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entre oscillation-frequencijo in vergelye proportionat makes whes

. For elements that are chemically related, the series

Double Orange.

doublet differ by the same amount. In this explanation The abnormality in a Maltese orange described in NATURE I do not understand the decomposition of the arbitrary of April 7 (p. 534) would appear of common occurrence in the curve in a series of superposed ellipses. For the moveQueensland or South Australian fruit. A friend assures me that ment is supposed not to be periodical, and Fourier's in a case recently received from Australia, 80 per cent. of theorem then would not apply, at least the periods of the the contents showed small oranges, more or less persect, either superposed ellipses would not be definite, as long as there embedded in the pulp or in the rind. The quality of the fruit

are no data except the arbitrary curve itself. I observed was in no way affected. It would, however, be interesting to obtain further testimony. Although the small

Besides, both Johnstone Stoney and Julius only try to oranges may not affect the commercial value of the fruit

, their explain one of a number of regularities that have been presence must be undesirable in the groves where perfection is observed in the spectra of the elements. A plausible sought.

GERALD) B. FRANCIS. suggestion about the movement of the molecules ought Katrine, Surbiton.

to explain more than one of the observed phenomena. I think it may be useful to point out the other regularities

that have been observed in the distribution of lines, and ON THE LINE SPECTRA OF THE ELEMENTS. for which as yet no mechanical explanation has been

attempted. THE HE distribution of the lines in the spectra of the (1) The doublets and triplets existing in the spectrum

elements is by no means so irregular as it might seem of an element can be arranged in series which show an at first sight. Since Lecoq de Boisbaudran, in 1869, diş: appearance of great regularity. These series seem to be covered the general plan in the spectra of the alkali analogous to the over-tones of a vibrating body. But metals, a number of interesting facts have been brought they possess a remarkable peculiarity, which, as far as I to light, which will probably one of these days find their know, is without analogy in the theory of sound. The mechanical explanation, and will then greatly advance our difference of two consecutive oscillation-frequencies deknowledge of the molecules.

creases as these increase, and there seems to exist a Mechanical explanations of some of the facts have finite limit to the oscillation-frequencies of a series. If n been attempted already. Lecoq de Boisbaudran explains represents integer numbers, the oscillation-frequencies of the fact that the rays of the alkali metals are, on the whole, a series may with great accuracy be represented by the less refrangible the greater the atomic weight, by observing formulathat the oscillations of a body suspended in a given

A Bn"? - Cno, elastic medium will become less frequent when the mass of the body is increased. This explanation, however, where A, B, C are positive constants. B has nearly the seems to me to remain rather vague and unsatisfactory

same value for all the series of the different spectra. A as long as it does not lead to any numerical results that is the limit towards which the oscillation-frequency tends, agree with the observations. Taken literally, it when n square root of the atomic weight, which is far from being are distinctly homologous, both in appearance of the the case.

lines and in the values of A, B, C, and with increasing A second well-established fact has received different atomic weight shift towards the less refrangible end of explanations by Julius 1 and by Johnstone Stoney.” It has the spectrum. Homologous series have been observed in long been observed by Hartley that in the spectrum of the following groups of elements :several elements a number of doublets or triplets of lines

Lithium, sodium, potassium, rubidium, cæsium ; appear, the oscillation-frequencies in each doublet or

Copper, silver ; triplet differing by the same amount. Recent measure

Magnesium, calcium, strontium ; ments by Prof. Kayser and myself have confirmed this

Žinc, cadmium, mercury ; observation. Julius believes that this phenomenon is

Aluminium, indium, thallium. due to a cause analogous to the combination tones in the theory of sound.

