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the corpuscular radiation is small. For a slightly more lished in 1571, with a second edition in 1591, wherein the penetrating primary beam a rapid increase in the intensity “composition of the instrument called Theodelitus is of both the secondary Röntgen radiation and the corpuscular represented as a “circle diuided in 360 grades or degrees, radiation takes place. This seems to suggest that the oi a semi-circle parted in 180 portions”; or again, the production of corpuscular radiation is in some way in- composition also of the Square and Planisphere or Circle timately associated with the emission of the Röntgen type named Theodelitus for measuring lengthes, breadths, and of radiation.

distances.It had a double scale," index,' (2) I had recently shown that when homogeneous radia- sightes," and the circle was 2 feet in diameter, and tion falls upon a thin layer of a substance which may act “ fastened in the top of some staffe.” He does not state as a secondary radiator, a portion is transmitted unchanged, how the name was derived, and spells it theodeand that the fraction of the remaining energy which is

and “theodolitus " alternately. William Bourne transformed into secondary Röntgen radiation decreases as (““ Treasure for Travailers," 1578) named the same instruthe primary beam becomes more penetrating. In the

horizontall or fatte sphere," and not theodelitus ; present experiments it is found that the corresponding frac- but when he speaks of the alidade he calls it only once tion of the remaining energy which is transformed into alideday, but otherwise always athelida. After this corpuscular radiation increases as the primary beam be- de Morgan, who first discussed the derivation in the comes more penetrating.

Philosophical Magazine, concluded that the “theodelited (3) The corpuscular radiation emitted by these metals circle” of Digges, who, however, does not that when subjected to homogeneous beams is itself surprisingly adjective, and athelidated circle of Bourne, homogeneous, whether the exciting beams are

various corruptions of the Arabic word al-idhâda (a sort very .

of rule), from which the word alidade, which carries the (4) The absorption coefficients of the corpuscular radiation sights or telescope of a theodolite, is derived. from a given metal excited by homogeneous secondary It has been suggested by various writers that theodolite Röntgen radiation vary with the nature of the exciting is derived from the Greek roots Béā (sight), dós (the way), radiation. These absorption coefficients are a decreasing and 1100s (a stone), for the latter root ditós (smooth) being linear function of the atomic weight of the secondary radiator.

I hope to publish further details of these experiments shortly.

CHARLES A. SADLER. George Holt Physics Laboratory,

Liverpool University.

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Drought in South-west Ireland. THE deficiency of rainfall in the south of Ireland, to which Mr. Armstrong refers in NATURE of October 21 (p. 487), has been apparent in the annual total rainfall for the last three years, the deficiency also affecting the southwest of England. At the same time, there has been a marked excess of rainfall in the north of Ireland, deficiency and excess being taken as synonymous with quantities below and above the average of many years. It is frequently found that parts of the country, often quite narrow strips, show a marked deficiency of rainfall for several successive years, and afterwards revert to an average condition or show an excess. The most probable explanation seems to me to be a change, perhaps a slight one, in the prevailing tracks of the centres of barometric minima, but I have not found data in a form suitable for testing the truth of the suggestion.

The extreme dryness of August was experienced over a large area of the south of Ireland, less than half an inch of rain having fallen over about 2800 square miles. In September less than half an inch fell over not more than 500 square miles.

I may perhaps be excused for pointing out that while Mr. Armstrong uses.“ absolute drought to describe a period of twenty-four hours without rain, it has been usual for many years to reserve the words “absolute drought for a period of more than fourteen consecutive days without recorded rainfall.

High ROBERT MILL. 62 Camden Square, London, N.W., October 25.

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Derivation of the Word " Theodolite." ALTHOUGH the etymology of the word theodolite has been discussed from time to time,' no satisfactory solution has hitherto been established. It was first used in England, and the earliest reference to it is contained in a book by Leonard Digges (completed and published by his son, Thomas) called Geometrical practical treatize, named Pantometria, diuided into three bookes, longimetria, planimetria, and stereometria, &c.,” first pub

1 Philosophical Magasine, vol. xxviii. (1846), note by de Morgan, po. 287-9. Poggendorff's Annalen. vol. cxxxiii. (1868), pp. 192. 349. Zeit. schrift für Vermessungswesen (1880). p. 55: (1883). p. 321 ;(1908), pp. 81-91 and 113-25. Vogler's Praktische Geometrie (1886), d. 361. Proc. Inst. C.E., vol. clxxiii. (1907-8). P. 330. Preussische Jahrbücher, note by Prof. Didolff, vol. cxvi. ! 1904), pp. 362-4.

substituted by others; also from Bedw (I see) and Solixos (long). Another suggested derivation is the English article the combined with the Arabic alidhada.

