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THE LATE MR. ARCHIBALD SMITH

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In 1862 he, conjointly with Captain Evans, the present chief of the Compass department, prepared the Admiralty

MR. ARCHIBALD SMITH was born at Glasgow Compass Manual, a book which has since been translated

in 1813; his father, Mr. James Smith, of Jordanhill, Lanarkshire, was well known as a geologist, and as the author of a learned and critical work on the Voyage and Shipwreck of St. Paul.

At the University of Glasgow Mr. Smith was a contemporary of the late Norman McLeod and of the present Archbishop of Canterbury, with both of whom he retained a friendship through life.

From Glasgow he went to Trinity College, Cambridge, where, while still an undergraduate, he commenced to contribute papers to the Mathematical journals; his first, a most important paper "On the Equation to Fresnel's Wave Surface," is an excellent example of the extreme neatness and elegance of his style; it was published under the signature A. S. in the Cambridge Phil. Trans. and in the Phil. Magazine.

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He, however, as the result well showed, did not allow his amateur mathematics to interfere with the regular course of Tripos reading, and he also found time for a good share of athletic exercise. He pulled in the Trinity boat of which the late Lord Justice Selwyn was stroke; all the oars in that boat were reading men, and were familiarly known as "Peacock's examples being a well-known tutor of the day). It was no doubt (Peacock owing to Mr. Smith's strong physical constitution which was thus well trained in early life, that he was able so long to sustain the great strain of mental effort and the want of rest to which he never scrupled to subject himself in after years when occasion required.

In 1836 he finished his undergraduate's career by taking the first place in the mathematical tripos as well as the first Smith's prize, and he was soon after elected a Fellow of his College. The second wrangler of his year was Bishop Colenso.

Having chosen the profession of the Chancery Bar, Mr. Smith became a pupil and a friend of Mr. James Parker, afterwards Vice-Chancellor, and is said to have acquired the sound legal learning and careful method which distinguished that judge. It was during the intervals of his laborious Chancery practice that he found time for the long series of magnetic investigations which has made him famous throughout Europe.

His connection with Magnetic Science arose from intimacy with Sir Edward Sabine, the late distinguished president of the Royal Society, and who was interested in the question of the Deviation of the Compass, first as member of a committee appointed by the Admiralty to consider the question, and afterwards as having undertaken the reduction and publication of the magnetic observations made by Sir James Ross in his Antarctic voyage.

In the years 1842 to 1847 Mr. Smith, at General (then Colonel) Sabine's request, deduced from Poisson's general equations, formulæ for the correction of the observations made on board ship. These were published in successive numbers of Sabine's "Contributions to Terrestrial Magnetism," in the Transactions of the Royal Society.

In 1851, at the request of Captain Johnson, the superintendent of the Compass Department of the Royal Navy, he deduced from the formulæ the convenient tabular forms, and computed the auxiliary tables for determining the co-efficients A, B, C, D, E, which have ever since been in use. These were published by the Admiralty in successive editions, but without the demonstrations or formulæ.

In 1859 Mr. Archibald Smith edited and published the voyage of Scoresby to Australia, which was undertaken chiefly for magnetic research; and in his introduction gave, for the first time, the exact formulæ for the effect of the iron of a ship on the compass, the former approximate formulæ being found insufficient.

into French, German, Russian, and Portuguese, and four parts, the first of which contains practical rules to gone through three editions. The work is divided into enable a seaman by the process of swinging his ship to obtain a table of the deviations of the compass on each point, and then to apply the tabular corrections to the courses steered. The second part is a description of which are that it enables the navigator from observations "Napier's graphic method," the practical advantages of equi-distant or not, to construct a curve in which the of deviations made on any number of courses, whether pensated, and which gives him the deviation as well on errors of observation are as far as possible mutually comthe compass courses as on the correct magnetic courses. Part III. contains the practical application to this subject equations deduced by Poisson from Coulomb's theory of of mathematical formulæ derived from the fundamental magnetism. Prior to this time it was considered sufficient to use approximate formulæ, going as far only deviation; but the very large deviations found in ironas terms involving the first powers of the co-efficients of plated ships of war rendered it desirable to use in certain cases the exact instead of the approximate formulæ, and this part was therefore re-written. The fourth part of the "Manual" contains charts of the lines of equal variation, equal dip, and equal horizontal force over the globe; the determine the deviation by astronomical observations, the first for the purpose of enabling the navigator at sea to tions undergo in a lengthened voyage, and to enable the two latter to throw light on the changes which the devianavigator to anticipate the changes which will take place on a change of geographical position.

