America is represented by a dozen or more species. Now, though an Erebia (E. Tyndarus, var.) occurs as far south in Europe as the Sierra Nevada, not a single species of any of these three genera occurs in North Africa, although the Atlas Mountains would seem eminently well suited for such Alpine insects. In this case, then, it seems clear that the same cause-the barrier of the Mediterranean-which in the case of the miocene flora

of Europe prevented any further retreat south, has operated to prevent any similar southerly spread amongst the victorious invaders from the north which pressed on the retiring host.

With regard to the general similarity in facies and richness between the East American and East Asiatic tree-flora, certain facts pointing in the same direction will at once occur to the zoologist. Thus the Menopomas of the Ohio and Alleghany have their only near relations in the gigantic Sieboldias of north-east Asia, one species of these occurring in Japan, the other being one of Père David's discoveries in Moupin. Similarly with the genus Polyodon amongst ganoids. Only two species of this genus are at present known, P. folium, inhabiting the Mississippi, P. gladius the Yang-tse-kiang. The recent discovery of at least two species of Scaphi rhynchus in Turkestan makes it probable that ere long species of that Americo-Asian genus will be found in the Chinese rivers as well. The parallelism in the case of the salamanders is particularly interesting, when one remembers the celebrated Andrias Scheuchzeri of the Eningen beds, and it tends to favour the view that at that time practical identity in the forms of animals and plants reigned throughout the northern temperate zone. W. A..FORBES

Cambridge, February 14

P.S.-The reported discovery (NATURE, vol. xix. p. 351) of a true alligator in the Yang-tse-kiang, will, if confirmed, add a still more remarkable case to those mentioned above.

Leibnitz and the Royal Society

PROF. TAIT and myself ought not to be at issue on this question. I suppose we both want to get at the facts; and, for my part, I have no more desire to whitewash a foul reputation than he can have to blacken a fair one. Where we differ appears to be, as to how far Leibnitz's reputation can stand the test of facts. The question, however, is not whether Leibnitz acted disingenuously in respect to Gregory's series, or any other subordinate matter, but whether he was indebted to something of Newton's, surreptitiously imparted to him, for his differential calculus. If the grounds upon which that charge was made are swept away, there is an end of it. But if, on the other hand, that is not found feasible, and evidence to character becomes a factor in the final decision, then it is right to examine into those subordinate matters. Till then, I, for one, decline to touch them. At the same time let me say that I never undertook to be bail for Leibnite's impeccability. All I said or say is, that on the published facts I believe that Leibnitz was led to the calculus by his own honest speculations, and had not the means of stealing from Newton, had he been that way disposed. But there are so many relative papers still unpublished, but publishable, that it is impossible to arrive at a true decision till at least some of them have been submitted to an authorised tribunal.

Prof. Tait recommends me to repeat the fruitless attempt of Dr. Slowman. I decline to follow the example of that ominously surnamed savant; for it is contrary to precedent that the pursuer should ask the defender to show his hand; and I am quite sure that "the proper authorities" abroad have too much sense to take the initiative. So I appeal to the Council of the Royal Society of 1879 (not that of 1712, as Prof. Tait gives it), and I do so for these two reasons :

1. The so-called Commercium of 1712, which was merely a statement, arriving at no decision on the principal question, contained several allegations (apparently inconsistent with known facts) which give colour to the charge against Leibnitz; it is then an obvious duty on the part of the Royal Society, who were on the occasion represented by the Committee, to give the proof, or make the reparation.

2. The first-published charge against Leibnitz, which was made by Wallis in 1695, was based on allegations said to have been derived from papers and letters in the possession of the Royal Society; it is but fair, then, that those papers and letters should be published.

I therefore once more respectfully urge upon the Royal Society to reopen the main question, and publish such of the relative

papers, &c., in their possession as directly bear upon the original charge. C. M. INGLEBY Athenæum Club, February 8

Ear Affection

is physiologically interesting, and by no means usual. Before THE experience of "P." as given in NATURE, vol. xix. p. 315, attempting an explanation it may be as well to assume that only hypothesis we get the greatest possible divergence from the one of "P.'s" ears was affected by the disorder, as by this healthy state. It would have beeh easy to ascertain which was the faulty organ at the time by requesting a musical friend to listen while "P." vocalised the note of the tuning-fork as conveyed to him by each ear separately. The discordant ear would then have been revealed.