In searching for a more satisfactory solution, the idea occurred to the writer that the word would naturally be compounded to represent the principal parts of the instrument, and when reading Prof. E. Hammer's latest and most interesting discussion in the Zeitschrift für Vermessungswesen, vol. xxxvii. (1908), pp. 81-91 and 113-25, he was impressed by one of the illustrations reproduced of Digges' theodolitus and description of it, with special mention of the words “sightes," " index," and double scale." He would submit, therefore, that the true etymology is from the Greek words θέα = a sight ; όδελός = any pointed instrument; itüsra circle or a felloe of a wheel. These Greek words appear to be those which would actually denote the three essential parts of the instrument, viz. the sight, the index arm, or alidade (Digges uses the word index, never alidade), which is represented as a pointed instrument, and the limb of graduated circle. The spaces on the circle appear like the



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be adınitted that Higgins, who stated these facts and a basis of a purely physical kind for the determinareasoned very justly upon them in his “ Comparative tion of atomic weights, for it means that the atomic View of the Phlogistic and Anti-phlogistic Hypo- weights of different gases stand in the same ratio to theses "

(1789), did not give any sign, by collating one another as the weights of equal volumes of the them, that he felt himself on the threshold of a great gases. discovery. Again, Gay-Lussac and Humboldt, taking The “ volume-theory," plausible as it seems, inup the study, for purposes of eudiometry, of the com- volved its author in difficulties one after another, bination of hydrogen and oxygen, found the ratio which finally became overwhelming. Or, arises as between these gases to be 2 : 1 as nearly as they could as the theory is formulated. Each atom of

This was in 1804. The observation arrested hydrogen, on combining with chlorine, could, as Gay-Lussac's attention. Curious to find if other such-Berzelius and Dalton understood the atom, yield only like cases exist, he began work which resulted in the one compound atom of hydrochloric acid. But the discovery of his law, one of the most important in volume of the hydrogen is half that of the hydroscience.

chloric acid which it produces, so that the atom of the • Gay-Lussac, like Newton, did not form hypotheses. element occupies only half the volume of the compound The memoir in which he set forth his work is remark- atom. Hence the theory must either be limited to ably free from speculative matter. His conviction was elements. or given up altogether. Years before that " in natural science, and above all in chemistry, Dalton had to face the same difficulty in the case of generalisation should come after and not before a nitric oxide. What he did at first was to abandon minute knowledge of each fact.” And assuredly the outright the hypothesis that atoms of different gases history of Gay-Lussac's law in science does show that have the same volume, and then to object even to a “ law of nature may prove a dangerous weapon Gay-Lussac's law. Dalton was “ for thorough." to the man who puts it to theoretical and practical What Berzelius did was to make the “ volumeuses, before its range and bearings in nature have theory” apply only to the elements. been accurately fixed.

In course of time another difficulty appeared. The The law when published aroused the widest interest. atoms of many important elements seemed to enter The world of science was just then pondering the into combination only by pairs. This strange result atomic theory in the form impressed on it by Dalton, arose in the following way. Berzelius began in the and it was obvious that theory and law must stand in year 1826 to ascribe the general formula RO to all the most intimate relation to one another. Strangely strong bases. Now, by the chemical equation for the enough, the law was objected to by Dalton of all formation of a chloride from a base-RO+H,C1,= people, and by him alone. In the second part of his RC1, +H,0—it is plain that the amount of acid needed ** New System of Chemical Philosophy," published in to form a chloride with one molecule of a base con1810, he made strictures on it, and concluded :—“ The tains two atoms of hydrogen and two of chlorine. truth is, I believe, that gases do not unite in equal That is, as Berzelius saw, the hydrogen enters into or exact measures in any one instance; when they chemical combination in pairs, and does the appear to do so, it is owing to the inaccuracy of our chlorine atom. experiments. In no case, perhaps, is there a nearer This, be it noted, involves a conception of the approach to mathematical exactness, than in that of element which is precisely the reverse of the modern one measure of oxygen to two of hydrogen ; but here one. Hydrogen is now supposed to consist of physical the most exact experiments I have ever made gave atoms, each of which can be halved when it enters 1'97 hydrogen to I oxygen." Berzelius wrote into chemical combination. The physical atom of Dalton protesting in the most courteous way against hydrogen is composed of two chemical ones. Berzelius the part of the atomic theory " which obliges you to had formed the conception of a chemical atom comdeclare as inaccurate the experiments of Gay-Lussac, posed of two physical ones. It applied to quite a on the volumes in which gases combine. I should large number of elements in addition to hydrogen, have thought rather that these experiments were the namely, to chlorine, fluorine, bromine, iodine, nitrofinest proof of the probability of the theory; and Igen, phosphorus, antimony, and arsenic.

