tliat the province of thera- 
peutics is to aid nature in combating disease, and that 
this may often be better accomplished by simple means 
than by tlie heroic measures hitherto thought necessary. 
In a word, scientific empiricism was beginning to gain a 
hearing in meilicine, as against the metaphysical precon- 
ceptions of the earlier generations. 


I have just adverted to the fact that Napoleon Bona- 
parte, as First Consul and as Emperor, was the victim 
of a mahidy which caused him to seek the advice of the 
most distinufuished physicians of Paris. It is a little 
shocking to modern sensibilities to read that these 
]>hysicians, <\xc(»pt C-orvisart, diagnosed the distinguished 
patient's malady as '"gale repercutee'' — that is to say, 
in idiomatic English, the itch ''struck in." It is hardly 
necessary to say that no ])hysician of to-(hiy would 
make so inconsiderate a diagnosis in the case of a royal 
patient. If by any chance a distinguished patient were 
afflicted with the itch, the sagacious physician would 
carefully hide the fact behind circumlocutions, and pro- 
ceed to eradicate the disease with all despatch. That 
the physicians of Napoleon did otherwise is evidence 
that at the beginning of the century the disease in ques- 



tion enjoyed a very different status. At that time, itch, 
instead of bein^ a most plebeian makuh% was, so to siiy; a 
court dfsease. It enjoyed a circulation, in bigh circles 
a.iid JO low, that moilern tbera[>cutics has quite denied 
it; anil tbtj pbysiciuns of the time gave it a fictitious 

I added imjiortauce by aseriljing to its intluence the ex- 
hianye of almost any obscuj'e malady that came under 
their observation. Long after Napoleon*is time, gale 
continued to hold this proud distinction. For example, 
llie imaginative Dr, Hahnemann did nut besitatt* to af- 
firm, as a positive maxim, that three- fourths of all the 
ills that flesfi is [mr to were in reality nothing but va- 
rious forms of **galc rcpercutee." 
All of wbicli goes to show how easy it may be for a 
niiUikeil preteniler to im|>ose on credulous Imuianity ; for 
nothing is moi-e clearly established in modern knowl- 
edge than the fact that *'ga!e riSpercutetj" was simply a 
same to hide a profound ignorance; no such tliseiise ex- 
ists, or ever did exist. Gale itself is a sufficiently tangi- 
Ibh* t^ality, to be sure; but it is a purely local disease of 
Hie skin, dne to a perfectly definite cause, and the dire 
Ifnternal conditions formerly ascrilied to it have really no 
lusal connection with it wliatever. Thistlefiiiitecau>se, 
every one nowadays knows, is nothing more or less 
l^han a microscopic insect which lias found loilgmcrit on 
the skin, and lias fmrrowed anil made itself at home 

there. Kill that insi-^ct, anti the disease is no more. 


benoe it has come to be an axiom with the modern 

jiivsician tfjat the itch is one of the three or four dis< 

?s that he positively is able to cure, and that very 

lily. But it was far otherwise with the physioians 

the 0rst third of our century, bec4iuae to them the 

lose of the disease u as an absolute mystery, 



It is true that here and there a physician had claimed 
to find an insect lodged in the skin of a sufferer from 
itch, and two or three times the claim had been made 
that tins was the cause of the malady, but such views 
were quite ignored by the general profession, and in 
1833 it was stated in an authoritative medical treatise 
that the '* cause of gale is absolutely unknown." But 
even at this time, as it curiously happened, there were 
certain ignorant laymen who had attained to a bit of 
medical knowledge that was withheld from the inner 
circles of tlie profession. As the peasantry of England 
l)efore Jenner had known of the curative value of cow- 
pox over small-pox, so the peasant women of Poland 
hud learned that the annoying skin disease from which, 
they suffered was caused by an almost invisible insect, 
and, furthermore, had acquired the trick of dislodging 
the pestiferous little creature with the iK)int of a needle. 
From them a youth of the country, F. Kenucci by 
nam(% learned the open secret. He conveyed it to Paris 
when he went there to study medicine, and in 1S34 
(lenKmstriited it to his muster, Alibert. This physician, 
at first sce[)tical, soon was convinced, and gave out the 
discovery to tlie medical world with an authority that 
led to early acceptance. 

Now the importance of all this, in the present con- 
nection, is not at all that it gave the clew to the method 
of cure of a single disease. AViiat makes the discovery 
epochal is the fact that it dropped a brand-new idea 
into the medical ranks — an idea destined, in the long- 
run, to i)rove itself a veritable bomi) — the idea, namely, 
that a minute and quite unsuspected animal parasite 
may be the cause of a well-known, widely prevalent, 
and important human disease. Of course the full force 




of this idea could only be appreciated in the light of 
later k^o^Ylel^ge; but even at the time of its coming it 
suJUceil to give a great impetus to that new medicai 
knowledge, based on microscopical studies, which had 
but recently been made accessible by the inventions 

^■of the lens-makers* The new knowledge clarilied one 

^mi'ery turbid medical pool, and pointed the way to the 

Holarilication of many others. 

" Almost at the same time that the Polish medical stu- 
dent was demonstrating the itch mite in Paris, it 
chanced, curiously enough, that another medical stu- 
dent, this time an Englishman, made an analogous dis- 
covery, of perhaps even greater importance, indeed, 
this English discovery in its initial stages slightly ante- 
dated the other, for it was in 1833 that the student in 
question, James Paget, interne in Saint Bartholomew's 
Ilospitid, London, while dissecting the muscular tissues 
of a human subject, found little specks of extraneous 

(matter, which, when taki.n\ to the professor of compara- 
tive anatomy » Ilichard Owen, were ascertained, with the 
aid of the microscope, to be tlie cocoon of a minute and 
hitherto unknown insect. (3wen named the insect Tri- 
I'hiwt ntjnralh. After the discovery was published, it 
_^ transpired that similar sjiecks had been observed by 
Bfidveral tmrlier investigatoi*s, but no one had previously 
^kuipected, or, at any rate, demonstrated their nature. 
I^Nor was the full story of the trichina made out for a 
long time after Owen's discovery. It was not till 1847 
that the American anatomist Dr. Joseph Leidy found 
the cysts of trichina in the tissues of |>ork; and another 
e or so elapsed after that before German workers, 
among whom were Leuckart, Virchow^ and Zen- 
:er, proved that the parasite gets into the human sys- 




tern through ingestion of infected pork, and that il 
causes a detinite set of svmptons of diseiise, which hillj* 

Orto had 1iol*ii rnistrikrn for rhcuinjiLLsui, lyphuid fcver^J 
and otht^r laaladics. Tiien llje niethcnd wurhl whb agojj 
for a time over the sabjoct of trichinosis ; govcirnment itiJ 
s|iectk>n of pork was estahlished in some parts of Ger-* 




many; Araericim pork was excluded altogether from 
France ; and tlie whole subject thus came prominently to 
public attt^iitlon. But imi>ortant as the trichina pamsite 
proved on its own account in the end, its greatest im- 
portance^ after all, was in the share it played in direct- 
ing attention at the time of its discovery in 1833 to the 
subject of microscopic parasites in general. 

The decade that folio wetl that discovery was a time 
of great activity in the study of microsco[)ic organisms 
and microscopic tissues, and such men as Ehrenberg and 
Ilenle and liory Saint Vincent and IColliker and Roki- 
tansky and Kcmak and Pujiirdin were widening the 

nds of knowleilgo of ihh now subject with detaib 
cannot Ije more than referred to here. But the 
crowning achievement of tiie period in this direction 
was ih© discovery made by the German J. L* Schoen- 
lein in 1839^ that a very common and moat distressing 
disease of the scalp, known as favus, is really due to the 
presence and growth on the scalp of a vegetable organ- 
ism of microscopic si^e* Thus it was made clear that 
not merely animal but also vegetable organisms of ol> 
orc^ microscopic species have causal relations t^ the 
diiseases with wliich mankind is afflicted. This knowl- 
ge of tlio parasites was another long ste[» in the direc- 
tion of scientiBc medical knowledge; but the heio:hts to 
whieli this knowledg** led were not to lie scaled, or even 

gnized^ until another generation of workers had en- 
thc field. 


Meantime, in quite another field of medicine, events 
irere developing which led presently to a revelation of 
r immediate importance to Immanity than any 



other discovery that had come in the century, perhajw 
in any field of si*ience whatever. This was the discov- 
ery of the painHlispelling power of the vapor of sul- 
phuric ether, inhaled by a patient undergoing a surgical 
oiHiration. This discovery come solely out of America, 
and it stands curiously isolated, since apparently no 
minds in any other country were trending towards it 
even vaguely. Davy, in England, had indeed originated 
the method of medication by inhalation, and carried cot 
some most interesting ex|)eriments fifty years eariier, 
and it was douI)tless his experiments with nitrous oxide 
gas that gave the clew to one of the American investi- 
giitois; but this was the sole contribution of preceding 
geuerations to the sul>ject, and since the beginning of 
the (•('Mtury, wiieii Davy turned his attention to other 
inutlers, no one liad made the slightest advance along 
the saiiu' liiu* until an American dentist renewed the 
inxisiiiration. Moreover, there had been nothing in 
Dmvv's ex|)<'riments to show that a surgical operation 
might !)<• renden'd painhss in this way ; and, indeed, 
the surir«'«)n> of Kuro|M» had acknowledged with one ac- 
cord tiiat Jill ho])c of lindiuir a means to secure this 
most iloirahlc end must be utterly abandoned — tliat the 
sui'iieon's knif.' must ever remain a synonym for slow 
aiid indesciil)al»l«' ttulure. I'y an odd coincidence it 
cliaiu'eil Sii" rirnjamin IJrodie. the acknowledged 
h'ader of l'jii:lisli surgeons, ha«l publicly expressed this 
as ills ilrli berate though regr<-tted opinion at a time 
when tlie qu«'st whjch he considi'rod futile had alreadv 
led to tilt; most, brilliant success in America, and while 
the announcement of the discovery, which then had no 
transatlantic cable to convey it. was actually on its way 
to the Old AVorhl. 








T 1 LO • 

\ [ < ''..iNr^ATKJNS. 



The Ainerican dentist just referred to, who was, with 
pone exception to be noted presciitly, tlie first man in the 
world to conceive that the ad minis t ration of u delinita 
drug might render a surgical operation painless, and to 
five the belief appHcation, was Di\ Horace Wells, of 
Hartford, CtainecticuL The drug with which he experi- 
mented was nitrous oxide; the operation wliieh he ren- 
^■dered painless was no more important than the extrac- 
Hlion of a tooth — yet it sufficeiJ tu mark a principle ; the 
^fceer of the experiment wiis 1844* 

■^ The exf>enments of Dr Wells, however, though im- 
portant, wei*e not sufficiently demonstrative to bring the 
|iuatter prominently to the attention of the medical 
rorld. The drug with which he experimented proved 
lot aJwaya reliable, and he himself seems ultimately to 
given the matter up, or at le.'ist to have relaxed his 
ts. But meantime a friend, to whom he had com- 
lunicateil his belief and expectatiotjg, took the matter 
ip, and with unremittin*^ zeal carried forward experi- 
iients that were destined to lead to more tangible re- 
|ult^ This friend was another dentist, I)r, W, T, G. 
Morton* of B-'Ston, then a young man, full of youthful 
"^energy and enthusiasm. He seems to have felt that the 
drug \vith which Wells bad ext»erimented was not the 
most practicable one for the purpose, and so for several 
lontlis he exiM^rimented with oilier allied ctjugs, until 
lally he hit upon sulphuric ether, and with this was 
ibla to make experiments upun anirtials, and then ujion 
>atientB in the dental chair, that seemed to him abso- 
itely demonstnitive. 
Full of eager enthusiasm, and absolutely confident of his 
Rulla, ho at once went to Br, J. C. Warren, one of the 
[foremoitt surgeons af I^M>ston, and asked permission to 
2 a 369 



test his discovery decisively on one of the patients at 
the Boston Hospital during a severe operation. The re- 
quest was granted ; the test was made on October 16, 1S40, 
in the presence of several of the foremost surgeons of 
the city and of a body of medical students. The pa- 
tient slept quietly while the surgeon's knife was plied, 
and awoke to astonished comprehension that the ordeal 
was over. The imiK)ssible, the miraculous, had been ac- 

Swiftly as steam could carry it — slowly enough we 
should think it to-day — the news was heralded to all the 
world. It was received in Europe with incredulity, 
which vanished before repeated experiments. Surgeons 
were loath to believe that ether, a drug that had long 
lield a place in the subordinate armamentarium of the 
physician, could accomplish such a miracle. But scepti- 
cism vanished before the tests which any surgeon might 
make, and which surgeons all over the world did make 
within the next few weeks. Then there came a linger- 
ing outcry from a few surgeons, notably some of the 
Parisians, that th(? shock of pain was beneficial to the 
patient, hence that anjcsthesia — as Dr. Oliver Wendell 
Holmes had christened the new method — was a proced- 
ure not to be advised. Then, too, there came a hue- 
and-cry from many a pulpit that pain was God-given, 
and hence, on moral grounds, to be clung to rather than 
renounced. But the outcry of the antediluvians of both 
hospital aixl i)ulpit (julckiy received its quietus; for soon 
it was clear that the patient w^ho did not suffer the 
shock of pain during an operation rallied better than the 
one who did so suffer, while all humanity outside the 
pulpit cried shame to the spirit that would doom man- 
kind to suffer needless agon^^ And so within a few 


n Ukf^n Hi thp timtt of his 4i90O7ttTf Of the moflCBihotte 
|wu|i«nies of sa 1 ph utio etlier 

TH 1- n; 'A.' YOHK 

rUP.;.lC '.I3RARY, 

TIL?-'. "^ F.">.-*ir'*"'''"*NS. 



months after that initial opopation at the Boston Hos- 
pital in 1840j other hatl injulo gooti its conquest of pain 
tbruughotit the civilized world. Only by the most ac- 
tive use of the imagination can we of this present day 
reali/vG the fidl meaning of tliat victory. 

It remains to he arlded tliat in the sul>sequent bicker- 
ings over the disco VL^ry — such bickeringis as f*Jlf>w every 
great advance— two other names came into prominent 
notice as sharers in the glory of the new nietijod. Both 
these were AmericaTis— theone. Dr. ('Iiarles T, Jackson, 
of Boston; the other, Br, Crawford W. Long, of Ala- 
bama. As to Dr. Jackson, it is sufficient tu say that he 
iteomf^ to have had soitio vague inkling of the peculiar 
properties of etlier before ^[orton's discovery, lie even 
suggested the use of this drug to Mtnlon, not knowing 
that ITorton had alrernly tried it ; hut this is tlie full 
^meiisnre of his association with the discovery. Hence it 
^Hs clear that Jackson's claim to equal share mth Mor* 
■ton in the discovery was unwarranted, not to say ab* 

Dr. Long's assi>ciation with the matter was far differ- 

Ient, and altogether honorable. By one of those coinci- 
dences so common in the history of discovery, he w^as 
experimenting with ether as a puin^destroyer simulta- 
neously witli Morton, though nei titer so much as knew 
of the existence of the other. While a meilical student 
I he had once inhaled otlier for the intoxicant effects, as 
other mt^dical students were wont to rhi, and when par* 
tially under inlluence of the drug he had noticed that a 
chance blow to his shins was painless. This giive him 
the idea that ether might be used in surgical operations; 
and in subsequent years, in the course of his practice in 
a small (icorgia town, he put the idea into successful 




execution. There appears to be no donbt whatever that 
he performed successful minor operations under ether 
some two or three years before Morton's final demon- 
stration ; hence that the merit of first using the drug, 
or indeed any drug, in this way belongs to him. But 
unfortunately Dr. Long did not quite trust the evidence 
of his owa experiments. 'Just at that time the. medical 
journals were full of accounts of experiments in which 
painless operations were said to be })erformed through 
practice of hypnotism, and Dr. Long feared that his own 
success might be due to an incidental hypnotic influence 
rather than to tiie drug. Hence he delayed announcing 
his apparent discovery until he should have opportunity 
for further tests — and opportunities did not come every 
(lay to the country practitioner. And while he waited, 
Morton anticipated him, and the discovery was maxle 
known to the world without his aid. It was a true sci- 
entific caution that actuated Dr. Long to this delay, but 
the caution cost him the credit, which might otherwise 
have been his, of giving to the world one of the greatest 
blessini,^ that science has ever conferred upon hu- 

A few months after the use of ether became general, 
the Scotch surgeon Sir J. Y. Simpson discovered that 
another drug, chloroform, could be administered with 
similar ofTocts; that it would, indeed, in many cases pro- 
duce anaesthesia more advantageously even than ether. 
From that day till this surgeons have been more or less 
divided in opinion as to the relative merits of the two 
drugs; but this fact, of course, has no bearing whatever 
upon the merit of the first discovery of the method of 
aniesthesia. Even had some other drug subsequently 
quite banished ether, the honor of the discovery of the 




beneficent method of aniBsthesia would have been in no 
wise in valid a tad. And despite all cavillings, it is un- 
ec^uivDcally e3tablislie<i thnt the man ivhu gave that 
method to the world was Williain 1\ G, Morton. 

■ This discovery of the anaestbetic power of drugs was 

'' destined presently, in addition to its direct beneficences, 
^ tf> aid greatly in the progress of acientific mtjilicinej by 
H facilitating those experimental stndies of animals from 
Hwbich, before the day of anajsthesia, many humane 
Bjrfjysicians were withheld, and which in recent years have 
Vied to discoveries of such inestimable value to humanity. 

But for the moment this possibility was quite overshad* 
^owed by ttie direct benefits of ansestbesia, and the long 
"strides tliat were taken in scientific medicine during the 

first fifteen years after MorU^n's discovery were raainl}^ 
Hindependent of such aid. These steps were taken, in- 
H|nd, in a field that at first glance might seem to have 
HRery slight connection with rnodtcinu. Moreover, the 

chief worker in the field was not himself a physician, 

lie WHS a chemist, and the work in which he w*as now 
^engaged was the study of alcoholic fermentation in vi- 
Hnons liquors. Yet these studies pavetl the way for the 
HrnifMt important advances that medicine has made in any 
Bcientury towards the plane of true science; and to this 
Hman more than to any other sin^de individual — it might 
Halmost be said more than to all other individuals— was 
™dae this wonderful advance. Tt is almost superHuous to 

add that the name of this marvellous chemist was Louis 

The studies of fermentation wdnch Pasteur entered 






upon in 1854 were aimed at the solution of a contro- 
versy that liad been waging in the scientific world with 
varying degrees of activity for a quarter of a century. 
Back in the thirties, in theday of the early enthusiasm over 
tlie perfected microscope, tliere had arisen a new inter- 
est in the minute forms of life which Leeuwenhoek and 
some of the other early workers with the lens had first 
describcMl, and which now were shown to be of almost 
universal prevalence. These minute organisms had been 
studietl more or less by a host of observers, but in par- 
ticular by the Frenchman Cap^niartl Latour and the Ger- 
man, of cell-theory fame, Theodor Schwann. These 
men, workin*; independenth^ had reached the conclu- 
sion, about 1837, that the micro-organisms play a vastly 
more iiii|>ortant role in the economy of nature than any 
one pn^viously had supposed. They held, for example, 
that tlh* minute specks which largely make up the sub- 
staneo of y«'jist are living vegetable organisms, and that 
tlh» irrovvth of tlies(» organisms is the cause of the ini- 
[)oi'tant and familiar process of fermentation. They 
(»ven cauK* to hold, at least tentatively, the opinion that 
tlh' soniewliat similar micro-ori^anisms to be found in all 
l)utrefyini; matter, animal or vegetable, had a causal re- 
lation to the pro(!ess of putrefaction. 

This view, i)articularly as to the nature of putrefac- 
tion, was expi'essed eV(Mi more outspokenly a little later 
by iIk! Freneli botanist Turpi n. Views so supported 
naturally gained a following; it was equally natural 
that so radical an innovation should be aiitagonized. In 
this case it chanced that one of the most dominatiu!^ 
scientific minds of the time, that of Liebig, took a firm 
and agirn^ssive stand against the new doctrine. In 1S31) 
ho promulgated his famous doctrine of fermentation, in 






which he stocxl out firmly against any 'Witalistic" ex- 
planati'in of the plienoinena, alleging that the presence 
of laicro-orgfUiisms in fonnenting and putrefying sub- 
stances was merely incideritai, and in no sense causal. 
This opinion of the great Gerraan chemist was in a 
measure substantiated by experiments of liis compatriot 
llelmholtZj who^e earlier experiments conliruiedj but 
ter ones oontradictedj the observations of Schwann^ 
and this comljinud uuLhority gave the vitahstic concep- 
tion a blow from which it had not rallied at the time 
[•when Pasteur entered the field. Imleed, it wascurrent- 
y re^ijarded as settled that the early students of the 
mil) j act hatl viLstly overestimated the importance of mi- 

And so it came as a new revelation to the generality of 

scientists of the titne, when, in 1857 an<l the succeeding 

hairdecade, Pasteur published the results of his re- 

searclies, in which the question had been put to*a series 

of altogether new tests, and brought to unequivocal 


lie provt>d that the micro-organisms do all that his 

ost imaginative predecessors had suspected^ and more. 

|Without them, ho proved, there would be no fermenta- 

km, no putrefaction — no decay of any tissues, except by 

he slow process of oxidation. It is the microscopic 

(WL*it plant wfiich, by seizing on certain atoms of the 

molecule, liberates tlie remaining atoms in the form of 

flwnic acid and alcohol, thus effecting fermentation; 

it is another microscopic plant — a bacterhini, as Devaine 

ad christeneit it^whioh in a similar way effects the 

estructioD of organic molecules, producing the condi- 

ion whicli wo call putrefaction. Pasteur showeii, to 

e amazement of biologists^ that there are certain forms 



of these bacteria which secure the oxygen which all or- 
ganic life requires, not from the air, but by breaking up 
unstable molecules in which oxygen is combined ; that 
putrefaction, in short, has its foundation in the activities 
of these so-called anaerobic bacteria. 

In a word, Pasteur showed that all the many familiar 
processes of the deca}' of organic tissues are, in eflfect, 
forms of fermentation, and would not take place at all 
except for the presence of the living micro-organisms. 
A piece of meat, for exami)le, suspended in an atmos- 
phere free from germs, will dry up gradually, without 
the slightest sign of putrefaction, regardless of the tem- 
perature or other conditions to which it may have been 

There was nothincr in these studies bearino: directlv 
upon the question of iinimal diseases, yet before they 
were finished they had stimulated progress in more than 
one field of pathology. At the very outset tiiey sufficed 
to start afresh the inquiry as to the role played by mi- 
cro-organisms in disease. In particular, thev led the 
French physician Devaine to return to some interrupted 
studies which he had made ten years before, in reference 
to the animal disease called anthrax, or splenic fever, a 
disease that cost the farmers of Europe millions of 
francs annually through loss of sheep and cattle. In 
18r>(), Devaine had seen multitudes of bacteria in the 
blood of animals who had died of anthrax, but he did 
not at that time think of them as having a causal rela- 
tion to the disease. Now, however, in 18G3, stimulated 
by Pasteur's new revelations regarding the power of 
bacteria, he returned to the subject, and soon became 
convinced, through experiments by means of inocula- 
tion, that the microscopic organisms he had discovered 



rare the f'eritablc and the sole cause of the infectious 
ili&ease iintlirax. 

The publication of ttiin belief in 1H63 ai'oused a furor 

kof controvei-sy. That a micmscopio vegetable could 
piusc ix virulent systemic disease was an idea altogether 
too startling to be accepted in u day, and the generality 
of biologists and physicians demanded more convincing 
proofs than Devainc as* yet was able to offer* 

Natariilly a liost of other investigatoi's all over the 
or Id t^ntcred the fieltL Foremost among these was the 
GermaD Dr* Robert Koch, who soon corroborated all 
that Devaine had observed, and carried the experiments 
furthor in the direction of the cultivation of successive 
|enerati^ins of the bacteria in artificial media, inocuk- 
lions l>eing made from such pure cultures of the eighth 
?neratioiu with the astonishing result that animals thus 
Inoculatefl at once succunilied to the disease. 

8iicli experinit*nts m^vui demonstrative, yet the world 
ras anoonvinced, and in 1876, wliile the controversy 
jTim still at its height, Pasteur was prevailed upon to 
take the matter in hanth The great cbemi^t was be- 
coming more and more exclusively a biologist as the 
Hxreurs passed, a nil in recent ycnars his famous studies of 
^Kbe silk- worm diseases, which he }iroveddueto bacterial in- 
Hf6ction,and of thequestion of spontaneous generation, had 
Hgiven him umx|ualled resources in mtcroscupical technique. 
^And so when, with ttie aid of his laboratory associates 
I Duclaux and Cliamhcrland and Roux, ho took up the 
[looted ji nth rax question, the scientific world awaited 
ie issue witii battxl breath. And wlicn, in 1877, Pas- 
sur wns reiuly to report on his studies (^f anthrax, he 
«ne forward with such a wealth of demonstrative ex- 
eriments— experiments the rigid accuracy of which no 



one would for a moment think of questioning — going to 
prove the bacterial origin of anthrax, that scepticism 
was at last quiets for all time to come. 

Henceforth no one could doubt that the contagious 
disease anthrax is due exclusively to the introduction 
into an animal's system of a specific germ — a micro- 
scopic plant — which develops there. And no logical 
mind could have a reasonable doubt that what is proved 
true of one infectious disease would some day be proved 
true also of other, perhai)s of all, forms of infectious 

Ilitherto the cause of contagion, by which certain 
maladies spread from individual to individual, had been 
a total mystery, quite unillurained by the vague terms 
'^ miasm,'' *' humor," '* virus," and the like cloaks of ig- 
norance. Here and there a prophet of science, as Schwann 
and llenle, had guessed the secret; but guessing, in sci- 
ence, is far enough from knowing. Now, for the first 
time, the world ktiew, and medicine had taken another 
gigantic stride towards the heights of exact science. 