In the first two and in the last group the series consist If iwo rays, with oscillation-frequencies a, b, combine of doublets, while in the remaining two groups they conwith other rays, p, q, r, s, to oscillation-frequencies

sist of triplets. Thus we may say that the spectrum

shows a relationship between the elements similar to + a

that between their chemical properties. It is interesting b + 8 B 9+ B + B S + B,

to note that magnesium forms a group with calcium and the same difference a - B will occur several times. That strontium, and appears more nearly related to them than the doublets under consideration are in many cases re

to zinc, cadmium, and mercury. markably strong is accounted for by the fact that the (3) The doublets and triplets in each group broaden as

In the first group the intensity of the combination tone is proportional to the the atomic weight increases. product of the intensities of the primary tones, so that it difference of oscillation-frequencies is nearly proportional must become very strong when the amplitude of the to the square of the atomic weight. The constant differprimary tones is sufficiently increased.

ence of the oscillation-frequencies in the doublets and Johnstone Stoney gives a different explanation of the triplets may also be noted in the values of A, B, C. For doublets. He supposes that the path of the molecule

a series of doublets or triplets we have two or three from which light emanates is an ellipse, which by dis- different values of A, but only one value of B and one turbing forces is gradually changed, and he shows that value of C. on this supposition, instead of one ray, two rays or more

(4) In each of the spectra of sodium, potassium, rubiwould originate, and the oscillation-frequencies of these dium, and cæsium, a series of doublets has been observed, rays would differ by an amount depending on the rate of in which the oscillation-frequencies do not differ by a change of the ellipse. If now, instead of the ellipse, the constant amount, the difference diminishing inversely path of the molecule is any other curve, it can be con proportional to nt. For these series A and B have only sidered as consisting of a number of superposed ellipses, one value each. The least refrangible doublet of the all of which change in the same way on account of the series has the same difference of oscillation-frequencies disturbing forces. To each of the ellipses a doublet of as the doublets in the other series of the same element. lines corresponds, and the oscillation-frequencies of each In the spectrum of lithium there is a homologous series of

single lines. All the lines of these series have the same "Julius, Annales de l'Ecole Polytechnique de Delft, tome v. (1889). Stoney, Trans. of the Roy. Dublin Soc., vol. iv. (1891).

' Lithium has here to be excepted, whose lines are all single.

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character ; they are strong and easily reversed, and in Patagonia and various parts of Argentina have shown all of them the first doublet is situated on the less refran- that the deposits containing mammalian remains, instead gible side of the spectrum, and all the others in the violet of being exclusively of Pleistocene age, comprise a large and ultra-violet. The series shift towards the less re- portion of the Tertiary period, probably extending down frangible side with increasing atomic weight.

at least as far as the Oligocene ; although the exact For further details the reader is referred to the follow- correlation of the different beds with European deposits ing memoirs :-Kayser and Runge, “ Ueber die Spectren is probably premature. der Elemente," Abhandl. der Berl. Akademie, 1890-92; With these preliminary observations, and asking our Rydberg, “ Recherches sur la constitution des spectres readers at the same time to bear in mind that a considerd'émission des élements chimiques," Kongl. Svenska able part of our knowledge is still in a very imperfect and Vetenskaps-Akademiens Handlingar, Bandet 23, No. 11, crude condition, we propose to glance at some of the 1890.

C. RUNGE. peculiarities presented by the more remarkable forms

of Ungulates described from the deposits in question.

Since the date of the publication of the results of

Darwin's voyage in the Beagle, we have been gradually ABERRANT FOSSIL UNGULATES OF acquiring a knowledge of the structure of that remarkSOUTH AMERICA.

able South American Ungulate known as Macrauchenia,

of which the complete osteology has been described by Till within the last few years palæontologists and Burmeister. This animal