; confess to you, that I will not so readily think Gay- The very natural comment on this was made by Lussac at fault, especially where the point is one of Gmelin, that the "existence of the physical atom was good or of bad measurement.” Nothing, however, improbable and its adoption superfluous and trouble. could ever remove the distrust Dalton felt in the law.

One could arrive at Gmelin's system of The chemists who accepted both Dalton's theory and chemical formulæ by suppressing every pair of Gay-Lussac's law had themselves to solve the problem physical atoms in Berzelius's formulæ, and putting in of defining the relation between the two. No more a chemical atom instead. Thus H,O became HO. than Dalton would Gay-Lussac do anything to help Nobody could help seeing that Berzelius's system them. Even so late as the year 1814, in his memoir simply led the way to Gmelin's. This was a great on iodine, and in the one on prussic acid of the blow to the “ volume-theory,” for Gmelin's system following year, he ignores the atomic theory. He differs from Berzelius's only by leaving out the uses the word “ molecule " for the sake of convenience, “ volume-theory and all its consequences. and that is all. Yet there must be a connection The above as an objection to the theory was per. between the specific gravities, that is, the weights of ceived and felt to be overwhelming only in course of equal volumes, of different gases and their atomic time. As already explained, from the first the theory weights. This connection is the primary subject of could include in its scope only the elements. But a paper by Prout, published in 1815. Here he before long Berzelius liad to limit the theory still advanced his famous hypothesis that the atomic further. So long as it is applied to elements the weights of the elements are multiples of the atomic molecules of which are of the same degree of comweight of hydrogen, but there is good reason to think plexity, hydrogen and oxygen, for instance, the that the hypothesis was conceived after the data had physical method of finding atomic weights is in agreebeen rounded off.

ment with the chemical. The ratio H,/0,, which the Berzelius had already, in 1813, if not earlier, given former method gives, is the same as the ratio H/O his solution of the problem. This was his “ volume- given by the latter. But this is a matter of accident. theory,” that equal volumes of different gases contain About the year 1826 Dumas succeeded in finding the the same number of atoms. This hypothesis affords vapour-density of elements such as mercury and phos




phorus, and was therefore enabled to calculate their the year 1819, in conjunction with Dulong, he deterrespective atomic weights by the physical method. mined the atomic weight of carbon by the physical For mercury the ratios are Hg/0, (physical) and method. The process adopted was to weigh a certain Hg/O (chemical), and for phosphorus P.70, (physical) bulk of carbon dioxide and subtract the weight of the and P/O (chemical).

same bulk of oxygen. The difference is the weight of These discrepancies forced Berzelius to limit the the carbon, on the incorrect assumption that carbon “ volume-theory to gaseous elements, and to such as dioxide contains exactly its own bulk of oxygen. The are easily converted into gas. Finally, when dis- atomic weight was found to be . 76'44 (0= 100) or crepancies, no less serious, arose in the case of sulphur 12'23 (O=16). This datum, which as a matter of fact and of arsenic, he decided to abandon the theory. is much too high,' was long used in chemistry. This was in 1833, after he had held to it for twenty Berzelius should not have fallen into this error, for he years.