Meantime in a different, though allied, field of medi- 
cine there had been a complementary growth that led 
to immediate results of even more practical importance. 
I mean the theory and practice of antisepsis in surgery. 
This advance, like the other, came as a direct outgrowth 
of Pasteur's feruKMitation studies of alcoholic beverages, 
though not at the hands of Past<3ur himself. Struck by 
the boundless implications of Pasteur's revelations re- 
garding the bacteria. Dr. Joseph Lister (the present 
Lord Lister), then of Glasgow, set about as early as 


fim J05&FH UfiTKH 

T !•■ t" NV vV YORK 

p!;r:j': library. 

T • L r> ,- s •r • ■ - : • ■« \ S . 


1860 to make a wonderful application of these ideas. If 
putrefaction is always due to bacterial development, he 
argued, tins must apply as well to living as to dead tis- 
sues; hence the putrefactive changes which occur in 
wounds and after operations on the human subject, from 
wliich blood-poisoning so often follows, miglit be abso- 
lutely prevented if the injured surfaces could be kept 
free from access of the germs of decay. 

In the hope of accon]plisliing this result, Lister began 
experimenting with ilriigs that miglit kill the bacteria 
without injury to the patient, and with means to pr^ 
vent furtlier access of germs once a won ml was freed 
from them. How well he succeeded, all the world 
knows; how bitterly he w*as antagonized for about a 
score of years, most of the world has already forgotten. 
As early as 1867, Lister was able to publish results 
pointing towards success in his great project; yet so in- 
credulous were surgeons in general that even some years 
later tlje leading surgeons across the Channel had not 
, so much as heard of his eiforts. In 1S70 the soldiers of 
^aris died, as of old, of hospital gangrene ; and when in 
1S71 the French surgeon Alphonse Gn^rin, stimulated 
by Pasteur's studies, conceived the idea of dressing 
wounds wttli cotton in the hope of keeping gerras from 
entering them, he was quite unaware that a British con- 
temporary had preceded him by a full decade in this ef- 
fort at prevention, and had made long strides towai'ds 
complete success. Lister's priori ty^ however, and the 
superiority of his method, were freely admitted by the 
Frencli Academy of Science, which in I8S1 otficially 
crowned his achievement, as the Royal Society of Lon- 
don had done the year before. 

time, to be sure, as everybody knows, Lister^s 

By I 



new methods had made their way everywhere, revolu- 
tionizing the practice of surgery, and practically banish- 
ing from the earth maladies that hitherto had been the 
terror of the surgeon and the opprobrium of his art. 
And these bedside studies, conducted in the end by 
thousands of men who had no knowledge of microscopy, 
had a large share in establishing the general belief in 
the causal relation that micro-organisms bear to disease, 
which by about the year 1880 had taken possession of 
the medical world. But they did more; they brought 
into equal prominence the idea that, the cause of a dis- 
eased condition being known, it- may be possible as 
never before to grapple with and eradicate that condi- 

The controversy over spontaneous generation, which, 
thanks to Pasteur and Tyndall, had just been brought 
to a termination, made it clear that no bacterium need 
be feared where an antecedent bacterium had not found 
lodgment; Listerism in surgery liad now shown how 
much might be accomplished towards preventing the 
access of germs to abraded surfaces of the body, and 
destroying those that already had found lodgment 
there. As yet, however, there was no inkling of a way 
in which a corresponding onslausjlit might be made upon 
those other germs wliich find their way into the animal 
organism by way of the mouth and the nostrils, and which, 
as was now clear, are the cause of those contagious diseases 
which, fii-st and last, claim so large a proportion of man- 
kind for their victims. How such means might be 
found now became the anxious thought of every im- 
aginative physician, of every working micro-biologist. 

As it happened, the world was not kept long in sus- 
l>ense. Almost before the proposition had taken shape 



iQ the minds of the other leadet*s, Pust^ur liful tuuml h. 
soIqiioo. Gaid^ by the empirical succi-inti of *}tynimrf 
be, like many olbersL, bad long practmcl ir]r>eiihi.Miiti njt* 
pefiinafita, and on the 9th of February, IHHii, \m nn- 
nouo^ed to the French Acatlemy of *Sci«nc« that In* (in^l 
found m meibcKl of so ralucing tho virulence of ^i iUm^h^* 
gierm ibat^ when intrcKlucefl into tho uynUim of ji «fi4- 
ceptible animal^ it pnxluced only a mild form ut MfA4)#f 
leaae* ^^hieh, however, sufficed to protfsr^t nffftUtM IUh 
I Qsnal tiruknt form exactly iik vaccinia \)rt,u^*AA nf^fufiiti 
smaU-pox. The particular diHf?iw*o eip?niii*f#ii.^4 wHh 
Wits that infectious malady of p< sultry kuoivfi ' if 

ns '* chicken cholera." In i}eU>lHif of Ui*' *' - / ^f 
Pasteur announced the method fty irlrk^i Um^ n^hhti^ 
ation of the Tirus," as he termed it hud ffMnfi tfto^iftti 
about--by cultivation of the dmrnrngmm In ifUM^ 
media, exposed to the air, and km 4M m4 kMhtmia 1^ 
asaert his belief that the meihod •^orilrf f^^^^s ^ ^, 

ble of gf^eralization ''— tltat h Up my, i4 t$f^tf*whfffi f/^ 
other tliseiises ttian the pctrtieolar "^-^ ' - -' -' - 
I Within a few inoatbi be nuuh 
for in February, ISvSl, be Mmmm¥l 1^ Hfm 
that, with the aid. aa heta9% f4 im m^- 
Chainl>erland ami Uoux^fm kdtA ^AiU^ 
irirus of the anibraji mwsn^m^ f>y 
couM protect sbeepv and 
fatal malady* 
This aonoaooaumft mm bwni i n^nfo l y 4ff^l^m^^ f^ 
w that bfi}ii)|liiC it Uf 



rlA The 

Izing the 

to Pasteor thai im %l\fs3^ Mmmmf 


ffif pfHfifmA 



drove of fifty sheep, half of which were to be inoculated 
with the attenuated virus by Pasteur. Subsequently all 
the sheep were to be inoculated with virulent virus, all 
being kept together in one pen, under precisely the same 
conditions. The "protected" sheep were to remain 
healthy; the unprotected ones to die of anthrax; so 
read the terms of the proposition. Pasteur accepted 
the challenge; he even permitted a change in the pro- 
gramme by which two goats were substituted for two 
of the sheep, and ten cattle added ; stipulating, however, 
that since his experiments had not 3'et been extended to 
cattle, these should not be regarded as falling rigidly 
within the terms of the test. 

It was a test to try the soul of any man, for all the 
world looked on askance, prepared to deride the maker 
of so preposterous a claim as soon as his claim should be 
proved baseless. Not even the fame of Pasteur could 
make the public at large, lay or scientific, believe in the 
possibility of what he proposed to accomplish. There 
was time for all the world to be informed of the proced- 
ure, for the first "preventive" inoculation, or vaccina- 
tion, as Pasteur termed it, was made on the oth of May, 
the second on the 17th; and another interval of two 
weeks must elapse before the final inoculations with the 
unattenuated virus. Twenty-four sheep, one goat, and 
five cattle were submitted to the preliminary vaccina- 
tions. Then, on the 31st of May, all sixty of the ani- 
mals were inoculated, a protected and an unprotected 
one alternately, with an extremely virulent culture of 
anthrax microbes that had been in Pasteur's laboratory 
since 1S77. This accomplished, the animals were left 
together in one enclosure, to await the issue. 

Two days later, the 2d of June, at the appointed hour 

;enti:rv's pkogress in sciextific medicine 

of rendezvous, a vast crowd^ composed of veterinary sur- 
geons, ne^vs paper correspondents, and farmers from far 
itui near, gathered to witness the closing scenes of this 
DicDtilic tourney. Wliat they saw was one of the most 
dramatic scenes in the history of peaceful science^a 
scene whicli, as Pasteur declared afterwards, ^'amazed 
the assenibty/* Scattered about the enclosure^ dead, 
n^iog, or manifestly sick unto deatli, lay the unprotected 
iknimals, one and all; while each and every ^* protected" 
LnimaJ stalked unconceniedly about with every appear- 
100 of perfect health. Twenty of the sheep aad the 
ae goat were already dead ; two other sheep expired 
inder the eyes of the s}>ectators; the remaining victims 
lingered but a few hours Iongi3r. Tims in a manner 
theatrical enough, not to say tragic, was proclaimed the 
unequivocal victory of science. Naturally enough, the 
unbelievers struck their colors and surrendered without 
terms; tlie principle of protective vaccination, with a 
virus experimentally pre])ured in the laboratory, was es- 
tablished beyond the reach of controversy. 

That memorable scientitic battle marked the begin- 
ning of a new era in medicine. It was a foregone con- 
pi union that lire principle thus establishetl would l>e still 
irther geuerali/.ed; that it woidd be applied to human 
maladies^ that, in all probability, it would grapple sue- 
fc.*Si»fully, sooniT or hu*r, with many infections diseases. 
Phat ex|»eclation iuis advanced rapidly towards realiza^ 
ion. Paj^teur himself made the application to the hu- 
lan subjec't in the tlisease hydrophobia, in 1885, since 
rhich time that hitherto most fatal of maladies has 
irgely lost its terrors. Tliousands of ixvmrns, bitt-en 
mad dogs, have been snatched from the fatal eonse- 
jenccH of that mishap by this method, at the Pasteur 



Institute in Paris, and at the similar institutes, built on 
the model of this parent one, that have been established 
all over the world, in regions as widely separated as 
New York and Nha-Trang. 



In the production of the rabies vaccine Pasteur and 
his associates developed a method of attenuation of a 
virus quite different from that which had been employed 
in the case of the vaccines of chicken cholera and of an- 
thrax. The rabies virus was inoculated into the system 
of guinea-pigs or rabbits, and, in effect, cultivated in the 
systems of these animals. The spinal cord of these in- 
fected animals was found to be rich in the virus, which 
rapidly becaine attenuated when the cord was dried in 
the air. The preventive virus, of varying strengths, was 
made by maceration of these cords at varying stages of 
desiccation. This cultivation of a virus within the ani- 
mal organism, suggested, no doubt, by the familiar Jen- 
nerian method of securing small-pox vaccine, was at tlie 
same time a step in tiie direction of a new therapeutic 
procedure which was destined presently to become of 
all-absorbing importance — the method, namely, of so- 
called scrum-therapy, or the treatment of a disease with 
the blood serum of an animal that has been subjected to 
protective inoculation against that disease. 

Tiie possil)ility of such a method was suggested by 
the familiar observation, made by Pasteur and numerous 
other woi'kers, that animals of different species differ 
widely 'u\ their susceptibility to various maladies; and 
that the virus of a given disease may become more and 
more virulent when passed through the systems of suc- 



3170 individaals of one species, and, contrariwise^ less 
"and less virulent when passed through the systems of 
successive individuals of anoUier species. These facts 


suggested the theory that tlie blood of resistant animals 
might contain something directly antagonistic to the 
virus, and the hope that this something might be trans- 
ferred with curative effect to the blocjd of an infected 
iigceptibla animal Numerous ex|>eriraenters all over 


the world made investigations along the line of this al- 
luring possibility, the leaders perhaps being Di-s. Behring 
and Kitasato, closely followed by Dr. Roux and his as- 
sociates of the Pasteur Institute of Paris. Definite re- 
sults were announced b}' Behring in 1892 regarding two 
important diseases — tetanus and diphtheria — but the 
method did not come into general notice until 1894, 
when Dr. Boux read an epoch-marking paper on the sub- 
ject at the Congress of Hygiene at Buda-Pesth. 

In this paper, Dr. Boux, after adverting to the labors 
of Behring, Ehrlich, Boer, Kossel, and Wasserman, de- 
scribed in detail the methods that had been developed 
at the Pasteur Institute for the development of the cura- 
tive serum, to which Behring had given the since familiar 
name antitoxine. The method consists, first, of the cul- 
tivation, for some months, of the diphtheria bacillus 
(called the Klebs-Loettler bacillus, in honor of its dis- 
coverers) in an artificial bouillon, for the development 
of a powerful loxine capable of giving the disease in a 
virulent form. 

This toxine, after certain details of mechanical treiit- 
ment, is injected in small but increasing doses into the 
system of an animal, care being taken to graduate the 
nmount so that the animal does not succumb to the 
disease. After a certain course of this treatment it is 
found that a ])ortion of blood serum of the animal so 
treated will act in a curative way if injected into the 
blood of another animal, or a human patient, suffering 
with diphtheria. In other words, according to theory, 
an antitoxine has been developed in the system of 
the animal subjected to the progressive inoculations 
of the diphtheria toxine. In Dr. Roux's exjierience 
the animal best suited for the purpose is the horse, 




ough almost any of the domesticated anitiiaJi will 
serve the purpose. 

But Dr, Roux's paper did not stop with the description 
of laljoratory methods. It told also of the pnictical ap- 
plication of the serum to the treatment of nomerous cases 
of di|>litberia in the hospitals of Paris^applicattons that 
had met with a gratifying measure of success* lie made 
it cleur that a means had be^n found of coping success- 
fully with what had been one of the most virulent and 
intractable of the diseases of childhood* Hence it was 
not strange tliat his paper made a sensation in all circles, 
metiicml and lay alike- 
Physicians from all over the world flocked to Paris to 
learn tlie details of the open secret, and within a few 
months the new serum- therapy had an acknowleilged 
standing with the medical profession everywhere What 
it had accomplished was reganled as but an earnest of 
wliat the new method might accomplish presently when 
ap[)lied to the other infectious dise^ises. 

Elfurts at such applications were immediately begun 
in numberless directions— bad, indeed, been under way 
in many a laboratory for fiome vears before. It is too 

'■ *■ r 

early yet to sj>eak of the results in detail. But enough 
hai^ been done to sliow that tliis methoil also is suscep- 
tihlti of the widest generalization. It is not easy at the 
resent stage to sift that which is tentative from that 
bich will be permanent ; hut so great an authority as 
Bell ring does not hesitate to aflirni that to-ilay we pos- 
sess, in addition to the diphtheria antitoxine, equally 
ijiocitic antitoxines of teUnus, cholera, typhus fever, 
neumonia, and tuberculosis — ^a set of disciises which in 
e aggregate account for a startling proportion of the 
ml death-rate. Then it is known that Dr, Tersin, 


with the collaboration of his former colleagues of the 
Pasteur Institute, has developed, and has used with sue* 
cess, an antitoxine from the microbe of the plague which 
recently ravaged China. 

Dr. Calmette, another graduate of the Pasteur Insti- 
tute, has extended the range of the serum- therapy to 
include the prevention and treatment of poisoning by 
venoms, and has developed an antitoxine that has al- 
ready given immunity from the lethal effects of snake 
bites to thousands of persons in India and Australia. 

Just how much of present promise is tentative ; just 
what are the limits of the methods — these are questions 
for the future to decide. But, in any event, there seems 
little question that the serum treatment will stand as the 
culminating achievement in therapeutics of our century. 
It is the logical outgrowth of those experimental studies 
with the microscoj>e begun by our predecessors of the 
thirties, and it represents the present culmination of the 
rigidly experimental method wliich has brought medi- 
cine from a level of fanciful empiricism to the plane of 
a rational experimental science. 



A LTTTLB over a hundred years ago a reform move- 
Tiient was afoot in thtj world in the interests of tin? in- 
sane. As was fitting, the nioveiuent sbowed itself Hrst 
in America, where these unfortunates were hmnatiely 
mred for at a time when their treatment elsewhere was 
worse than brutal, but England and France riuickly fell 
into line. The leader on this side of the ivater was the 
famous Philadelphian, Dr, Benjamin Rush/* the Syden- 
ham of America" ; In England, Dr. William Tuke inau- 
gurated the movement; and in France, l>r* Phihpi^e 
[Pinelj single-handed, led the way< Moved by a com- 
( ition spirit, thcnigh acting quite independently, these 
men raisetl a revolt against the traditional custom 
which, spurning the insane as demon-haunted outcasts, 
hail condemned these unfortunates to ilungeons, chains, 
and the lash. Hitherto few people had thought it other 
than the natural course of events that the ** maniac" 
should te thrust into a dungeon^ and perhajjs chained 
to the wall with the aid of an iron band riveted per- 
inanently about his neck or waist. Many an unfortu- 
nate, thus manacled, was hehl to the narrow limits of 
I his chain for years tfjgether in a cell to which full day- 
light never |>enetrate<l ; sometimes— iron being expen* 


sive — the chain was so short that the wretched victim 
could not rise to the upright posture, or even shift his 
position upon his squalid pallet of straw. 

In America, indeed, there being no Middle Age prece- 
dents to crystallize into established customs, the treat- 
ment accorded the insane had seldom or never sunk to 
this level. Partly for this reason, perhaps, the work of 
Dr. Kush, at the Philadelphia Hospital, in 1784, by 
means of which the insane came to be humanely treat- 
ed, even to the extent of banishing the lash, has been 
but little noted, while the work of the European lead- 
ers, though belonging to later decades, has been made 
famous. And perhaps this is not as unjust as it seems, 
for the step which Rush took, from relatively bad to 
good, was a far easier one to take than the leap from 
atrocities to good treatment which the European re- 
formers were obliged to compass. In Paris, for exam- 
ple, Piiiel was obliged to ask permission of the authori- 
ties even to make the attempt at liberating the insane 
from their chains, and notwithstanding his recognized 
position as a leader of science, he gained but grudging 
assent, and was regarded as being himself little better 
than a lunatic for making so manifestly unwise and 
hopeless an attempt. Once the attempt had been made, 
liowever, and carried to a successful issue, the amelio- 
ration wrou«;ht in the condition of the insane was so 
patent that the fame of Pinel's work at the Bicetre and 
the Salpetrier<» went abroad apace. It required, indeed, 
many years to complete it in Paris, and a lifetime of 
elTort on the part of Pinel's pupil Esquirol and others 
to (extend the reform to the provinces; but the epochal 
turning-point iiad been reached with Pinel's labors of 
the closing years of the eighteenth century. 









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The significance of tliis wise and humane reform, in 
the present connection J is tlu' fiict that these studies of the 
insane gave euipbasis to the navel idea, which by-and-by 
became accepted as bej^ond question, that *'domonincal 
possession " is in realitj' no more than the oiitwani ex- 
pression of a diseased condition of the brain. This real- 
imtion raade it clear, as never before, bow intimately 
the inind and the botly are linked one to the other. And 
so it chanced that in striking tlie sLuckles from the in* 
sane, Pinel and his confreres struck a blow also, un- 
wittingly, at time -honored philosophical traditiorm. 
The liberation of the ii>sane from their dLiiigeons was 
an augury uf the Hb*n*ation of pi^yohology from the 
musty recesses of metaphysics* Hitherto psychology, 
in so far as it existed at all, was but the subjective 
study of individual minds; in future it must became 
objective as well, taking into account also the relations 
which the mind bears to the body, and in particular to 
the brain and nervous system* 

The necessity for this collocation was advocate<l quite 
as earnestly, and even more directly, by another worker 
of this [K*riod, whose studit*s were allied to those of 
alienists, and who, even more actively than they, focab 
ized his attention uix^n the brain and its functions. This 
earliest of s|>ecialists in brain studies was a German by 
birth, but Parisian by adoption, Dr. Franx Joseph Gall, 
originator of the since notorious system of pbrenology. 
The merited disrepute into which this system has fallen 
through the ejfixjsitions of peripatetic charlatans should 
not make us forget that Dr. Gall hims«*lf was appar- 
ently a highly edacJited phys^ician, a careful student 
of the brain and mind according to the best light 
of his time, and, withal, an earnest and honest be* 



liever in the validity of the system he had originated. 
The system itself, taken as a whole, was hopelessly 
faulty, yet it was not without its latent germ of truth, 
as later studies were to show. How Hrmly its author 
himself believed in it is evidenced by the paper which 
he contributed to the French Academy of Science in 
1808. Tlie paper itself was referred to a committee of 
which Pinel and Cuvier were members. The verdict of 
this committee was adveree, and justly so; yet the sys- 
tem condemned had at least one merit which its de- 
tractors failed to realize. It popularized the conception 
that the brain is the organ of mind. Moreover, by 
its insistence it rallied about it a band of scientific sup- 
porters, chief of whom was Dr. Kaspar Spurzheim, a 
man of no mean abilities, who became the propagandist 
of phrenology in England and in America. Of coui'se 
such advocacy and popuhirity stimulated opposition as 
well, and out of the disputations thus arising there grew 
presently a general interest in the brain as the organ of 
mind, quite aside from any preconceptions whatever as 
to the doctrines of Gall and Spurzheim. 

Prominent among the unprejudiced class of workers 
who now appeared was the brilliant young Frenchman, 
Louis Antoine Desmoulins, who studied first under the 
tutorage of the famous Magendie, and published jointly 
with him a classical work on the nervous system of ver- 
tebrates in 1S25. Desmoulins made at least one discov- 
ery of epochal importance. He observed that the brains 
of persons dying in old age were lighter than the aver- 
a^^e, and gave visible evidence of atrophy, and he rea- 
S()U<'(1 that such decay is a normal accompaniment of 
senility. Xo one nowadays would question the accu- 
racy of this observation, but the scientific world was 



rnot quite readj for it in 1825 ; for when Desmoulins an- 
nounoecl his discovery to the French Academy, that 
august and somewhat patriarchal body was moved to 
t)ujte unscientific wrath, and forbade the young icono- 
clast the privih^ge of further hearings* From which it 
is evident that the partially liberatetl spirit of the new 
psychology had by no means freed itself altogaLher, at 
the close of the first quarter of our century, from the 
mcUipbysical cobwebs of its lung incarceration* 



While studies of the brain were thus being inaugu- 
rated, the nervous system, which is the channel of com- 
munication between the brain and the outside world* 
was being interroguteil witli even more tangible I'esults* 
The inaugural discoFery was made in 1811 by Dr. 
(afterwanls Sir Charles) Bell^ the famous English sur- 
geon and ex |>eri mental physiologist. It consisted of 
the observation that the anterior roots of the spinal 
nerves are given over to the function of conveying 
motor impulses from the brain outward, whereas the 
pi^teriiir ru<jts convey s<jlely sensory impulses to the 
brain from without Hitherto it had been supposed 
that all m^rves have a similar function, and the peculiar 
tbstribution of the spinal nerves had been an unsolved 

BelFs discovery w;is epochal; but its full significance 
was not appreciated for a decade, nor, intleed, was its 
validity at fiiNt ailmitted. In Paris, in parti cidar, then 
tlie court of final appeal in all matters scientific, the al- 
leged discovery was looked at askance, or quite ignore^l 
But in 1*^23 the subject was taken up by tlie nH^ogni7><l 
8c 401 


kader of French physiology— Fran <;ois Magendle — in 
the course of bis cotaprehcniiivo axperimental studies of 
the nervous system, aiui Betls conclusions were subject- 
ed to the most rigid experiinental tests, aud found aho- 

getlier ndid. Bell himself, 
meiinwbile, had turiitHJ [m 
attention to I he cranial 
nerves, and had proved 
tbat these also are divisible 
into two sets— sensory and 
motor, Sometinms. indeed, 
the two sets of ti laments 
Mreci>mbined into one nerve 
curd, but, if traced to t!»eir 
origin, these are found to 
arise from different brain 
centres. Tims it was clear 
that a hitherto unrecog- 
nized duality of ftinction 
pertains to tlie entire extra- 
cranial nervous system. 
Any impulse sent from the periphery to the brain nm«t 
be conveyed along a |K?rfeetly definite channel; the 
response from the brain, sent out to the peripheral 
muscles, must t raverse an ef|ually definite and altogether 
different com*se. If either channel is interrupted— as by 
the sectiorj of its jmrticular nerve tract— the corregpond- 
ing message is denied transmission as effectually as an 
electric current is stopped by the section of the trans- 
mitting wire. 

Experimontei*s everywhere soon confirmed the obser- 
vations of Bell antl Magendie; and, as always happens 
after a great discovery; a fresh impulse was given to in- 


Itlll CIM1ll«t. DKLL 


stigationsj in filtjed fields. Nevertheless, a full decade 
llapsed before another discovery ut comi*undjIe impor- 
tance WHS made. Then Maj^hall Hall, the most famous 
of Eiiglisli physicians of his day^ made his classical ob- 
servatioris on the plmnomena that henceforth were to lie 
tnuvvti as reflex action. In 1833, while experimenting 

ine day with a det*ii[>itnted newt» he observed that the 
headless creature's hiiiiis would contract in direct re* 
sponse to certain stiumli. Such a response CDuld no 
)nger Im >;ix^urod if the spinal nerves supplying a part 
rere severed. Uence it was clear that res[K>nsive cen* 
exist in the spinal cord capable of receiiring a sen- 
ary messa^ and of transmitting^ a motor impulse in 
9ply— a function hithertt* supposed to be reserved for 



the bi*ain. Further studies went to show that such phe- 
nomena of reflex action on the part of centres lying out- 
side the range of consciousness, both in the spinal cord 
and in the brain itself, are extremely common ; that, in 
short, they enter constantly into the activities of every 
living organism, and have a most important share in the 
sum total of vital movements. Hence, Hall's discovery 
must always stand as one of the great mile-stones of the 
advance of neurological science. 