The fault of hearing must have been due either to some mechanical misadjustment of the auditory apparatus, by which a wrong sensation was conveyed to the brain, or else to some deep-seated brain or nerve lesion, which led to a faulty conception of the original sound. Let us consider briefly the first of these cases.

by "P." I gather that the discord was mostly conspicuous when From the exceedingly scanty description of his disorder given the note was high pitched (such as when whistled). Now it sometimes happens from paralysis of the chorda tympani nerve, or even from occlusion of the Eustachian tube, that the tension of the ear-drum is preternaturally increased. Such affections, as aurists well know, frequently intensify to a distressing degree. the hearing of high pitched notes, whilst they correspondingly diminish the sound of the lower tones of the chromatic scale. This result is probably obtained by the fact that the tense membrane responds more readily to the rapid vibrations of the higher tones than it does to those of a slower rate. We must also remember that the power of lessening the tension of the membrane is in such cases very seriously impaired, and, as a consequence, the power of adjustment also. I do not suppose that in "P.'s" case there was any actual paralysis of the tympanic muscles, but it is just possible that there may have been a certain degree of misadjustment of the drum of the affected ear due to a feeble and imperfect contraction of one or the other of the muscles referred to. If the disorder was, as I surmised, accompanied with great tenseness of the membrane, the laxator tympani would be the faulty muscle. We might, I believe, under such circumstances, expect the ear-drum to vibrate dis. cordantly in response to a note, for Helmholtz's experiments with stretched strings would suggest that this is feasible within certain limits. As a matter of fact this discordance is rare, and therein rests the interest of "P.'s" case.

I can scarcely believe that in his case any of the deeper structures of the ear were seriously implicated, otherwise he would hardly have made such a rapid and complete recovery as he did. Brighton, February 10

W. AINSLIE HOLLIS

YOUR correspondent "P." (NATURE, vol. xix. p. 315) desires an explanation of the phenomenon of alteration in the pitch of sounds, which he has experienced in his own person whilst suffering from temporary deafness. Your second correspondent on this subject, Dr. Wallich (p. 340), was under my observation at the time of his experiencing the same peculiar and comparatively rare aberration, and I was able myself to verify his statements. I propose with your permission to give an explanation which correspondent "P." appears satisfactory to myself, and hope it may be so to your

Persons suffering in this way find that sounds heard by the affected ear appear to be sharper or flatter than their true pitch as heard by the other ear, and hence a sound may even appear double.

The internal ear, or labyrinth, must be the part affected, and in all probability it is the cochlea which is at fault. Now most authorities are agreed that the pitch of a sound is appreciated by. the cochlea in the following manner. Each tone, or division of a tone, has its corresponding portion on the spiral lamina of the cochlea, which under ordinary circumstances can only be affected by that tone. So that the sound-wave produced by a certain tone passes along the keyboard (as it were) of the spiral lamina until it reaches its own key, which it strikes or so affects as to cause an impression to be sent from that portion of the lamina to the brain. Hence the appreciation of variation in the pitch of sounds.

This theory being accepted, for an explanation of the aberration in question we have only to suppose some slight physical alteration in the contents of the cochlea, which would cause the sound wave to strike or affect the wrong portion of the lamina spiralis, and thus a false impression would be carried to the brain. URBAN PRITCHARD

Now attention is drawn to the above allow me to give another experience.

On two separate occasions while playing the English concertina, and more particularly when single notes or simple chords were struck, I noticed that each was followed by a loud and distinct note an octave lower which appeared to be that of its fundamental tone. The musical tones of the voice of any person addressing me, also, had their deeper reverberations in a similar manner, these being numerous and of rapid succession; the confusion arising was very like that which is heard in a hall unsuitably constructed for sound.