had received a warning two years before against the The only sound application of the law to theoretical danger of the physical method. He had determined chemistry was made by Avogadro in 1811. In con- the atomic weight of sulphur by an experiment, similar sidering his teaching, it is best to set aside the word to the carbon dioxide one, with sulphur dioxide, and atom and its associations, at least in the first place, he set aside the result, which was 103-35 (0= 100), and to use the word “ molecule " instead. Avogadro's because it differed so much from the figure, 100 7, hypothesis is that equal volumes of different gases which he had obtained by a chemical method. contain the same number of molecules. In that case Dumas and Stas found it necessary, in the year the weights of equal volumes of gases are proportional 1839, to embark on a re-investigation of the atomic to their molecular weights.

weight of carbon. Dumas had been analysing the The hypothesis has a special and important conse- hydrocarbon naphthalene, and had obtained the quence regarding the constitution of the molecule. anomalous result, again and again, that the perFor instance, each molecule of hydrogen, with the centages of carbon and hydrogen added up to much necessary chlorine, yields two molecules of hydro- | more than 100. As a result, the atomic weight of chloric acid. But each molecule of the acid contains carbon was found to be 75'00, instead of 76-44, as hydrogen, and therefore the hydrogen molecule has Berzelius had said. certainly been halved. This conception of the molecule

This was

severe blow to Berzelius. He had of an element as a thing which may consist of parts endured many reverses. One cherished conviction of is an inevitable consequence of Avogadro's hypothesis, his had gone after another. Chlorine and nitrogen and it was boldly accepted by him. The mere possi- had proved to be elements and not compounds of bility of such a thing was scouted by Thomson, and oxygen, the “ volume-theory” had become untenable, Berzelius, and Graham as utterly subversive of the his electrochemical theory was undermined, and his atomic theory. Yet it forced itself forward again and system of chemistry was threatened by Gmelin. again upon Ampère, Dumas, Prout, Waterston, Berzelius was yet the great master of atomic-weight Krönig, Gerhardt, Laurent, Clausius. Finally, in determination. Even that satisfaction was now denied 1860, Cannizzaro was able to convert chemists to him; none of his atomic weights was to be above Avogadro's hypothesis and all its consequences. Since suspicion any longer, all because he had made an then the hypothesis, based as it is upon Gay-Lussac's unjustified use of Gay-Lussac's law, twenty years law, has been the fundamental doctrine of chemistry. before. There is a strange irony in the difficulties in

One thing about the definition of the law is worth which Berzelius involved himself time and again by noting. Nothing is said in it, but much is implied, his use of this law, in view of the protest he had made regarding the conditions under which the gases are against Dalton's refusal to accept it. measured. The teacher would do well to direct atten

A. N. MELDRUM. tion to this. There is the obvious assumption that the different gases concerned in a particular experiment are measured under the same temperature and

ANEMOGRAPHIC OBSERVATIONS IN INDIA.1 pressure. But the definition implies another assumption, namely, that different gases behave in the same Eliot, whose loss, while he was still capable of way under the same conditions. Otherwise the com- much useful work, all meteorologists deplore. They bining ratio, say, of hydrogen and chlorine, could not deal with the changes in wind direction and force at remain constant over a range of temperature and the stations, showing both the diurnal and the pressure.

seasonal variations, and form a store-house of inOf course, we know that the combining ratio of formation for anyone who wishes to study the Indian two gases does not remain strictly constant when the monsoons. conditions alter. The fact that a gas such as carbon Saugor Island is situated in the north-west of the dioxide deviates considerably from Boyle's law and Bay of Bengal on the coast, about sixty-five miles in Charles's law leads to the expectation that Gay- a direct line from Calcutta, and ninety if the bends of Lussac's law is itself only an imperfect description of the river are followed. The land around it is perfectly the facts. The expectation is verified, for even the flat, and only a few feet above the sea, so that the combining ratio of hydrogen and oxygen is not exposure is an excellent one. strictly 2 : 1, but has been ascertained to be 2'00285 The land at Alipore is also flat, but there are many (Scott), 2'0037 (Leduc), and 2'0027 (Morley). This is trees in the district the tops of which are level with or an important consideration, for molecular and atomic above the anemometer. As might be expected, the weight data obtained on the assumption that Gay- winds are far stronger at the coast station. Lussac's law is strictly accurate must be defective. Saugor Island lies in the track of the circular storms The physical method cannot lead to the same result (cyclones) of the Bay of Bengal, and it is of interest as the chemical until a correction is introduced, and to compare the maximum hourly velocity in these then the discrepancy is found to disappear. One 1 A Discussion of the Anemographic Observations recorded at Sangor systematic way of making this correction has been Island from March, 1880, to February, 1904. Also at Alipore, Calcutta,

from March, 1877, to February, 1904. Vol. xviii., part ii. devised and used by M. Daniel Berthelot, and another

mark from September, 1883, to April, 1887. Also at Nagpur from January, by M. Guye.