All these considerations as to nerve currents and 
nerve tracts becoming stock knowledge of science, it 
was natural that interest should become stimulated as 
to the exact character of these nerve tracts in them- 
selves; and all the more natural in that the perfected 
microscope was just now claiming all fields for its own. 
A troop of observers soon entered upon the study of the 
nerves; and the leader here, as in so many other lines 
of microscopical research, was no other than Theodor 
Schwann. Tlirough his efforts, and with the invaluable 
aid of such other workers as Remak, Purkinje, Ilenle, 
Miiller, and the rest, all the mystery as to the general 
characteristics of nerve tracts was cleared awa3\ It 
came to be known that in its essentials a nerve tract is 
a tenuous fibre or thread of protoplasm, stretching be- 
tween two terminal points in the organism — one of such 
termini being usually a cell of the brain or spinal cord ; 
the other, a distribution point at or near the periphery — 
for example, in a muscle or in the skin. Such a fibril may 
have about it a protective covering, which is known as the 
sheath of Schwann; but the fibril itself is the essential 
nerve tract ; and in many cases, as Remak presently dis- 
covered, the sheath is dispensed with, particularly in 
case of the nerves of the so-called sympathetic system. 



This 8\ in pa the tie system of ganglia and nerves, by- 
^bye, had long t)een a puzzle to the physiologists. Its 
mglia^ the seeming centres of the system, usually mi- 
nute in size^ and never very large, are found everywhere 
through the organism, but in particular are g^ithered 
^intu a h>ng double chain which lies within the body cav- 
H|ty^ outride tlie spinal cohiran, and represents the sole 
nervous system of the nun-vertebrated organisms. Fi- 
lirils from these ganglia were seen to join the cmnial 
aud spinal nerve iibrils, and to accompany them every- 
^■R^berei but what sjieciid function they subserved was 
^■ong a mere matter of conjecture, and led to many ab- 
^■ord specuiations* Fact was not substituted for conject- 
^pir€ until about the year 1851, when the great French- 
man Claude Bernard conclusively proved that at least 
^^ne chief function of the sympathetic librils is to cause 
^■on traction of the waUs of the arterioles of the system, 
^Btius regulating the blood supply of any given part. Ten 
"^years earlier Ilcnle had demonstrated the existence of 
^annular iKinds of muscle tibres in the arterioles, hitherto 
^■b much mooted question, and several tentative explana- 
^tiorjs of the acti(m of these fibres had been made, par- 
ticularly by the brothers Weber, by Stilling, wlio, as 
early as 1840, had ventured to speak of *' vaso-motor" 
aerves, and by Scljitf, who was hard upon the same 
track at the time of Bernard's discovery. But a clear 
light wm not thrown fin tlie subject until Bernard's ex- 
periments were made in 1851. Tlje exi>eriments were 
soiJU after ci>n firmed and extended hy BrownSt^quarti, 
Waller, Ihulge* ami numerous others, and henceforth 
physiologists felt tbat they understood how the blood- 
>ph' of any given part is regulated by the nervous 



In reality, however, they had learned only half the 
story, as Bernard himself proved only a few years later 
by opening up a new and quite unsuspected chapter. 
While experimenting in 1858 he discovered that there 
are certain nerves supplying the heart which, if stimu- 
lated, cause that organ to relax and cease beating. As 
the heart is essentially nothing more than an aggrega- 
tion of muscles, this phenomenon was utterly puzzling 
and without precedent in the experience of physi- 
ologists. An impulse travelling along a motor nerve 
had been supposed to be able to caifte a muscular con- 
traction and to do nothing else; yel here such an im- 
pulse had exactly the opposite effect.* The onl}^ tenable 
explanation seemed to be that this particular impulse 
must arrest or inhibit the action of the impulses that 
ordinarily cause the heart muscles to contract. But the 
idea of such inhibition of one impulse by another was 
utterly novel, and at first difficult to comprehend. 
Gradually, however, the idea took its place in the cur- 
rent knowledge of nerve physiology, and in time itciirae 
to be understood that what happens in the case of the 
heart nerve-supply is only a particular case under a very 
^^eneral, indeed universal, form of nervous action. Grow- 
ing out of Bernard's initial discovery came the final un- 
derstanding^ that the entire nervous system is a mechan- 
ism of centres subordinate and centres superior, the 
action of the one of which may be counteracted and 
annulled in effect by the action of the other. This ap- 
plies not inerely to such physical processes as heart- 
beats and arterial contraction and relaxing, but to the 
most intricate functionings which have their counterpart 
in psychical processes as well. Thus the observation of 
the inhibition of the heart's action by a nervous impulse 




lied the point of departure for studies that led to 
a better mulerstanding of the mod us operandi of the 

KTs activities than had ever previously been attained 
ae most subtle of psychologists. 
xiie work of the nerve physiolDgists had thus an inn- 
porta nt bearing on questions i>f the mind* J?yt them 
was another couipariy of workers of this period who 
made an even more direet assault upon the "citadel of 
: tbouglit/' A remarkable school of workers had dovel* 
' o[>ed in Germany, the leadei*s being inerj who, having 
more or less of innate metaphysical bias as a national 
irthriglit, had also the instincts of tfie empirical seien- 
list, and whose educational equipim^nt included a pro 
found knovvle<lge not alone of physiulogy and psycholo* 
y, but of physics and mathemuttes as well. These men 
ndertook the novel task of interrogating the relations 
of boily and mind from the stand point of physics. 
They sought to apply the vernier and the balance^ as far 
ad inigi(t l>e, U> tfu> intangible procesf^es of mi ml 

The movement had its pr-ecursory stages in the early 

n of the century, notably in the mathematicn! psy- 

ology of llerbart, but its fii-st deHniti^-eoutput toultract 

eneral attention came from the master-hand of Hermann 

elmhoh/. in 1S5L It cuJisisted of the accurate measure- 

ent of the s|>t?etl of transit of a nervoun impulse along 

a nerve tract. To make such nieasurement had been re- 

gartled iis imj^osnible, it being supposed that the tlightof 

Ihe nervous impulse was practically instantaneous* But 

lelmhi*ltz readily demonstmted tlie contrary, showing 

he nerve cor*! is a relatively sluggish message- 





bearer. According to his experiments, fii^t perfonuetl 
upon the frog, tlie nervous ** current" travels less than 
one hundr^ feet per second. Other experiments per- 
formed soon afterward by Ilelmholtic himself, and by 


various followers, chief umong wtiom was Du Bois^Eey- 
mondj modified somewhat the exuct figures at lirst ob- 
tained, but did not change the general bearings of the 
early results. Thus the nervous irntmlse was shown to 
be something far different, as regards speed of transit, 
at any rate, fixim the electric current to which it had 




m 1*R0€ 

^P>eeQ so often likened. An eleetnc current would Ihish 
half-way round the gloljo ^vhile ii nervous impulse cuuJd 

^-imvel tiie length of the human Ixnly — from a man's foot 

^w> his brain. 

^M The tendency to bridge the gulf that hitherto had 

^separated the physical from tiie pj^ychical worfd was 
further evidenced in the foiluwing decade by Uehidioltz^s 

B^markable hut highly technical study of the sensations 
of .sound and of color in connection with their pliysical 
causes, in the course of which he revivx^i the dfjctrine 

Hof color vision which that utlior great physiologist and 
physicist^ Thomas Yonng» had advanced lirdf a century 
before. The same tendency was further evidencetl by 
the appeamnce, in 1852, of Dr. Hermann Lotze's famous 
Mi'iiizinuche Pmjehi)l-i*tjfey mlei' l^ht/nhUHjie (for SmU^ 
with its challenge of the old myth of a ** vital force.*- 
But the most delinitiveexpi^ssion of the new movement 
was signalized in ISGO, when Gustav Fechner pubhshed 
bis classical work called Pmjeh(fphtfmk. That title in 
trod need a new w^ord into the vocabnhiry of science. 
Fechner explained it by saying, '*! mean by psycho* 
phvsics an exact theory of the relation between spji it 

^and bmly, and, in a general way, between the physical 

Band tlie psychic worlds/' The title became ftimons,anJ 
the brunt of many a controversj^. So also did another 
phrase which Fechner introduccil in the course of bis 
book— the phrase " physiological psychology." In mak- 
ing ihat happy collocation of woixls Fechner virtually 
ichristened a new science. 

The chief purport of this classical book of the German 
[ijsycho-physiologtst was the elaboration and explication 
I of experiments based on a method introduced more than 
|lwenty years earlier by his countryman E- IL Weber, but 



which hitherto had failed to attract the attention it de- 
served. The {nethod consisted of the measurement and 
analysis of the definite relation existing between exter- 
nal stimuli of varying degrees of intensity (various sounds, 
for example) and the mental states they induce. Weber's 
experiments grew out of the familiar observation that the 
nicety of our discriminations of various sounds, weights, 
or visual images depends upon the magnitude of each 
particular cause of a sensation in its relation with other 
similar causes. Thus, for example, we cannot see the 
stars in the daytime, though they shine as brightly then 
as at night. Again, we seldom notice the ticking of a 
clock in the daytime, though it may become almost pain- 
fully audible in the silence of the night. Yet again, the 
difference between an ounce weight and a two-ounce 
weight is clearly enough appreciable when we lift the 
two, but one cannot discriminate in the same way be- 
tween a five-pound weight and a weight of one ounce 
over five jwunds. 

This last example, and similar ones for the other senses, 
gave Weber the clew to his novel experiments. Reflec- 
tion upon every -day exi)eriences made it clear to him 
that whenever we consider two visual sensations, or two 
auditor}' sensations, or two sensations of weight, in com- 
parison one with another, there is always a limit to the 
keenness of our discrimination, and that this degree of 
keenness varies, as in the case of the weights just cited, 
with the magnitude of the exciting cause. 

Weber deteiMuined to see whether these common ex- 
periences could be brought within the pale of a general 
law. Ills method consisted of making long series of ex- 
periments aimed at the determination, in each case, of 
what came to be spoken of as the least observable dif- 





ferenc© between the stimuli. Thus if one holds an ounce 
weight in each hand, and has tiny weights added to one 

tbem, grain bj grain, one does not at first perceive a 

fersnoe; but presently, on the addition of a certain 
grain, he does become aware of the difference. Noting 

w how many grains have been added to produce 
effect, we have the weight which represents the 
least appreciable difference when the standard is one 

Now repeat the experiment, but let the weights be 
e4ioh of five pounds. Clearly in this case we shall be 
obligeil to add not grains, but drachms, before a differ- 
ence between the two heavy weights is perceived. But 
whate^rer the exact amount added, that amonnt repro- 
B^nli^ th e st i ra u hi s proil uc i n g a j u st perce i va ble sensa t i o n 
of diffemnce wlien the standard is five pounds. And so 
on for indefinite series of weights of varying magnitudes. 
Now came Weber's curious discovery. Not only dfd he 
find that in repeated *'xp*^riments with the same pair of 
weights the measure of '* just ]>erceivab!e difference'- re- 
maineil approximately fixed, but lje found, further, that 
a remarkable fixed relation exists between the stimuli of 
different magaitudo. If, for ^'xample, he had found it 
necessary, in tlie cnse of the ounce weights, to add one- 
fiftieth of an ounca to tlie one before a differtmce was 
detecte^l, he found also, in the case of the five pound 
weights, that one-fiftieth of five pounds must be added 
before producing the same result, And so uf all other 
weights; the amount addeil to produce the stimuhm of 
*^ least ajtjvreciable differtince" always bore the same 
mathematical relation to the magnitude of the weight 
used, bo that ma^^nitude great or small. 

"Weber fournl ihat the sann 





stimuli of the slsnsations of sight and of hearing, the dif- 
ferential stimulus bearing always a fixed ratio to the 
total magnitude of the stimuli. Here, then, was the law 
he had sought. 

Weber's results were definite enough, and striking 
enough, yet they failed to attract any considerable meas- 
ure of attention until they were revived and extended 
by Fechner, and brought before the world in the famous 
work on psycho-physics. Then they precipitated a veri- 
table melee. Fechner had not alone verified the earlier 
results (with certain limitations not essential to the pres- 
ent consideration), but had invented new methods of 
making similar tests, and had reduced the whole ques- 
tion to mathematical treatment. He pronounced Webers 
discovery the fundamental law of psycho -physics. In 
honor of the discoverer, he christened it Weber's I-,aw. 
He clothed the law in words and in mathematical for- 
mula^, and, so to say, launched it full tilt at the heads 
of the psychological world. It made a fine commotion, 
be assured, for it was the tii'st widely heralded bulletin 
of the new psychology in its march upon the strongholds 
of the time-honored metaphysics. The accomplishments 
of the microscopists and the nerve physiologists had been 
but preliminary — mere border skirmishes of uncertain 
import. I>ut here was proof that the iconoclastic move- 
ment meant to invade^ the very heart of the sacred ter- 
ritory of mind— a territory from which tangible objec- 
tive fact had been su])|H)sed to be forever barred. 

Hardly had the alarm been sounded, however, before 
a new movement was made. While Fechner's book was 
fresh from the ])ress, steps wore bem^ t^iken to extend 
the methods of the physicist in yc^t another way to the 
intimate processes of the mind. As Helmholtz had shown 



he rate of nervous impulsion along ibe nerve tract to 
e raeasiirfible, it was now soiigla to measure also tbe 
ime required for the central nt^rvous mechanism to per- 
form its work of receiving a message and sending out a 


csponse. This was coming down to tbe very tbresbold 
}( mind. Tlie attein[it was first made by Professor 
Donders, in I8t»l, but definitive results were only ol> 
tained after many years of experiment on tbe part of a 
host of observei's. The chief of these, and the man wbo 
(laft stood in the forefront of tbe new movementf and 



has been its recognized leader throughout the remainder 
of the century, is Dr. Wilhelra Wundt, of Leipzig. 

The task was not easy, but, in the long run, it was 
accomplished. Not alone was it shown that the nerve 
centre requires a measurable time for its operations, but 
much was learned as to conditions that modify this 
time. Thus it was found that different persons vary in 
the rate of their central nervous activity — which ex- 
plained the "personal equation" that the astronomer 
Bessel had noted a half-century before. It was found, 
too, that the rate of activity varies also for the same 
person under different conditions, becoming retarded, 
for example, under influence of fatigue, or in case of 
certain diseases of the brain. All details aside, the es- 
sential fact emerges, as an experimental demonstration, 
that the intellectual processes — sensation, apperception, 
volition — are linked irrevocably with the activities of 
the central nervous tissues, and that these activities, like 
all other physical processes, have a time element. To 
that old school of psychologists, who scarcely cared 
more for the human head than for the heels — being in- 
terested only in the mind — such a linking of mind and 
body as was thus demonstrated was naturally disquiet- 
ing. l>ut whatever the inferences, there was no escap- 
ing the facts. 

Of course this new movement has not been confined 
to Germany. Indeed, it had long had exponents else- 
whore. Thus in England, a full century earlier. Dr. 
Hartley had cliampioned the theory of the close and in- 
dissoluble do])end('nce of mind upon the brain, and 
formulated a famous vibration theory of association that 
still merits careful consideration. Then, too, in France, 
at the beginning of the century, there was Dr. Cabanis 



with his tangiblej if crudely pb rased, doctrine that the 
brain digests impressiuns and secretes thought as the 
stomach digests food and the liver secretes bile. More- 
over, Herbert Spencer's Prhwipks of PAych^dogy^ with 
its avowed Ci>ordintLtion of luind and body and its vital- 
izing theory of evolution, appeareti in 1855, half a decoile 
before the work of Fechner. But these influences, 
though of vast educational value^ were theoretical rather 
than demonstrative, and the fact remains that Llio experi- 
inentahvorlc which iirst attempted to gauge mental opera- 
tions by physical principles was mainly done in Gurmanyi 
Wundt's PhtjHiolotjkul I^Hf/c/tnlo^t/, with its full pre- 
liminary descriptioJis of the anatomy of the nervous sys- 
tem, gave tangible expression to the growth of tlie new 
movement in 1874; and four years later^ witli the open- 
ing of his laboratory of Pliysiological Psychology at the 
University of Leipzig, the new psychology may be said 
to have g-ainetl a }>ermanent foothold, and to have forcetl 
itself into official roeognition. From then on its con- 
quest of the world was but a mutter of time. 

It should be noted, however, that there is one other 
method of strictly experimental examination of this men- 
tal liehl, latterly much in vogue, which had a ditrerent 
origin. This is the scientific investigation of the phe- 
nomena of hypnotism. This subject was rescued from 
the hands of charlatans, rechristened, and subjectLHl to 
accurate investigation by Dr. James J3ruid, of Mane li es- 
ter, as early as 184L But his results, after attracting 
momentary attention, fell from view, aiul, despite desul- 
tory efforts, the subject was ntit aguin accorded a gen- 
eral hearing from the scientific world until 1878, wiien 
Dr. Charcot took it up at the Salpetriire in Paris, fol- 
lowed soon afterwards by Dr, Kudolf Ueidenhain^ of 



Breslau, and a host of other experimenters- The valnoi 
of the methuil in the study of mental states was soon 
apparent. Most of Urakrs experiments were repeated, 
anti in tbe main his results were confirmed. Ills exphv 
ivation of liv pilot ism, (jr artificial gomnamlmlism, as a , 

self-induced state, independent of any occult or siijier- 
sensihle inllnence^ soon gained gtmeral credence. Jlisl 
l>elief that the initial stages are due to fatigue of ner-j 
vous centres, usually from excessive stimulation »haii not[ 
been supplanted, though Bup|ilfMuente<l by notionsi grow* 



:ig oat of the new knowledge as to subconscious raen- 
llitj in general^ and Liie inhibitory inflneiico of one 
sntiii over anutlier in the central nervous mecbauism. 

These studies of the psychologists and pathologists 
bring the illations of mind and body into sharp relief, 
liiiit even more defirnte in this regiird was tlie work of 
he bruin physiologists. Chief of these, during tiie mid- 
lie period of the century, was the man who is some- 
nmes spjkeii of as the *' fatlier of lirain pfiysioh^gy/' 
pjlarie Jean Pierre Flourens, of tlio Jardin des Plantes 
ft Paris, the pupil and worthy successor of Magendie. 
Us ex|X!rimertts in nerve physiology were begun in the 
Irst quarter of the eontury, but Ijis local experiments 
upon tlie brain itself were not cuhninnted until a.bout 
^42. At this timet the old dispute over phrenoh»gy had 
Tiroken out afresh, and the stiuiies of Flonrens were 
imed, in part at h*ast, at tlie strictly scientiJic investi- 
Ation of this tronbli*some topic. 

In the course of these studies Flourens discovered tliat 
in the medulla tihlongiita, the purt of the brain which 
i;4>nnects that f»rgaii witli tne spinal cord, there is a cen- 
of minute sixo wliich cannot be injured in the least 
Hthout causing the instjint death of the animid o|ier- 
ml upon. It may la* added that it is this spot which 
reiichcd by the needle of the garroter in Spanish exe- 
itions* and that the same centre al^o is destroyed when 
criminal is ^* successfully*' lianged, this time by the 
f(*rc!ed intrusion of a process of the second cervical ver- 
tebra. Flourens named this spot the '"vital knot/' Its 
extreme in«[>ortance, as is now understood, is due to the 
20 Ul 


fact that it is the centre of nerves that supply the 
heart; but this simple explanation, annulling the con- 
ception of a specific " life centre," was not ai* once ap- 

Other experiments of Flourens seemed to show that 
the cerebellum is the seat of the centres that co-ordinate 
muscular activities, and that the higher intellectual fac- 
ulties are relegated to the cerebrum. But beyond this, 
as regards localization, experiment faltered. Negative 
results, as regards specific faculties, were obtained from 
all localized irritations of the cerebrum, and Flourens 
was forced to conclude that the cerebral lobe, while 
being undoubtedly the seat of higher intellection, per- 
forms its functions with its entire structure. Tliis con- 
clusion, which incidentally gave a quietus to phrenology, 
was accepted genoi'ally, and became the stock doctrine 
of cerebral physiology for a generation. 

It will be seen, however, that these studies of Flourens 
had a double bearing. They denied localization of 
cerebral functions, but they demonstrated the localiza- 
tion of certain nervous processes in other portions of the 
brain. On the whole, then, they spoke positively for 
the principle of localization of function in the brain, for 
which a certain number of students contended; while 
their evidence against cerebral localization was only 
negative. There was here and there an observer who 
felt that this negative testimony was not conclusive. In 
particular, the (German anatomist Mi^Miert, who had 
studied the disposition of nerve tracts in the cerebrum, 
was led to believe that the anterior portions of the cere- 
brum must have motor functions in preponderance; the 
posterior portions, sensory functions. Somewhat simi- 
lar conclusions were rciiched also by Dr. Hughlings- 



Jackson, in England, from his studies of epilepsy. But 
no positive evidence was forth-coming until 1861, when 
Dr. Paul Broca brought before the Academy of Medi- 
cine in Paris a case of brain lesion which he regarded as 
having most important bearings on the question of cere- 
bral localization. 

The case was that of a patient at the Bicetre, who for 
twenty years had been deprived of the power of speech, 
seemingl}'^ through loss of memory of words. In 1861 
this patient died, and an autopsy revealed that a certain 
convolution of the left frontal lobe of his cerebrum had 
l>een totally destroyed by disease, the remainder of his 
brain being intact. Broca felt that this observation 
pointed strongly to a localization of the memory of 
words in a definite area of the brain. Moreover, it 
transpired that the case was not without precedent. As 
long ago as 1825 Dr. Boillard had been led, through 
pathological studies, to locate definitely a centre for the 
articulation of words in the frontal loh>e. and here and 
there other observers had ma^le tentativf^ in the same 
direction. Boillard had even fo!lowe*J the matter up 
with pertinacity, bat the world was not rearly to listen 
to him. Now, boireTer, in the half decade tliat fol- 
lowed Bnxa's annoanoement^ interestt rff^. to fearer- 
heat, and tbroagh the effciita of I>oca, fV^illard, and 
numerous others it was ffrored tis^i a T*:r\r^rAft r-^ntr*^. 
having a strange dominaccon orf:r •be merwfr;/ ♦-/ ^K^^vv- 
late words has its seat in tiw: tbiri rxjti7rA\TAr,n %? Vi*^ 
frontal lobe of the certhmm^ rn^i^ir In r,h^ ;t>fr. r»«»m> 
sphere. That part of ihtft bnin Ir^iA ^^c:p: v**in <r^i'r^^ v, 
the Englisb-spealda^ woriii as* to** 'Wirv r'«%i %r' T-^-v*;* 
a name vrhkh^ tlnawdr ^aurtngtu. ziut l.^w^'V^^^r'-i vv ■- 
patriots hare bees aS^ v> %^^^kq^ 


This discovery very naturally reopened the entire 
subject of brain localization. It was but a short step to 
the inference that there must be other definite centres 
worth the seeking, and various observers set about 
searching for them. In 1867 a clew was gained by Eck- 
hard, who, repeating a forgotten experiment of Haller 
and Zinn of the previous century, removed portions of 
the brain cortex of animals, with the result of producing 
convulsions. But the really vital departure wiis made 
in 1870 by the German investigators Fritsch and Ilitzig, 
who, by stimulating definite areas of the cortex of ani- 
mals with a galvanic current, produced contraction of 
definite sets of muscles of the opposite side of the body. 
These most important experiments, received at first with 
incredulity, were repeated and extended in 1873 by Dr. 
David Ferrier, of London, and soon afterwards by a 
small army of independent workers everywhere, prom- 
inent among whom were Franck and Pitres in France, 
Munck and Goltz in Germany, and Ilorsley and Schafer 
in England. The detailed results, naturally enough, 
were not at first all in harmony. Some observers, as 
Goltz, even denied the validitv of the conclusions hi toto. 
But a consensus of opinion, based on multitudes of ex- 
periments, soon placed the broad general facts for which 
Fritsch and Ilitzig contended beyond controversy. It 
was found, indeed, that the cerebral centres of motor 
activities have not quite the finality at first ascribed to 
them by some observers, since it may often happen that 
after the destruction of a centre, with attending loss of 
function, there may be a gradual restoration of the lost 
function, proving that other centres have acquired the 
capacity to take the place of the one destroyed. There 
are limits to this capacity for substitution, however, and 



rith tbisqualitication the definiteness of the localization 
\{ motor functions in the eerel>ral cortex has become an 

c<^epto(l part of Unim physiology. 


Nor is such lix^iilization conlined to motor centrea 

itor experimt*Ttts, [mrticuhirly of Forner iind of Munck, 

>ved that the centres of vision are equally restricteil 

their location, ibis time in the posterior lobes of the 



brain, and that heari-ng b<as likewise its local habitation. 
Indeed, there is every reason to believe that each form 
of primary sensation is based on impressions which main- 
ly come to a definitely localized goal in the brain. But 
all this, be it understood, has no reference to the higher 
forms of intellection. All experiment has proved futile 
to localize these functions, except indeed to the extent 
of corroborating the familiar fact of their dependence 
upon the brain, and, somewhat problematically, upon 
the anterior lobes of the cerebrum in particular. But 
this is precisely what should be expected, for the clearer 
insight into the nature of mental processes makes it plain 
that in the main these alleged " faculties " are not in 
themselves localized. Thus, for example, the " faculty" 
of language is associated irrevocably with centres of 
vision, of hearing, and of muscular activity, to go no 
further, and only becomes possible tiirough the associa- 
tion of these widely separated centres. The destruction 
of Iirocu's centre, as was early discovered, does not alto- 
gether (le])rive a patient of his knowledge of language, 
lie may be totally unable to speak (though as to this 
there are all degrees of variation), and yet may compre- 
hend wiiat is said to him, and be able to read, think, and 
even write correctly. Thus it appears that Broca's cen- 
tre is peculiarly bound up with the capacity for articu- 
late si)eech, but is far enr)ugh from being the seat of the 
faculty of language in its entirety. 