The nuisance, for such it amounted to, I was troubled with for a couple of days each visitation, the abnormal state of hearing being peculiar to the left ear only. JOHN HARMER

Wick, near Arundel

Intellect in Brutes

THE following case will perhaps interest those who believe that the reasoning faculty in man and animals differs in degree only, and is essentially the same in kind. Some years ago a plumber told me that he had, on several occasions, been called in to examine into the cause of leakage of water-pipes under the flooring of houses, and had fourd that the rats had gnawed a hole in the leaden pipe to obtain water, and that great numbers of them had made it a common drinking-place, as evidenced by the quantity of dung lying about. The plumber brought me a piece of leaden pipe, about inch in diameter and inch in thickness, penetrated in two places, taken by himself from a house on Haverstock Hill. There are the marks of the incisors on the lead, as clear as an engraving; and a few hairs and two or three of the rats' vibrissæ have been pinched into the metal in the act of gnawing it. This crucial proof of brute intelligence-a rat will not drink foul water-interested me so much, that I ventured to send an account of it to Dr. Chas. Darwin, asking his opinion on the means by which the rats ascertained the presence of water in the pipe. To this he replied: "I cannot doubt about animals reasoning in a practical fashion. The case of rats is very curious. Do not they hear the water trickling?" It may be conceded that this explanation is the most probable, and if it be the true one we have an example of an animal using his senses to obtain the data for a process of reasoning, leading to conclusions about which he is so certain that he will go to the trouble of cutting through a considerable thickness of lead. Obviously man could do no more under the same conditions. ARTHUR NICOLS

OUR ASTRONOMICAL COLUMN

THE COMPANION OF ALGOL.-There are grounds for suspecting that the light of the small star about 80" distant from Algol in the S.P. quadrant is also variable. Schröter in his letter to Bode, wherein he first drew attention to this object, mentions that he detected it with a 7-feet reflector on October 12, 1787, and although small it was distinctly seen. Soon afterwards he estimated its distance from Algol at 1′ 30′′. On April 9, 1788, the star was not to be found, and he therefore concluded that it must be variable. In 1792, when he was in possession of a 13-feet reflector, which he describes as the most powerful instrument then available in Germany, he re-examined the vicinity of Algol, and on March 9 saw the companion much brighter than before, and compares its distinctness in the larger telescope with its faintness in the smaller one with which he had discovered it. But on April 5, in a state of atmosphere at least as favourable as on March 9, with the same instrument and magnifying power, not the slightest trace of the companion could be perceived; on increasing the power to 370, with the utmost straining of the eye, the faintest glimmering was now and then suspected in its position. Schröter then, in this second com

munication to Bode, expresses himself more confidently as to the variability of the small star.

In the early part of the year 1874 the writer of these lines made several ineffectual attempts to observe the companion, using various powers on a 7-inch refractor; though the skies were favourable enough, nothing could be glimpsed in its place. It was not therefore without surprise that upon re-examining the vicinity under similar conditions on September 9 of the same year, the companion was caught at once, and seen with great distinctness. It was measured with Mr. J. G. Barclay's 10-inch refractor at Leyton, by Mr. Talmage, on October 2 following, when the angle was found to be 194°4 and the distance 79"02; the magnitude was estimated 11'12. An observation by Smyth in 1835 is recorded, but his distance is much too small; it is not stated whether he found the companion himself or whether his knowledge of its existence was due to Schröter's communications to Bode. It does not occur amongst the objects in the Bedford Cycle," which were re-measured by Secchi.

While upon the subject of variable stars we may just mention that Andromedæ, to which attention is directed in the last number of the Monthly Notices of the Royal Astronomical Society as "a new variable star," is no novelty: we referred to the star as almost certainly entitled to insertion in the catalogues of such objects, four years since (NATURE, vol. xi. p. 308).

"A MISSING STAR."-From a letter addressed by Prof. C. H. F. Peters, Director of the Observatory, Clinton, New York, to the Superintendent of the Naval Observa tory, Washington, which Admiral Rodgers has communicated to the Astronomische Nachrichten (No. 2240), it appears that he has strangely misinterpreted a note with the above heading, which was lately printed in this column. We referred to an object observed at Washington, with Hygeia in 1850, and afterwards sought for at that observatory and elsewhere on the assumption that it might possibly have been a trans-Neptunian planet, and in view of the failure of a careful search on this hypothesis, we remarked: "the only likely explanation appears to be that there was a variable star in this position, and that the observations in right ascension were affected with greater error than might be expected, considering (that on two of the days of observation several comparisons were made."