1882, to December, 1902.

Vol. xix., part i.

At Roorkee from September,

1879, to August, 1904. At Lahore from January, 1889, 10 May, 1905. Berzelius was led into a grave numerical error by

Mussoorie from May to October, 1877 to 1888. (London: Harrison and his unqualified acceptance of Gay-Lussac's law. In Sor.s.)

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storms with that which occurs in other places. Unfor- front, partly from the side. This curious disposition tunately, the factor that has been used is not given, of the branching is met with, not only at Cretas, but but it is probably the old erroneous factor 3. It is also at Cogul (Lerida), and in France in the reindeer in few years that this velocity exceeds 50 miles per drawings of the Portel grotto. This points to a closer hour-31 on the present scale of the Meteorological connection in late Quaternary times of the tribes of Office—and there are few stations on the British coast Aragon and Catalonia with those of the Ariège than at which this is not often exceeded. One instance of with any others. 90 (66 corrected) is given.

The second part of the article describes a series of It does not seem unlikely that the violence of the rock paintings at Cogul, in Lerida (Catalonia), which tropical hurricanes is somewhat overestimated owing was brought to the public notice in 1907. The to the contrast with the usual calm of the tropics, and surface painted measures about

across, and also, perhaps, because the proximity of violent winds lies beneath a ledge of rock. Altogether there are from different directions produces a very irregular and five distinct pictures. Two are hunting scenes, of dangerous sea.

which the figures are drawn schematically. M. C. The memoirs also contain curves showing the direc- Rocafort regards this as a hieroglyphic inscription, tion and magnitude of the daily variation. The results possibly of the Iberian period, but the authors confor St. Helena have lately been treated in a similar sider that it cannot be thus separated as regards manner with very interesting results. The daily oscil- date from the accompanying paintings. The third lation of the barometer, more particularly the second picture (measuring. 75 cm. across) represents a stag term in the harmonic series with the twelve-hour surrounded by hinds. The animals of this group are period, must be associated with the transfer of a con- less realistic than those of Cretas, but none the less siderable mass of air from place to place, and it is of the execution is delicate, and the attitudes graceful interest to try and trace this transfer in the anemo- and lifelike. metric records from various parts of the globe. These The right-hand lower scene apparently reprevariations, as they are shown at the mouth of the

sents nine women dancing round a man, four Ganges and in Northern India, are very fully dis- being to the right of the man, and five to the cussed. The conditions are naturally very different left. The man is much smaller than the women, and at the different stations, both in space and with the has no clothing beyond an ornament at the knees; changing seasons, and the causes that produce local the women are all wearing petticoats reaching to the winds are so complex that it is almost hopeless to try knees, while the upper part of the body is bare The and correlate cause and effect. At all the stations figures are painted in black, red, or black and red; the the change from hour to hour seems to be

man is dark brown rather than black. The outlines large by day and small by night, from which of the four right-hand figures are emphasised by enone may perhaps conclude that local heating by graving. The whole group measures 68 cm. across. the sun plays an important part in the pheno- The dress of the women presents a superficial

analogy with the Cretan series, but the lifelike charAlthough the observations at Mussoorie were only acter of the Minoan figures and many details are in taken during the summer, they are of especial interest, strong contrast with the stiffness of the Cogul since the station stands on the summit of one of the “ ladies." Much more definite evidence would be outer ridges of the Himalayas at an elevation of some

necessary in order to establish any connection between 6500 feet above the sea. The hourly and monthly the two series. values, as at the other inland stations, are very com- The style of the animal frescoes at Cogul, as of plex; but there is, as might be expected, a distinct

those of the Calapatà (Cretas), is that of our Quatertendency for the air to run up the slope of the moun- nary drawings, not of later art. This indication is tains during the day. and down during the night. corroborated by the presence, not far from the painted Naturally, also, the winds are stronger than at the rock at Cogul, of small Magdalenian stations with stations in the plains.

