OF

WORKS ON INDIA AND THE EAST.

A Treatise on Attractions, Laplace's Functions, and the Figure of the Earth. By John H. Pratt, M. A. Macmillan & Co. Cambridge (and sold by Messrs. R. C. Lepage, & Co. Calcutta). Second Edition: pp. 122.

This book is chiefly a republication of a portion of Archdeacon Pratt's larger work on the Mathematical Principles of Mechanical Philosophy,' published at Cambridge twenty-five years ago, with additions suggested by circumstances connected with the Great Trigonometrical Survey of this country-and for this reason we notice it in these pages. Some time since a reference was made to the author by the late Surveyor General regarding the effect of the attraction of the Himmalaya Mountains upon the plumbline, by which the instruments of observation are fixed with reference to the vertical. In the measurement of the two portions of the Great Arc of Meridian in the longitude of Cape Comorin, and lying between Kaliana (lat. 29° 30' 48") and Kalianpur (24° 7' 11") and between Kalianpur and Damargida (18° 3' 15"), Colonel Everest, the previous Surveyor General, had found that the first came out greater by 5.24, and the second less by 3. 79, than the corresponding arcs marked out in the heavens by the verticals or plumb-lines at the terminal stations. These errors are equivalent to about 1-10th and 1-14th of a mile. This was a very unexpected result. For in the course of the laborious survey he had abandoned one station (Takal Khera), although much time and trouble had been bestowed upon it, because he found that a neighbouring line of elevated table-land affected the plumb-line at that place by a quantity somewhat less than 5", that is, less than the larger of the two quantities under notice. Moreover he had selected Kaliana, the highest station north, so far from the foot of the Himmalayas as to be, as he thought, altogether out of the influence of that mountain region. The existence of these two outstanding errors, notwithstanding the care bestowed, was therefore viewed with disappointment.

The question proposed by Sir A. Waugh to the author of the treatise before us was to account for these errors. The first seemed most likely to arise from mountain attraction; but the second lay the other way, which was inexplicable. The results of Mr. Pratt's investigations, with the details of calculation, are published in the volumes of the Philosophical Transactions for 1855, 1859, 1860; and the mathematical principles and formulæ by which they were obtained are demonstrated in the present treatise. He has shewn (1) that the effect of the Himmalaya Mountains is very much greater than had ever been conceived, producing in reality deflections of the plumb-line far greater than the errors to be accounted for; so great is the effect that their influence is felt, not merely at Kaliana, but all over the continent of India; (2) that the deficiency of matter in the Ocean south of India has a similar effect, although it had never been imagined that any disturbing influence could proceed from that source; and (3) that even such slight variations in the density of the solid crust below, as are very likely to exist, but are hidden from our eyes, will have the same effect. These three sources of disturbance give a new importance to the problem of attraction. The methods of calculation are laid down in the fourth Chapter of the first part of this treatise; pp. 43-62. The effect of these causes of derangment is such, that the latitude of a place obtained from an observation of the sun or other heavenly body, in which case the plumb-line is used to obtain the vertical, may be out by as much as half a mile, more or

less according to its situation (p. 118). This result seemed to deprive the important survey operations of this country of that high character for accuracy which they have borne.

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In prosecuting the subject further, however, Mr. Pratt has demonstrated a property of the arcs which very much overcomes the evil effect of these large disturbing causes. The property is this. Let the latitude of a station, taken as a starting point, be found by a celestial observation. This will be wrong, by the whole amount of local attraction at that place, causing the plumb-line to deviate from the true vertical. Connect this place with other places by measuring the arcs which join them. Find the latitude and longitude of these places by applying these measured lengths to the trigonometrical formulæ of Conic Sections used in survey operations, remembering to use the mean-axes of the Earth in the calculation, and the resulting latitudes and longitudes of these new stations will be affected with the same errors as those which affect the starting point, but with no others. Hence, this important result the relative position of places marked down on a map, as determined solely by geodetic calculations, is quite correct; but the map as a whole will be wrong in its position on the terrestrial spheroid by the whole error in the observed latitude and longitude of the starting point (see p. 118). If the latitude and longitude of any of these places laid down in the map are also obtained by observations on the heavens they will in general be different to those marked in the map; the difference arises from the difference of local attraction at that place and at the starting point. These differences of latitude and longitude are therefore the correct measures of the differences of local attraction at the several stations and at the starting point. (p. 116). Thus suppose we start from Damargida and observe its latitude. This will be wrong by the whole amount of local deflection at that place. But the latitudes of Kalianpur and Kaliana, derived from that of Damargula by means of the measured lengths of the joining arcs and the mean axes, will be correct relatively to Damargida and to each other. But a comparison with the heavens, shows that there is local attraction at Kalianpur and Kaliana different to that at Damargida, such as to make the plumb-line at Kalianpur hang 3.79 more towards that at Damargida than it otherwise should do, and that at Kaliana 5.24 more from that at Kalianpur than it should. These quantities, then, which Colonel Everest detected, are (supposing his observations and calculations all correct) the accurate measures of the difference of local attraction at the several places (p. 117). This we regard a most satisfactory termination of the enquiry.