Prof. Peters, however, explains the difficulty by referring several transits to the first instead of to employed, in which case the star is identified with the second wire of the movable plate of the micrometer Lalande 36613, and Prof. Hall has found, on examining the original observing-books, that Mr. Ferguson had altered several correct observations to correspond with erroneous ones, and Admiral Rodgers accepts the explanation as satisfactory. But Prof. Peters is alarmed about the matter now that NATURE "stirs it up again," and writes to the Superintendent of the Washington Observatory "in order that nobody thereby might be induced to spend months and years upon a renewed search," and to "stop any further perpetuation of the credence, that a trans-Neptunian planet is revealed by the Washington Observations. It will be seen that our suggestion was that a variable star might exist in the observed position, and was in no way .connected with a renewed search for a trans-Neptunian planet. Prof. Peters must entertain rather odd notions as to the probable knowledge of his astronomical confrères respecting the contents of the ecliptical region of the sky, if he believes that any one would be induced, by remarks that we might offer, to undertake in these days a search for a distant planet close to the ecliptic amongst stars of the ninth magnitude!

COMET 1871 V.-Dr. B. A. Gould, with his usual energy, has secured an excellent series of post-perihelion places of the comet discovered by Dr. Tempel on November 3, 1871, which in a fortnight's time sank below

the European horizon. The discussion of these observations in conjunction with those made in the northern hemisphere, will lead to a much more precise knowledge of the orbit than we have at present.

OLBERS' COMET OF 1815.-In a recent note upon this comet it should have been stated that, acting upon the wish expressed by Olbers at the time, Triesnecker printed his observed differences of right ascension and declination between the comet and comparison-stars in Zeitschrift für Astronomie, vol. ii. The Vienna observations, therefore, admit of a new reduction, in addition to those previously named.

IN

DIURNAL OSCILLATIONS OF THE

BAROMETER

N the "Meteorological Notes" which appeared in NATURE, vol. xviii. p. 198, some interesting results are referred to, which show marked differences in the diurnal variations of the barometer at places quite near to each other, as Greenwich, Kew, Oxford. It is remarked especially that the forenoon maximum in the months of May to July occurs near 9 A.M. at Greenwich, and near 8 A.M. at Kew; while at Falmouth and Valentia it is delayed to II A. M., or noon, and occurs in June as late as 2 P.M. at Helder.

Having made several investigations relatively to these questions (which I have not been able to publish as yet in detail), I think it may not be without advantage to give at present conclusions relating to the results above noticed.

It is obvious that it is of the highest importance with relation to the research as to the cause or causes of the remarkable semi-diurnal oscillations of the barometer, that we should have only real variations of atmospheric pressure to deal with, and not instrumental irregularities; and that, if there is any part of the mean diurnal variations which is due to local causes, we should be able to separate that part from any other which may be due to general or cosmic causes.

When it is remembered that the range of the mean diurnal variation with us is from two to three hundredths of an inch of mercury, and that the epochs of maximum or minimum may be shifted an hour by a difference of one or two thousandths of an inch, it will be seen how essential it is that the instruments, the observations, and the corrections shall be the best, in order to be sure that we have real variations of atmospheric pressure before

us.

In order to obtain the best possible results, my investigations have been limited to observations made in firstclass observatories with standard instruments. From observations made during several years at Makerstoun, Dublin, Greenwich, and Brussels, I have sought by the harmonic analysis the functions of sines which represent them most accurately. I give here the equations for the means of the three months in question-May, June, and July. The variation, v, is in ten-thousandths of an inch of mercury; the origin for each of the four stations M, D, G, and B, is mean midnight (0 = 0);—

M, v 56 sin (+ 355°) + 68 sin (20 + 143°) + 21 sin (36 + 1710)
D, v 51 sin (+ 3580) + 72 sin (20 + 1440) + 25 sin (30 + 153°)
G, v 63 sin (+3460) + 88 sin (20 + 143°) + 25 sin (30 + 1540)
B, v 43 sin (e + 354o) + 92 sin (28 + 140°o) + 24 sin (30 +1700)

The terms on the right of each equation represent the oscillations, whose superposition completes the whole diurnal variation. We find

From the 1st term that the epochs of the maximum and minimum were the same within a few minutes at M, D, and B (as shown by the arguments 355°, 358°, and 354°), differing at Greenwich from the others by about 40m.