All Mr. Smith's investigations were undertaken as of the recognitions which he received. labours of love; but we must not leave unnoticed some

Society was awarded to him, and he was elected a correIn the year 1865 one of the Royal medals of the Royal sponding member of the Naval Scientific Committee of Russia; in the following year the Emperor of Russia, gold compass emblazoned with the Imperial arms, and with a most complimentary letter, presented him with a set with brilliants.

present of 2,000l., and intimated the fact to him in a Recently, too, our own Government offered him a handsome letter from the First Lord of the Admiralty, begging his acceptance, not by way of recompense, but as a mark of the high appreciation which the Government had for the services he had rendered.

The history of Mr. Archibald Smith's legal life is soon told. He attained the reputation of being an eminently tice at the bar which was above the average both in concise and perspicuous draughtsman, and made a pracextent and importance.

appointed Mr. Smith his Secretary; but the early death When Sir James Parker was made Vice-Chancellor he of Sir James brought these duties to a close. Later, a declined. It is said that the important change which Judgeship in Queensland was offered to him, which he has substituted figures for words as to dates and sums occurring in bills in Chancery was made at the suggestion of Mr. Archibald Smith.

In 1868, when the Universities of Glasgow and Aber-
deen were formed into a parliamentary constituency the
liberal electors chose Mr. Smith as their candidate, and
for the new seat.
they did their best, though without avail, to bring him in

give up work; but he had greatly rallied; and the attack
About two years ago he was compelled by ill-health to
which ended fatally was totally unexpected, and of but a
few hours' duration. In private life those who knew Mr.
Smith best admired him most; he leaves unnumbered

friends to testify to the noble simplicity of his disposition, and to the true warmth of his heart, which was always open amongst his multifarious and engrossing work.

NEW EXPERIMENTS FOR THE DETERMINATION OF THE VELOCITY OF LIGHT BY M. ALFRED CORNU

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N exact value of the velocity of light is equally interesting to astronomers, for it enables us to calculate an important and not exactly known number, namely, the distance from the sun to the earth, for which cause the learned world is looking forward with so much impatience to the passage of Venus on the disc of the sun, as the observation of this phenomenon, it is hoped, will fill up this chasm. It is interesting to physicists likewise, it is evident, but especially since the remarkable researches of Prof. Clerk-Maxwell, who has found an unexpected relation between the theories of light and electricity.

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M. Alfred Cornu's experiments, to which we now call attention, have for these reasons a great interest.

The first who busied himself with this difficult question was Roemer, a Dane, at the Observatory of Paris, where Picart had called him; but the observation of the eclipses of Jupiter's satellites, although giving a pretty good value of the velocity of light, offers, notwithstanding, some causes of error, especially the difference of brightness of Jupiter's satellites at their maximum or minimum distance from the earth; and it requires moreover an exact value of the diameter of the terrestrial orbit.

M. Fizeau (1849) showed that it was not necessary to employ astronomical phenomena, and that it was possible on the surface of the earth to make use of relatively short distances, such as four or five English miles. This rather bold experiment was much spoken of. He operated between Montmartre and Suresnes, near Paris, at a distance of about five English miles and a half.

Léon Foucault, some time after, putting into execution a project of Arago, proposed another method founded on the revolving mirror of Sir Ch. Wheatstone. The value obtained by him, 189,000 miles (298,000 kilometres) was made use of by astronomers, who deduced for the parallax of the sun a number (8′′. 86), that is in concordance with the best observations of the transit of Venus.

The number obtained at first by M. Fizeau was higher, but it was given by him, who dwelt upon all the difficulties of such a measurement, with hesitation.

