superintendence over the Gaikwar, and a British political agent resides at Baroda. The town is fortified, but has no great strength. Thornton states the population at 140,000. Barodd contains the chief court of the state, the Gaikvvar himself presiding in appeals from the decisions of the other courts in his territory. The town contains only one higher class school, the High School, attended in 1872 by 658 pupils, of whom 155 were learning English, 221 Marhathi, and 282 Gujrdthi. There are also two vernacular schools in the town. The late Gaikwdr, Malhar Rao, was installed in 1871. The princes of Baroda date their im portance from the Marhatta confederacy, which in the last century spread devastation and terror over India. Shortly after 1721 the ruling chief, one Peldji, carved a fertile slice of territory out of Gujarat. Another enjoyed the title of "Leader of the Royal Troops" under the Peshwa. During the last thirty-two years of the century the house fell a prey to one of those bitter and unappeasable family feuds which are the ruin of great Indian families. In 1800 the inheritance descended to a prince feeble in body and almost idiotic in mind. British troops were sent in defence of the hereditary ruler against all claimants ; a treaty was signed in 1802, by which his independence of the Peshwd, and his dependence on our own Government, were secured. Three years later these and various other engagements were consolidated into a systematic plan for the administration of the Barodd territory, under a prince with a revenue of three quarters of a million sterling, per fectly independent in all internal matters, but practically kept on his throne by subsidiary British troops. Since then the history of the Gaikwdrs has been very much the same as that of most territorial houses in India : an occa sional able minister, more rarely an able prince ; but, on the other hand, a long dreary list of incompetent heads, venal advisers, and taskmasters oppressive to the people. Of late years they have been more than usually unfortunate. Family feuds raged fiercer than ever, and the late Gaikwar was long imprisoned by his brother, the former ruler, on a charge of attempted fratricide. The miserable scan dals of the Baroda Raj need not be revived here. Suffice it to say, that Malhar Rao found himself suddenly brought from prison and placed upon the throne, and that his conduct as ruler was what might have been expected in such a case. Frequent complaints of his mismanage ment and oppression were brought before the British Government, and in 1873 a commission of English officers was appointed to inquire into the affairs of the state, and its management by the Gaikwdr. Sinee then mis rule has advanced with a rapid foot. After one or two feints at reforming his government, the Gaikwar returned to his old courses. An attempt in 1874 to poison the British Resident at his court brought affairs to a crisis, and early in 1875 the Gaikwar was tried by a mixed com mission of eminent British officers and natives of rank. A unanimous verdict was not obtained touching the particular attempt at poisoning ; but Lord Northbrook, as Viceroy of India, found it necessary to depose the Gaikwar, and to appoint another member of the Barodd, family to rule in
his stead.
BAROMETER, the instrument by which the weight or pressure of the atmosphere is estimated. The barometer was invented by Torricelli, a pupil of Galileo, in 1643. It had shortly before been found, in attempting to raise water from a very deep well near Florence, that, in spite of all the pains taken in fitting the piston and valves, the water could by no effort be made to rise higher in the pump than about 32 feet. This remarkable phenomenon Tor ricelli accounted for by attributing pressure to the air. He reasoned that water will rise in a vacuum only to a certain height, so that the downward pressure or weight of the column of water will just balance the pressure of the atmosphere ; and he further argued that if a fluid heavier than water be used it will not rise so high in the tube as the water. To prove this, he selected a glass tube about a quarter of an inch in diameter and 4 feet long, and her metically sealed one of its ends ; he then filled it with mercury and, applying his finger to the open end, inverted it in a basin containing mercury. The mercury instantly sank to nearly 30 inches above the surface of the mercury in the basin, leaving in the top of the tube an apparent vacuum, which is, indeed, one of the most perfect that can yet be produced, and is called after this great experimenter, the Torricellian vacuum. He next converted the mercurial column into a form suited for observation by bending the lower end of the tube, thus constructing what has since been called the siphon barometer. The fundamental principle of the barometer cannot be better illustrated than by his experiment (see fig. 2). In truth, a scale is all that is re quired to render this simple apparatus a perfect barometer. The heights of the columns of two fluids ia equilibrium are inversely as their specific gravities; and as mercury is 10,784 times heavier than air, the height of the atmosphere would be 10,784 times 30 inches, or nearly five miles, if it were composed of layers equally dense throughout. But since air becomes less dense as we ascend, owing to its great elasticity and the diminished pressure, the real height of the atmosphere is very much greater. From observations of luminous meteors, it has been inferred that the height is at least 120 miles, and that, in an extremely attenuated form, it may even considerably exceed 200 miles.
Various fluids might be used in constructing barometers. If water were used, the barometric column would be about 35 feet long. The advantages, however, which water barometers might be supposed to possess in showing changes of atmo spheric pressure on a large scale, are more than counter balanced by a serious objection. The space in the tube above the column of water is far from being a vacuum, being filled with aqueous vapour, which presses on the column with a force varying with the temperature. At a temperature of 32 Fahr. the column would be depressed half au inch, and at 75 a foot. Since in mercurial baro meters the space at the top of the column is one of the most perfect vacuums that can be produced, the best fluid for the construction of barometers is mercury. It is there fore the only fluid used where scientific accuracy is aimed at. Pure mercury must be used in filling the tubes of barometers ; because if it be impure, the density will not be that of mercury, and, consequently, the length of the columns will not be the same as that of a column composed of pure mercury alone. Even should the density happen to be the same as that of pure mercury the impurities would soon appear, impeding the action of the fluid as it rises and falls, and thus rendering the instrument unfit for accurate observation. In filling barometer tubes, air and moisture get mixed with the mercury, and must be expelled by boiling the mercury in the tube. It being essential that the mercury be quite freed from air and moisture, no barometer should be used till it has been well ascertained that this has been done. Some time after the instrument has been hung in an observing position, let it be inclined gently and with care, so that the mercury may strike against the top of the glass tube ; if there is no air within, a sharp metallic click will be heard, but if the sound is dull, the air and moisture have not been entirely expelled. If the mercury should appear at any time to adhere some what to the tube and the convex surface assume a more flattened form, it may be concluded that air or moisture is present. If on examining the mercury with a lens minute bubbles are visible, air is present. In all these cases the instrument must be rectified.