In a similar way. most of the supposed isolated " fac- 
ulties" of higher intellection appear, upon clearer anal- 
ysis as complex aggregations of primary sensations, and 
hence necessarily dependent upon numerous and scattered 
centres. Some " faculties," as memory and volition, may 
be said in a sense to be primordial endowments of every 






nerve cell— even of every body cell. Imleei), an ultimate 
ftnalysis relegates all intellection, in itsprniiordial adum- 
i>ratioMs, to every purtiule of livin*^ matter. Dut socli 
refinements of analysis, after nil, cimnot hide the fact 
iliat certain forms of higlier inlellection involve a pretty 
dL*flnite collociition and elaboration of special sensations* 
Such sjiocialization, indeed^ seems a necessary accompani- 
ment of nienral evolution. That every such siiecialized 
unction has itji lueuMzed centres of co-ordination, of some 
ich sign i ilea nee as the demonstrated centres of art ic li- 
te speech, can hanlly be in doubt^thougii this» be it 
nndersttjod, is an induction, not as yet a demonstration. 
In oilier words, there is every rejison to believe that nu- 
erotts "centres^'' in this restricted sense, exist in the 
br;un that have as yet ehidesl tlie investigator. Inileed, 
tlie current conception rogards the entire cerebral cortex 
:is chiefly composed of centres «>f ultimate co-onlination 
of iuipresstons» which in their cruder form are received 
by more primitive nervous tissues — ^the basal ganglia, 
til© cerebellum, and medulla, ami tlio spiual conL This 
^f course is eipii valent to postulating the cerebral cortex 
as the exrlusivo J5<mt of higher iutellection. Tliis prD|> 
osition, however, to which a safe induction seems to lead, 
is far afield from the substantiation of tlie old conception 
of bi*ain locah^ation, which was based on faulty psy- 
ehology* and eqmdly faulty inductiim:^ from few premises. 
The details of ( fall's syst^iu, as projwundcil by genera- 
tions of his mostly unworthy follotrers, lie quite beyond 
the pale of scientific discussion, Tet,asT liave said, a germ 
of truth was there— the idea of specialization of cerelnvnl 
functions — and modem investigators have rescued that 
ccntml conception from the phrenological rubbish heap 
which its discoverer unfortanat<^sIy left it buried* 




The common ground of all these various lines of in- 
vestigations of pathologist, anatomist, physiologist, phys- 
icist, and psychologist is, clearly, the central nervous 
system — the spinal cord and the brain. The importance 
of these structures as the foci of nervous and mental ac- 
tivities has been recognized more and more with each 
new accretion of knowledge, and the efforts to fathom 
the secrets of their intimate structure has been unceas- 
ing. For the earlier students, only the crude methods 
of gross dissections and microscopical inspection were 
available. These could reveal something, but of course 
the inner secrets were for the keener insight of the mi- 
croscopist alone. And even for him the task of investi- 
gation was far from facile, for the central nervous tissues 
are the most delicate and fragile, and on many accounts 
tiie most (litticult of manipulation of any in the body. 

Special methods, therefore, were needed for this essay, 
and brain histology has progressed by fitful impulses, 
each forward jet marking the introduction of some in- 
genious improvement of meclianical technique, which 
placed a new weapon in tiie hands of the investigators. 

Tiie very beginning was made in 1824 by Rolando, 
wiio first thought of cutting ciiemically hardened pieces 
of brain tissues into thin sections for microscopical ex- 
amination—the basal structure upon which almost all 
the later advances have been conducted. Miiller pres- 
ently discovered that bichromate of potassium in solu- 
tion makes the best of fluids for the preliminary preser- 
vation and hardening of the tissues. Stilling, in 1842, 
perfected the method by introducing the custom of cut- 
ting a series of consecutive sections of the same tissue, 



in order to trace nerve tracts and estalJisb spaeinl rela- 
tions. Then from time to time mechanical ingenuity 
atldod fresh details of improvement. It was found that 
l^ieces of hardened tissue of extreme delicacy can be 
made betti^r subjt*ct to manipukition by being itiipreg- 
iiated with collodion or celloidine, an<l embedded in par- 
affine. Latterly it has become usual to cut sections also 
from fresh tissues, nncbangc^d by chemicals, by frees; lug 
them iiuildotdy with vaporized etiier, or^ butter, carbonic 
acid. By these metliods, and with the aid of perfected 
microtomes, the worker of i^ecent periods avails himself 
of sections i>f brain tissues of a teimousuess whicli the 
early in vest iga tons con hi not approach. 

But more important even tlian the cutting of thin sec- 
tions is the process of nniking the ditferent parts uf the 
section visible, one tissue differentiated from another. 
The thin section, as the early workers examined it, was 
practically colorless^ and even the crudest details of its 
structure were made out with extremt* ditficnlty. Remak 
did, ind<jed, munage to discover that the briun tissue is 
cellular, as early as 1833, and Ehrenberg in the same 
year saw that it is also fibriUarf but beyund this no great 
advance was rtiade until 185^, when a siKlden impidse 
was receivtjd from a new process introduced by (Terlacb- 
The process itself was mtist simpk% consisting essentially 
of nothing more tlian tlie treatment of a microscopical 
pHtion with a solution of carmine. But the result was 
wonderful, for when such a section wa** placed under 
the lens, it no longer appeared homogeneous. Sprinkled 
tli rough its substance were seen irregular bodies that had 
taken on a beautiful color, while the matrix in which tliey 
were embeddeil remained unstained. In a word» the cen- 
iral nerve cell had sprung sudflenly into clear view. 



A most interesting body it proved, this nerve cell, or 
ganglion cell, as it came to be called. It was seen to be 
exceedingly minute in size, requiring high powers of the 
microscope to make it visible. It exists in almost infi- 
nite numbers, not, however, scattered at random through 
the brain and spinal cord. On the contrary, it is confined 
to those portions of the central nervous masses which to 
the naked eye appear gray in color, being altogether 
wanting in the white substance which makes up the chief 
mass of the brain. Even in the gray matter, though 
sometimes thickly distributed, the ganglion cells are 
never in actual contact qne with another; they always 
lie embedded in intercellular tissues, which came to be 
known, following Virchow, as the neuroglia. 

Each ganglion cell was seen to be irregular in con- 
tour, and to have jutting out from it two sets of mi- 
nute fil)res, one set relatively short, indefinitely numer- 
ous, and branching in every direction ; the other set 
limited in number, sometimes even single, and starting 
out directly from tiie cell as if bent on a longer journey. 
Tiie numerous filaments came to be known as proto- 
))]asmic processes; the other fibre was named, after its 
discoverer, the axis cylinder of Deiters. It was a natural 
inference, though not clearly demonstrable in the sec- 
tions, that these filamentous processes are the connect- 
ing links between the different nerve cells, and also the 
channels of communication between nerve cells and the 
])oriphery of the body. The white substance of brain 
and cord, ap})arently, is made up of such connecting 
fibres, thus bringing the different ganglion cells every- 
where into communication one with another. 

In the attempt to trace the connecting nerve tracts 
through this white substance by either macroscopical or 





micmscopical metbodt^, tnost truportant aid is given by 
a method origJimted by Waller in 1852. Earlier than 
that, in tS39^ Nasse had discov*ered tbat a se^'ered nerve 
cord degenerates in its ]ieripberal [lorriuns. Waller dis- 
covered that every nerve H bre, sensory or motors tuis a 
nerve cell to or from which it leads, which dominaN^s 
its nutrition, .so that it can only retain its vitality ivhite 
its connection with that cell is intact, 8ach cells he 
natne<l tropliic ce titles. Certain cells of the anterior 
part of tlie spinal cord, for ezample, are the tro|>bic 
centres of the spinal motor nerves. Other trophic cen- 
tres, gtivorning nerve tnicts in the spiiml cord itself, are 
in the various n*^ions of the brain. It oe<;urred to 
Waller that by destroying such <^ntres, or by severing 
the connection at various regians between a nervous 
tract and its tropldc centre, shari)ly delined Iraetw could 
be made to degenenite* and their lr>cation couhl sub^'- 
quently be accurately defined, as the ilegenerated tis* 
sues take on a changed asj>ect, both to niaerascojjical 
and iiiicra.scopical observation, Roc^ognition of this 
principle thus gave the exi>eriinenter a new weapon of 
great efficiency in tnicing nervous connections. ^lore- 
over, the same prineipte has wide application in cuse of 
the human subject in disease, such as tlie lfsif>n of nervt* 
tracts or the destruction of centres by localized tumors, 
by embolisms, or by truiunatisins. 

All these variou!^ inothods of anatomical examination 
combine to make the conclusion almost unavoidable 
that the central ganglion cells nre the veritable ''cen- 
tres** of fiervouj^ activity to whicfi si» many other lines 
of reaearch have pointed, Ttie conclusion \\m strength- 
encwl by exiierimenls of the students of motor localim- 
tion, which showinl that the veritable centres of their 



discovery lie, demonstrably, in the gray cortex of the 
brain, not in the white matter. But the full proof came 
from pathology. At the hands of a multitude of ob- 
servers it was shown that in certain well-known diseases 
of the spinal cord, with resulting paralysis, it is the 
ganglion cells themselves that are found to be destroyed. 
Similarly, in the case of suflFerers from chronic insani- 
ties, with marked dementia, the ganglion cells of the 
cortex of the brain are found to have undergone degen- 
eration. The brains of paretics in particular show such 
degeneration, in striking correspondence with their men- 
tal decadence. The position of the ganglion cell as the 
ultimate centre of nervous activities was thus placed be- 
yond dispute. 

Afeantinie, general acceptance being given the histo- 
logical sclieme of Gerlach, according to which the mass 
of the wiiite substance of the brain is a mesh-work of 
intercellular fibrils, a proximal idea seemed attainable of 
the way in which the ganglionic activities are corre- 
lated, and, through association, built up, so to speak, 
into the higher mental processes. Such a conception ac- 
corded beautifully with the ideas of the association ists, 
who had now become dominant in psychology. But 
one standing puzzle attended tins otherwise satisfactory 
correlation of anatomical observations and psychic anal- 
yses. It was this: Since, according to the histologist, 
the intercellular fibres, along which impulses are con- 
veyed, connect each brain cell, directly or indirectly, 
with every other brain cell in an endless mesh-w^ork, 
how is it possible that various sets of cells may at times 
be shut otF from one another? Such isolation must 
take place, for all normal ideation depends for its integ- 
rity quite as mucli upon the shutting out of the great 



mass of asdoiRaiJOBs as iq«ji(& ii»e ixKsiBSKiai of ontaiii 
otb^ associaiiODS. For cxumrtie^ a $3Ad«ni ia ^n^iriii^ a 
mathematkal pfofaina laaia fov' ii>e xdoom^i benx'^me 
quite oUirious to lhi& spxial asdcuriaiioos that have to 
do with geograpiir. Bamral bisSofT, and tbe lik«L Bat 
does bisiologr gire aaj cieir lo tiie war in whieii saeh 
isolation mar be effect^ed i 

Attempts were made to find an aiiswer throogb coo- 
sideratiuD of tlie renr peculiar character of tbe blood* 
supply in the brain. Here, as now bene eUe« the ter> 
minal twi«:s of the arteries are aiTan:b:ed in doseil sv$> 
tems. not anastomosing freely with neighboring srstems. 
Clearly, then, a restricted ar^a of the brain may, through 
the controlling influence of the raso-motor nerves, be 
flushed with arterial blood, while neighboring parts re- 
main relatirely ansemic. And since vital activities un- 
questionably depend in part upon the supply of arterial 
blood, this peculiar arrangement of the vascular mech- 
anism may very properly be supposed to aid in the 
localized activities of the central nervous ganglia. But 
this explanation left much to be desired— in {particular 
when it is recalled that all higher intellection must in 
all probability involve multitudes of widely scattercii 

No better explanation was forth-coming, however, 
until the year 1S>9. when of a sudden the mystery was 
cleared awav* by a fresh discovery. Not long l>ofore 
this the Italian histologist. Dr. Camille Golgi, had dis- 
covere<I a method of impregnating hanleneil bniin ti?;. 
sues with a solution of nitrate of silver, with the result 
of staining th^nerve cells and their processes almost in- 
finitely l)etter than was possible by the method of Ger- 
lach, or by any of the multiform methoils that other 



workers had introduced. Now for the first time it be- 
Ciirae possible to trace the cellular prolongations definite- 
ly to their termini, for the finer fibrils had not been 
rendered visible by any previous method of treatment. 
Golgi himself proved that the set of fibrils known as 
protoplasmic prolongations terminate by free extremi- 
ties, and have no direct connection with any cell save 
the one from which they spring. He showed also that 
the axis cylinders give off multitudes of lateral branches 
not hitherto suspected. But here he paused, missing 
the real import of the discovery of which he was hard 
on the track. It remained for the Spanish histologist, 
Dr. S. Ramon y Cajal, to follow up the investigation by 
means of an improved application of Golgi's method of 
staining, and to demonstrate that the axis cylinders, to- 
gether with all their collateral branches, though some- 
times extending to a great distance, yet finally termi- 
nate, like the other cell prolongations, in arborescent 
fibrils having free extremities. In a word, it was shown 
that each central nerve cell, with its fibrillar offshoots, 
is an isolated entity. Instead of being in physical con- 
nection with a multitude of other nerve cells, it has no 
direct i)hysical connection with any other nerve cell 

When Dr. Cajal announced his discovery, in 1880, his 
revolutionary claims not unnaturally amazed the mass 
of histologists. There were some few of them, however, 
wlio were not quite unprepared for the revelation; in 
particular Ilis, who had half suspected the independence 
of tlie c(^lls, because they seemed to develop from disso- 
ciated centres ; and Forel, who based a similar suspicion 
on the fact that he hud never been able actually to 
trace a fibre from one cell to another. These observers 



len came reatlily to repeat CajaFs experiments. So 

*alsti did the veteran liistologisL Kidliker, and soon after- 

w;ml? all the leadei^ everywhere. The result was a 

pmctically unanimous confirmation of the Spanish his- 

t<>h>gist's claniis, and within a few months after his an- 

^^jiounceuients the old theory of uoion of nerve cells into 

^nn endle4SS niesli-work was completely dincarded, and 

^Bhe thefiry of isolated nerve elements — the theory of 

^Tieumns, as it came to be called— was fully established 

in its place. 

PAs to how these isolated nerve cells functionatej Dr. 
Cajal gave the clew from the very tirst, and his expla- 
^^nation has met with universal approval. 
^H In the motlilied view, the nerve cell retains its old 
position as the storehouse of nervous energy. Each of 
the filaments j fitting out from tixe cell is held, us before, 
^to he indeed a transmitter of impulses, but a transmit- 
Hter that operates intermittently, like a telephone wire 
"that is not always *' connected/' and, like that wire, the 
nerve libril ojierates by contact and not by continuity. 
tTnder projier stimulatfon the ends of the fibrils reach 
out, come in contact with other end fibrils of other cells, 
and conduct their destined impulse. Again they re- 
tract, and communication ceases for the time between 
(hose particular cells. Meantime, by a different ar- 
tngement of the Vfirious conduct* *rs, different sets of 
[dis are placed in connimnication, dilTerent associations 
^f nerirous impulses induced, different trains of thought 
tngfendt^red* Each fibril when retracted becomes a non- 
>ndiictor, but wlien extended and in contact with an- 
itber fibril, or with the body of another oell, it conducts 
is message as readily as a oontinuous fihiment could do 
-precisely as in the case of an electric wire, 



This conception, founded on a most tangible anatom- 
ical basis, enables us to answer the question as to how 
ideas are isolated, and also, as Dr. Cajal points out, 
throws new light on many other mental processes. One 
can imagine, for example, by keeping in mind the flexi- 
ble nerve prolongations, how new trains of thought may 
be engendered through novel associations of cells ; how 
facility of thought or of action in certain directions is 
acquired through the habitual making of certain nerve 
cell connections; how certain bits of knowledge may 
escape our memory, and refuse to be found for a time, 
because of a temporary incapacity of the nerve cells to 
make the projxjr connections; and so on indefinitely. 
If one likens each nerve cell to a central telephone- 
office, each of its lilanientons prolongations to a tele- 
phone wire, ho (?an iinugine a striking analogy between 
the modus operandi of nervous processes and of the tel- 
ephone system. The utility of new connections at the 
central office, the uselessness of the mechanism when 
the connections cannot be made, the ''wires in use'* 
that retard your message, i)erhaps even the crossing of 
wires, bringing you a jangle of sounds far different from 
what you desire — all these and a multiplicity of other 
things that will suggest themselves to every user of the 
telephone may be imagined as being almost ludicrously 
])aralleled in the operations of the nervous mechanism. 
And that jKirallel, startling as it may seem, is not a mere 
futile imagining. It is sustained and rendei*ed plausible 
by a sound sul)stratum of knowledge of the anatomical 
conditions under which the central nervous mechanism 
exists, and in default of which, as pathology demonstrates 
with no less ccM'titudo, its functionings are futile to pro- 
duce the normal manifestations of higher intellection. 




In the preoediiig cbapiers I have endeaToted to OQi- 
line the storr of the achievements of our century in 
J-he various fields of |mre scrierice- In so l*road an at- 
Dmpt, with ID such spacia! limits, it has of course been 
Impossible to (hvell npon detaiin, or eren to hint at 
pery minor discovery. At l>e8t one coold bnt sani- 
jarize the broad sweep of progpess somewlmt bm a bat- 
Ic might be descriljed by a distant eye-witness, telling 
tl>e genenil «lirection of action, of the movements 
^f large masses, the names of leaders of brigades and 
divisions* but necessarily ignoring the lesser fluctuations 
ft advance or rei^^ssion and tlie individual gallantry of 
ae nink and file. In particular, interest hits centreti 
ijKin tlie storming of the various special s trough oldii uf 
lorant or prejudiced opposition, which at Imt hard- 
en triumphantly occupied by the band of proj^*«*#. 
each case where such a stronghold has falh:!ii, ti.#* 
ictory Ijns b<^en achieved solely through the destlriMrtir*? 
^mcy nf newly discovered or newly marRhaUed fairlii 
-the only weapons which the warrior of i6Ctefi» d^^lu 
airm for. Facts must be marshalled, of i^^mntif^ 
kmt the guidon of a hypothesis, hnr f 
ily lead on to victory if t!if *"ir*- -f^ ^^ 

Zm 4.i. 


it. Once planted victoriously on the conqaered ram- 
parts, the hypothesis becomes a theory — a generaliza- 
tion of science — marking a fresh coign of vantage, which 
can never be successfully assailed unless by a new host 
of antagonistic facts. Such generalizations, with the 
events leading directly up to them, have chiefly occu- 
pied our attention. 

But a moment's reflection makes it clear that the bat- 
tle of science, thus considered, is ever shifting ground 
and never ended. Thus at any given period there are 
many unsettled skirmishes under way ; many hypoth- 
eses are yet only struggling towards the strongholds of 
theory, perhaps never to attain it; in many directions 
the hosts of antagonistic facts seem so evenly matched 
that the hazard of war appears uncertain ; or, again, so 
few facts are available that as yet no attack worthy the 
name is possible. Such unsettled controversies as these 
have, for the most part, been ignored in our survey of 
the field. But it would not be fair to conclude our 
story without adverting to them, at least in brief ; for 
some of them have to do with the most comprehensive 
jind important questions with which science deals, and 
the aggregate number of facts involved in these unfin- 
ished battles is often great, even though as yet the 
marshalling has not led to final victory for any faction. 
In some cases, doubtless, the right hypothesis is actually 
in the field, but its supremacy not yet conclusively 
proved — perhaps not to be proved for many years or 
decades to come. Some of the chief scientific results of 
our century have been but the gaining of supremacy for 
hypotheses that were mere forlorn hopes, looked on 
with general contempt, if at all heeded, when the eigh- 
teenth century came to a close — witness the doctrines of 




the great age of the eailh, ol the immaterialit j of belli 
of the unduktorr ebaract^ of light, of ebemicftl lUom* 
icy, of or^fitc eTolatioii. Cootr^wise, the opposite 
ideas to all of these had seemingly a safe anpretiiaioj 
oRti! the new factft drove them from the field. Who 
shall say, then, what forloni hope of to-day^s science 
may not be the oonqaeiiiig host of tomorrow) All 
that one dare attempt is to eite the pretensions of a few 
hvp^theses that are struggling oirer the still contested 

^m Oar snn being only a minor atom of the stellar peb- 
ble, solar problems in general are of course stellar prob* 
lenis also. But there are certain special questions re- 
garding which we are able to interrogate the sun because 
of his proximity, and which have« fartherraore, a pecnl- 
iar interest for the residents of our little glohe because 
of our dependence opon this particular star. One of the 
most far*reaching of these is as to when* the sun gets 
the heat that ha gives off in such liberal quantities. We 
have already seen that Dr. Mayer, of eonservation-o(- 
energj fame^ was the first to ask this question. As soon 
as the doctrine of tlie persistence and convertibility of 
energy was grasped, about the middle of the century, it 
became clear that this was one of the most puzzling of 
questions. It did not at all siiffiee to answer that the 
sun is a ball of tire, for computation showed that, at the 
present rate of heat-giving, if the sun were a solid mass 
of coal, he would be totally consumed in about five thou- 
sand years. As no such decrease in size as this implies 



had taken place within historic times, it was clear that 
some oilier explanation must be sought. 

Dr. Mayer himself hit upon what seemed a tenable 
solution at the very outset. Starting from the observed 
fact that myriads of tiny meteorites are hurled into the 
earth's atmosphere daily, he argued that the sun must 
receive these visitants in reall}^ enormous quantities — 
sufficient, probably, to maintain his temperature at the 
observed limits. There was nothing at all unreasonable 
about this assumption, for the amount of energy in a 
swiftly moving body capable of being transformed into 
heat if the body be arrested is relatively enormous. Thus 
it is calculated that a pound of coal dropped into the sun 
from the mathematician's favorite starting-point, infin- 
ity, would produce some six thousand times the heat it 
could engender if merely burned at the sun's surface. 
In other words, if a little over two pounds of material 
from infinity were to fall into each square yard of the 
sun's surface each hour, his observed heat would be ac- 
counted for; whereas almost seven tons per square yard 
of stationary fuel would be required each hour to i)roduce 
the same effect. 

In view of the pelting which our little earth receives, 
it seemed not an excessive requisition upon the meteoric 
supply to suppose that the recjuisite amount of matter 
may fall into the sun, and for a time this explanation of 
his incandescence was pretty generally accepted. But 
soon astronomers began to make calculations as to the 
amount of matter which this assumption added to our 
solar system, particularly as it aggregated near the sun 
in the converging radii, and then it wa^ clear that no 
such mass of matter could be there without interfering 
demonstrably with the observed course of the interior 



planets. So ao other source of the sun^s energy had to 
be sought. It was found forthwith by that other greiit 
German, Helm hoi tz, who pointed out that the falling 
matter through \vhich heat inuy be generated miglit just 
as well IjMj within the substance of the sun as without ; 
in other words, that contraction of the sun's heated body 
is quite sufficient to account for a long-sustainetl heat- 
supply which the mere burning of any itnown substance 
could not approach* Moreover, the amount of matter 
thus falling towards the sun's centre being enormous— 
namely, the total substance of the sun— a rehitively small 
amount of contraction would be theoretically sufficient 
to keep the surrs furnace at par, so to speak* 

At first sight this explanation seemed a little puzzling 
to many laymen and s^^me experts, for it seemetl to im- 
ply, as Ijord Kelvin pointed out, that the sun contracts 
l^ecause it is getting cooler, and gains heat IxM^ause it 
contracts. Bat this feat is not really as paradoxical as 
it seems, for it is not implied that there is any real gain 
of heat in tlie sun's mass as a whole, but quite the reverse. 
All that is sought is an exi>lanation of a maintenance of 
lieat-giving capacity relatively unchanged for a long, but 
not an interminable, period. Indeed, exactly here comes 
in the novel and startling feature of Helmlioltz's calcu- 
la t ion . Acco rd i n g to ^fa y er's m eteori c h y [)ot h es i s , t h e re 
were no data at hand for any estimate whatever as to the 
sun's permanency, since no one con hi surmise wdiat might 
be the limits of the meteoric supply. But llelraholtz's 
estimate implied an incandescentbody cooling— keeping 
up a somewhat equable temperature through contraction 
for a time, but for a limited time only ; destined ulth 
mately to become liquid, solid; to cool below the tem- 
perature of incandescence— to die, Not only so, but it 



became possible to calculate the limits of time within 
which this culmination would probably occur. It was 
only necessary to calculate the total amount of heat 
which could be generated by the total mass of our solar 
system in falling together to the sun's centre from " in- 
finity " to find the total heat-supply to be drawn upon. 
Assuming, then, that the present observed rate of heat- 
giving has been the average maintained in the past, a 
simple division gives the number of years for which the 
original supply is adequate. The supply will be ex- 
hausted, it will be observed, when the mass comes into 
stable equilibrium as a solid body, no longer subject to 
contraction, about the sun's centre — such a body, in 
short, as our earth is at present. 