From the 2nd term, that of the semi-diurnal oscillation,

The exact agreement in the epochs of maxima and minima and the regularity of the variation of range with latitude in the semi-diurnal oscillation show that this oscillation obeys a general law. Dr. Lamont has supposed that the Ist term, or single oscillation, is due to variation of temperature; this, I believe, is not the case. When we compare the terms for different seasons of the year, we find that for the same place the epochs of maximum and minimum may vary twelve hours in the single oscillation, while the epochs deduced from the same term for the temperature variations do not differ one hour. Not only so, I have found on the South Indian Ghats that the epochs deduced from the 1st term of the barometric equations vary seven hours in ascending 6,000 feet; while those shown by the 2nd term are absolutely

constant.

For all these reasons I conclude that the semi-diurnal oscillation of the atmospheric pressure is due to a cosmic cause, independent of local influences, while the single diurnal oscillation shows that part of the solar action which is modified by atmospheric conditions yet to be determined. The results for the four stations just given are a few links in a long chain of facts which tend to prove that the semi-diurnal oscillation of the barometer is due to an action of the sun, which is repeated equally, twice in each day, like the solar oceanic tide.

It will be seen, I think, from the results obtained from the Brussels, Greenwich, Dublin, and Makerstoun observations that the differences noticed at the beginning of this article cannot be allowed to enter as data into the domain of meteorology without much greater study of all the circumstances on which they depend. The facts of atmospheric variations are very difficult of explanation, but if we begin to admit results which may be purely instrumental among these facts explanation will become impossible.

It is a fact that the true temperature of the mercurial columns has not always been obtained, and when we have to discuss observations with self-registering instruments, many sources of error, including those of temperature on the apparatus itself, have to be cared for. At stations near the sea, such as Helder, Valentia, and Falmouth, we have also to remember that in the varying height of the partial base of the atmosphere, through the solar oceanic tide, there is a real cause of diurnal barometric oscillation whose amount and epochs should be ascertained and deducted before exact comparisons can be made with observations inland. At the same time I would remark that of the stations here considered Dublin is near the sea, while the others are more or less distant from it. JOHN ALLAN BROUN

region to make it the local representative of that plant. Its home is the sub-littoral zone of South-western Marocco, where it is common between the rivers Tensift and Sous.

A few scattered trees only are said to be found north of the Tensift; but it seems to be not infrequent in the hilly district between the Sous and the river of Oued Noun, making the total length of its area about 200 miles. Extending from near the coast for a distance of thirty or forty miles inland, it is absolutely unknown elsewhere in the world. The trunk always divides at a height of eight or ten feet from the ground, and sends out numerous spreading, nearly horizontal branches. The growth is apparently very slow, and the trees that attain a girth of twelve to fifteen feet are probably of great antiquity. The minor branches and young shoots are beset with stiff thick spines, and the leaves are like those of the olive in shape, but of a fuller green, somewhat paler on the under side. Unlike the olive, the wood is of extreme hardness, and seemingly indestructible by insects, as we saw no example of a hollow trunk. The fruit, much like a large olive in appearance, but varying much in size and shape, is greedily devoured by goats, sheep, camels, and cows, but refused by horses and mules; its hard kernel furnishes the oil which replaces that of the olive in the cookery of South Marocco, and is so unpleasant to the unaccustomed palate of Europeans. The annexed cut, showing an average Argan, about twenty-five feet in height, and covering a space of sixty or seventy feet in diameter, with another, where goats are seen feeding on the fruit, exhibits a scene which at first much amused us, as we had not been accustomed to consider the goat as an arboreal quadruped. Owing to the spreading habit of the branches, which in the older trees approach very near to the ground, no young seedlings are seen where the trees are near together, and but little vegetation, excepting small annuals; but in open places, and on the outer skirts of the forest, there grows in abundance a peculiar species of Thyme (7. Broussonnetii), with broadly ovate leaves and bracts that are coloured red or purple, and the characteristic strong scent of that tribe. It is interesting to the botanist as an endemic species, occupying almost exactly the same geographical area as the Argan. As we afterwards found, it is replaced in the interior of the country by an allied, but quite distinct, species. Its penetrating odour seems to be noxious to moths, as the dried twigs and leaves are much used in Mogador, and found effectual for the preservation of woollen stuffs."