M. Alfred Cornu left aside Foucault's method (viz., that of the revolving mirror) which is liable to serious objections, and employed that of M. Fizeau, although he had tried the two methods of experiment at the Polytechnic School, where many physicists were able to see them.

M. Fizeau's method is free from all objection. A ray of light is sent between the teeth of a cog-wheel, and it is reflected at a great distance, so as to bring it back to the point of departure. If the revolving motion given to the wheel is sufficiently rapid, the ray on its way back meets a tooth, instead of a free passage, and does not pass through; when the speed is double, the ray meets the following interval, and passes through again, and so forth alternately for increasing rates of revolution.

Thus the returning ray alternately presents a minimum (or an extinction) and a maximum; but the speed of rotation (in order to be measured) must be kept constant during several seconds in those moments; it is one of the

Everyone knows that in one of the last meetings of the British Associa tion Sir William Thomson has estimated them at their real value.

greatest difficulties of the experiment, for that speed is enormous. Let us add the want of precision in the evolution of a maximum or a minimum.

M. Alfred Cornu has obviated all those difficulties:1. By giving a speed of rotation not constant but increasing or decreasing according to a regular law, which he registers by means of electricity; so that he easily knows the speed at every moment.

2. By registering in the same manner the exact time in which the ray of light disappears and maxiappears again: and thus he does

mum or minimuni, but two instants which are equally distant from the moment that is to be determined.

The various results are traced by fine needles that run on a sheet of paper covered with lamp-black, and rolled round a revolving cylinder. If the needles remain motionless, they describe a helix on the black paper, which becomes a straight line when the cylinder is unrolled. But these points are extremities of armatures of electro-magnets, and are moved when the electricity passes through; and during all the time the current passes, the traced line is above the level of the normal line.

The annexed sketch shows a part of an experiment made in the month of July 1872.

The line a on the right hand side represents the increasing speed of the wheel; each time a cog of the apparatus, in its movement of rotation, touched a certain wire, the electric current had passed through, and deviated the needle for the time the cog was passing (from A to B, from C to D). During the time, from the beginning of one devia tion to the other (from A to C, from C to E, from E to G), 50,000 teeth had passed. We clearly

see that these intervals are decreasing, because the speed increases.

The median line indicates seconds which are sent by an electric clock.

The third line has been obtained by the observer himself by means of a Morse-key; he made the electric current pass during the time the light was invisible; P Q and RS. The sketch thus shows two extinctions and two reappearances of light. It is the beginning of the experi

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Copy of the Automatic Registrations.

This method, moreover, obviates one of the greatest difficulties in physical experiments, namely the noting down of various numbers, that diverts the observer and complicates operations. Furthermore, there remains not only the remembrance of the experiment made, but an exact, real, and living drawing.

M. A. Cornu has, moreover, changed the rather large and expensive apparatus of M. Froment for another,

strong and small, for it is not bigger than the fists. He uses the works of a common clock, which do not cost more than a sovereign. He has only replaced the largest wheel of the scapement by another one, lighter and more finely toothed. Special experiments, not mentioned in his present memoir enabled him to choose the most proper diameter for that cog wheel. A strong spring drives the wheel 700 or 800 revolutions in a second.

A drag has been added, in order to check the speed. By a special arrangement, the rotation of the wheel can be reversed, in order to eliminate certain errors that might result from the apparatus itself.

In order to try the improvements of the appa atus, a first series of experiments was made between the Polytechnic School and a tower of the telegraph office, at a distance of about one mile and a half (2 kilometres and a half). The observer could perceive a window of this tower amid a forest of chimneys. The distance was too short: he prudently did not publish the result.

A second series was attempted by him between the Polytechnic School and the Valérien Hill, at a distance of about six miles and a half (10 kilometres 310 metres).

But a transparent atmosphere is seldom now to be obtained in misty Paris If we go up to the garret where the observer stands, we perceive a sea of roofs below; on the right Montmartre Hill, on the left the heights of Meudon, and in the front the Valérien fortress; in one of the rooms in the barracks the mirror and the collimator were esta-blished.