This calculation was made by Lord Kelvin, Professor 
Tait, and others, and the result was one of the most truly 
dynamitic surprises of the century. For it transpired 
that, according to mathematics, the entire limit of the 
sun's heat-giving life could not exceed something like 
twenty-five millions of years. The publication of that 
estimate, with the appearance of authority, brought a 
veritable storm about the heads of the physicists. The 
entire geological and biological worlds were up in arms 
in a trice. Two or three generations before, they hurled 
brickbats at any one who even hinted that the solar sys- 
tem might be more than six thousand years old ; now 
they jeered in derision at the attempt to limit the life- 
bearing period of our globe to a paltry fifteen or twenty 

The controversy as to solar time thus raised proved 
one of the most curious and interesting scientific dispu- 
tations of the century. The scene soon shifted from the 
sun to the earth ; for a little reflection made it clear 





the data regarding the sun alone were not suffl- 
ciently detinite* Thus l)i\ CroU contended that if the 
parent bodies of the sun hail chanced to be '^ dying 
stars'' before collision, a vastly greater supply of heat 
would have been engendered than if the matter merely 
fell together* Again^ it cotikl not be n\^erlooked that a 
host of meteors are falling into tlio sun, and that this 
source of energy J though not in itself sufficient to ac- 
count for all the heat in ijuesLit>n, might be sufficient to 
vitiate utterly any exact calculations. Yet again. Pro- 
fessor Lockyer called attention to another source of 
variation, in the fact that the chemical combination of 
elements hitherto existing separately must praduce large 
quantities of heat, it being even suggested that this source 
alone might possibly account for all the present output 
On the whole, then, it became clear that the contraction 
theory of the sun's heat must itself await the demonstni- 
tion of observed shrinkage of the solar disc, as viewed by 
future generations of observers, before taking rank as an 
incontestable theory, imd that computations as to time 
based solely on this hypothesis must in the meantime be 
viewed askance* 

But, tlie time controversy having taken root, neW 
methods were naturally found for testing it The ge- 
ologists sought to estimate the period of time that must 
have been n3quireil for the deposit of the sedimentary 
rocks now obser^etl to make up the outer crust of the 
earth. The amount of sediment carried through the 
mouth of a great river furnishes a clew to the rate of 
denudation of the an3a drained by that riven Thus the 
studies of Messrs. Humphreys and Abbot, made for a 
different purpose, show that the average level of the 

rritory drained by the Mississippi is being reduced by 


about one foot in six thousand years. The sediment is, 
of course, being piled up out in the Gulf at a proportion- 
ate rate. If, then, this be assumed to be an average rate 
of denudation and deposit in the past, and if the total 
thickness of sedimentary deposits of past ages were 
known, a simple calculation would show the age of the 
earth's crust since the first continents were formed. 
But unfortunately these "ifs" stand mountain-high 
here, all the essential factors being indeterminate. 
Nevertheless, the geologists contended that they could 
easily make out a case proving that the constructive 
and destructive work still in evidence, to say nothing 
of anterior revolutions, could not have been accom- 
plished in less than from twent^^-five to fifty millions of 

This computation would have carried little weight 
with the physicists had it not chanced that another com- 
putation of their own was soon made which had even 
more startling results. This computation, made by Lord 
Kelvin, was based on the rate of loss of heat by the 
earth. It thus resembled the previous solar estimate in 
HK^thod. But the result was very different, for the new 
estimate seemed to prove that since the final crust of 
the earth formed a period of from one hundred to two 
hundred millions of years has efapsed. 

With this all controversy ceased, for the most grasp- 
in*^ geolot^ist or biologist would content himself with a 
fraction of that time. AVhat is more to the point, how- 
ever, is the fact, which these varying estimates have 
made pat(Mit, that computations of the age of the earth 
based on any data at hand are little better than rough 
guesses. Long before the definite estimates were under- 
taken, geologists had ])roved that the earth is very, very 





old, ami it ciin hardly be said tbat the attempted com- 
ptitiitions have atldod mucli of detiniteness to tbat propo- 
siiiun* They have, indeed, proved that the jteriod of 
time to be drawn upon is not infinite; but the nebular 
hyjiothesis, to say nothing of oommon-sense, carried us 
as far as tliat long ago. 

If I be uoinputations in question have failed of their 
direct purpose, however* tbey have been by no taeans 
lacking in important collatentl results. To mention but 
one i>f these. Lord Kelvin was lod by this controversy 
orer the eartb^s age to make his famous computation in 
which lie proved that the telluric structure, as a w^bole, 
must have at least the rigidity of steel in order to resist 
the mooTi's tidal pull as it does. Hopkins bad, indeed, 
made a somewhat similar estinutte as early as 1839, 
proving tbat the earth*s crust must be at least eight 
bundretl or a thousand miles in thickness; but geologists 
bad utterly ignored this computation, and the idea of a 
thin crust on a fluid interior had continued to be the 
orthodox geological doctrine. Sinm3 Lord Kelvin's 
estimate was made, bis claim that the final crust of the 
earth could not have formed until the uuiss was solid 
tlmaighoul* or at least until a honeycomb of solid matter 
had been briilgeil up from centre to circumferencej has 
gained pretty general acceptance. It still remains an 
open question, however, as to what proportion the lacunm 
of molten matter bear at the present day to the sotiilitied 
portions, and therefore to what extent the earth wilt he 
subject to further shrinkage and attendant surface 
contortions. That some such lacuna do exist is doman- 
sttrated daily l>y the ptienomena of voleancxjs. So, after 
alh the crust theory has been supplanted by a compro- 
mise theory rather than completely overthrowing and 



our knowledge of the condition of the telluric depths is 
still far from definite. 

If so much uncertainty attends these fundamental 
questions as to the earth's past and present, it is not 
strange that open problems as to her future are still 
more numerous. We have seen how, according to Pro- 
fessor Darwin's computations, the moon threatens to 
come back to earth with destructive force some da\\ 
Yet Professor Darwin himself urges that there are ele- 
ments of fallibility in the data involved that rob the 
computation of all certainty. Much the same thing is 
true of perhaps all the estimates that have been made 
as to the earth's ultimate fate. Thus it has been sug- 
gested that, even should the sun's heat not forsake us, 
our day will become month-long, and then year-long; 
that all the water of the globe must ultimately filter 
into its depths, and all the air fiy off into space, leaving 
our earth as dry and as devoid of atmosphere as the 
moon ; and, finally, that ether-friction, if it exist, or, in 
default of that, meteoric friction, must ultimately bring 
the earth back to the sun. But in all these prognosti- 
cations there are possible compensating factors that 
vitiate the estimates and leave the exact results in 
doubt. The last word of the cosmic science of our 
century is a ])rophecy of evil — if annihilation be an evil. 
But it is left for the science of another generation to 
point out more clearly the exact terms in which the 
prophecy is most likely to be fulfilled. 



In regurd to all these cDsrtiic and tollurio probleins, 

it Will be seeo, there is always the same appeal to one 

central rule of action— the law of gravitation. When 

we turn from uiacrocosra to microcosm it would appear 

as if new forces of interaction were introtluced in the 

powers of cohesion and of chemical action of molecules 

nnd atoms. But rx>rd Kelvin has aigued that it is pos 

Kible to form such a conception of the forms and space 

relations of the liltiiiiate particles of matter that their 

mutual attractions may be explained by invoking that 

flume law of graviUtion which holds the stars and plan* 

ts in their course, What» then, is this all-com passing 

power of gravitation which occupies so central a position 

in the scheme of mechanical things? 

H The simple answer is that no man knows. The wisest 

Iihysicist of lo-dsiy will assure vuu that he knows abso- 

^Jutely nothing of the why of gravitation— that he can 

Htio more explain why a stone tossed into the air falls 

Hback to earth than can the boy who tosses the stone, 

Hijut wliile this statement puts in a nutshell the scientific 

B»tatui£ of explanations of gravitation, yet it is not in 

humao nature that speeulative scientists should refrain 

from the effort to explain it. Such efforts have been 

made; yet, on the whole, they are surjirisingly few in 

umber; indeed^ there are hut two that nrted claim onr 

Ltention here* ami one of these has hanlly more than 

tstorical interest. One of these is the so-called ultra* 

(landane-corpuscle hypothesis of Lo Sjige; the other is 

ed on the vortex theory of mat tor. 

' 443 


The theory of Le Sage assumes that the entire uni- 
verse is filleil with infinitely minute particles flying in 
right lines in every direction with inconceivable rapidity. 
Every mass of tangible matter in the universe is inces- 
santly bombarded by these particles, but any two non- 
contiguous masses (whether separated by an infinitesi- 
mal space or by the limits of the universe) are mutually 
shielded by one another from a certain number of the 
particles, and thus impelled towards one another by the 
excess of bombardment on their opposite sides. What 
applies to two masses applies also, of course, to any 
number of masses — in short, to all the matter in the 
universe. To make the hypothesis workable, so to sav, 
it is necessary to assume that the " ultra-mundane " par- 
ticles are possessed of absolute elasticity, so that they 
rebound from one another on collision without loss of 
spoed. It is also necessary to assume that all tangible 
matter has to an almost unthinkable de^i^ree a sieve-like 
texture, so that the vast i)roportion of the coercive par- 
ticles pass entirely through the body of any mass they 
encounter^ — a star or world, for example — without really 
touch in<^ any ])art of its actual substance. This assumj)- 
tion is necessary because gravitation takes no account 
of mere corporeal bulk, l)ut only of mass or ultimate 
solidarity. Thus a very bulky object may be so loosely 
meshed that it retards relatively few of the corpuscles, 
and hence gravitates with relative feebleness — or, to 
ado])t a more familiar mode of expression, is light in 

This is certainly heaping hypotheses together in a 
reckless way, and it is perhaps not surprising that Le 
Sage's conception did not at first arouse any very great 
amount of interest. It was ])ut forward about a century 



>, but for two or thret* genemtions remained prac- 
tically uruioliced* The pbiloso{)ljerB of the iirst half of 
>ur century suem to have ilespaired of explahiing gravi* 
tution, tlioiigli Faraday Jong ex peri merited in the hope 
of est4iblishi!ig a relation between gravitation and elec- 
tricity or umgnetism. But not long after the middle of 
the century, when u new science of dynamics was claim- 
ing paranitiunt importance, and physicists were striving 
to express alt Uingible phenomena in terms of matter in 
motion^ the theory of Le Sage was revived and given a 
large measure of attention. It bad at least the merit of 

r explaining the facts without conflicting with any known 
ineclmniciil law, which was Tuore than could be said of 
any other guess at the question that had ever been 

More recently, however, another explanation has lieeu 
found which also meets this contlition. It is a concep- 
tion based, like most other physical speculations of the 
last generation, upon the hy|Hjthesis of the vortex atom, 
and was suggested, no doubt, by those speculations which 
Consider electricity and magnetism to be conditions of 
strain or twist in the substance of the universal ether, 
1 In a wonl, it supposes that gnivitation also is a form of 
[Strain in this ether — a strain that may bo lil^ened to a 
tiuction vvluch the vortex atom is supfiosed to exert on 
the ether in which it lies. According to this view, gravi- 
tation is not a push from without, but a |mll from within; 
not duo to exterior influences, but an inherent and iudis- 
solulile pro]>erty of matter itself. The conceptiiju has 
the further merit of correlating gravitation with elec- 
tricity, magnetism, and light, as a condition of that 
strange ethereal ocean of which modern physics takes 
80 much account But here, again, clearly^ we are but 




heaping hypothesis upon hypothesis, as before. Still, a 
hypothesis that violates no known law and has the war- 
rant of philosophical probability is always worthy of a 
hearing. Only we must not forget that it is hypothesis 
only, not conclusive theory. 

The same caution applies, manifestly, to all the other 
speculations which have the vortex atom, so to say, for 
their foundation-stone. Thus Professors Stewart and 
Tait's inferences as to the destructibility of matter, based 
on the supposition that the ether is not quite frictionless, 
Professor Dol bear's suggestions as to the creation of 
matter through the development of new ether ripples, 
and the same thinker's speculatipns as to an upper limit 
of temperature, based on the mechanical conception of 
a limit to the possible vibrations of a vortex ring, not 
to mention other more or less fascinating speculations 
based on the vortex hypothesis, must be regarded, what- 
ever their intrinsic interest, as insecurely grounded, until 
such time as new experimental methods shall give them 
another footing. Lord Kelvin himself holds all such 
speculations utterly in abeyance. '' The vortex theory,-' 
he says, *' is only a dream. Itself un proven, it can prove 
nothing, and any speculations founded upon it are mere 
dreams about a dream." 

That certainly must be considered an unduly modest 
pronouncement regarding the only workable hypothe- 
sis of the constitution of matter that has ever been 
imagined; yet the fact certainly holds that the vortex 
theory, the great contribution of our century towards 
the solution of a world-old problem, has not been car- 
ried beyond tlie stage of hypothesis, and must be passed 
on, with its bunlen of interesting corollaries, to another 
generation for the experimental evidence that will lead 



to its acceptance or its refutation. Our century has 
given experimental proof of the existence of the atorn^ 
but has not been able to fatbom in the same way the 
exact form or nature of this ultimate particle of matter. 
Equally in the dark are we as to the explanation of 
it strange affinity for its neighbors which every atom 
lifests in some degree. If we assume that the power 
b'bieb holds one atom to another is the same which in 
Fcase of larger bodies wo term gravitation, that answer 
irries us but a little way, since, as we have seen, gravi* 
ttUion itself is the greatest of mysteries. But again^ how 
chances it that different atoms attract one another in such 
varying degrees, so that, for example, fluorine unites 
with everything it touclies, argon with nothing? And 
how is it that different kinds of atoms can bold to them- 
selves such varying numbers of fellow-atoms^oxygen 
jne^ hydrogen two, antl so on ! These are questions for 
the future* The wisest chemist does not know why tlie 
simplest cheTUical experiment results as it does* Take, 
for exampks a %vater-like solution of nitrate of silver, 
anil let fall into it a few drops of another water-like solu- 
tion of hydrochloric acid ; a white insoluble precipitate 
of chloVide of silver is formed. Any tyro in chemistry 
^oould have pn?diated the result witli abstjlute certainty* 
^feut the prediction would have been based purely upon 
^Brevious empirical knowledge — solely upon the fact that 
^^he tiling had been done before over and over, always 
with the same result* Why the silver forsook the ni- 
trogen atom, and grappled the atom of oxygen^ no one 
knows. Nor can any one as yet explain just why it is 
I that the new compound is an insoluble, colored, opaque 
^nub^tance^ whereas the antecedent ones were soluble, 
oolorlf^, and transparent. iTore than that, no one can 



explain with certainty just what is meant by the famil- 
iar word soluble itself. That is to say, no one knows 
just what happens when one drops a lump of salt or 
sugar into a bowl of water. We may believe with Pro- 
fessor Ostwald and his followers, that the molecules of 
sugar merely glide everywhere between the molecules of 
water, without chemical action ; or, on the other hand, 
dismissing this mechanical explanation, we may say 
with Mendeleef that the process of solution is the most 
active of chemical phenomena, involving that incessant 
interplay of atoms known as dissociation. But these 
two explanations are mutually exclusive, and no one can 
say positively which one, if either one, is right. Nor is 
either theory at best more than a half-explanation, for 
the why of the strange mechanical or chemical activi- 
ties postulated is quite ignored. How is it, for example, 
that the molecules of water are able to loosen the inter- 
molecular bonds of the sugar particles, enabling them to 
scamper apart ? 

But, for that matter, what is the nature of these in- 
termolecular bonds in any case ? And why, at the same 
temperature, an^ some substances held together with 
such enormous rigidity, others so loosely ? Why does 
not a lump of iron dissolve as readily [is the lump of 
sugar in our bowl of water? Guesses may be made to- 
day at these riddh^s, to be sure, but an^^thing like tena- 
ble solutions will only be possible when we know much 
more than at present of the nature of intermolecular 
forces, and of the mechanism of molecular structures. 
As to this last, studi(»s are under way that are full of 
])roniise. For the past ten or fifteen years Professor 
Van 't Hoof of Amsterdam (now of Berlin), with a com- 
pany of followers, hns made the space relations of atoms 




a spet^ial stutly, with the result that so-called stereo 
cberuistry has atuiiied a firm iKJsition. A triilj amaz- 
ing insight hus> been gained into tlie space relations of 
the moleculeis oX airbon eompountls in particular, and 
other cooi pounds ary under investigation. But these re- 
sults, wonderful though they seem when the intricacy 
of the subject is considered, are, after all, only lenia- 
tive* It is* demonstrated tliat some molecules have their 
atoms arranged in perfectly detinite iind unalterable 
schemes, but just how these systems are to bo meehani- 
cally pictured — wlietber as miniatuw planetary systems 
or what not — t^raains for the investigators of the future 
to determine* 

It appears, then, that whichever way one turns in the 
m of the atom and molecule, ona finds it a land of 
mysteritis* In no field of science have more startling 
discoveries been made in our century rlian here; yet 
nowhere else do there seem to lie wrider realms yet un- 



tin the life history of at least one of the myriad star 
systems there has come a time when, on the surface of 
one of the minor mem hers of the group, atoms of mat- 
tor have been aggregated into such associations as to 
c3onstitute what is called living matter. A question 
that at once suggests itself to any one who conceives 
^ even vaguely the rt^Iative uniformity of conditions in 
^B the ditr<*n*nL j^tar ;^a"oups is ns to whether other worlds 
H llian ourtj have also their complt^ment of living forms, 
" Tho 4piestion has interested speculative science more 

2v 440 


perhaps in our century than ever before, but it can 
hardly be said that much progress has been made tow- 
ards a definite answer. At first blush the demonstration 
that all the worlds known to us are composed of the 
same matter, subject to the same general laws, and 
probably passing through kindred stages of evolution 
and decay, would seem to carry wnth it the reasonable 
presumption that to all primary planets, such as ours, a 
similar life-bearing stage must come. But a moment's 
reflection shows that scientific probabilities do not carry 
one safely so far as this. Living matter, as we know it, 
notwithstanding its capacity for variation, is condi- 
tioned within very narrow limits as to physical sur- 
roundings. Xow it is easily to be conceived that these 
peculiar conditions have never been duplicated on any 
other of all the myriad worlds. If not, then those more 
complex aggregations of atoms which we must suppose 
to have been built up in some degree on all cooling 
globes must be of a character so different ^om what we 
term living matter that we should not recognize them as 
such. Some of them may be infinitely more complex, 
more diversified in their capacities, more widely re- 
sponsive to the influences about them, than any living 
thing on our earth, and yet not respond at all to the 
conditions which we apply as tests of the existence of 

This is but another way of saying that the peculiar 
limitations of specialized aggregations of matter which 
characterize what we term living matter may be mere 
incidental details of the evolution of our particular star 
group, our particular planet even — having some such 
relative magnitude in the cosmic order as, for example, 
the exact detail of outline of some particular leaf of a 




beat's to the entire subject of vegetable life. But^ 
*n the otlier hand, it is also conceivable that the condi- 
tions oil alt phi nets comparable in position to ours, 
though never absolutelj' identical, yet pusa at some stage 
through su iimilar an epoch that on eiich and every one 
of tiiem there is developetl something measurably com- 
parable, in human terms, tu what we here know as liv- 
ing matter; differing widely, perhaps^ from any partic- 
ular form of living being here, yet still conforming 
broadly to a definition ol living tilings. In tliat case 
ttie life-bearing stage of a planet must be considered as 
having far more general significance; perhaps even as 
constituting the time of fruitage of the cosmic organ- 
i!;m, though notldngbut banian egotism gives warrant to 
this particular presumption. 

Between these two opposing views every one is free 
to choose according to his preconceptions, for as yet 
science is unable to give a deciding vote* Equally open 
to disousBion is that other question^ as to whether the 
evolution of universal atoms into a '' viud" association 
occurre<l Init once on our globe, forming the primitive 
mass from wliich all the diversified forms evolved, or 
whether such shifting from the so-called non- vital to the 
vital was many times rei>eated —perhaps still goes on in- 
cessivntiy. It is quite true tliat the testimony of our 
fltury, so far as it goes, is all against the idea of 
spontaneous generation • ■ under existing conditions. It 
hm been clearly enough deinonstrated that the bacteria 
nd other low forms of familiar life whicb formerly were 
supposed to originate ** spontaneously '' had a quite dif* 
ierent origin. But the solution of this special case leaves 
the general problem still far from solved. Who knows 
what are the conditions necessary to the evolution of the 



ever-present atoms into " vital" associations ? Perhaps 
extreme pressure may be one of these conditions ; and, 
for aught any man knows to the contrary, the " spon- 
taneous generation " of living protoplasm may be taking 
place incessantly at the bottom of every ocean of the 

This of course is a mere bald statement of possibilities. 
It may be met by another statement of possibilities, to 
the effect that perhaps the conditions necessary to the 
evolution of living matter here may have been fulfilled 
but once, since which time the entire current of life on 
our globe has been a diversified stream from that one 
source. Observe, please, that this assumption does not 
fall within that category which I mention above as con- 
traband of stnence in speaking of the origin of worlds. 
The existence of life on our globe is only an incident 
limited to a relatively insignificant period of time, and 
wiietiier the exact conditions necessary to its evolution 
pertained but one second or a hundred million years does 
not in the least matter in a philosophical analysis. It is 
merely a question of fact, just as the particular temper- 
ature of the earth's surface at any given epoch is a ques- 
tion of fact, the one condition, like the other, being tem- 
porary and incidental. But, as I have said, the question 
of fact as to the exact time of origin of life on our globe 
is a question science as yet cannot answer. 

But, in any event, what is vastly more important than 
this question as to the duration of time in which living 
matter was evolved is a comprehension of the philosophi- 
cal status of this evolution from the "non-vital" to the 
" vital." If one assumes that this evolution was brought 
about by an interruption of the play of forces hitherto 
working in the universe — that the correlation of forces 



I involved ivas unique^ acting th^ii and then only — by that 

[jissum|!ttQn he removes tlie question of the origin of life 
utterly from tlie domain of science — exactly as the as- 
suniittion of an initial push would remove the question 
of the origin of worlds from the domain of science. But 
the science of to-day most emphatically iiemurs to any 
such asJiumptioiL Every scientist with a wide grasp of 
fae^i, who can think cleiirly nnd without prejudice over 
the field of what is known of fosinic l* volution, must \ye 
driven to helieve that the al letted wide gap between 
vital and non- vital uiatter ts largely a ligjiient of prej- 
udiced himitui understamling. In i\m bitjader view tlier© 
geem no gaps in tlie seliemc of cosmic evohition^no 
break in the aicesaant reciprocity at atomic actions, 

I whether those atotns be floating as a ^'tim mist^^ out in 
one pjirt of space, or aggregated into the brain of a man 
in anotlier part. And it seurns wf^ll vvithni the range of 
scientific ex|iectation that the laboratftry wr)rker of the 
future will learn how so to duplicate telluric conditions 
(hat the play of univei^al forces will build living matter 
out of tln^ inorganic in the laboratory, as they have done, 

[find perhaps still are doings in the terrestrial oceans* 
To the timiil reasoner I hat assumption of possibilities 

[may seem startling, l^ut assuredly it is no mure so than 

[soenied, a eenlury ago, the assumption that man htis 
ovoUed, through the agency of "natural laws" only, 
from the lowest organism. Yet the timidity of that 
elder day has Iwen obliged by the progress of our ceiv 

Itai^ to a<lapt its coticeptions to that assured sequence 
of evenls* An<i sotne day, in all prohahility, the timid- 
ity of to-day will Ihj uhligetl to take that final logical 

l«tep which today '« knowledge foreshadows as a future 

[if not a present necessity* 



Whatever future science may be able to accomplish in 
this direction, however, it must be admitted that present 
science finds its hands quite full, without going farther 
afield than to observe the succession of generations 
among existing forms of life. Since the establishment 
of the doctrine of organic evolution, questions of hered- 
ity, always sufficiently interesting, have been at the very 
focus of attention of the biological world. These ques- 
tions, under modern treatment, have resolved them- 
selves, since the mechanism of such transmission has 
been proximately understood, into problems of cellular 
activity. And much as has been learned about the cell 
of late, that interesting microcosm still offers a multi- 
tude of intricacies for solution. 

Tlius, at the very threshold, some of the most element- 
ary principles of nieclianical construction of the cell are 
still matters of controversy. On the one hand, it is held 
by Professor O. Biitschli and his followers that the sub- 
stance of the typical cell is essentially alveolar, or foam- 
like, comparable to an emulsion, and that the observed 
reticular structure of the cell is due to the intersections 
of the walls of the minute ultimate globules. But an- 
other ecpially authoritative school of workers holds to 
the view, first expressed by Frommann and Arnold, 
that the reticulum is really a system of threads, which 
constitute the most important basis of the cell structure. 
It is even held that these fibres penetrate the cell walls 
and connect adjoinint^ cells, so that the entire body is a 
reticulum. For the moment there is no final decision 
between these oi)posing views. Professor Wilson of 
Columbia has suggested that both may contain a meas- 
ure of the truth. 