Stopping at Shedma, Aïn Oumast, Sheshaoua, Misra ben Kara, Marocco was at last in view. From whatever side it be approached, this city presents an imposing appearance. The western side presented an outline about a mile and a half in length. Massive walls some thirty feet in height, with square towers at intervals of about 170 yards, completely inclose it, and on two sides at least it is girdled by a wide belt of gardens in which the date palm, the olive, and fig, are conspicuous objects. We must refer the reader to the volume for an account of the sojourn in Marocco. Some difficulties with the Governor were got over by the quiet determination of Sir Joseph Hooker, whose knowledge of the Oriental character acquired in Asia here stood him in good

service.

The outline of the Great Atlas range was quite visible from the terraced roof of the house in Marocco occupied by the travellers, though owing to the prevalence of clouds they failed to secure a satisfactory sketch of these. Through the kindness of Sir J. D. Hay, they are, however, enabled to insert a copy of a drawing made in 1829 by Mr. William Prinsep, the correctness of which they endorse. On May 8 Marocco was left for the mountains. The cavalcade was a large one, consisting of thirty-seven souls and thirty-three horses and mules. The baggage formed a good load for nine mules. The route lay south-east, but the upward slope became hardly

perceptible, when before sunset they were compelled to stop for the night at the house of the Kaïd of Mesfioua, at an elevation of about 2,400 feet over the sea. The next morning they were off pretty early, and soon began to ascend, often riding along hollow ways between high banks or lofty hedges formed of tangled shrubs and climbing plants, in which were mingled some familiar forms with several altogether new.

"The date-palm had disappeared soon after we entered the hills; here, and elsewhere on our route, it seems to be confined to the lower region, rarely attaining the level of 3,000 feet above the sea. Its place was here supplied by the palmetto (Chamarops humilis), which seldom forms a trunk, perhaps because it is not allowed to attain a sufficient age. As we advanced, the vegetation constantly offered a more varied and attractive aspect; and one of our first prizes was a new species of thyme (Thymus maroccanus, Ball), somewhat like the species of the Argan zone, but with oblong leaves and uncoloured bracts. Of comparatively familiar forms there were Cistus monspeliensis and C. polymorphus, the first species of that genus that we had seen in South Marocco, the pretty little Cleonia lusitanica, with many other Labiatæ. Of plants new to our eyes by far the most interesting was the curious Polygala balansa. To those who know only the milkworts of Europe and North America it must seem strange to hear of a large shrubby Polygala, with branches that end in a sharp point, few small leaves, so quickly deciduous that it generally appears quite leafless, and large flowers of a showy purple-red colour. In truth, although there is great variety of form in this large genus, the species which is common throughout the lower valleys of the Great Atlas is very distinct from all its congeners. In Arabia and South Africa there are some species forming dwarf bushes with spinescent branches, but in other respects very different. When full grown this is six or eight feet in height; and the round, green, almost leafless stems give it, when the flowers are absent, much the appearance of Spartium junceum, the large broom of Southern Europe.

"After riding some way up a rather steep stony track, we reached a grove of very fine olive trees, and our escort came to a halt. We had reached Tasseremout. For some time we had seen a large pile of solid masonry which crowned the hill immediately above the olive grove. This seemed to deserve a visit; but, on the other hand, the attractions of the surrounding vegetation were irresistible to botanists. The matter was settled by Hooker proceeding to visit the castle with the Kaïd, while Ball botanised, and Maw secured living specimens of some of the more interesting plants."

The castle of Tasseremout is one out of a large number of similar buildings standing on the northern outworks of the Great Atlas chain that will afford interesting matter for inquiry to future travellers when the country becomes more accessible, and the lessened jealousy of the natives will make a thorough examination of them less impossible than it would be at present. The natives vaguely attribute their construction to Christians or Romans, the same word conveying either meaning; but the Jews often explain this to mean Portuguese. The general character of these buildings, as far as our information goes, is tolerably uniform. The walls are of great thickness and built of rough hewn stone: the arches are always rounded and the lower chambers vaulted; and they are evidently places of defence. There is little reason to believe that the Portuguese, who held at one time or other most of the Atlantic coast of Marocco, ever established a firm footing inland, and still less that they had such a hold on South Marocco as would be implied by the erection of a chain of forts along the foot of the Atlas. On the other hand, the history of Mauritania during the long period of the decline of Rome, and preceding the Saracen conquest, is an almost complete blank, save for a few apocryphal stories.