We say "termination." There is, however, one desideratum yet; viz. a means of determining the absolute latitude and longitude of some one place, by which the map may be correctly fixed. But we learn from the author of this treatise, by personal communication, that there is no prospect of this ever being discovered: it is so impossible to get altogether out of the influence of local attraction; and even to know that we are so, if we happen to be in a spot where all influences exactly balance each other.

The Treatise before us, besides giving a concise but complete view of the interesting problem of the Figure of the Earth, treated both mathematicophysically and geodetically, contains discussions and solutions of such problems as these; The thickness of the earth's solid crust is great (p. 83): The form of different parts of the earth's surface differs from that of the mean form (p. 100), a thing which geology would a priori lead us to expect (p. 101): Geodesy furnishes no evidence how much geological changes have affected the level (p. 118): The sea-level is much affected in some places by local attraction; the level at Karachi is nearly 600 feet higher than at Cape Comorin from this cause (p. 122).

History of the Siege of Delhi, by an Officer who served there, with a sketch of the leading events in the Punjab connected with the Great Rebellion of 1857. Edinburgh: Adam and Charles Black. History becomes more and more authentic the further we recede from the time and events described. How incorrect and unjust were the opinions entertained of Cromwell before Carlyle collected the materials for a faithful account of the great Protector, and gave them to the world in a way that only a soul imbued with similar grandure could have done. To the same untiring pen we owe our knowledge of the inner workings of the French Revolution. He tells us what it really was that made people cut each other's throats in such a mad way. The facts of an eventful period must be collected at the time and by the chroniclers of the day. The grouping of the facts and the deductions from them must be left to calmer and more impartial minds. An account of the Battle of Bull's Run written at Richmond the next day by an enthusiastic Southerner would be of as little value to the historian as one written by a New York senator, though some grains of truth might be obtained by a careful comparison of the two. This general rule serves to guide us in the study of great events where the true motives of men are too deep, and the circumstances that surrounded them too varied, to be apprehended by one generation, and where opposite opinions are held, perhaps with equal conscientiousness, by the parties of the day. This applies in a more limited sense to the description of events to which there is but one side, or at least but one with which we have anything to do. Here facts are wanted-what was done rather than what was thought or intended; and the chief object of narrators should be to gather new facts, to explain the old as they go on. The materials are gradually being collected for a comprehensive history of the mutiny. Among them is much wood, hay and stubble, but the book we are about to notice represents true metal, perhaps brass or iron, in the structure of which it forms a component part, and where it will in course of time find its appropriate place. Though wanting, perhaps, in that ardent and exciting tone which characterised works written during the progress of the mutiny, it has the advantage of being a complete sketch of the event around which all others clustered, and but for the success of which India might have been lost to us. The author, a member of the Indian Medical Service, is peculiarly fitted to describe the Siege of Delhi. He has waited till the whole drama is finished, before presenting his description of it to the public. Unlike some officers who have been led to publish to the world narratives of events in which they were the accidental and astonished actors, hurried along by the rapid march of events, and without a thought of the prominent part they played in the scenes through which they passed until all was over and the desire to become authors suddenly arose in their minds, the author of this interesting volume evidently entertained the intention of writing a detailed account of the siege while it was going on before him. Subsequent leisure has enabled him to correct his notes by all the available official documents and other reliable sources of information. The result is an account of the Siege of Delhi, which must be looked upon as final, so far as that act of the great Mutiny drama is concerned. He has been able to correct several slight errors of fact into which the author of the Red Pamphlet and others have fallen. It is chiefly as a chronicle of facts, that this book is valuable. The information is conveyed in a graceful and perspicuous style, but in his deductions and generalizations, though generally sound, we are not aware that the author has propounded anything new. He states his views fearlessly and distinctly, but not always with that evidence of breadth and depth of thought which carry conviction with them.