, which had the general proporzoologists were being continually startled by the tions and size of a horse, conforms in several respectsdiscovery of strange forms of extinct Ungulates which more especially in having three-toed feet, in which the rewarded the researches conducted in the Tertiary rocks middle (third) digit is symmetrical in itself—so markedly of the United States. The animals thus brought to the with the Perissodactyles, that by common consent it has notice of the scientific world have, to a very large extent, been generally regarded as an extremely aberrant memmodified our conceptions of the relationships of the ber of that group. The molar teeth are, indeed, more various groups of hoofed or Ungulate Mammals to one like those of the Rhinoceros and Palæotherium than of another; and have led to the very general adoption of any other Old World Ungulates, while the infolding of the view of the ordinal unity of all these multifarious the enamel of the crowns of the incisors is a character types. Several of them, indeed, so far as we may judge known elsewhere only in the horses. The absence of from their mere skeletons, indicate signs of a transition any gap in the dental series, and the nearly even height between the Perissodactyle and Proboscidean modifica of the teeth, are characters in which Macrauchenia agrees tions of Ungulate structure ; but none of them tend in with the Old World Anoplotherium. Perissodactyle affinithe least degree to break down the hard and fast line of ties are indicated by the presence of a third trochanter demarcation between the Perissodactyle (odd-toed) and on the femur ; but in certain peculiarities in the ankleArtiodactyle (even-toed) modifications, which is main- joint this animal differs from all typical Perissodactyles, tained throughout all the known Tertiary deposits of the and agrees with the Artiodactyles. Moreover, a certain Old World. Moreover, after a little “shaking down,” peculiarity of structure in the vertebræ of the neck is the whole of these North American Ungulates, with the repeated elsewhere only in the camels and llamas, which exception of the curious Rodent-like Tillotherium, fall form an isolated group of Artiodactyles. In the complete fairly well into their places in the Ungulate order ; closure of the orbit by bone, Macrauchenin resembles although some of the earlier and smaller types present the horses and many Artiodactyles ; but in the narial indications of close affinity with the common stock from aperture being situated on the top of the skull between which we may presume both Ungulates and Carnivores the orbits (whence the nostrils were probably produced to have taken origin.

in the form of a proboscis), it is absolutely peculiar. At the present time the wave of discovery of new forms There are thus many indications that, while Macraucheappears to be passing from the northern to the southern nia is a specialized form that can in no sense be regarded half of the New World ; so that while the palæontologists as the ancestral type from which Perissodactyles and of the United States are to a great extent engaged in the Artiodactyles have originated, it retains certain generalized important task of revising and completing the preliminary features which were probably directly derived from such work of the last twenty years, their confrères in Argentina ancestral stock. are almost flooding scientific literature with descriptions- Among the Ungulates discovered in Patagonia is sometimes, it is to be feared, rather crude and hasty ones one named Proterotherium, which was at one time re-of a number of new or hitherto imperfectly known forms ferred to the Artiodactyles, but subsequently placed among of extinct mammals. This descriptive work has been the Perissodactyles. In the skull, so far as can be mainly undertaken by Messrs. Ameghino, Burmeister, gathered from Ameghino's description, the orbit is closed, and Moreno. Unfortunately, however, the greater part as in Macrauchenia, but the narial aperture appears to of it is still in the form of preliminary notices, unaccom- have had the normal position. The molar teeth are so panied by illustrations ; while on several points the three like those of true Perissodactyles that they were origindescribers above mentioned are by no means in accord, and ally described under the name of Anchitherium ; but the it is quite clear that unnecessary names have frequently rest of the dentition is very peculiar. Thus, in the upper been published. There is, indeed, one large illustrated jaw there appears to have been only a single pair of inwork published by Dr. Ameghino ; but since, so farcisors in the premaxillæ, these being pyramidal and as we are aware, there is only a single copy in the obliquely truncated like the canines of the pigs; and as Natural History Museum) in England, palæontologists there were no canines, it may be inferred that there was have not the opportunity of paying it that attention in a long toothless interval in the jaw. In the lower jaw private study which its importance demands.

there were two pairs of incisors, and no canines. The In spite, however, of these drawbacks, the information lower molar teeth were inserted by four distinct roots-a at present before us—imperfect though it be-introduces feature unknown in any existing Perissodactyle, although us to several groups of extinct Ungulates totally unlike occurring in the pig. In the limbs, both the front and any found in all the rest of the world put together, and hind feet were furnished with three complete toes, much which are of especial interest as tending to a certain ex- resembling those of Hipparion; the ankle-joint is, how. tent to break down the distinction between Perissodactyles ever, said to resemble that of the Artiodactyles. We and Artiodactyles. It should be observed, before pro- have no information as to the third trochanter of the ceeding further, that the explorations conducted in femur. On the whole, this genus appears to indicate a

Perissodactyle-like Ungulate, somewhat more specialized together with Acrotherium seems to show that these as regards its dentition than Macrauchenia, but exhibiting South American Ungulates ran riot in the disregard of strongly-marked Artiodactyle affinities in the ankle-joint. all rules as to the number and arrangement of their

