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It is characteristic of the work of a really for the innumerable workers who have been, great genius, either in Science, Literature and will be, more or less influenced by his or Art, that it is not displaced and cannot methods and their tremendous productbe displaced by that which may come iveness. after it.

His views as to the proper attitude of the A bit of scientific work may later be philosopher in his relations to unexplored found to be erroneous as to data, and, there regions of human experience are concisely fore, in the wrong as to conclusions, but if expressed in this noble sentence from his it be the work of an aggressive, original Presidential Address before the British Asthinker, it will always have great value. sociation for the Advancement of Science, in In the brilliant galaxy of physicists, or, as 1871 : “Science is bound by the everlasting he would himself call them, natural philos- law of honor to face fearlessly every probophers, which the present century has pro- lem which can fairly be presented to it." duced, it is moderation to say that none When he comes, however, to touch upon outshines Lord Kelvin, and it will not be some problems which have long been of denied that none has equalled him in ag great interest to the human race, but which gressiveness and originality. The range of have been assumed, usually, to lie outside subjects upon which he has touched during the domain of experimental or exact science his long

active life so extensive as to (and he touches upon them not infrequently certainly justify the use of the term Natural in the volume under consideration), it is not Philosopher in its broader sense (and cap- difficult to see a very decided bias towards italized at that), for he has never touched a certain views, and a promptness to accept department of human knowledge without propositions not always well supported by leaving it richer and more extensive for his evidence, very greatly in contrast with contact with it. That he has not been in- what is found in more vigorously scientific variably infallible is recognized by no one discussion. more fully than by himself, and the new This series of popular lectures and adeditions of his earlier papers which have dresses is published in three volumes, the been issuing from the press at intervals dur- first and third having already appeared. ing the past few years, bear most interest- The second (issued later than the third), ing evidence of his readiness to change his to which attention is now invited, contains attitude on great questions whenever the the important addresses on geological physverdict of later investigations is against him. ics which have attracted so much attention It is delightful to note the occasional par- during the past quarter of a century, toenthetical' not’ put to-day into a sentence gether with a number of lectures and short which twenty years ago declared very pos- papers on subjects related to general physics itively that there is so and so, or, 1 and extracts from addresses as president of can,' etc., completely reversing the mean- the Royal Society since 1890. The geologiing of statements which were once made cal papers are of great interest and have with a good degree of confidence. What- had much to do with the moulding of the ever else

may be said, it cannot be asserted views of geologists as to Dynamical Geology. that Lord Kelvin has ever lacked the cour- The series begins with a short note covering age to express his own views in most forci

but a single octavo page, entitled, The ble and unmistakable language. Indeed, in Doctrine of Uniformity in Geology Briefly this respect, especially, he has set a splendid Refuted,' read at Edinburgh in 1865. It standard of unswerving scientific honesty fairly opens the ball,' and may be regard

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ed as the key note to the more elaborate dis- not as a mere passer-by, but as one conquisitions which followed at intervals up to stantly interested in their grand subject, recent dates. These papers are so well and anxious in any way, however slight, to known, or ought to be so well known, to all assist them in their search for truth.” geologists as to make it only necessary to It seems difficult to over-estimate the imsay here that they will be found collected portance of these geological addresses, not in this volume in convenient form and with only to the geologist, but to the physicist as a few notes and occasional comments by the well. They not only have a general interest distinguished author, made while the collec- to both, but are of special importance to tion was being prepared for the press. The each. To the one they open new possibilimost important of the earlier papers are the ties of a somewhat exact and satisfactory address On Geological Time,' given in Glas- treatment of a most important but hitherto gow, early in 1868, and that on Geological rather unmanageable department of his subDynamics ' at the same place about a year ject; and to the other they offer a most inlater. In the first of these will be found structive illustration of the power and scope the somewhat severe strictures upon

British of the methods of exact science, when apPopular Geology' which brought forth the plied by one who may justly be called not a interesting and pointed criticisms of Huxley master, but the master. in his address to the Geological Society of Of the other addresses, none, of course, is London, and in the second the replies to more important or interesting than the Huxley's criticisms and futher remarks upon British Association Presidential Address of the subject. Nearly ten years later came a 1871, so well known to all. One of the * Review of the Evidence Regarding the Physical earliest, on "The Rate of a Clock or ChronoCondition of the Earth,' read at the British As- meter as Influenced by the Mode of Suspension,' sociation meeting at Glasgow ; two papers is most entertaining and suggestive as an exread before the Geological Society of Glas- ample of the many “side-lights of a regow, on 'Geological Climate,' and on the In- markable intellectual activity. Of great ternal Condition of the Earth;' and after the historical value is the Royal Institution leclapse of another ten years a paper before the ture of 1856 on the Origin and Transformasame society on Polar Ice Caps and their In- tion of Motive Power—already republished in fluence in Changing Sea Levels.' In these Volume II. of the Mathematical and Physical much of the ground of the earlier addresses Papers ;' and one of the most interesting is is again gone over, in the light of later dis- that of late date (1892) on the 'Dissipation covery in geology, physics and astronomy. of Energy. In this much attention is given

