leader in victualling and arming the defenders of Lucknow ; and to this it was owing that the little garrison, so closely beset, was not only sustained in practical plenty, but was able also to spare enough to feed the additional force brought to its aid by Havelock and Outram. He acted, it must be confessed, with rashness in making the sally which resulted in his repulse at Chinhut; but if his instructions had been duly carried out, it is possible that defeat might have been averted, even if a victory had not been gained.

Sir Henry possessed in an eminent degree two rare qualities fitting him for high command: he displayed great judgment in the first choice of officers to serve under him, and he enjoyed the faculty of winning their warm and devoted attachment. The unfeigned sorrow with which his departure from the Punjab was regarded by the whole body of those who had served under him, affords conclusive evidence of the strength of the feeling which bound the hearts of the followers to their leader.

So passed away, in mature manhood, in broken health, indeed, but with energies still unimpaired, one of those great men by whom our dominion in India has been gained and upheld. As a soldier and a statesman he was a worthy successor of Clive and Hastings; but his moral qualities placed him far above those founders of our Empire in the East. It may be said of him with truth that he was as much distinguished by practical benevolence as he was by the fulfilment of his more direct duty to the Government that he served. He won to an uncommon extent the affections of those whom he ruled; and to the hold which he and the Englishmen trained in his school gained over the minds and hearts of the people it is in no small degree attributable that in the trying crisis of 1857 they took part heartily with us. He left behind him in the Punjab many worthy followers-men like Nicholson, Edwardes, and others-qualified alike to command and to conciliate; and such of his disciples, civil and military, as still survive are held in honour alike by their fellow-labourers in the public service, and by the people whom they governed. His bodily presence has passed away from the land in which he laboured, but his memory will long be cherished and honoured as the worthy representative of the justice and moderation of the British Government.

ART. VI.-1. The Sun: Ruler, Fire, Light, and Life of the Planetary System. By RICHARD A. PROCTOR, B.A., F.R.A.S. London: 1871.

2. A Rediscussion of the Observations of the Transit of Venus, 1869. By E. J. STONE, Esq. Monthly Notices of the Royal Astronomical Society,' Supplementary Notice. Vol. XXVIII.

1868.

3. The Transit of Venus in 1874. By R. A. PROCTOR, B.A. 'Monthly Notices of the Royal Astronomical Society.' Vol. XXIX. No. VIII. June, 1869.

4. Address to the Mathematical and Physical Section of the British Association for the Advancement of Science, delivered at the Section at the Brighton Meeting, August 14, 1872. BY WARREN DE LA RUE, Esq., F.R.S., &c. &c. 5. Lord Lindsay's Preparations for Observations of the Transit of Venus, 1874. By Lord LINDSAY and Mr. DAVID GILL. Monthly Notices of the Royal Astronomical Society.' Vol. XXXIII. No. I. November,

1872.

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6. Letter from the Astronomer Royal to the Secretary of the Admiralty, expressing his Views on certain Articles which had appeared in the Public Newspapers in regard to the approaching Transit of Venus. Monthly Notices of the Royal Astronomical Society.' Vol. XXXIII. No. V. March, 1873.

IT

T is impossible to over-estimate, in a scientific point of view, the importance of knowing exactly how far the sun is from the earth. That distance is the great natural unit which has to be employed in measuring the vast spaces of the universe stretching around the earth and sun-the standard yardmeasure, as it has been aptly called, of the sidereal survey which astronomical science is ever pushing out into the surrounding immensity. But over and above this consideration there is also the bearing that a correct determination of this quantity has upon the physical investigations which are now being so successfully carried through by the combined powers of the spectroscope and telescope. A few thousand miles added to, or taken from, man's estimate of the remoteness of the bright luminary materially affects the conclusion which has to be drawn in regard to the nature of the agencies that are there pursuing their appointed work in providing movement and organising force for the service of dependent worlds.

Notwithstanding the deep and clear insight which astronomers have now secured into the arrangements of the surrounding universe, it is only three brief centuries of time since the sun was believed to be a body not more than a few times as wide again as the earth floating in space five millions of miles, or something less than seven hundred of the earth's diameters, away. The old German astronomer, Kepler, after a revision of certain observations of Tycho Brahe's, for the first time conceived, what was then held to be the vast idea, that the sun must be as much as thirteen millions of miles from the earth. About the year 1670, the Italian Cassini, by the help of increased instrumental facilities, found reason to stretch Kepler's thirteen millions into something more than eighty-five millions; and, since Cassini's time, the eighty-five millions have been still further extended by yet other refinements of observation. It is not unworthy of remark that in all these several advances towards a more adequate idea of the vast distance of the sun, the one thing which each successive investigator set himself mainly to accomplish was the discovery of how large our familiar earth looks when it is seen from the sun; for to know how large any body of already ascertained size appears is substantially to know how far it is away. By exact measurement performed by the most patient and laborious application of the surveyor's theodolite and chain, man has found that his earth measures 7,925 geographical miles across in its broadest diameter. Now nothing can be more obvious than that it is possible to determine by the simplest application of geometric principles how large a sphere that is 7,925 miles across must look at any given distance. With every successive withdrawal from the position of the observer it gets to look less and less. How far, then, by this estimate is it withdrawn from the sun, and how small does it look from that remote post of observation? Marvellous as it may seem, there are ways in which this can be ascertained. Far as the sun is away in the trackless void, and impossible as it is to take human organs of vision there to look back upon the earth, there is nevertheless something else appertaining to the organisation of man that can be made to perform the inscrutable journey-namely, the human intellect. This bond-defying and illimitable power it is which is to be commissioned afresh upon the work a few short months hence, when a numerous staff of carefully equipped observers. start for remote regions of the earth to watch from those vantage grounds the planet Venus sweeping, as a black speck, across the sun's bright face.