Still more remarkable are the generalized affinities dis- teeth. The genus in question is Trigodon, founded played by the group known as the Toxodonts, of which upon the lower jaw of an animal about the size of a pig, the first representative was also discovered during Darwin's but evidently related in the structure of its cheek-teeth to memorable voyage. These Ungulates cannot be included Toxodon. In this mandible the middle of the extremity in either the Perissodactyla or Artiodactyla, and, there of the long and narrow symphysis is occupied by a single fore, come nearer the original generalized Ungulate stock cylindrical incisor tooth, flanked by a pair of larger inthan the animals already noticed. Toxodon, from the cisors, and these, again, by the still larger triangular Pleistocene of Argentina, was of the approximate size of canines. If normal (and from Dr. Moreno's description a Hippopotamus, and its osteology is tolerably well known. and figure it would seem to be so) this single median It takes its name from the curvature of the molar teeth, incisor is totally unique in the whole mammalian class. which approximate in structure to those of the Rhinoceros, A still more remarkable and puzzling group is typically and, like the incisors, have ever-growing roots. The front represented by the long-known Typotherium from some of teeth are separated from the cheek-teeth by a consider the Tertiaries of Argentina, which, while presenting many able interval ; the upper dental series being reduced in dental characters connecting it with the Toxodonts, has number by the loss of the outermost incisors and the upper incisors resembling those of the Rodents ; with canines, and the lower by the disappearance of the first most of which it also agrees in the presence of clavicles, premolars; the lower canine is, moreover, rudimentary. which are invariably absent in all true Unzulates. The

The feet conform to the Perissodactyle type in having number of the teeth is similar to that obtaining in many three toes, of nearly equal size, and also in the inter- Rodents, with the exception that there are two pairs of locking of the bones of the upper and lower rows of the lower incisors. An allied type has, however, three pairs wrist- and ankle-joints. In the absence of a third tro of these teeth, thus departing further from the Rodent chanter to the femur, and also in the articulation of the type ; and the skull of both genera is constructed on the fibula with the calcaneal bone of the ankle, as well as Ungulate plan. All the teeth are rootless. From other in the structure of the palatal and tympanic regions of beds in Argentina we have the genus described as Hegetothe skull, Toxodon is, however, constructed on a decided therium, which, while having rootless teeth, differs from Artiodactyle type; so that its characters are to a great Typotherium in possessing the whole typical series of 44, extent intermediate between the existing members of the without any marked interval between them. Here, then, two groups.

we have almost entirely lost the Rodent features which are Going back to the earlier Tertiaries of Argentina and so marked in Typotherium, and thus revert nearer to a Patagonia, a number of Ungulates allied to Toxodon, normal Ungulate type ; it is unknown whether clavicles but with much more generalized characters, have been were present. Still more generalized is an allied group brought to light. The skulls from Patagonia brought typified by Interatherium, in which the dentition is back by Darwin, and named Nesodon, also belong to this always complete, the anterior premolars have distinct same generalized group. In Nesodon there is the full roots, and the incisors conical roots. This genus and complement of 44 teeth ; and the same formula also the allied Protypotherium thus appear to be connected obtains in the recently described Protoxodon, in which both with Typotherium and the Toxodonts; the specific the feet are known to have been tridactylous in both name rodens applied to one of the species of Protypolimbs, although retaining rudiments of the metacarpals therium apparently indicating the existence of Rodentof the first and second digits, and being of a longer and like upper incisors. more slender type than in Toxodon. The allied animals The existence of these intermediate forms renders it described as Acrotherium, some of which were about the exceedingly difficult to come to any satisfactory conclusize of a pig, present a peculiarity totally unknown among sion as to whether Typotherium really has any genetic other Ungulates ; and, indeed, in any Eutherian Mammals affinity with the Rodents (among which it was placed by except some individuals of the small African long-eared the late Mr. Alston); for if there be such relationship it fox (Otocyon). This peculiarity consists in the presence would seem to imply the descent of all Rodents from a of eight cheek-teeth on either side of each jaw; the con- form more or less closely allied to Interatheriuma view stancy of this character being proved by its occurrence which can scarcely be maintained. in a considerable number of specimens. Whereas, how- That these Typotheroids were, however, in some ever, in Otocyon the eight cheek-teeth are reckoned as manner connected with the Toxodonts is tolerably clear; four premolars and four true molars, in Acrotherium and there are nearly equally clear indications of a more there are said to be five premolars and three true molars. or less distant connection between the Toxodonts and If this interpretation be correct, it is difficult to point out the Macrauchenias. The most probable explanation of a probable derivation for this most remarkable type of the latter relationship is that both groups took origin from dentition, since no other heterodont mammals are definitely generalized Ungulates allied to those found in the Eocene of known to have more than four premolars.