Again, it is a question whether the finer granules seen 



withiti the cell are ur are not typical stracfcures, " capa- 
ble of assimilation, grovvLb, and division, and hence to 
lie regardt^d as elt^uieiiUiry units of structure standing 
between tlie ciiU and tlie ultimate nioiecules of living 
matter/^ The more philosophical thinkers, like Spencer, 
Darwin, llaeckelj Michael Foster, August Weismann, 
and many others, believe that such ''intermediate units 
must exisi, whether or not the microscope reveals them 
to view* Weisinann, who has most fully elaborated a 
fpotheticid scheme of tlie relations of the intracellular 
ills, identi litis the larger of these units not with the 
oi^inary granules of the cell, but witfi a remarkable 
structui^ cnih^il chromatin, which becomes aggregated 
vvitbin the cell nucleus at the time of cellular division — 
a structuro which divides into definite parts, and goes 
tb rough some most suggestive manoeuvres in the 
process of cell multiplication. All these are |>uzzling 
structures; and there is another miiutte bmly within 
the cell, called the centroBome, that is quite as much 
so. This structure, discovered by Van Beneden. has 
been regarded as essential to cell division, yet some 
recent botanical studies seem to show that sometimes 
it is altogether wanting in a dividing celL 

Jn a wortl, the architecture of the cell has been shown 
by modern researches to be wonderfully compUcated, but 
the accumulating researches are jnst at a jx^int where 
much is altscure about many of the observeii phenomena. 
The immediate future seems full of promise of advances 
upon present understrindtng of cell processes. But for 
the moment it remains for us, as for preceding genera* 
tions, about the most incompt*ehensible, scientifically 
speaking, of observed phenomena, that a single micro- 
scopic egg cell should contain within its substance all 



the potentialities of a highly differentiated adult being. 
The fact that it does contain such potentialities is the 
most familiar of everyday biological observations, but 
not even a proximal explanation of the fact is as yet 

Turning from the cell as an individual to the mature 
organism which the cell composes when aggregated 
with its fellows, one finds the usual complement of open 
questions, of greater or less significance, focalizing the 
attention of working biologists. Thus the evolutionist, 
secure as is his general position, is yet in doubt when 
it comes to tracing the exact lineage of various forms, 
lie does not know, for example, exactly which order 
of invertebrates contains tlio type from which verte- 
brates sprang, though several iiotly contested opin- 
ions, each exclusive of the rest, are in the field. Again, 
there is like uncertainty and difference of opinion 
as to just which order of lower vertebrates formed 
the direct ancestry of tlie mammals. Among the mam- 
mals themselves tliei-e are several ordei's, such as the 
whales, the elephants, and even man himself, whose ex- 
act lines of inore immediate ancestry are not as fully 
revealed by present paleontology as is to be fully 

All these, however, are details that hardly take rank 
with the general problems that we are noticing. There 
are other questions, however, concerning the history 
and present evolution of man himself, that are of wider 
scope, or at least of seemingly greater importance from 
a human standpoint, which within recent decades have 
come for th(^ first time within the scope of truly induc- 
tive science. These are the problems of anthropology 
— a science of such wide scope, such far-reaching col- 



lateral implications, that as yet its specific field and 
functions are not as clearly defined or as generally rec- 
ognized as they are probably destined to be in the near 
future. The province of this new science is to correlate 
the discoveries of a wide range of collateral sciences — 
paleontology, biology, medicine, and so on — from the 
point of view of human history and human welfare. 
To this end all observable races of men are studied as 
to their pliysical characteristics, their mental and moral 
traits, their mannei^s, customs, languages, and religions. 
A mass of data is already at hand, and in process of 
sorting and correlating. Out of this eflFort will probably 
come all manner of useful generalizations, perhaps in 
time bringing sociology, or the study of human social 
relations, to the rank of a verital)le science. But great 
as is the promise of anthropology, it can hardly be de- 
nied that the broader questions wnth which it has to 
deal — questions of race, of government, of social evolu- 
tion — are still this side tlie fixed i)lane of assured gener- 
alization. No small part of its interest and importance 
depends upon the fact that the great problems that 
engage it are as yet unsolved problems. In a word, 
anthropology is perhaps the most important science in 
the hierarchy to-day exactly because it is an immature 
science. Its position to-day is perhaps not unlike that 
of paleontology at the close of the eighteenth century. 
May its promise find as full fruition! 


Adams, John, his deterniination of 
the exact location of Neptune, 48 ; 
correctB Laplace in reference to the 
moon^s acceleration, 61. 

A«liiiii!*, Professor, his investigation 
of meteor showcrit, 69. currents, their classification 
and the laws governing them, 182- 

Aerolites, study of their origin and 
character, 157-162. 

Agnssiz, Jean Louis Rodolphe, his 
Indief in the special-creation hy- 
pothesis, 106 ; his advocacy and es- 
tablishment of the glacial theory, 
134-136; on the reception of sci- 
entific truth, 163. 

Alil>ert, Jean Louis, makes known 
the cause and cure of the itch, 362. 

Alpha Centauri, its comparative dis- 
tance from tiie earth, 66. 

Amici, Oiovanni Battista, his inven- 
tion of the reflecting microscope, 
827, 828. 

Ampere, Andr6 Marie, establishes the 
connection of magnetism and elec- 
tricity, 207; confirms the atomic 
theory of Avogadro, 268 ; discovers 
the properties of ammonium, 267. 

Ansesthesia, discovery of the method 
of, 866-875. 

Anatomy, eighteenth -century prog- 
ress in the science, 86. ^S^ Anat- 
omy and physiology. 

Anatomy and physiology, their prog- 
ress in the nineteenth century. 
821-863 ; Cuvier's classification of 
the animal kingdom and his 'Maw 
of co-ordination," 821, 322; Bi- 
cbat*8 generalization of the animal 

organs, 822, 828 ; and his division 
of all animftl structures into tis- 
sues, 824 ; improvements in micro- 
scopes and lenses, and the inven- 
tion of the compound microscope, 
324-828 ; rise of histology and its 
triumphs, 328-836; establishment 
and development of the cell theory, 
836-346 ; investigations of the proc- 
esses of digestion and respiration 
and of the functions of the human 
organs, 346-853. 

Anthrax, discoverv of its cause and 
remedy, 380, 381, 387-889. 

Anthropology, its far-reaching pos- 
sibilities and its unsolved prob- 
lems, 456, 467. 

Anti-cyclone, description of, 190. 

Antisc|»8i.<4, the theory and practice 
of, 382-386. 

Antitoxine, its discovery and appli- 
cation, 390-892. 

Anti-trade-winds, their cause and 
effects, 178, 186, 186. 

Arago, Dominique Francois, his pio- 
neer work in celestial photography, 
76 ; champions Fresnel's undulatory 
theory of light and the feu<l which 
his advocacy engendered, 202-204, 
226 ; discovers that magnets may l)e 
produced by electrical induction,208. 

Arcturus, its comparative brightness, 

Asteroids, their discovery and theo- 
ries regarding, 44-48. 

Astronomy, its development during 
the eighteenth century, 5-17; the 
"nebular hypothesis," its amplifi- 
cation and completion, 18-17; prog- 
ress of the science during the 



nineteenth centurr, 44-87; dis- 
covery of Cerea, by Piazzi, 44 ; of 
Palla^ and Vesu, by Olbera, 44, 
47; and of Juno, by Harding, 47; 
Hencke*8 discovery of a fifth as- 
ivnnd h followed by a thorough 
investigation of the asteroidal sys- 
tem, 47 ; l»ow the asteroids are 
accounted for, 47, 48 ; discovery of 
Neptune, predicated by Bessel and 
I^vcrrier, is accomplished by Dr. 
(ialle, 48, 49 ; lA-venier's predica- 
tion of a trans-Neptunian planet, 
49 ; discovery of the moons of 
Mars by Profess<)r Hall, 49 ; dis- 
covery of Saturn's crajn; ring, 49, 
5«»; Saturn's rinjrs discussed and 
their nature determined, 50 ; theo- 
ries ret^anling the acx'cleratiou of 
the moon, and how it is accounted 
for, 50-53 ; speculations reirarding 
comets and th<,» <lisc(»very of their 
nature and constituents, 58-»»<>; the 
stmly of fjouhle stars by Wiiliain 
aini John Herschel an«l otiieis, 
♦)o-r.r> ; star distance <leterrnined, 
<;r>-0*»; and star motion, mass, an<i 

Auenbragger Ton Auenbrog, his in- 
▼ention of the percussion method 
for studying disease, 355. 

Aurora, the, speculations re^rding 
cause of, 162-167. 

Auscultation, its discovery and de- 
relopnient as an aid to diagnosis, 
856, 359. 

Avogadro, Amadeo, his hypothesis as 
to the numbers of ultimate par- 
ticles in volumes of gases, and his 
invention of the term " molecule " 
as the unit of physical structure, 
258, 269. 

Bactkria, investigations relating to, 

Baer, Karl Ernst Ton, his anatomi- 
cal researches, 337. 

Bary, Heinrich Anton de, his dis- 
covery of the identity of the ani- 
mal and vegetable cell, 340. 

Bastian, Henry Charlton, revives 
Pouchet's theory of " s{>ontaneous 
•generation," 320. 

Beatmiont, Klie de, his contention as 
totlieorij'in of mountains, 130, 145. 

hriirhtin'ss reckoned, tiU, 7o ; solar Behriiifr. Dr., his discoveries in serum- 

and sidereal investipitiotjs by '■ therapy, 392. 

means of the spectroscope, 70-7H ; j Fiell, Sir riiarlos, his epochal psy- 

discMvcry of "invisible" or <lark 

stars, 74-7G ; trinmplis of celestial 

pliotn»rraphy, 7»» - S3, 2Sr), 28t> ; 
Lockyer's *' meteoric hypothesis," 
83-80 ; speculations as to the po- 
tentialities of the stellar universe, 
80, 87 ; some unsolved solar and 
telluric problems, 435-112. 

Atomic theory, discovery and devel- 
opment of, 2.')2-202. 

Atom";, Bor^eovicli's speculations re- 
j^ardiii^, 241; their combininfj 
weijrhts deteirniniMl and the fiiethod 
of ('xpressincj them invented, 254, 
255, 25H, 200 ; law of the specific 
heat of, 200-202 ; establishment of 
the law of valency, 209-275 ; their 
character and properties investi- 
pited. 275-278; Prout's theory of 
tlie atomic weights and compound 
nature of the elements, 278-280, 
283-287; some unsolved problems 
regarding, 447-449. 

chological disc(»very, 401, 402. 

Bernard, Claude, his study of the 
pancreas, 347 ; his discovery of the 
glycogenic function of the liver, 
351, 352; his discoveries relating 
to the nervous system, 406, 406. 

Bernoulli, Daniel, originator of the 
kir)etic theory of gases, 242, 243. 

Berthollet, Claude Louis, aids in 
the development of a new chemistry, 
32; his theory of chemical com- 
bination, 255. 

Berzelius, Johan Jacob, confirms 
and advocates Dalton*8 atomic the- 
ory, 256, 259; his extension of the 
binary theory and estiiblishmcnt of 
theoretical chemistrv, 264, 265, 267, 

Bessel, Friedrich Wilhelm, predicts 
the existence of a tran.s-Uranian 
planet, 48; his successful measure- 
ment of the parallax of a star, 66 ; 
his discovery of " invisible'* stars, 74. 



Bichat, Marie Francois Xavier, his 
generalization of the animal orj^ans, 
322, 323; his classification of ail 
animal striietures into tissues, 824. 

Biela, Willielra von, his discovery of 
the comet bearing his name, 58 ; 
and its after career and destruc- 
tion, 68, 59. 

Binary composition of all chemical 
compounds, theory of, 262-265. 

Biology, the great advances in the 
science made possible through 
eighteenth-ceiilury explorations, 36, 
36; its progress during tlie nine- 
teenth century, 288-320; eighteenth- 
century theorie:* of organic evolu- 
tion, 288-2i»3 ; Lanniick's theory 
of the transmutation of species, 
293-297 ; Cuvier's tlieory of special 
creation and tixiiy of species, 297- 
302; Oken's theory of "sponta- 
neous generation " and of evolution 
of species, 298, 320 ; Darwin^s 
theory of Xhe origin of species by 
natural selection, or the " survival 
of the fittest," 302-3U); triumph 
of Darwin's theory and how it was 
effected, 310-317; theories regani- 
ing the "origin of the fittest," 
317-319 ; consideration of the next 
step in organic evolution, 320. 

Biot, Jean Baptistc, his investigation 
of the L'Aigle wrolite, 168 ; op- 
poses the undulatorv theory of light, 
203, 223. 

Black, Joseph, discoverer of latent 
heat, 84, 171. 

Blood, the, discoveries relating to, 
329, 349. 850. 

Boerhaave, Hermann, his theory of 
the respiratory function, 89. 

Boillanl, Dr., his researches in cere- 
bral physiology, 419. 

Bois-Reymond, Emil dn, his psycho- 
physiological researches, 408. 

Bond, William C, his discovery of 
Satum*8 inner ring, 49. 

Boscovich, Ruggiero Giuseppe, bis 
speculation as to the ultimate con- 
stitution of matter, 241. 

Bmid, James, his investigation of 
hypnotism, 416. 

Brain, the. Cabani.s's conception of 

the action and functions of, 414, 
416. iSfe« Psychology. 

Biedichin*s cometary tlieory, 64, 66. 

Hrewster, Sir David, refuses to accept 
the theory of the conservation of 
energy, 218; his suggested im- 
provement of, 325, 326. 

Broca, Paul, his discovery of cerebral 
localization, 419, 422. 

Brodic, Sir Benjamin, his untimely pre- 
diction regarding nneesihetics, 366. 

Brongniart, Alexandre, how he ac- 
counted for the bowlders on the 
Jura, 181 ; his study of strata 
around Paris, 188. 

Brontotheridat^ or IVanotherett^ their 
line of descent, 121. 

Brown, Robert, his discovery of the nu- 
cleu' of the vegetable cell, 380, 381. 

Brown-Scquard, Charles j^douard, his 
investigations of the nervous sys- 
ttni, 406. 

Bruno, Giordano, believed some of 
the planets inhabited, 12; burned 
at the stake for teaching that our 
earth is not the centre of the uni- 
verse, 16. 

Buch, Leopold von, his conception of 
the origin of mountains and of the 
erratic bowlders on the Jura, 180 ; 
dis.sents from the doctrine of special 
creation, 801. 

Buck land, William, his discovery of 
fossil bones at Kirkdale, Yorkshire, 
and his deductions therefrom, 96; 
how he accounted for the bowlders 
on the Jura, 181 ; adopts the glacial 
theory, 186. 

Buffon, Comte de (Georges Louis Le- 
clere), his early advocacy of the 
theory of transmutation of species, 
291, 292, 818. 

Bunsen, Robert Wilhelra, with the 
assistance of Kircbhoff, perfects the 
spectroscope, 70, 288. 

Burnham, S. W., his enthusiastic 
search for double stars, 66. 

BUtschli, Professor, his theory of cell 
formation, 464. 

Cabanis, Pikrrk Jkam Gkoroe, his 
conception of the action and func- 
tions of the brain, 414, 416. 



Carnot, Sadi, discovers that heat and 
mechanical work are mutually con- 
vertible, 213. 

Ciiipeiiter, William Benjamin, his 
I iieory of oceanic circulation, 180; 
his advocacy of Bacr'a anatomical 
theories, 337. 

Catastrophisni. discussions regarding 
the theory of, 97-99, 126, 130. 

Cavendish, Henry, discovers hydrogen 
gas and the composition of water, 
31, 34, 263. 

Cell theory, the, its conception and 
development, 330-346 ; some of its 
unsolved problems, 454-466. 

Chambers, Robert, his anonymous 
argument for ilie theory of trans- 
mutation of S{)ecics, 300, 301. 

Cliarcot, Jean Martin, his revival of 
hypnotism, 416. 

Charpentier, Jean de, first ridicules 
and then becomes an enthusiastic 
advocate of the glacial theorv, 

Chemistry, the contest it gave rise to 
and its advances in the eighteenth 
century, 29-35; the plilogision 
theory, 20-31 ; discovery of hytlro- 
gen <;:is, 31 ; discovery of oxygen, 
which led to the development of the 
"new chemistry," 81-35; solving 
the mysteries of respiration, 39-41 ; 
progress of the seienee durintr the 
nineteenth century, 252-287; dis- 
covery and development of the 
atomic theory, 252-255; discovery of 
the laws of atomic weights, the spe- 
cific heat of Jitoms, and of isomor- 
phism, 255-262; study of the theory 
of the binary composition of chemi- 
cal compounds and the establish- 
ment of theoretical chemistry, 262- 
265 ; discoveries in organic chemis- 
try and the establishnusnt of the law 
of moh'cular structure, 265-269 ; 
discovery of the law of valency, 
and the establishment and develop- 
ment of isomerism, 269-275 ; de- 
termination of the character and 
properties of atoms and molecule?, 
275-278 ; discovery of the law of 
atomic weights unci of the *Maw of 
octaves " lead to an investigation 

of the probable compound nature 
of the elements, 278-287. 

Chladni, Ernst F. F., his theory of 
meteorites, 169, 160, 161, 162. 

Chloroform, discovery of its ansM- 
thetic properties, 874. 

Christol, M., his discovery of human 
fossils in tiie south of France, 111. 

Christy, Henry, his important find in 
the caves of Dordogne, 113. 

Clark, Alvan, Jr., his discovery of a 
**dark star," the companion of 
Sirius, 76. 

Clausius, Rudolph Julius Emanuel, 
aids in establishing the doctrine of 
the conservation of energy, 228- 
226 ; investigates the kinetic theory 
of gases, 242-244; points out the 
way to measure the size of mole- 
cules, 244 ; measures the energy of 
a molecule of gas, 245. 

Climate, and the study of the influ- 
ences which affect it, 172-182; 
how that of northern India is af- 
fected by the monsoons, 191. 

Clouds, classification of, and their 
formation, 169-172. 

Comets, theories regarding, and the 
determination of their character 
and origin, 53-60; photographed, 

C(mservation of energv, discoverv of 
the law of, 209-221.' 

Contagion, its cause discovered, 880- 

Co-ordination, Cuvier^s law of, 822. 

Cope, Edward Drinker, his important 
discoveries in the Rocky Mountain 
region, and the story they tell, 114- 
121 ; advocates Lamarck's theory of 
the origin of favored species, 318, 

Corpuscles, red blood, discovery of, 
349, 350, 

Corvisart, Jean Nicholas de, intro- 
duces the percussion method into 
medical practice, 354-366. 

Couper, A. S., his investigations of 
the affinities of different elements, 

Croll, James, his " pre-nebular the- 
ory," 86 ; contends for many Ice 
ages, 136; his estimate of the 



weight of the ice-sheet over New 
England, 160; his theory of the 
Gulf Stream, 180, 181, 182; his 
theory of solar lieat, 439. 

Crookes, William, his ultra-gaseous 
theory of matter, 247; advocates 
the Proutian theory of the com- 
pound nature of the so-called ele- 
ments, 287. 

Cuvier, Georges, his doctrine of the 
correlation of parts, 36 ; his study 
and investigation of fossil bone.^, 
which lead to the establishment of 
vertebrate paleontology, 91-94, 96 ; 
his belief in catasirophism, 98, 
181 ; his disbelief in the authen- 
ticity of human fossils. 111; his 
investigation of strata near Paris, 
188 ; his theory of special creation 
and fixity of species, 297, 299-302 ; 
his classification of the animal 
kingdom, 321 ; his law of co-ordi- 
nation, 322; opposes GalPs phre- 
nological system, 400. 

CycloDe, description of, 186. 

Daodirre, Louis Jacquks Mande, 
his perfection of photography, 284. 

Dalton, Jolin, his solution of the 
problem of evaporation and pre- 
cipitotion, 168, 169, 171, 172, 262, 
268 ; his explanation of the trade- 
winds, 178, 182; his conception of 
the chemical atom and his atomic 
theory, 263-265, 259, 260, 262. 

Darwin, Charles Roh4Mt, and his 
Oriffin of Specie*, 105-108, 802- 
810; cited by Lyell to prove a 
change of level in continental 
areas, 126; his theory of latent 
heat, 171 ; his construction and 
establishment of the theory of the 
origin of species by natural selec- 
tion, 802-317. 

Darwin, Erasmu.s, how he accounte<l 
for the aurora, 1 63 ; his prophetic 
conception of the transmutation of 
species, 290, 291, 296. 

Darwin, Professor G. H., his determi- 
nations as to the comparative mo- 
tion of the earth and moon, 51, 62. 

Davy, Humphry, his experiments in 
photography, 2; endorses Thomp- 

son's theory of heat, 27; experi- 
ments on respiration, 40 ; his sug- 
gestion to account for the molten 
condition of the earth, 125 ; dis- 
covers that the cause of chemical 
and of electrical attraction arc 
identical, 206; proves the trans- 
formation of labor into heat, 210; 
melts ice by friction, 226 ; his the- 
ory of the properties of particles of 
matter (or atoms), 241, 242; non- 
committal as to Dalton's atomic 
theory, 269 ; his remarkable dis- 
coveries which led to the theory of 
the binary composition of chemical 
compounds, 262-265 ; originates the 
method of medication by inhala- 
tion, 366. 

Dawes, Rev. W. R., his discovery of 
a new ring around Saturn, 49, 60. 

Dawson, Sir William, his study of the 
Laurentian system of Canada, 189. 

Deluc, Guillaume Antoine, his theory 
of evaporation, 168, 170. 

Desmoulins, Louis Antoine, his psy- 
chological researches, 400. 

Devalue, a French physician, discov- 
ers the cause of the in fectious dis- 
ease anthrax, 380, 381. 

Deville, Sainte Claire, his investiga- 
tion of the chemical process known 
as dissociation, 273. 

Dew, the problem of its formation 
solved, 167-172. 

Digestion, investigation of its proc- 
esses, 39, 847-352. 

Diphtheria, the serum treatment for, 
392, 393. 

Dissociation of molecules and atoms, 
investigated by Deville, 273 ; an 
unsolved problem, 447, 448. 

Donati, Giovanni Battista, spectro- 
scopic researches of, 70. 

Donders,Frans Cornells, makes the first 
attempt to time nervous action, 418. 

Dove, Heinrich Wilhelm, his study of 
the winds, 182, 183. 

Draper, Uenry, successfully photo- 
graphs a nebula, 79. 

Draper, John William, his pioneer 
work in celestial photography, 76 ; 
his application of photography to 
spectrum analysis, 285. 



Du1)oi^t, Eugene, his find of the ape- 
man fossil in the island of Java, 

Dujardiii, Felix, his histological re- 
searches, 389. 

Dulong and Petit's discovery of the 
specific heat of atoms, 260* 261. 

Dumas, Jean Baptiste Aiidrd, his 
work in orgjinic chemistry, 266, 
268, 279, 280, 346, 347. 

Dunn, Sorj^cjiiit, liis principal work in 
weatlier obsei v.ition, 190. 

Dutrocljct, Itciio Joachim Henri, his 
study of the processes of digestion, 

Earth, the, Thomson's estimate of its 
longevity, 74, l.'i^; some unsolved 
problems re«;»rihiig, 435-442. 

Ehrenberg, Christian (iottfried, dis- 
putes Mohl's cell theory, 343 ; dis- 
covers tlu* Hl>rilhir character of 
brain tissue?, -125. 

Electricity, conception of, in the 
ci»:litcentli c«'nt>n y, 24 ; how af- 
fccteti by the tjiseovery of Volta, I 
28. 2'.) ; its rehitionsljij) to i^alvan- 
isni (h'nioiist rated, 204, 205 ; the 
cause <»f clieinieal and electrical 
action <ienionstiate«l to l)e identi- 
cal, and the science of niauneto- , 
electricity establisJMMl, 2()0-2n<J ; | 
its liisL use in signalling, 207. i 

Electujcheniisiiy, its accidental dis- 
covery throu^di the ex|)eiiinents of 
Nicholson and Carlyle, 28 ; Davy's 
theory of, 2<K'.. 

EIe«'tr<) - niMu;netisin, Ilelinlioltz an<i j 
Hertz's studv and development of, ' 
227, 228. * I 

Encke, Johann Fran/, determines tlie I 
oibital movement of comets, 57. I 

E-ipy, Janu-s I'./ilard, his theory of | 
wind storms, I '.♦(). . 

Etlier, sui|»hurie, discovery of its \ 
aiuesthetic |>roperiie>, 3(')0-374. ' 

Etih'r, the, and ponderable matter, 
its (lisplaccuieiit of the "imponder- , 
ablcs," 228, •J12'.» ; its liiseovery, and 
speculations as to its constitution , 
and properties, 2:^()-23() ; cxperi- I 
m«Mits of Ileitnholtz and Thomsofi I 
to prove the vortex theory of atoms. 

286-240 ; theories as to the distri- 
bution, mutual relations, properties, 
and dimensions of molecules, 241- 
245 ; also as to their outline, ac- 
tion, temperature, and energ\\ 245- 
261 ; the hypothesis that the vor- 
tex whirl is the essence of matter 
itself, 251. Sfe Chemistry. 

Euler, Leonhard,his extraordinary con- 
elusion as to the midnight temper- 
ature at the equator, 175. 

Evans, John, aids Prestwich in mak- 
ing report on the paleolithic im- 
plements found at Abbeville, 109. 

Evaporation and precipitation, the- 
ories regarding, and the determina- 
tion of their causes, 167-172. 

Evolution, theories of, 288-297, 802- 
810, 817-320 ; some unsolved prob- 
lems regarding, 454-456. 

Falconer, Hugh, verifies the paleo- 
lithic find of Perthes at Abbeville, 

Faraday, Michael, attributes the aurora 
to niajrnetism, 164 ; establishes and 
develops the science of magneto- 
electricity, 208. 209, 226 ; refuses 
to accept the doctrine of the con- 
s»rvation of energy, 218; his con- 
ception of an invisible, all- pervad- 
ing plenum, 234 ; liquefies carbonic- 
acid gas, 249 ; confirms Berzelius's 
theory of biiniry combinations, 265. 

Favus, its cause discovered, 865. 

Fcchncr, Gnstav Theo<ior, his re- 
searches in the new science of 
*'phvsiol«jgical psvchology," 409- 

Fermentjition and putrefaction, inves- 
tigation of the processes of, 875- 

Ferrel, William, his rediscovery of 
the cause of atmospheric circula- 
tion, 183, 184. 

Ferrier, David, his experiments in 
brain localization, 420, 421. 

Fizeau, in|)polyte L., his experiments 
on light. 222; his experiments on 
ether, 234. 

Flouren«i. Marie Jean Pierre, his ex- 
periments in nerve physiologv*, 
417, 418. 



FbrbeSf jftmes Davy* ])m?e« ibut 
mdimit liitat A.nd Itgitt cojtfurnj to 
Hie mnm hwi^, %2\ 225, 

ForaUT, Ik'Oi-ge, lib rptimrkiibltt cli- 
mitti! ub^rVAtlotiitf 1 71^, 

For«tef, Thitm**! hl» tlieor? of mem* 

Kut»oi« It, Llotu Ilia vx|ieriit»i'titB to 
prove tlio ijridulutoiv ri«turt' of 

light, tn. 