The apparatus that sends forth the ray of light (an instrument with a large aperture) was laid on a solid timberwork; in front of the eyepiece is the little machine; on the left side the source of light is established, a ray of which, reflected by a glass, is sent between two teeth of the wheel.

But the Mont Valérien is concealed by mist; the window of the barrack is hardly distinguishable, although the sky is cloudless. Paris is covered with a damp and dusty veil. The sun sets behind the fortress, and suddenly the mist disappears and the air becomes transparent. The ray of light between the teeth of the wheel is to be seen in the telescope as a faint star in the midst of the inverted image of the window; it is a star of the sixth magnitude, the intensity of which increases and becomes of the first magnitude with the transparency of the air. But it is necessary to make the experiments hastily, for that transparency will not last more than one hour. *

An obstacle nearly checked the observer; the image often scintillated, and was agitated in such a manner that it was impossible to pursue the experiment. It was the warm air of a chimney unluckily standing in the way of the ray of light, the kitchen chimney of the Lycée Louis le Grand. M. Cornu waited for the holidays, and the operations were at last worked out.

He thus made more than a thousand experiments, and calculated 690 of them.

In order to determine the distance between the two stations, he compared the measures previously determined, and made himself a triangulation; the average of those numbers gave him the number above cited, about six miles and a half (10 kilometres, 310 metres).

He did not at once take the average of the numbers of his experiments, but he gave a greater value to the numbers obtained under the best circumstances. It appears evident that the results deduced from the fifth disappearance of the light are superior to those deduced from the first one, because of the more exact value of the velocity of the wheel, and that the favourable atmospheric condition rendered the disappearance and reappearances of light more plain.

The average thus obtained gives for the velocity of light * The source of light was Drummond's lime-light, or only a petroleum lamp. It was necessary sometimes, in the finest weathers, to moderate it, in order to have a disappearance of light more favourable to observations than a minimum of intensity.

189,300 miles in a second; by dividing the number by the refractive indices of the air (10003) we obtain the number 189,200 miles in a second in a vacuum; the possible error in this value is about 300 ·

M. Fizeau had found about 194,000 miles (312,000 kil.); Foucault 189,000 miles (298,000 kil.). The physicists will wonder at the concordance between M. Cornu's number and that of Foucault, obtained by an entirely different method; and so will the astronomers; for this number of 189,000 miles gives by calculating the value of the parallax of the sun the number 8".86; and it is exactly the one recently obtained by M. Leverrier as a consequence of three series of observations made on the movement of planets, particularly of Mars and Venus.

If experiments on the velocity of light were made again under good topographic and atmospheric conditions, and between two stations, the distance of which would be known by a geodetic calculation, a value of this velocity would be obtained with an error less than 1000 Astronomical methods do not easily perhaps give such an approach.

The author concludes his paper by saying: "It is to be desired for the honour of French science, that those great works relative to the velocity of light, begun by Roemer at the observatory of Paris, pursued and simplified by some learned Frenchmen, should be finished in France with a precision worthy of their astronomical and physical importance." M. C.