numerous flint flakes in some cases retouched) of

the type usual in France. Thus it is certain that in ROCK PAINTINGS OF THE LOWER EBRO. the immediate neighbourhood of the painted rocks VERY interesting article on this subject by MM.

there existed stations of the late Palæolithic age, conA

l'Abbé Breuil and Juan Cabré appeared in the temporary with our civilisation of the Reindeer age; January-February number of l'Anthropologie. The it is also highly probable that the whole of these openfirst part of the paper deals with the painted rocks on air frescoes are to be attributed to the peoples living the Calapatà at Cretas (Teruel) first observed by M. there; those of single animals afford further beautiful Cabré in 1903, although it was not until 1906' that specimens of Quaternary art in animal-drawing. The he communicated his discovery, having then realised hunting pictures at Cogul introduce a historic scenic its significance in relation to Quaternary art. The episode as yet unknown in mural art. The dancing pictures, which are painted under a shallow shelter, scene described raises a small corner of the veil drawn represent animals in various attitudes, and show con- over the social life of those remote ages, and the style siderable vigour of execution. Close by, flint flakes of dress tells us something of the use to which the are to be found which exhibit no Neolithic characters, Magdalenian seamstresses put those fine eye-needles but rather Magdalenian. The paintings comprise which the caves of the Cantabrian Mountains, the three deer, a bull, and a small subject difficult to de- Pyrenees, and Dordogne have so long yielded to the termine. All are done in dark red, and are outlined astonished eyes of investigators. by a very lightly engraved line; certain details, such as eyes and nostrils, are added in the same way, as

PROF. HUGH BLACKBURN. they would not otherwise appear in a monochrome without shading. The first deer, measuring. 30, cm.

THE unexpected decease of Prof. Hugh Blackburn,

who occupied the chair of mathematics in the by 25 cm., is represented in a graceful attitude in University of Glasgow from 1849 to 1879, was the act of rising to its feet; the second (33 cm. by announced by Principal Sir Donald MacAlister to the 27 cm.) is walking rapidly towards the first, the great audience of students and friends assembled to movement being admirably depicted. It is interesting hear the inaugural address of Prof. Gibson. The to note that in all the stags drawn in profile the news came as a great shock to such former students antlers are conventional, as if seen partly from the were present, among them his then retiring




successor, Prof. Jack, and Prof. Gibson himself, and " Principia." Later, Prof. Blackburn published a reProf. Blackburn's old student, colleague and life-long vised and extended edition of Sir George Airy's friend, Prof. Ferguson. It was well known that treatise on trigonometry from the “Encyclopædia Prof. Blackburn's health had broken down seriously Metropolitana," which appeared in a separate cabinet in the spring, and that there had been no sensible form in 1855. improvement, but the actual news was unexpected. William Thomson entered in 1846 on his splendid

Prof. Blackburn's family have been connected with tenure of the chair in natural philosophy in Glasgow, Glasgow for at least three centuries. An ancestor of which he filled for fifty-three years. Two years later his, Peter Blackburn, was one of the “regents " of his father, the professor of mathematics ihere, died the slowly growing University, from 1574. He was unexpectedly, and it was probably largely due to appointed when the Town Council handed over to the Thomson's entire conviction of the exceptional L'niversity grants made to themselves of lands and mathematical ability of his friend that Prof. Blackburn buildings by Queen Mary in 1567. From that time was appointed in 1849 to succeed Prof. James until Peter Blackburn was appointed a regent in | Thomson. 1874 the University had been all but moribund. His students always felt for him the greatest affecBlackburn was brought from St. Andrews, where he tion and respect. Every teacher's qualities are aphad graduated, and he acted as regent shortly before praised by the world very much as Mr. Lowe used to the arrival of the great reformer Andrew Melville. judge primary teachers under the famous revised code During Melville's epoch-making six years as prin- |-by results. Prof. Blackburn had many distinguished cipal, and for two years after it, Mr. Blackburn acted pupils who took high places in the mathematical as third or principal “regent.” The regents used world. I may name Dr. Thomas Muir, who was an each to take the students committed to them through admirable assistant to the professor, and who has all their subjects, and for their whole university never, in spite of his engrossing duties as director of course. Melville revolutionised this system, setting education in Cape Colony, intermitted his work on each regent to teach some special branch of the

determinants. There was Sir Charles Abercrombie graduation course to all the students. Mr. Black-Smith, formerly Auditor-General in Cape Colony and burn was, in fact, “ professor " of physics and astro- now Vice-Chancellor of the Cape University ; Mr. nomy in the modern sense until he left for Aberdeen, Dickson and Mr. Dodds, formerly tutors of Peterhouse; two years after Melville had left for St. Andrews. Prof. Pinkerton, of Cardiff, and Mr. Nixon, of Balfast.