Fouit^my^ Afil«iij*e Fi 11119^8 , aula La- 
vui^let in Ur' ik'velujirneut of ii 
ii(?w ehii'imEiiri IT, ^2, 

Fninkliititip EiJn>in|, ili^uovet^ Ihe 
difference iii c'urni'iitiiiiiij: twjwer of 
dilTereiit atoii)^^ whiLh lei^ib to tbo 

Fimtikltii, Rt^ijjitiiihu trte^ lu uci^aunt 
for t'VJi|Hjmi,iiJH, IttS 

Fmtmhoror, Jtmoivh, perfet^ts tlia te- 
ifViHmg lele^copc mid laveiita tbe 
iielioitujler^ ©5 ; flUgg^rAt^ the im- 
proven 11^11 1 tif ihe t^pt!i;tn}5u0|ie, 70. 

Freanel^ AogU!*tki Jeiiii, htis hivonii- 
((iillcjiis of ihe pht^nomei^ii of liybt, 

FHtucVi, (iiisUiv, Lb neRijirdieA relal^ 
m^ t«» hniiti lwrtU7,!aUjnj iW. 

Frajnmniin^ Professor, hi ft theory of 
eelJ foniiHtJoo, 45i. 

Fiihhtjtl, Dr., Im di?HH>very of ihe 

NfJiiidtMttiiii EjkiiUi no. 

gy4tcm of fdiieiiulot^^F^ 'Mli, 100, 42!f. 
Onlle, Joliiiiiii (ii* diii'irU'd by 
liCfverrier, diaeoverw Keprttist?^ 4ll. 

ilvmii, hnl^i, ftriii thi* hivwucm mid 
IfflipUeiiiioii of the gnUntiic biittury^ 

57* 28- 
fiaKmiie bnttery, tlic fjir- reaching 

«ITeeua i>f itn hivuiilioit, 27-2i>, 
G«iIr»iiism,ir>vdi;*o<»vc*iy utiii fRr-reiu'li- 

tng effect?*, 27-'iy; *t^ kiiiMhip to 

cl^ctjridty di'm*iii!.tmtca, 201-iOfl. 
OftilSA, Rarl Frit* ■ In irk, hl^ flr^L le^t 

<if tll«! ft]*'elriti t**k*crJiTd*, 20?, 
GiiyJjiif9<ac, Jo&e|ili Linii*. )m uxperi- 

titcnt^ MTPtli trnri*J. Avlii. I( Tpid to thv 

diteoTf^rv of tlio Iitij)i% tifiO— 

21V 8 ; bit3 di!*iOV(H\ td I'vuuoyeru 

2rtrt, S^"*?, 
fiiHikiJi^v^ Its ghostly obumcter in ih'.* 

j eighteenth eeirtnry^ 17-1 9 j H niton 
leiLmi'a to ityMteiiiiiti/jL* thfj science, 
hut hiB Tfitfjty f^f tkr Ettrfh is |iihi. 
iionnced hereiitnl, 19-23 ; VViUiatn 
8mitir^ fli'i^t ^LTotogieul map of 
Engliind, IH); prii^re^s of tlio fcr* 
etiee diiKn^ tlic nitietceiilhceiKitry, 
lt!^^lA(l; eonirtjversy between lIiq 
Ni'littiraist?; lir^d ihi* Phi ton bt* ix*- 
gurdiiig ieriv;4iriid piLetiomeniif ntid 
the eatrtblL'ihini'lit of tlie tltoory of 
thcldCtei^ ]2;{-12S; UycuAsmii re- 
KArdiug ihi; ehuiigeii in luiid hiu. 
ftitws, wfjether t'iitiielyst«ie ur 
griidiinl, 125-I:j0; eatublitjhment 
of tl le glii ei* I theory, I SO- \m \ 
Htudy of thi* eArtir^ str»ta, »iid 
theif i'ljiss<it]oUhin, 1^16*14^; enn- 
aiderjuion iif ihe ovirienoe wliich 
shows tlie NgeAiid growth of inuun- 
tftiitjs and eoiitmeiiti*, 145-160 :evi- 
deiiecsi of thtf ^Udiii epoclt, IftO, 
IAS; reii<^on8 for helievittg in the 
l^nidiml dimltHitioii of ehnngea \x\ 
the Anrfjtee of the ejiith owhig 10 
\X& ti^in^m-^lxim, 1^^-156, 

flitrhnnlt^ Clnirteft Ki^dfii le, workinc hi 
the field of or^jiiiie elieinbiry, 2fi6- 
%^%\ revives Avog:*dio*» hiw, 260. 

G«rkch'» hist4ih»gicjif sehemi* of the 
bmiii, 428, 

Germ theory, F«?!tenr**i mid TyntUll'* 
iiflvrx*4U7 of, 320, ase, 

Gill, Duvid, piiotograph* 4 cornet, l^^. 

(t I field tiieoiy, the e^lnblighment of^ 
|^0--]Sfl ; the work of tbt^ icie'Bh««t 
tn Jfew Knglund, 1 60. 

(joctlie, Johunti Wulfgnng t^nn, lilft 
doetrino of the imet]ininr|diii;!^efl of 

PR^t^a6, \m, 2B&-'*yi. 

Ool^l, Ciitnitte, hiHi method of ^%Hm- 

hi|; nerve celta ^nd their prooe«sc«, 

429, 4:iO. 
Griivitvition, its eiinse an ani^otved 

prubh-ni, 44H-446. 
Gmy, At!(]i^iin mdeut |^r(^»|i]tgandlftt of 

thi* Dtirwinmn th<?ory. afs, 
Qiilf St re run, the, f>pei?Tilatbnft »fl to 

its effeei on dlmate, l78.-18i, 182. 

HAni^Kv, JoflM. hi^ expktmtldTi of the 

tnftdf-wii*d«» Hft, 
fiueckel, Krn^t lleinrioh, ftxi enthiiai^ 




utic advocate of the Darwinian 
the^iry, ZVi, 414; favoni the La- 
luaickian dit-on of the origin of 
f.ivore<i sii»^-i«'*. 318. 

Iliihneiiiunii, Christian Samuel Fried- 
lii'h. his 1>*-Iu.*f in the prevalence 
of the itch, 361. 

Ilall, A<»ph, iiid •liM.'Overy of the 
iii'KMi.s of M:tr-«. 49. 

11a) i, Mar!*hull, hi» services in the 
pnclice <»f iiic«iicinc, 359, 360 ; his 
iiiifM>rlaut p-^xchologicil di:»coverv, 
403, 404. 

Haiier, Aihrec-lit von, hi^ idea of the 
fuiu-ti«>n of r<*>pinition, 39. 

llardiiif;, of liilienthal, hi.s discovery 
<»f Juno, 47. 

Uarllry, David, his as.<^>ciaiiona1 the- 
ory of psycliolo«:y, 414. 

lloat, how ri'irardtMl in iln' oijjhtecnth 
ccnmiy, 21; Tlioiu|)son\«4 vibratory 
theory of, 2»>, 27 *, tlic inv«'Sti;ration 
of, lu'lps to Sijlvc the prohl* in of 
cvMpination and |>i('cipit.ition, 171 ; 
Hiiiiihoidl's >tndy of its distrihu- 
tion on tip- snrfact' of the «rlobo, 
17') -177; di>«cov»My of its natuir 
ami properti.-s. 222-221 ; the sourctr 
ol aiiiiiial h'Mt discov<Mv<l, 34<.». 

Ileid.'tiii.iin, K'i<ioIf, hi< rxperi- 
nuMits in h^[»notisIn, 415, 410. 

llrhiiholt/., Ilrnnann Lndwig Kerdi- 
nan<l v(»n, iiis thtrory as to the dis- 
iMopancy Ix'twrcn tlie motion of 
the «"ailh and the Mioon, SI ; his 
theory of M)hir ener«:v. 71. 4'>7; 
his share in the diseov«Ty of th<« 
doctrine of tiie coiis'-rvation of 
•'niM<?y. 211, 217, 221. 225, 4:i7; 
hi-iehM'tro-niaixnetie iIummv of li«j:ht. 
227. 228; his c il(Milations to prove 
th(? vortex theorv of atoms, 2.'{8; 
oppo«;e«* the vitalistie ooneeplion of 
ferm«'!»t:ition. 370; his researeh<;s 
and diseov<'ries in psvcho-iihvsics, 

lleiiekf, an amiteur astronomer, dis- 
r jvt-rs a fifih aslt-roi'l, 47. 

Henderson, Thomas, Astronomer Roy- 
al of Seotlaml. tl)e first to siieeess- 
fnllv iiHTisiire a star's p.-irallax, fiO 

Ilenle, Friedrieh (insfav Jakob, his 
auatoiuical researches, 332 330, 

' 352 ; his stmly of the neiroos sjb- 
i teiu, 404. 

Herbart, Johann Fried rich, founder 
I of rnathematicai psychology, 4«»7. 
j Herschel, Caroline, aidin<; William in 
' his investigations, 6, 7. 
I Uerschel, Sir John, his study of 
double stars, 63, 64, 66 ; refuses to 
accept the doctrine of the conserva- 
tion of energy, 218; his improve^ 
nient of the microscope, 326, 327. 

Herschel, Sir William, his improve- 
ment of the telescope and his 
astronomical discoveries, 5-12, 
226; his nebular hypothesis, 13- 
16 ; his theory of the asteroids, 47 ; 
his stuily of double stars and dis- 
covery of their relative change of 
{H)sition.s, 63, 65 ; his unsuccessful 
efforts to solve the problem of suir 
di.-iance. 65 ; his study of sun- 
spots, 166. 

Hertz, Huiurich, confirms Helmholtz's 
electro- magnetic theory of liglit, 
227, 228. 

Hinrichs, Gustav, his investigations 
confirm the *' law of ocuives," 2S0. 

Histolo^ry. See Anatomy and Physi- 
oloijy ; Psyehology. 

Flooke, Robert, his happv guess as to 
the nature of light-, 198. 

H<M»ker, Sir Jjj.sfph Dalton, his aid 
sou<rlit by Darwin in the publi- 
cation of liis (hiqin of tSpecifn, 
307. 309, 310; becomes his con- 
vert, and <lisel[)le, 313. 

Howard, Eclwanl, his conclusion as to 
aerolites. 158. 

Howaid, liuke, his clas.sification of 
clouds and his tluH)ry of their for- 
mation, 169. 170; his theory of d<'w 
formaliorj, 170. 

HuiT'^ins, William, his spectroscopic 
researches, 70, 80. 

Hund)oIdt, Alexander von, his discov- 
eries in terrestrial magnetism, 167; 
his studv of heat distribution and 
its climatic effects, 175-177. 

Hunter, John, discovers the processes 
! of digestion, 39, 347. 

Hntti.n, James, his geological inves- 
i t'naiions and his TTuory of the 
. Karfh, 19-23, 123, 129, 158; gen- 



trn,] nt^cvpHnHfe of liis |imfif)sJUfm 
tbiU **tiim' iri iuiig/* y7, lU:i; hi.* 
ftilkiwrn? kiiuwii us rkiUntUl^, \'i'd\ 
jiTnl ibeir II E^ 111 iiiJccti'i^ii m [iruvmi*; 
lb*? igMLHJtijj (irigfii uf rtu'ka, 126 j 
Ilk iliiM*ry uf nihi, lijft, 17*2, 

||u](Ufji', TliomiLfli Hinifv^ihi? k'si^oii he 
ihiiWB f itiiii iluT «?vide{ii.f of pnWHJii 
toliigv, 117, 11^; ti'L» e^Uttmlu ul 
Dunriti, ill 7. 

Huyi^ei'.^, ClirUtmii, urigiiMUor of llie 
umluliiturv ibeory of light, 1V»8; 

Hviitt, A.f nilviiCMk'a lh0 thLKirj iif 

i.fiMiiirL-k 1^ Ui ihii ot'lgiii uf fiivurctj 

epecii^B, 3 IB. 

Hydfogfu gjJi!*, discovery of, 3L 

Hydfupholik, Mii^eoVL'ry uf Us cnm* 

hy iirulcclivi!' vjtcciimUuli, '^H\\ ^iWil. 

UomeUiL^ 41&-417. 

ICEBKHG TlfKOUT, the, ill*CII(*wifHl fC- 

gnrding, iaO-136; ihe eltot^ta of 
lilt* ico-aheet in New Eugliind, IftfL 

♦* ImfHtMilf rubles/' ttic^ eijuthUwdlli- | 
Cvtilury i'fiiHifJversj rvgnni'm^ the 
liilur*? itf, 24-27 ; the iilndy tif, hi 
the nitielt^fiit-li t*iiimy* 102-228 ^ 
lbr<ir eilKiH^hmetii, 224, 220. 

lobnlntiiiri ftHghiiiUnl by Havy aa s 
iii«?th(nl of tiH'^JkntJoti, Hrtiiv 

1ni^jtiii\ thu, reform in trejihnent of, 

liuirrK'riNriji^ iliPOO^epy of^ 274. 
IsoTiniriihiHiTi, iliBCTjn'ry of, 2(11. 
Ituh (;*gTtk* riy^MTC'iiti*!' *'), it!* cunse 
And cnrc Uifi^t^uvrrud, 3<jt>-H$S{^ 

JiCK^oN, TMAHtiui T., Ills claims to 
thu di«o«>v«»ry of ibc rtniiwllioili: 
prcjpt'iti* s of fltht»f, 373. 

Jennc'i, Kdwtird, rind his discovery of 
v*m 11(11 ion, 42, i'i. 

Jirtile, JftfiiL*:^ Pfi^SL'oit, ills^eovera the 
Uw of the 11101^' I till iiiiiMil e«i«iiTaIenit 
of iieiit, the ctirnrr-Btntie of Uie Itn* 
of the coneierirfition of eiierj^^v, 218, 
2U»an, 218, 221, 22a, 22&/ 

K.A)tT, Ihu iiNt/iii., nim'i^tveM the idem of 
the irtiottmutiition of sjivdes, 21^1, 


lvL*i^1or^ Prufe!ii^i>r« hii^ i.*Miit'ltii<iujnB! us 

lo tU^ chifcritcUT of nehiik^, K3. 
Kekult% A., hifl invt'StigAtioiji* (eftd Ut 

tbe t'^jUblihhmeut of ilie htw of 

Tuleiii-y, 271. 
Ki'U in^ Lord. ^^ Thorojion, W Mlinhi. 
Kiiieliu itieiH-y of fiaM'& iTifei^tigatf-d 

by CliiUfjiti.'^ uiid Mux well, 24 2-24 fi. 
Kiivliliutf, iiu^Uv Uohut'L, hkh Itiin. 

Htfii^ {lerfectd the ^peeLroiiif'opi^ <tnd 

hi veil M the tm'thod of spiH^titiiii 

unnlvHi-^, 7t-», 2*iLi, 
Kirkdale, Yoiksbire, Eit|^l(tnd, dis- 

euvcrv of tu^&i\ bones In cnw nt, 


Kb'wnn, Hiehnrd, calcti lutes emfiiri* 

ecitly the tcfUiiM^^tUf e* of »U lutl* 

tudes, I7&. 
KiUi^Htu, Dr., II li-adei" m ibe dt^velop* 

iiiriii of at^ruui l.her;i|jy« *i92. 
Koqh, Hubt^rt, his Ijucieriiil iuve^tl* 

gMtions, H^l. 
Kulilker, Hu did f Albert, confirms tbe 

thLWV of isolated nerve cdls, 4SL 

LAK?<!*jtc, RicwiTBisociULi HTAcmnii, 
di recover* aod [JiactiiK's tbi> nof^rn^ 
tAtioii tOi'Hioil hi dia^notthig dU- 
riiae« of the Jnf*rt uud loiip, S5K, 

I^agmnge, Joseph Loy i*, »y»tein(ittKef 
Kewtoii'f* hypfJtht^ais of uiiivtih&ai 
gniviLiition, 15; nceontitif for the 
iict'idiirak'd mi>tion of rhc motm, 6fX 

LnitiJiruk, Jeun Bnpti^^te, oppose* the 
llKHjry of ^pffciiil eroalioo, lo5t', hi? 
theory 4)f the tmii^mntalliHi of 
jspe<?ies, 29(J-2H7 ; liis nek't'Lioi^ i*f 
tbo word '* biology " ro eit press tlie 
jjeieoee of livMTg tbin^'*, 2M8. 

binffley, Hiimuel Her(>oijt, 9pectrCK 
seopic researche* of, 70. 

l^plnet!, Pierre Biinon de, aoif^t5li ibe 
probh'r»i» of uniTcraal trravltAtiOTt, 
15; fompletcti Hefseberw ijebnhir 
hypothosifl^ 1ft, 1ft J his tbc^jry of 
Sflturn*a Hug}*, 5f» ; how he *c- 
«*oniiled for the Tiimin^t acculeralioii, 
60 i how hf* nct'oiiuteil for neridiles, 
158 i opposes F refiners und^ilatot'y 
theory uf lipht, Wli. 

Lurtet, ifeduinird, bis hnportunl fliid in 
tlie eavtrsi of Dordogn^ji, 1 1 3, 


Latourf Cag^iard, discoverer of pep- i 
Bin, 347 ; his microscopical re- 1 
searches, 376. | 

Laurent, Augustus, his work in or- I 
gallic cheniistry, 266, 268. | 

Lavoisier, Antoine Laurent, his chem- 
ical experiments and discoveries, 
26, 31-33; his tragic fate and the 
triumph of his doctrines, 33-35 ; 
his experiments on respiration, 40. 

** Law of octaves,'* the, its discovery 
and development, 280, 283. I 

Leeuwenhoek, Antonius von, liis mi- 
croscopical researches, 329, 876. 

Leidy, Joseph, his discoveries of the I 
Tertiary jHjriod in the Rocky Moun- 
tain rej^ion and the truth they teach, 
114-121; his investigation of the 
Trichitui xpiralM, 363. 

Lenz, Professor, first proposer of 

of the compound microscope, 327, 
328 ; his discovery of the true form 
of red blood corpuscles, 829 ; Win 
discovery and development of anti- 
sepsis in surgery, 382-386. 

Lockyer, J. Norman, his "meteoric 
hypothesis," 83-86; his endorse- 
ment of the theory that our sck 
called elements have a compound 
nature, 286, 287; his theory of 
solar heat, 439. 

Lod;;e, J. Oliver, his theory of two 
etliers, 235. 

Logiin, William L, his geological in- 
vestigations in Canada, 139. 

Long, Crawford W., his investiga- 
tions of the anaesthetic properties of 
ether, 373. 374. 

Lotze, Rudolf Hermann, his advocacy 
of psyclio-physiolog}', 409. 

gravitation as the cause of oceanic Louis, Pierre Ciiories Alexandre, his 

circulation, 180. 

Le Sage's hypotliesis of the cause of , 
graviiution, 448-445. I 

Leiickart, Karl Georg Friedrich Ru- 
dolf, Ills investigations of the 
Trkhlua spiralis, 363, 864. 

Lt'vrrrit'r, TrWain Jean Joseph, his . 
calrulatioiis h'ad to the discovery | 
of Xcptiine, 48,40; his further cal- I 
culations as to tlie location of a I 
liy|)oLlietical planet known as Vul- 
can, 4U. 

Liebi;^, Justus vo!j, foremost among 
tlie workers in organic chemistry, 
2«)t), 2»J8, 274 ; his important clu'in- 
ieal rerearelies, 846, 847 ; (ii^e<)vers 
the source of animal heal, 849 ; 
opposes Pasteur's doctrine of for- 
iiMMitation, 87t), 87lK 

Lif«'. some unsolved prolilems of cos- 
mic and telluric, 449-4 r»8. 

Lij^ht, how regardetl in the eighteenth 
century, 24 ; establishment of the 
uiididat«)ry theory of, 192-204, 228; 
Ilelmholtz's elt'ctro-ma^netic the- 
oiy (.f, 227, 22S. 

Licpiefaction of air, of carhonic-acid 
^as, hydrojijen, and of other perma- 
lUMit ^ases, 249 ; tlie rpiesiion as to 
the li(piefacti«)n of air in our outer 
atmosphere, 250. 

Lister, Sir Joseph, his im[U'ovement 


introduction of the ** statistical 
method " into the practice of med- 
icine, 8r)0. 

Lubbock, Sir John William, advocates 
the Darwinian theory of natural 
selection, 313. 

Lyell, Charles, the apostle of uniform- 
itarianism, 99-102. 125, 126. 1.80; 
convinced by Darwin, endorses the 
transmutation theory, 1<>7, 108, 
813; his advocacy of the glacial 
theory, 181, 132; his citation of a 
fact from Playfair which is undis- 
puted, 158; his aid sought by 
Darwin in the publication of his 
Ori(/in of S}xrieH^ 807, 809. 

Magkndik, Francois, his services in 
the ralior>al practice of medicine, 
859, 8r)0 ; his studies of the ner- 
vous system, 400, 402. 

Magnetism, its relations to electricity 
(iiscovered, and the science of mag- 
neto-electricity founded, 207-209.' 

Mai^iK.'to-eleetricity, Faraday estab- 
lishes and develops the science of, 
20S, 209. 

.Malrhus, Thomas Robert, how his 
f^ssaii on Population aided Darwin 
in formulating liis theory of the 
origin of species by natural selec- 
tion, 805, 306. 


0, M., bit deflGriptlon of « qid^ 
te^tiih-ceuturj mime I e^ 157» 
Uikrn^ ilUugvery of its dbvtiu moona, 

Miii^k, OLlitilel Chftrlea^ his diacoyerj 
)>r new Ti^rtiarj epeciea in the 
Aocky MomjUiia region, and what 
I he J signify , H 4- 1 *2 i . 

MiUiMMJun, the Wurren^ description of, 

Mttupy, Matihew Fonuine, bis Ihe- 
oi y of tiie Gulf St pen m, 178-160, 

MuKwf]]!^ Ja[ti4e^ Oiei'k^ determined the 
diai'iicitif of ^tunr^ Hiigii^, 50; hia 
thtH}ri<!d ill r*jferoiic<* to eleiari^itjf 
uttil wagiJL>tl«rQ, 4tid to U|;l(t Jind 
diH^irtf-JuiignenHttif 2'i7; lib (jestt- 
mony ttB to tlie GStistenLe of mi nil- 
pervudiug pletmm, "ItOi, tM ; his 
invesiigiiiuin of the ktiiifik theory 
tif giiit*M, 2 12-214. 

MuyLTf JuHues llobcrt vuri^ hk ^Imr^ 
ifi e3tJ4bli:*bing tiie (Wtrine of the 
con^«5rv&tion of euergv* 3£li* 215- 
217, 221, 23ft, iM, uh. 

Medicnt Acieui:!: : Jci nadir's L^ghte^nth* 
tjeiiturjr discovery of tht; metiiod of 
pfevcntin;^ a mall-pox, 42, 43 ; prog- 
r^tua of ihu aci^nctf duHng tht* tiiiie- 
ic^^rith cuntiiry, SS^^HWi: disiiov- 
cry and devulopine^ni of ppreussfon 
And Ansciiltation irj the ibiigTioamg 
or«lkeii)ie, 3B4-S69 ; iMiroiluctton of 
lh« " sliiti^tienl tiiL^thoii.'* SSO; 
oiittiei of *' gala f^peieutuc ** (iteh), 
of trichino^jjj, Aiiil of fsfcvui dia- 
e^yewid, 3fl0^fiti5; illariivfipy of 
ftnHifitljestn, atii^^JITfi ; proci^ssW of 
formentiilitiii iiiirf pu ire faction hu 
^mii^AlCsd^ ti*i& ^ UBO ; entjsfi ol 
contagion dkctiveietl, 380-382 ; 
difl4H>very and eHULbUalniiLtiti of 
mnli^up^b in iurgery, K82-SSrt; 
dittcovery and dpvplopftipnt of pra^ 
laollvu Taeci nation by Tiro^ \ifv- 

\mKd in the Jfiboratory aM-.lWt» ; 

► diflCOTfiry and devcslopment vt the 
I ^therapy method of curing 
dlBUJIAe, S»f»-^94, 

M.irl^um, Mr, on the effeeta of aun^ 

Meniluicfif, Dmitri, confirmd the ** law 
of octaves'' niiUer the tttio of 

'' periodic kw,' ' 280, 283 ; faia dl#* 
SiM^iatiou iheof J of atoms, 44& 

^^ Meteoric hypothesis,^* the, of J* 
Kortnati Lockyer, fiS^fi, 

Meteorites. See Aerohte^ 

Mt:teorology, ltd etghtetiUth - century 
atudeata* viewa of the inipouder* 
ablija, 25, 26 ; Itts triumphs and 
failures in tht? iiinete<?nth century, 
IfiV-ldl ; study and determlujitinn 
of th0 origin and nature of aeiti- 
Uteti, 157-102; speenlationB regard- 
tug the aurora 162-167; probk^in 
of dew formation ^olvi^d^ and of 
eJijqd^, nun, «now, and hoaivfrosit, 
367-172; iludy of eliiuatiu con- 
ditions, and speculatioua as to the 
Liiduenee:) wbiuh affect thtfm« 172- 
I52f IBl ; iierial eurronts iuvesti* 
l^itt«Hl, Htjd iheir tawa deti^rnnued, 
182-191; tbe greatts^t ti-itimpii of 
pnieiicftl meteorology^ UH, 

Meteoriip deiefminatiou of ihelr origin 
and ch&raotert 59, 60. 