What is called in the hard language of technical astronomy

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the parallactic displacement, or parallax, of the sun, means virtually, when it is reduced to the simplest form of expression that the case admits of, how large does the earth look from the sun?' Thus, if one man stood at some given point on the earth, and a second man was placed at some opposite spot of its circumference exactly a full diameter of the earth away, and an observer in the sun looked forth upon these two Terrestrians, he would see them an earth's breadth asunder. The two earth-stationed men, on the other hand, would look at the observer in the sun along lines which respectively converged to his place; and the exact angle of convergence by which the lines met there would obviously be identical with the angle of divergence by which the two men are looked at from the sun. In the first case-that, namely, of convergence-the angle is observed by the consentaneous action of two remote men upon the earth, and that angle is called the parallax' of the sun. In the second case-that, namely, of divergence-the apparent size of the earth is gauged as it is seen from the sun. Therefore, the parallax of the sun, or displacement of it caused by viewing it from opposite sides of the earth, and the apparent size of the earth considered as if viewed from the sun, are one and the same thing.

It may be here necessary, as a piece of passing and incidental, but not altogether irrelevant, explanation, to say that the astronomer in his actual treatment of this piece of investigation, has found it convenient to deal with the half-diameter, rather than with the whole diameter, of the earth; and this, simply because he found it possible to compare the observed position of the sun when just sinking out of sight upon the horizon with the fixed and known position of the luminary as it would be seen if contemplated from the centre of the earth; or, what is the same thing, from a position on the earth's surface diametrically between that centre and the centre of the sun. The solar displacement deduced from this method of observation was called the horizontal parallax' of the sun. It is not necessary to allude here more in detail to this earlier form of the problem, because the method has been so entirely superseded by the more precise and interesting procedure that depends upon the passage of Venus across the sun's face. It is only necessary, in regard to it, to remark that the main principle which has been described is, nevertheless, in no way affected by this method of procedure; for, whatever is learned in the matter regarding the half-diameter of the earth needs only to be doubled to apply to the whole. To observe the

'horizontal parallax' of the sun is the same thing as to ascertain half the apparent size of the earth measured from the sun. The language of the horizontal parallax observation is still used by observers, because it affords a convenient average standard of comparison. Observations from a different base are reduced to the expression they would have had if the exact half-diameter of the earth, which lies between its circumference and centre, had been employed.

Now when this most interesting observation of the sun's parallax is attempted in the routine of terrestrial astronomy, it is found that the two lines which run from widely severed observers, and which meet at the sun, are so very nearly in the same direction-so very nearly parallel with each other that it requires the nicest effort of visual discrimination to discover that they are convergent and not parallel. If the reader will take the trouble to lay down upon paper two lines diverging from each other by an angle of one degree, thus

and will then conceive this angular space to be again split into 450 subdivisions, he will get some approximation to a notion of what the quantity is that has to be dealt with when this, the horizontal parallax of the sun, with a basis of nearly 4,000 miles, is under examination. It is just one of these exquisitely minute subdivisions that has to be measured. The quantity, indeed, is so very fine that it overtasks the faculties which are at command when it is dealt with in a straightforward direct way. The expedient is, therefore, adopted of dealing with it indirectly. The nearest neighbour of the earth, the planet Venus, is made a sort of stepping-stone. The astronomer, by a subtle exertion of the mighty magic which it is his privilege to wield, transports himself to the planet Venus at the convenient contingency when it happens to be directly between the earth and sun, and there notes, in the first place, how large the earth looks from this stage of the journey, and then how large the sun looks out in the other direction; and then, as he already knows from another source, which, however, must be further alluded to immediately, what are the relative distances of Venus and the sun, he discovers first how far Venus is from the earth, and afterwards how much farther the sun is than Venus. This, indeed, is substantially what astronomers are about when they send carefully prepared expeditions forth to remote regions to observe the transit of Venus' across the sun's face.

In the process of observing this occurrence, the sun's face