It is curious to find the name Peter surviving after But Prof. Blackburn was much more than a three centuries in the family of which Prof. Blackburn mathematician. His university speedily discovered his was a member. His eldest brother was Peter Black

administrative and financial strength, and made him burn, long M.P. for Stirlingshire and chairman of successively convener of its library and its finance the Edinburgh and Glasgow Railway before it was committees. Mr. Blackburn was, perhaps. more merged into the North British. His second brother, trusted and more responsible than any of his colColin Blackburn, afterwards the famous Lord Black-leagues in the removal of the old college from the site burn of the High Court of Appeal, was eighth it had occupied for four centuries, after it had become wrangler in 1835, and Hugh Blackburn, the youngest unsuitable and perhaps insanitary, to the present brother, was fifth wrangler in 1845. It was a memor- splendid buildings. Among his colleagues his authority able year at Cambridge. William Thomson, after

was always great, and he owed this to the strength wards Lord Kelvin, then a boy of eight, came across

and simplicity of his character, and to the clearness from Belfast to Glasgow, where, in 1832, his father

of his practical and judicial mind. Students and colhad been appointed professor of mathematics. At the leagues alike, who knew him better than others could, age of twenty-one he was second wrangler and first

honoured him and believed in him. Of a sensitive Smith's prizeman, and founder and editor of the and artistic nature, he did not, however, care, after famous Cambridge and Dublin Mathematical Journal. thirty years, to continue services which increasing To its first volume Prof. Blackburn contributed a

deafness made irksome and difficult. paper on the variation of elements in the planetary

For years, Prof. Blackburn, in declining strength system. Nothing quite like that first volume had pre- and health, never left the estate, beyond the Mull of viously appeared in the British mathematical world.

Ardnamurchan, where he had found a home in 1879, Side by side with Prof. Blackburn's paper were one by

and where he died. Cayley (senior wrangler in 1842); a note on induced magnetism on a plate, by William Thomson ; a paper by Sir William Rowan Hamilton, Irish Astronomer

NOTES. Royal; and another on quadrature of surfaces of the Sir RAY LANKESTER writes to inform us that he has second order, by Mr. John H. Jellett, fellow, and heard from the representatives of the late Prof. Anton tutor, and afterwards provost, of Trinity College,

Dohrn to the effect that the Zoological Station at Naples · Dublin. In the same volume there were papers by remains the property of the heirs of its founder. Neither Leslie Ellis, senior wrangler in 1840; by Boole, afterwards the famous professor at Cork; by Augustus the German Government nor any German society have de Morgan, London; by Stokes, senior wrangler in acquired any rights in its future disposition. Dr. Reinhardt 1841; by D. F. Gregory, fifth wrangler in 1837; by Dohrn, who has for two years been the acting director of Townsend, of Dublin, and Liouville, of Paris, with the Zoological Station of Naples, is now director, and has four other papers by the young editor himself. In that inherited from his father (by agreement with his brothers) splendid galaxy of men of mathematical genius Prof. the actual property and the leases granted by the Naples Blackburn took a distinguished place, and he had municipality as to the site. We wish Dr. Reinhardt deeply impressed his friends, and Thomson, no doubt, Dohrn success and happiness in carrying on the work of in particular, by inventing and exhibiting in his his eminent father.

his well-known pendulum with double suspension. A little later the two_young Scotchmen,

The Meteorological Office has received reports of Thomson and Blackburn, went to Paris together on a

observations of an aurora on the nights of October 17, 18, mathematical and physical pilgrimage, and all their and 19, at several places in England, Scotland, and Ireland. lives they remained attached and devoted friends. In An aurora is also reported in the French Bulletin Inter1871 they published together the full text of Newton's national as having occurred at Haparanda on the night

W. J.


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