the United States, and known as the Condylarthra, which If, however, the cheek-teeth really prove to be four appear to have been the common ancestral stock of both premolars and four true molars, there might be a possi- the Artiodactyle and Perissodactyle modifications of the bility of direct inheritance of the fourth molar of the order. On this view the retention of characters common Marsupials, although even then there is the difficulty to both the groups last-mentioned by the Toxodonts and that none of the Lower Eocene Ungulates of the United Macrauchenias is readily accounted for; the MacrauStates are known to have possessed more than three of chenias having acquired sufficiently well-marked Perissothese teeth. And the probability accordingly suggests dactyle characters to admit of their inclusion in that itself that the additional tooth may be an acquired re- group, while the Toxodonts cannot be placed in either dundancy. There are a number of other more or less of the two existing divisions of typical Ungulates. Having closely allied types which have received distinct generic thus diverged at an early epoch (perhaps in the neighnames, such as Colpodon and Adinotherium, but it is at bourhood of Central America) from the original generalpresent somewhat difficult to realize all their distinctive ized Ungulate stock, the ancestral Toxodonts and features and peculiarities. One genus, however, if the Macrauchenias become the dominant forms in South specimen on which it was established is normal, is so America, where they appear to have developed into remarkable as to call for special notice; and taken such numerous and unexpected modifications of struc

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ture, as to render the task of deciphering their mutual the average change of any two consecutive days on the relationships and determining their exact systematic posi- Fahrenheit scale. tions an exceedingly difficult, if not an impossible one. At the same time, however, it does not appear to us that the existence of these puzzling and aberrant types need

Toronto interfere in the least degree with the commonly-accepted classification of the Ungulates, although there may be January

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4'5 THE CHANGEFULNESS OF TEMPERATURE

December

6.7 AS AN ELEMENT OF CLIMATE. ON NE of the features in which the climates of great continents most contrast with those of oceanic

Year
63

47 islands, and those of higher latitudes with the climates of the tropics, is the greater range through which the temperature varies between night and day, and between

These three stations serve to illustrate the fact, amply winter and summer. Another, perhaps not less im-confirmed by the general tables, that temperature is subportant, is the greater changefulness of the temperature than in the summer ; either December or January being,

ject to greater and more rapid changes in the winter from day to day. Both of these are comprised under the general expression variability of temperature, and

as a rule, the month of greatest variability. they are similar in their effects on living organisms, but

Since the publication of this memoir, the inquiry thus they depend on very different causes, and in their local

started by Dr. Hann has been followed up by several association are often manifested in very different

writers with especial reference to particular countries. degrees ; places with a great annual and diurnal range

Prof. O. Döring, for instance, has thus discussed the of temperature, displaying great constancy of climate statistics of the Argentine Republic ; Herr E. Wahlén, at any given season of the year, while others, at which

those of 18 stations in Russia ; Dr. V. Kremer, those of the former variations are moderate in amount, are,

57 stations in Northern Germany; and Mr. Robert Scott, nevertheless, subject to irregular vicissitudes of consider

those of 7 observatories in the British Isles, at which the able magnitnde. The Punjab and Sind may be cited as

temperature has been recorded by thermographs since examples of the former class, Western and Central 1869. These are Valentia, Armagh, Glasgow, Aberdeen, Europe of the latter.