Indeed these same topics recur again and to the principle of Carnot, and here also ocagain, sometimes incidentally in other ad- curs a remarkable statement which the audresses in the volume, and Lord Kelvin thor himself has thought worth while to makes it entirely clear that in thus taking print in italics ;—it is :-"The fortuitous conup the discussion of geological problems course of atoms is the sole foundation in Philosoand applying to them the methods and phy on which can be founded the doctrine that it data of physics and astronomy, he does not is impossible to derive mechanical effect from heat wish to be considered an interloper. In otherwise than by taking heat from a body at a his reply to Huxley, who had rather point higher temperature, converting at most a definite edly intimated that view of the situation, proportion of it into mechanical effect, and giving he good-naturedly remarks: "For myself out the whole residue to matter at a lower temI am anxious to be regarded by geologists, perature."

The address on the opening of the Bangor The temperature data computed and Laboratories will be of interest to all who plotted on maps as isotherms are not availhave to do with their like; that on the occa- able in locating the boundaries of the zones, sion of the unveiling of Joule's statue will because they show the temperature of arbiinterest everybody who cares for or who trary periods—periods that have reference knows of the greatest generalization of to a particular time of year rather than a modern science. In short, every page of particular degree or quantity of heat. this volume is deserving of the careful It is assumed that the distribution of perusal of all who are devoted to Natural animals and plants is governed by the Philosophy in its most comprehensive sense, temperature of the season of growth and and who wish to know something of the reproductive activity--not by that of the spirit of one whose splendid contributions entire year. The difficulty is to measure to physical science are, as a whole, greater the temperature concerned. than those of any other philosopher of the Physiological botanists have long mainpresent time.

tained that “the various events in the life The mechanical execution of the book of plants, as leafing, flowering and maturdoes not seem to be quite in keeping with ing of fruit, take place when the plant has the classical character of its contents, and been exposed to a definite quantity of heat, its pages are occasionally marred by negli- which quantity is the sum total of the daily gent proof reading. T. C. MENDENHALL. temperatures above a minimum assumed WORCESTER POLYTECHNIC INSTITUTE.

to be necessary for functional activity.”

The minimum used by early botanists was Laws of Temperature Control of the Geographic the freezing point (0° C or 32° F), but reDistribution of Life.

cent writers believe that 6° C or 42.8° F In the December issue of the National more correctly expresses the temperature of Geographic Magazine, Dr. C. Hart Merriam the awakening of plant life in spring. “The announces the discovery of the laws of substance of the theory is that the same stage temperature control of the geographic dis- of vegetation is attained in any year when the tribution of terrestrial animals and plants. sum of the mean daily temperatures reaches the Dr. Merriam has been engaged on this same value, which value or total is essentially problem for sixteen years and believes he the same for the same plant in all localities. has at last obtained a formula which ful- This implies that the period necessary for fills the requirements. He states that in the accomplishment of a definite physiothe Northern Hemisphere animals and logical act, blossoming, for instance, may be plants are distributed in circumpolar belts, short or long, according to local climatic the boundaries of which follow lines of peculiarities, but the total quantity of heat equal temperature rather than parallels of must be the same. The total amount of latitude. Between the pole and the equator heat necessary to advance a plant to a given there are three primary belts or regions— stage came to be known as the physiological Boreal, Austral and Tropical. In the constant of that stage.” But students of United States the Boreal and Austral have geographic distribution are not concerned each been split into three secondary trans- with the physiological constant of any stage continental zones, of which the Boreal are or period in the life of an organism, but known as the Arctic, Hudsonian and Cana- with the physiological constant of the species itdian; and the Austral as the Transition, self-if such a term may be used. “If it Upper Austral and Lower Austral.