Begining with a rapid sketch of the rise and fall of the successive dynasties by which India has been held since the brilliant entry of Mahmoud of Ghusnee, the first Mahomedan Conqueror, he comes to the conquest of the Punjab and the annexation of Oude. His opinions of Lord Dalhousie and his policy are unfavourable. He might, however, have supported his opinions by a greater array of argument than he does. Such great questions are not to be so lightly dealt with. He says on this point :

'This immense accession of territory did not satisfy the Governor-General, Lord Dalhousie. A policy came into fashion, the programme of which was to seize all the independent states of India. A few common-places upon the predominance of the Anglo-Saxon race were thought sufficient to justify the iniquity of the scheme. Lord Dalhousie followed it up. He assembled an army, and, without any previous declaration of war, or cause of hostility, and contrary to the express promises of his own Government, stripped the King of Oude of all his possessions. The alleged cause was that the country was ill governed. The "atrocious Macchiavellism," that one power has a right to invade and seize upon the dominions of another, because it believes it can govern them better, might soothe the feeble disapproval which the measure met with from some at home, but nobody in the East believed we had such philanthropic motives for the action. It was not forgotten how, a few years before, we had sold the beautiful valley of Cashmere for a sum of money, to Golab Singh, one of the most odious tyrants that ever desolated Central Asia, and had lent our troops to force the people to submit to his hated sway. The Mahomedans have a close sympathy with one another; to degrade a prince of their religion is to put out one of the lights of Islam. The King of Oude had long been our friendliest and truest ally. The country might be ill governed; most eastern countries are so; but one thing is clear, they preferred the rule of their native princes to ours. Moreover, the great part of the sepoys in our service came from Oude, where they retired after having gained their pension. Under the native rule they enjoyed privileges, such as exemption from some taxes, which were lost to them under that of the British. Hence even the Hindoo soldiers were very much disgusted with the seizure of Oude. They expressed their indignation in the most open manner, and told the King that, if he had resisted, they would have thrown down their arms and fought for him.' To meet these immense additions to our territory there was no increase of the European troops in India. Some of them, indeed, had been sent away to the Russian war, and others to the recently conquered province of Pegu. The King of Oude's army amounted to nearly sixty thousand men, and large bodies were in the pay of the nobility. There were said to be two hundred and forty-six forts in the country, none of which were dismantled. We took into our service about one-fifth of the regular army, and disbanded the rest, and, to keep all down, placed one regiment of British soldiers in the city of Lucknow. Lord Dalhousie, it is true, applied for more troops. The Government, however, seems to have thought, that, since he could quietly seize upon a large kingdom without reckoning on any reinforcement, none was needed to retain possession of it. Lord Dalhousie was a man of great administrative ability and energy, but everything he did seems to have drifted the native army to mutiny, a danger of which he certainly was not sufficiently prescient.'

The cause of the Mutiny he ascribes to a combination among the Sepoys to defend themselves from the threatened deprivation of caste, taking afterwards a wider aim. He says, "there is not a particle of proof that any Mutiny "would have occurred in 1857 had it not been for the greased cartridges."

As the leading incidents of the rebellion are so well known we shall confine our remarks, for the most part, to those parts of the volume which present anything not found elsewhere and to its general merits and demerits. Passing over the story of how we lost Delhi-how the gallant Willoughby de fended the magazine to the last, and then blew it up with two thousand of his country's enemies-regardless of his own life if he could but gain anything for the British cause by a noble death-how he escaped as if by a miracle from the scene of destruction, fled through the Cashmere gate, and reached Meerut only in time to die, we come to the days when the spirit of the British Soldier was up all over the North of India-when avenging hosts assembled and marched to the city of the Moguls to try whether right or wrong should triumph.

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