Falmouth, Stonyhurst, and Kew. At all these stations Now, although from a sanitary point of view these

the variation was found to be less than at Oxford; but two kinds of variation are of equal importance, the

this may be partly due to the longer period (15 years) degrees in which they have respectively engaged the

over which the records extend, and partly also to the fact different. While the daily and annual range of tempera: whereas the Oxford register was for 10 years only, and attention of climatologists and others are strikingly that the daily means compared are those of the twenty

four hourly measurements of the thermograph curve, ture of all the more important and many minor places the observations less numerous. that have furnished meteorological registers are now

On the general average well known, or are easily ascertainable from published of the year, it was greatest at Kew (2°:7), and least at records, the first systematic inquiry into the changeful- Falmouth and Valencia (109). ness of temperature as an element of climate was that

Finally, Dr. Hann has resumed the subject in a made by Prof. Hann in a memoir published in the memoir published in the Transactions of the Vienna Sitzungsberichte of the Vienna Academy of Sciences in Academy, in which he discusses the temperature records 1875. In this paper, Dr. Hann tabulated the results of

of 66 stations in the Austrian Empire and the adjacent ninety stations, seven of which are situated in the territories, of which one-half extend over from 10 to 20 southern hemisphere, and the remainder chiefly in years, and the majority of the remainder over at least Europe, Siberia, Canada, and the United States. The five years; all, however, are corrected to the period consisted in taking out from the daily registers, of gener affords the means of comparing the results of any decade extraction of the data was not a little laborious, since it 1871-80. In the case of Vienna, not less than 91 years

have been included in the reckoning, and this register ally from five to ten years, the differences of the mean temperatures of every pair of successive days throughout with those of a long period. the whole period; then classifying them according to

The first point that stands out in the results of this algebraic sign, as rises or falls of temperature, and also, discussion is that even a period of ten years is inin certain cases, according to their incremental values: sufficient to give more than an approximate value. The The means of these different categories were then taken general mean change at Vienna, between any two conmonth by month, and the results are given in numerous

secutive days, is 304 F., but in the decade 1861-70 it tables in the memoir. The changefulness of tempera

was only 30:26, whereas in the decades 1801-10 and ture at any given place is the general mean of all 1871-80 it averaged 30:53. The means of the individual changes during the period considered, irrespective of months show much greater variation ; that of December their being rise or fall. As instances of these, I take the especially, ranging between 302 and 4°3 in different following three stations, representing respectively the decennia, or through 30 per cent of the general mean climates of Siberia, England, and Canada. They show

for the month. It is evident that when computed from

shorter periods than ten years the discrepancies will 1 The term "variability" of temperature, adopted by Mr. Scott for the element now in question, has been already used in so many different senses, 1 "Die Veränderlichkeit der Temperatur in Oesterreich," von J. Hann, that in this paper I have adopted in preference the term "changefulness," W.M.K. Akad., aus dem Iviii. Bande der Mat. Naturwiss. Classe der k. which is not open to the same objection.

Akad. d. Wissenschaften.

be still greater.

In order, therefore, to obtain com- ant from a medical point of view that the statistics of all parable values, even for neighbouring stations, it is health resorts should be analyzed in the manner of which essential that the data compared should be those of the Prof. Hann has here given so admirable an example. same interval.

H. F. B. Both as regards season and amount, the changefulness of temperature depends very greatly on local geographical circumstances, so that neighbouring places

FORESTRY IN AMERICA.1 very often differ greatly from each other. In Europe it increases from west to east and from south to north; IT cannot be said that, as far as the issue of reports increases also on the whole with altitude, but very irre- cultural Department at Washington has been idle ; if gularly, being great on exposed plateaux, and compara-only this activity would resolve itself into the estabtively small on mountain peaks. Places situated in lishment of a State Forest Service, and the formation of valleys show very great differences, according to their State forests out of the wreck of the former forest wealth exposure. Among the Austrian stations, those on the of North America ! southern slopes of the Alps have the greatest vicissitudes, An important series of papers on forest matters has owing to the warmth they acquire in sunny weather and come to hand, and though they date as far back as the consequent greater fall of temperature when a change 1889, they are probably new to many of the readers of of weather sets in. In general the changes of temperature NATURE. at high elevations are greater than at low altitudes in The first paper is by Dr. James, Professor of Public summer, but less in the winter season. In the high Finance and Administration in the University of Pennsylmountain valleys in spring the changes are much smaller vania, and is entitled “The Government in its Relation than on the neighbouring plains.