is true that the same stage of vegetation is

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attained in different years when the sum of poses, and without attempting unnecessary
the mean daily temperatures reaches the refinement, the mean normal temperature
same value, it is obvious that the physio- of the six hottest consecutive weeks of sum-
logical constant of a species must be the mer was arbitrarily chosen and plotted on
total quantity of heat or sum of positive tempera- a large contour map of the United States,
tures required by that species to complete its cycle as in the case of the total quantity of
of development and reproduction.Now, “ if heat."
the computation can be transferred from the On comparing this map with the zone
species to the zone it inhabits—if a zone map, the isotherms of 18°, 22° and 26°C
constant can be substituted for a species con- were found to conform respectively to the
stantthe problem will be well nigh solved." southern boundaries of the Boreal, Transi-
This Dr. Merriam has attempted to do. tion and Upper Austral zones, leading to
“In conformity with the usage of botanists, the belief that “animals and plants are re-
a minimum temperature of 6°C (43°F) stricted in southward distribution by the mean
has been assumed as marking the inception temperature of a brief period covering the hottest
of the period of physiological activity in part of the year."
plants and of reproductive activity in ani- Except in a few localities the northern
mals. The effective temperatures or degrees boundary of Austral species coincides with
of normal mean daily heat in excess of this the southern boundary of Boreal species,
minimum have been added together for but for a distance of more than a thousand
each station, beginning when the normal miles along the Pacific coast a curious over-
mean daily temperature rises higher than lapping and intermingling of northern and
6°C in spring and continuing until it falls southern types occurs. On looking at the
to the same point at the end of the season." temperature maps this is at once explained,
The sums thus obtained were plotted on a for the mean temperature of the six hottest
large scale map of the United States, and consecutive weeks from about lat. 35° north-
isotherms were run which were found to ward to Puget Sound is truly Boreal, being
conform to the northern boundaries of the as low as the mean of the corresponding
several zones. This is shown by colored period in northern Maine and other points
maps. The data seem to justify the state- well within the Boreal zone. On the other
ment that “ animals and plants are restricted hand, the total quantity of heat is found to
in northward distribution by the total quantity be the same as that required by Austral
of heat during the season of growth and repro- species. “It is evident, therefore, that the
ductive activity."

principal climatic factors that permit Boreal
In the case of the southern boundaries of and Austral types to live together along the
the zones, it was assumed that animals Pacific coast are a low summer tempera
and plants in ranging southward would en- ture combined with a high sum total of
counter, sooner or later, a degree of mean heat."
summer heat they are unable to endure. A table is given showing the actual gov-
“ The difficulty is in ascertaining the length erning temperatures, so far as known, of the
of the period whose mean temperature acts northern and southern boundaries of the
as a barrier. It must be short enough to several zones.
be included within the hottest part of the In conclusion, Dr. Merriam calls attention
summer in high northern latitudes, and to the subordinate value of humidity as
would naturally increase in length from the compared with temperature. “Humidity
north southward. For experimental pur- and other secondary causes determine the

presence or absence of particular species in

NOTES. particular localities within their appropriate

PHYSICS. zones, but temperature predetermines the

The newly discovered gas is to be the possibilities of distribution; it fixes the limits beyond which species cannot pass; it

subject of a discussion at a meeting of the defines broad transcontinental belts within Royal Society on January 31st, when Lord

Rayleigh and Prof. Ramsay will present which certain forms may thrive if other conditions permit, but outside of which they

their paper. This will be the first meeting

under a resolution of the Council of the cannot exist, be the other conditions never

Society passed last session, whereby certain so favorable."

meetings, not more than four in number, Grasses of TennesseePart II.-F. LAMSON

are to be devoted every year each to the SCRIBNER.—University of Tennessee,

hearing and consideration of some one imAgric. Exper. Sta. Bull., VII. 1-141, 187

portant communication, or to the discussion figures. 1894.

of some important topic.—Nature. The first part of this important work treat

PERSONAL. ing of the structure of grasses in general, The University of Berlin is seriously issued two years ago, is now supplemented crippled by the deaths of Helmholtz and by the part here noticed, containing descrip- Kundt. Their places cannot be filled, but tions and figures of all species known by the

Prof. Kohlrausch will probably be called author to inhabit Tennessee. Carefully pre- to one of the vacant chairs. pared keys to the genera and species are a feature of the book. The cuts are good, al

The Physical Review has published excel

lent portraits of Helmholtz, Kundt and though printed on paper hardly firm enough to bring them out to the best advantage.

Hertz, with biographical sketches by the

editor-in-chief, Professor Nichols. ProbaThe descriptions are diagnostic and couched in strictly technical language ; on this point bly the best account so far published in it is remarked : “Attempts to avoid tech

English of the work of Helmholtz is that nical or hard' words often result in obscur

contributed to the Psychological Review for ing the meaning of the author, and an undue January by Professor Stumpf, of the Unisimplicity of expression is often apt to be versity of Berlin. offensive by implying a lack of intelligence Mr. F. Y. Powell, of Christ's College, on the part of the reader.” As the book is succeeds Froude in the Regius Professorintended primarily for the farmers of the ship of Modern History at Oxford. State, this may be considered by some as a

ZOOLOGY. position of doubtful value.

It is to be regretted that the rules of no- A PICTURE-PUZZLE of a remarkable kind menclature adopted by the botanists of the appears in the Zoologist for December. It American Association for the Advancement is a reproduction of two photographs of a of Science, which are practically those ap

Little Bittern, showing the strange attiproved by the zoologists, have not been tude assumed by the bird to favor its constrictly followed. This will seriously ham

cealment. One of the figures shows the per the usefulness of the book, for some of the bird standing in a reed-bed, erect, with the names used by Prof. Scribner have be- neck stretched out and beak pointing upcome obsolete.

wards; and in this position it is difficult N. L. B. to distinguish the bird at all from the

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