Merer, Lotbar, bia tontrination of 
the '" biw of octave*!,*' 280, 

Micro4icop«, ninctetiuib - eentury im- 
provcmenta in, 324-328 ; the inven- 
tion of tbo cotu pound microBcopet 
327, 328. 

Mijier, William Allen, hifl spcctro* 
Bcopie investigation a, 711 

Mitjicberliuh, Eilhiii-^, bia discovoij of 
laomorphism, 26 L 

Mold, Hfigo von, hl» diftcovery of 
protopUi^ni, aaa, !139; liiA iheorf 
of cell formation, S43, 344. 

Mobr, Karl Friodrich, hia ahure in the 
tijJ9eovt*ry of the doctrine of tho 
conservation of <L*nergy« 314, 21&, 
221, 22&. 

Mol*t^ul(?», tlieonea 110 to their dla- 
trihution, properties, dknenaioni, 
etc., 242-351, 276-278 ; their iao. 
wiorphoiib pmpwrty, 261 ; e«LabUiftb- 
meiit of the Isiw of niolecubr atruct- 
IIP**, 2rtft-26fl, 272-27ft ; some un- 
solved problems regarding, 148.449. 

Moon, the, how ita acoeleratlon ia ac- 
counted ftif, 50-63. 

Motion, WiDiani, T. O., demonatmle* 
the practi^tthiUty antl l>eiiefit of 
anifdtbefia, lt09, 310, 37a. 



Morveau, Guyton de, and the new 
chemistry, 32. 

Miiller, Johannes, his discovery of 
the resemblance between animal 
and vegetable cells, 381, 832, 887; 
his study of the nervous system, 
404 ; his discovery of the means of 
hardeuiug and preserving brain 
tissues, 424. 

Murchison, Roderick Impey, combats 
the uniformitarianisni of Lyell, 130; 
his classidcatioii of transition rocks 
into chronological groups, 138. 

Xapoleon Bonaparte, how his choice 
of a physician inliuenced the prog- 
ress of medical science, 864, 356, 

Neanderthal skull, its discovery and 
description, 110. 

Nebuhe, investigation of, and the<jries 
concerning, i;i-17, 7^-87. 

" Nebular hypothosis," the, its con- 
ception and coinplt'tion, i;^-17, 84. 

Neptune, how it was discoveied, 48, 


Neptuiiists, theory of the, 123-125. 

Nervous sy.slem, the, discoveries re- 
lating to", 401-407. 

Neurons, the theorv of, 48n, 4.^1. 

New plioto-rrupliy, die, 2, 5, 284-2§r>. 

Newburg, New York, ileseriptiou of 
the mastodon found there, 119. 

Xewliinds, .lolin A. R., di>eovers the 
*' law of octaves," 280. 

Newton, Professor, determines the 
true eliaraeter of meteor showers, 

Newton, Sir Isaac, his hypotliesis of 
universal gravitation, systematized 
by La|)laee and liajT^range, 15 ; pro- 
nouneed impious and heretical in 
1700, U» ; his blow at the super- 
natural character of comets, 51. 

OcKAN cruRKNTS, sj)eeulations as to 
tlieir efftH'ts on climate, 178-182. 

Oersted, Hans Christian, liis discovery 
of tlie (icth'ction of the mairnetie 
needle by electric currents, 207. 

Oken, Lorenz, his extension of the 
theory of metamorphoses of parts 
to the animal kingdom, 289 ; his 

theory of spontaneoni generation 
and of the evolution of species, 296. 

Olbers, Heinrich Wilhelm Matthias, 
bis discovery of Pallas, 44, 47 ; his 
explosion theory of the asteroids, 
and the objections to it, 47; his 
discovery of Vesu, 47 ; teaches the 
true chai-acter of the comet's tail, 
64 ; his theory of aerolites', 168. 

Olmsted, Denison, determines the cos- 
mical origin of shooting-stars, 161. 

Origin of species by natural selection, 
theory of, 302-810. 

" Origin of the fittest," speculations 
regarding, 317-319. 

Owen, Sir Richard, sustains Lyell's 
hypothesis of special creation, 106; 
his discovery of the Tri^hitui spi- 
ralis, 863. 

Paleontology, the work of its eigh- 
teenth-century devotees, 28 ; the 
story of its progress during the 
nineteenth century, 88-122; the 
true character of fossils first recog- 
nized by Da Vinci, 88; William 
Smith's early paleontological discov- 
eries aiui his deductions therefrom, 
89-91 ; Cuvier's studies and inves- 
tigations, which result in the estab- 
lishment of vertebrate paleontology, 
91-94, 96; Buekland's Kirkda'le 
discovery and the contention re- 
garding it, 95 ; other fossil discover- 
ies, and the general acceptance of 
Ilutton's pmposition that " time is 
long," 95-97 ; the theory of catas- 
trophism overthrown and the doc- 
trine of uniformitarianism es- 
tablished, 97-102 ; controversy 
regarding the theory of special 
creation, 102-106 ; Darwin's Origin 
of S/)fcitn^ and the general accept- 
ance of his transmutation theory, 
105-109 ; fossil discoveries of Fal- 
coner, Fuhlrott, Schmerling, and 
others, which demcmstrate the ex- 
istence of paleolithic man, 109- 
114; discovery of new Tertiary 
species in the Rocky Mountain 
region, and of vertebrate fossils 
elsewhere, which prove the truth 
of evolution, 114-121. 



Piilipenlietni, Gottfried Hem rich, ht!i 
di ecu very of ihe . function of Ihe 
patiereit^, Ml. 

fnsUiur, Loiiif^ liisi. nienicc^a tn the 
€fliisu of or«;4nif clitMnisltv, -f^*n 
%1i^ ST5; reftitee* Poucluft'^ thtiury 
of p|ininariL»nu» gcufriiiioii, 32<^ 
3$t» ; hln ^Uniy of fcrtDcntution und 
piTtrefucttoii, aTG-JIS^) ; hi* disctrv- 
**ry Kiid ifi^tuhlHhtiioiU of proteetivc 
vitt;cUmtioii, ;t^7-SltK), 
ll*»'ircte', B(.MijiiiM*ii, 4isiiroVL'a LitptncKJ^s 
tlit*ory of Siitiirii*a Hugs, 34 1. 

Pciin, GiaiiviNi'^ buw Jir uucuiiniod 
for lliti' foBsii diHL'tivci'i^ Al Kirk^ 
dHhv »fi. 

repsiii, it!4 discovery, 847- 

Pcfviissston, it* diBCov^ry and develo|>- 
meiu 11^ u ini'tlKfii of cltagiitj^uig 

|f iirrAiidhi^ H f'lisioim^lnjnr.ur of t]i<: 
Alpii, L'ofici.4vftt* tliL* gkciiil thi;ory, 

P^rtiii'^t M, IJdiicher dea^ his ptiho- 
If tilt'.' diKfrnferles Kt AbiH*vili<p^ lf>!l. 

Pliio^iston, th<? eightw*rith-evrittify 
lh*^ory r>f, 21*-^^. 

I*hoioi;ii4»1iv\ fc"3ipci"imetila m, by D^fy 
iiti4 Wedg^njod, "i; its servset;^ in 
fipLHiiuiM Jitialysirt, SfM-tlfiftj (KT- 
fc?tuwj by Dttgtitirrc utid Draper, 
2«4. 295. 

Plirendlogy^ dngiit of th€ syilem^ 

|lc«, jMlviLiicTttN inmly in tbe«ei«*noc 
^firing t1> ' Nth cTiitui^, 2S- 
it!; com I r th«^ iiiituie ot 

aiij**iriii..:.^ 4/' 24-27; dia- 

covery of tlie f^lvftiiic lintl^ry itnd 
lU far rt!i»ii|iiii|r rv.^ult4, 27 -2&; 
pnjgrt(?fs tnnrle jri the mwtiti*i duf- 
ioj? the nitiineoiuU t-tiittiry, 11S2- 
129; i^ttidv uf ll-ffil nnd colors, utid 
th«t i«Ht.iblt^hiOffiit nf tlir; imdulor 
tory r hot m\ 11»2^ 2o i ; i d r^ 1 1 ( iiy of 
^alvjitiii! iiTid i^li-einiid action de- 
monatiftted. *iiti-2*>6; thv tttik Ue^ 
lw*!f*n irtjii^iii'tifiiii mid tilf^utridty 
4it»covi?ri*fU (ind the edt^iiw of mwjr- 
tiet<Kfli?ctric4ty founded, 207-2(>9; 
discover f of ilie kw of the coiiR*r- 
on of tiJM>tjr>\ 201J-221 ; tiipoov. 

P of tbe iiHliire mid [m^pt^rUt^^ uf 


heat, And the estublUhment of the 
science of thermo-dyniiniics, 322^ 
5^24; IIdnvholtJS*s deethMfj»*!:iietic 
theory of light, 2S7, 228 ; dispiatie- 
miiiiL of t\w. imfioiideriibleH in favor 

I of }ir) ull'perv^cliti;; etlier, 228, 2*iy; 

I ^oEiic unriolvini problems, 44^-441-1. 

Physiology, its dghleeiiih * crntuiT 
tnumphi*, 3P-41 ; disrovenes in 
brniii phvaioli^gyf 417^23. *SVc 
Aumtoniy and phj»io]o|^; Mi?diCHL 

Piii?^i, Gitihreppe, hift disoorery of 
Oerca^ 44, 

PiciieHn^, Edward Charles^ his spec- 
titKicopic research es, 70, 73, 

Piiii.'l, Philippe, hb aim torn icul iov^ea* 
tigation«, 324 ; iiiaugunitej in 
Fmnee u reform in the tmatnient 
<if Ih** irsaane. StlB-ftflU ; oppoi^es 
tiie aysttnn of phrenolii^v, 4 oil. 

PiihffftjtthrtfpuA fTtffuM^ tlie nfitr man 
/oBijiL fmin tiie iaLitnd ojf J^vn, \2(K 

riayfiur, tJoiin, hiti ndviK^jn-y *if the 
Htitliniiiiu thi^rr of iiits uarth, 123, 

Pbitdeii, the, fa4?ts concerning, 94, 

PluLomst», theory of the, 123^^23. 

Poia?40ii, Kill I eon iVnis, discovers the 
€?»ijflc of the atniosphtfic circnlft* 
tion, 184; op|>ot«e« the nniJulAtory 
thtmry of lifriii, 20?;, 

Poimhet, M, F, A., Idd tiiTOry of 
" epontani^ous (^enenttioti," i42l\ 

PrestwJeb, Joseph, mvcstigatt:-* the 
Abljtnillf find ftod timkei* rej^ort 
tlier%*(in, toa 

Prltj^Lli-y, Joseph, his discovery of 
oxysji^n, 3 J ; hiei inesplicjible o|ipo- 
HiCioo to tlie doclrrnf:« uf Lavoialef , 
a4, H5 ; im exptrhucnu on rc«pi- 
nition, 40. 

Prnloplasio, tU diawvery by Mold 
mil) [>oj-irdin, 3JKj:il-S4a 

Pron?*t, L^Miiti Jo-^cph, his thiiory of 
the combination uf chemical cl©- 
iiiiiotn, 2fi5, 25 ti. 

Pre ml, Williant, iiiii th^jry of ihc 
compound imtitre of the so-ciiUcd 
demon IP, 27S-2S7; hh discovery 
of hydroeiiiorie iicid in the giwiLfic 
Jidce, 347. 


Psychology, experimental, its advances 
during the present century, 395 
-432 ; the reform in the treatment 
of the insane, 895-401 ; discov- 
eries regarding the nervous sys- 
tem, 401-407 ; establishment and 
development of psycho- physics, 
407-417 ; discoveries in brain phys- 
iology, 417-423 ; establishment 
and development of brain histol- 
ogy, 423-432. 

Psvcho-phvslcs, discoveries relating 
to, 407-417. 

Putrefaction and fermentation, their 
processes investigated, 875-380. 

Rain, theories regarding, and the de- 
termination of its causes, 167-172. 

Ramon y Cajal, S., his discoveries re- 
lating* to nerve cells, 480, 431, 432. 

Riimsay, Andrew Crombie, how he 
account (!(1 for many of the lake 
basins, 153. 

Raukine, William John Macquorn, 
Ills researches prove the law of the 
eonservation of energy, 223, 224, 

Ileniak, Professor, his microscopical 
researches of the brain and nervous 
system, 401, 425. 

Respiration, its ]»roeesses investigated, 
:;i>-41, 349. 350. 

Hoiir<_'»'n, Professor, and the X ray, 
1, 2, 228. 

Uosse, Lord, his studies of nebula.' 
tlnoiiiih hU ?.ix foot reflector, 80. 

Roux, Dr., his seiviccs in tiie eause 
of ^riiim-thcrapy, 'M2, '-Wi. 

Riunford, Tount, set Tiionipson, I3en- 

Uu.-h, Hmjaniiii, his reform iji the 
ticiiUnent of the insane, 31)5, 396. 

KutlKM-foni, Daniel, his diseovery of 
!iitroLren, 34. 

RnllivM-foitl, Lewis Morris, his spec- 
troscopic researches, 70, 72. 

.SAiNT-irii.AiuK, (Ikoffkoy, lils advo- 
eaey of th«' transmutation theory, 
104 ; opposes ('uvicr's Sj)eeial-ere- 
iition hypothfsis, and partially t-n- 
doises the Laniarckian theorv , 300, 


Saturn, discoveries relating to, 49, 6o- 

Savary, M., acooonts for the elliptical 
orbits of double surs by the laws 
of gravitation, 64. 

Scheele, Karl Wilhelm, his discovery 
of oxygen, 81 ; his physiological ex- 
periments, 40. 

Schiaparelli, Giovanni Yirginio, his 
establishment of the cometary 
origin of meteors, 59. 

Schleiden, Matthias Jakob, bis dis- 
covery of the function of the cell 
nucleus, 881, 882, 345; his discov- 
ery of so-called free-cell formation, 

Schmerling, Anton von, his impor- 
tant discoveries at Engis, Westpha- 
lia, in. 

Schoenlein, J. L., discovers the cause 
of favus, 865. 

Schultze, Max Johann Sigismund, dis- 
covers the identical character of 
vegetable and animal cells, 840. 

Schwann, Theodor, his cell theorv, 
331-386, 337, 838, 343, 845; his 
discovery of pepsin, 847 ; his mi- 
croscopical researches, 376, 404. 

Scientific problems, some unsolved, 
433-457 ; regarding the sun and 
earth, 435-442; in physics, 443- 
449; of life and the evolution of 
living matter, 444-456 ; of anthro- 
pology, 456, 457. 

Scrope, G. Poulett, his work account- 
ing for the origin of volcanoes, 124. 

Secehi, Father Angelo, his researches 
in spectrum analysis, 70, 72. 

Sedgwick, Adam, his classification of 
transition rocks into chnmological 
groups, 138. 

Senun-therapy, discovery and devel- 
opment of the system of, 390- 

Shooting-stars, determination of their 
origin, 59, 60. 

Simpson, Sir J. Y., his discovery of 
chloroform as an anaesthetic, 874. 

Sirius and its *' invisible " companion, 
74, 75. 

Six, Mr., his theory of dew formation, 

Small -pox, Jenner's discovery of the 
means of its prevention, 42, 43. 



Smith, Willimn, ** the fmher of Eiig- 
Uflh (seology/^ \m pulooutolof^cjil 
diiieovcricA ui)d Ui» di^ductiouH 
tht-iKfroiOi 80-Ui ; tiU stutl/ of 
«NtmiJi mB 11 kvy ta the carth*^ chro^ 
nology, 137, 138. 

Sfjuih, J.iHH's, miU Jnhn Hei'scliel if* 

Sp^cjiil creatSorj, liiBcussioius relittiMg 
tu the hfr»oiliei»U of, ^ 1-147, iOi* 
105, 2^7-4102. 

Spot'ifoatMipe/itfl perfection by Kirch- 
ho IT iLiid Biinst-'n, ami lis saUir and 
sidtTi^ul ttnalyse^, 7<*-7tj, 5t8S, '284 ; 
'm Eifjcrumatitiu puwLM; 7*$ ; it» 
upplitrndon to nebiilic, i*C*, 

%i!C[riiiti Aimlj^ia, it^ remark a hie d)i« 
i^lusurfs, 70^711, 2 S 3-28 7. 

SpcjietT, Herbert, sifUot'sika the Dnr- 
wiiunn thLH>ry, Iil3<dtfj; fnvor^i the 
Idimttrekikm comHi|Huj|i of ibe ori- 
ptt uf fnvoTVit H|jcetc'£i, 813 1 ^^^s 
tlteoTctkul ueudy of fi,^y oh til i>gi, 4 16, 

SpontAiieouf jtencmtion, Pouch et'ii 
hypatbesJs (»f, 320. 

SpurKbfMiii, KuH^jir, iKdvociiCes phre- 
dogv. 400. 

i, cioiibk ur mt)1tlft!i» 9tnw. wtid 
ttiar elu^tei^t the iiivciatigntioiis of 
the iiiiiuleeritli cciuury retuting to, 

** SmtiBUml TnetliiMl.** llic» iLa iiitm, 

dutatoii itito triiMiiLyi! pnictice, 3fi*K 

Stctlioi*eopi»,its invt^iit'itiU *nd improves 

Storm e^mtre, d*.w*Hpli<>t» nf, 18*^ 189, 
Stnivi*. F. G W,, Isiir" ilbeovfry of 

dotible sUr*, iM : sulvtis the prob- 

letn of star distiiinH*, ttf*. 
SuO^ the, Its clcnxnt^ cllrietnered bv 

ftpfctnim ftfialveis, 70-72 ; Helm- 

hi>!t:^.'H theiiry of Buhir uiiiTj^yi, 74 ; 

jMUfir Il|l1l!>fitv(?d pprdtleui'* fi'K'tl'^Ji'l^t 

^:i.i-M:|; cfitiiJifltc 111^ to ita huiit- 

giving lifts 4m. 
Bun*»fHiU, eftrcu of, 160. 

tn^t of ilic frc« p«th of niolftciileA, 

TallKit, William Henry Foi, hb sei^ 
\\f^A in tl^e perfection of photug- 
rnphy^ 285. 

Tein peril 1 11 re^ the. nb^lute jcero ofj 

Ti'tnini!), lh(^£«eruiii treiitiiiciil for, Stt2. 
7?u or tf of M<f Hart ft, JHnies Out- 
loii'e, 20-23. 

Thci riKt'dyiiiimie2*> Mud bow the ffci* 
enec originaiedf 22*^, 224. 

Tliompsoii, Beijjnnuii (OiHiiil Rum- 
fijrd), Ids vibmlory tl^enry of ht^at^ 
2fl, 27 ; be provps (he tmhsfortnu- 

« tlon of Inbor ititu hi'iit. 210, 

Tboni»riiif Tiionm^ *fiv<itTJtt'S Il&ltoii^a 
utomic iheirry, 25y. 

Thniujsijij, Witlbiiii (liiird Kelvin), bis 
e^tiniiiie *jf the e^irth'e longevity, 
74, 1M, 441 ; nid^ Jonle 111 t^tnb- 
tithing tiii; dtjctibie of ttie cosi«ep^ 
Viition of energy, 218^223, 225; 
ilia diHTtrifte of the dixsipiidoii of 
energy, 22*'^, 224 ; his ^mdiujii in 
rbenno-dynmnics, 22^, 224, 227 ; 
lii^ cilculauon of the prubiilile deti^ 
Hity iiiid righiity of ether, 235 ; h»» 
eoneeption nf the vortci theory nf 
atoiDEtf iitid his verifying u^tjieri* 
menL'!, 2;fS-24(>; eakulnteB ttie 
dinienisbnit nf a inolLrtde, 244,, 
245; refuse** to iecogiii?!e fliiy n*- 
pulsive pi>wer m riioleeulea^ 246 ; 
hi8 estimate of the licAt-^Mng life 
uf the Sim, UH. 

7'itantttfntrrM^ mT Brtmhiiht^'iittx^ eroht- 
ihiii off 12L 

Twutnnl, M,. UU drtieoveFy of himmn 
fo^uil!! ill the Bonth of J•>uocl^ ni. 

Toitne und *iiiitojiUie, tbeif dieieov^iy 
niid iruiodni'tjort, yi>0-*iW4. 

Triiite-wtiKlK, simh of their ongin 
niid effect*, 177, 178, 182. 

Tru Ellin oita lion of s^pexc^Le^N^ d<K.*tr)ne of, 
|05-ltJ8, 2t»»-2W7, ;j\>2^1«, 317- 

Tievir»ntiit„ Gtkiifrietl Hetnhuhj, his 
lhi»<iry fif the triiiitimKitiition of 
species piibliHlieil the **iii}e year ill 
wlik^b Luiioirek** tirst iippfajcd, 
a^S; foresb*dtJWs the eeU theorv, 

Trirhitm ffnratU^ Its dbo^Terf, S6SI- 



Trichinosis, character of the disease 
and its discovered, 863-366. 

Tuke, William, inaugurates reform in 
treatment of the insane, 395. 

Tyndall, John, hi.** advocacy of May- 
er's doctrine of the cons<.'rvatiorj of 
energy, 221, 223; and of Darwin's 
theory of natural selection, 313; 
hi.s endorsement of the germ the- 
ory, 820. 386. 

ULTRA-iJASKors Or fourth state of 
matter, theory of, 247. 

Undulatory theory of light, establish- 
ment of, 192-204. 

Uniforiiiiiananism, Sir Charles Ly- 
ell's udv(K*aev of the doctrine of, 
99-102, 127,131. 

Yacci.nation, its discovery as a means 
of preventing smallpox, 42 ; its 
application as a ])reventative of 
other diseases hy virus prepared in 
tl>e laboratory, 38r»-3tM). 

VaitMicy, (levclopnieiit of the law of, 
2t)l», 275. 

Valentin, (Juhriol (lustav, his study 
of paiicn«;»-J, 817. 

Van 't Hoof, Trofrssor, liis estahlish- 
incnt of steieo-cheniistry, 448, 449. 

Venet/.. M., an I'arly believer in and 
ailvooale of the glacial theory, 134. 

VcrtelHate paleotitology, estahlish- 
nifnt of, 91-1»7. 

Vinci, Leonardo da, his early recog- 
nition of the true character of fos- 
sils, 88. 

Virchow, Riulolf, his denioJistration 
of Schwann's cell theory, 344, 345 ; 
his researches which lead to the 
discovery of trichinosis, 3»)3, 3G4. 

Volla, Count Alessandro, his inven- 
tion of the volfait- pile, 27, 28. 

Vortex theorv of atoms, the, experi- 
ments to pi<»v.', 28»)-21<); un un- 
solved j)r<.M.'n). 4 4r., 44 7. 

Vulcan, a liv})ot helical planet located 
hy licverrier, l\K 

Wai.lack, Alkukp UirssFLL, his re- 
markable concepiic.n of tlie theory 
of natural selection contemporane- 
ously with Darwin, 307-810. 


Waller, Professor, his discovery of 
" trophic centres," 427. 

Warren, John C, mounted, -described, 
and gave name to the mastodon 
found at Newburg, N. Y., 119. 

Water, its composition discovered, 31, 
34, 253. 

Weather bureaus, their principal oc- 
cupation, 186, 191. 

Weber, Ernst Heinrich, his experi- 
ments and discovery in psycho- 
physics, 409-412. 

Weber, Wiihelm Eduard, makes a 
practical test of the electric tele- 
graph, 207 ; his study of the ner- 
vous system, 405. 

Wedgwood, Josiah, invents the py- 
rometer, 24. 

Wedgwood, Thomas, his experiments 
in photography, 2, 5. 

Weismann, August, op^wses I>a- 
marek's theory of acquired vari- 
ations in the origin of favored 
species, 318; elaborates a hypo- 
thetical scheme of the relati<ms of 
intracellular units, 455. 

Wells, C. W., his solution of the 
problem of dew formation and of 
the precipitation of watery vapor 
in any form, 170-172. 

Wells, Horace, the first to administer 
an anfpsihetic in a surgical oper- 
ation, 369. 

Werner, Abraham Gottloh, the pro- 
pounder of the Neptunian theory, 
liis belief in the aqueous origin 
of the solids of the earth's crust, 
123; hi.s belief in the uniformity of 
strata over thewhole earth, 136, 137. 

Wilson, Patrick, his theory of dew 
formation, 171. 

Winds. Sr( Aerial currents. 

Wohler, Friedricli. his synthesization 
of urea, 265. 26ti ; his investigation 
substantiates the binary theory of 
Derzeliu<, 268 ; his discovery of 
isomerism, 274 ; his important ser- 
vices to physioloiry, 846, 347 

Wolff, Kaspar Friedrich, founder of 
the science of embryology, 36; 
foreshadows ilie cell theory, 336. 

Wollaston, William Hyde, discovers 
the identitv of galvanism and elec- 


tricity, 206 ; his ohservatio i of 
chemical combinations confirms 
Dal ton's atomic theorv, 266, 259 ; 
his improvement of lenses, 325, 
826, 327. 

Wortman, J. L., his fossil lineage of 
the edentates, 121. 

Wundt, Wilhelm Max, his psycholog- 
ical discoveries, 414, 415. 

" X RAT," its discovery, 1, 2, 228. 

Young, Charles Augustus, Ids spec- 
troscopic researches, 70. 

Young, Thomas, his establishment of 
the nndulatory theory of light, 27, 
192-204, 225; confirms the identity 
of galvanism and electricity, 205; 
practising medicine and studying 
£;;yptian hieroglyphics, 206; the 
real discoverer of the ether 281, 


• his cometary theory, 64, 65; his in- 
terpretation of the diversities in the 
spectra of stars, 78. 




Thii b<M»b ■• under do oireuinstanoes to b« 1 
imkcn tt&m the BuHdliii 1 


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