Explanation of the Diagram (see next page) ¦

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A, Source of light; a petroleum lamp. B, a combination of lenses to direct and concentrate the light. C, D, E, F, are shown from above in order to show the direction of the ray of light :C, glass plate, on the surface of which the light is reflected and sent into the telescope according to the direction of the arrows a is a little handle which permits of small motions being given to the little plate in order to arrange it properly. D, works of a common clock drawn to the of its linear dimensions.--It is used to put in motion the cog wheel Y, between the teeth of which the ray of light is sent forth. W, wire touched by a cog d of the axis of the third wheel, at each revolution; it is united to the electromagnet (of the plate G), and thus the number of revolutions revolving motions in a contrary direction, in order to eliminate cerduring a second is registered by r. b, ba, two barrels that give tain errors that might result from the apparatus itself. h, a wheel on the side of which a drag H bears (H has been drawn apart for greater clearness); /, horizontal axis of rotation; V, screw; when. ever by means of V the rod is brought to q, in the same manner is brought to u, and the extremity e does not rub on the side of the wheel. (Note.-A decreasing pressure is thus used, an increasing one is rendered impossible so as to prevent the delicate works from being broken.) D', front view of the same work the same things designed by the same letters primed. shows the respective situation of the two barrels b1 and b E, telescope; the light is transmitted to a distance of six miles and a half, and comes back on the same path: the apparatus that reflects it back is a telescope like E, and performing the office of a collimator the eye-piece of which is replaced by a little mirror properly disposed. F, eye-piece of E, with which the ray of light is observed at its return; it is observed through the glass-plate C on which it has been reflected. G, apparatus by which the various data of the experiments are registered. X, lamp-blacked cylinder. Y, moveable system bearing the electro-magnets l, m, n. The cylinder revolves without changing its place with an uniform rotatory motion given by a special apparatus. The movable system slides by a uniform motion communicated by means of a stretching weight. The manner of giving this motion has not been represented; the relative motion is the same as if the system were immove. able, and the cylinder going forwards and revolving in the same time. l, m, n, electro-magnets; p, q,, armatures; they terminate in needles and describe on the lamp-blacked paper the three lines drawn on the sketch. One extremity of the wire of the electro-magnets communicates with the earth, the other with a pole of a special pile; the other pole of the pile com municates also with the earth. On the way of the current that passes through from each particular pile to the three

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ON THE FERTILISATION OF FLOWERS BY flowers as apparently affording facilities for intercrossing
INSECTS AND ON THE RECIPROCAL
ADAPTATIONS OF BOTH

distinct individuals have been published; but there is no doubt that by far the greatest part of the work on this subject is still to be done. The most conspicuous flowers

DURING the last ten years, since, by his wonderful attracted, of course, in the first place, the attention of

work on Orchids,* Darwin anew turned the attention of naturalists to the remarkable connection

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inquirers, and much greater pains was taken to show the possibility of their cross-fertilisation by insects than to observe whether self-fertilisation may possibly take place if not visited by insects. Another very obvious deficiency of observations indispensable to be made on the subject in question resulted, the fertilisation of flowers by insects being studied by botanists but little acquainted with insects. From this cause, for the most part, when flowers were examined as to their intercrossing by insects, no complete observations were made as to the insects themselves which were supposed to visit and fertilise the flowers, and in many cases the agency of insects was over-estimated in consequence of not observing them directly.

Therefore, being myself acquainted with our flowers as well as with a great number of our insects, I thought it would be as agreeable as useful if I observed, as far as it was possible for me, the insects which really visit and fertilise our flowers, their adaptations to gain the honey

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FIG. 1.-Head of a humble-bee (Bombus muscorum L. 9)s en from ab ve, with the oral apparatus stretched out to its fullest extent (5: 1). between the structure of flowers and the insects visiting

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FIG 3-Lateral view of the sucking apparatus of a humble-bee (Bombus silvarum L.), representing all the four foldings partly commenced, partly imperfectly executed. away to show the folding of the base of the tongue (71). A piece of the tubular mentum is broken and the pollen, and on the other hand, the adaptations of our flowers to the insects that visit them; and having during a series of years bestowed all my leisure upon observations of this kind, I put them together in a work which was published some months ago ("Die Befruchtung der Blumen durch Insecten und die gegenseitigen Anpassungen beider." Leipzig, 1873.) Supposing that this book is in the hands of only very few Englishmen, I think it may be of some interest for the readers of NATURE if I make them acquainted with the principal new facts contained in my work, adding some observations made since its publication.

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1.-In what manner the hive- and humble-bees obtain the honey of the flowers

The first accurate description and drawing of the parts of the mouth of the hive-bee were given by Swammerdamm about two centuries ago, but he did not succeed in finding it as perforated at the end, and believed that it was a out the true function of the tongue; he described and drew simple sucking pipe. His successors saw that the tongue "Joh. Swammerdamm, Bibel der Natur. Aus dem Hollandischen übersetzt." Leipzig, 1752. Taf. xvii.

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