to Forests.” The Professor has evidently studied his In the British Isles, Mr. Scott found that the number subject thoroughly, and the remedy he proposes is the of rises exceeding 5° between any two consecutive days exact counterpart of that which has been so successfully was greater than the number of falls of the same amount, applied to the forests of India. He commences by stating and also that the mean value of the rises exceeds that of that the forests of any large country not only constitute the falls. In Austria, also, except in the Southern Tyrol a large portion of its wealth, but form the indispensable and on the coasts of the Adriatic, rapid rises are greater basis of a fourishing manufacturing and commercial than rapid falls in the winter, and less in the summer ; but industry. They are also one of the most important on the whole the former preponderate. In the south, elements in determining the climatic conditions of a however, rapid falls are greater than rapid rises at all region, and, through these, the distribution of the populatimes of year, and therefore also on the mean of the tion, of industrial pursuits, and of disease and health. year. This peculiarity is a still more marked charac- He states that the value of the forest crop in the teristic of lower latitudes, since in Northern India it was United States in 1880, the census year, was 700,000,000 found that rapid falls are about three times as numerous dollars (= £140,000,000), and that if the value of the total as rapid rises, and on the whole greater in amount. annual output of the mines, quarries, and petroleum wells

The duration of rises of temperature is somewhat were added to the estimated value of all steamboats and greater than that of falls, and both are rather greater at other craft on American waters, it would still be less than mountain stations than at lo levels. Thus the passage the value of the forest crop, by a sum sufficient to purchase of a wave of temperature, on the mean of the two all the canals, telegraph companies, and construct and stations Klagenfurt and Salzburg, occupies, on an average, equip all the telephone lines in the States. 4'56 days, on the Sonnblick 4'93 days; or, in other words, He then shows how Government has fostered agricul65 waves pass within the month at the higher and 7 at ture by offering, land on easy terms, by establishing the lower stations. The longest period of continuous model farms and agricultural schools, by improving the cooling that occurred at any station was ten days at the breed of stock, by free distribution of seed, and in many mountain observatory of Hoch Obir, and the longest other ways; it has also assisted manufactures by the continuous rise of temperature ten days at Klagenfurt. protective tariff, bounties, and exhibitions, &c.; and There is a marked annual periodicity in the length of that vast sums have been spent by the State on improving the temperature waves, with two epochs of maximum, rivers and harbours, and on the general means of comviz. in March and September, and two of minimum, in munication-railroads and roads. Game and fish are July and December. From the data afforded by certain also protected by the State, but although from their stations in Austria and Saxony, Dr. Hann computes forests the Americans have been drawing more natural the following formula for their annual variation in Central wealth than from all other sources together, yet practiEurope-

cally nothing has been done to preserve them from the

devastations of selfish people. Besides the great demands 4:813 + 0'138 sin (26° 45' + x) + 0.164 sin (318° 27' + 2x). on the forests for timber, three-fifths of the people in

the States use wood for ordinary domestic fuel, and the The last subject investigated in Dr. Hann's memoir is value of the wood fuel annually consumed is placed at the question whether the inter-diurnal changefulness of

325,000,000 dollars. temperature shows any periodical variation during the

Prof. James then treats at length of the vast indirect sun-spot period; for which purpose he takes the 90 value of forests in maintaining a steady supply of water years' registers of Vienna, Wilna, and Warsaw. He in rivers, and preventing floods. He shows that the finds that on the mean of these stations a certain minute maintenance of a system of factories and mills dependent variation is indeed apparent, but it is one of two maxima on a watercourse becomes impossible when the stream and two minima, and the whole range is so small that it is converted into a mountain torrent for one quarter of is doubtful whether it is other than fortuitous.

the year and is all but dry during another quarter; and In the foregoing paragraphs only a few of the more instances the River Schuylkill, from which Philadelphia important results of Prof. Hann's investigation have been noticed. His memoir contains many others of interest, too shallow and sluggish to carry off the ever-increasing

draws its water-supply, where the current has become well worthy of study, and forming important contributions to general climatology ; and like the original memoir, I "Department of Agriculture, Forestry Division. Bulletin No. 2.-Republished seventeen years ago, it will doubtless stimulate

port on the Forest Condition of the Rocky Mountains, and other Papers."

With a Map showing location of Forest Areas. Second Edition. (Washingothers to prosecute the subject. It is especially import- ton: Government Press, 1889.)

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