Page:Encyclopædia Britannica, Ninth Edition, v. 2.djvu/34

24 ing to an old bridge over the Guadalquivir winch is lined with fine trees. The town has an inconsiderable trade in cattle, grain, oil, and fruit. It is most widely known for its porous earthenware jars, called alcarrazas, which possess the property of keeping water cool in the hottest weather, and which are manufactured in great numbers from a whitish clay found in the neighbourhood. The Convention of Baylen was signed at Andujar in 1808; and the decree of the duke of Angouleme, by which all Spanish authorities were subordinated to the French, was published in the same town in 1823. Population, 14,096.  ANDUZE, a town of France, in the department of Gard, situated on the Gardon d Anduze, about 6 miles S.W. of Alais. It possesses considerable manufactures of serges, stockings, hats, silk, and leather, and has 5303 inhabitants, many of whom are Protestants.  ANECDOTE, a word derived from a privative and IK&L- Sco/xi, to give out or publish, means originally something not published. It has two distinct significations. First, the primary one is something not published, in which sense it has been used to denote either secret histories, Procopius, e.g., gives this as one of the titles of his secret history of Justinian s court, or portions of ancient writers which have remained long in manuscript and are edited for the first time. Of such anecdota there are many collections; the earliest was probably Muratori s, in 1709. Besides it, there are anecdota, by Bekker, Bachmaniij Cramer, Boissonade, Matranga, Miller, Wolff, Villoisin, Amaduci, Tischendorf, and, the most recent, Val. Rose, 1864-71. There are also anecdota of more modern writers; some of these are given by Martene and Durand, Thesaurus Novus Anecdotorum (1717), and Pez, Thesaurus Anecdotorum Novissimus (1721). Second, in the popular acceptation of the word, which is to be traced to their being, in the first instance, colloquial, anecdotes are relations of detached interesting particulars. Of such anecdotes the collections are almost infinite; the best in many respects is that com piled by Byerley and Clinton Robertson, known as the Percy Anecdotes (1820-23).  ANEL,, an eminent French surgeon, born at Toulouse in 1679. He is celebrated for his successful treatment of aneurism and fistula lachrymalis, and was the inventor of the probe and syringe still known by his name. He wrote several medical works, published at Amsterdam 1707, Turin 1713, and Paris 1822. He died about 1730.  ANEMOMETER, or ivind-measurer (from ave/xos, wind, and /xerpoy, a measure), a contrivance for indicating the rate and direction of the wind. Ever since the birth of true experimental science, it has been recognised as a matter of great importance and interest to man that he should know something of the laws according to which the atmospheric currents and changes are produced. Among meteorological phenomena, none deserve more attention than the elements of the wind ; and none have received more. Yet anemometry has been all along the least suc cessful department of meteorology, partly owing, of course, to the nature of the agent to be dealt with, which is the very type of fluctuation, and partly to a mistaken path of observation that was too long followed. The error which, from the days of Hooke, in the middle of the 1 7th century, to within a comparatively recent period, misdirected the efforts of inventors, was the idea that the elements to be determined in the case of the wind are its direction and pressure, whereas practically they are its direction and velocity. If the currents of air were anything like uniform, it would be a comparatively simple matter to deduce the velocity from the pressure ; but their variability is so very great, that the relations between the velocity and the pressure become unworkably complex. We know, from the elementary principles of dynanrc?, that the pressure at any instant will vary as the square of the velocity. Obviously, therefore, the relative variations of the pressure will be twice as great as those of the velocity; and the latter are too great, as we find them, to encourage us to double them artificially. It must also be remembered that, from the inertia of the indicating apparatus, errors will in every case arise ; and these also will be doubled if we take the pressure instead of the velocity variations. From all this it will appear that comparatively little importance is to be attached to the earlier and to all statical modes of anemometry. The essentials of every anemometer are two : (1), a wind- vane, to show changes of direction; and (2), a luind-gauge, to show changes of velocity, or of force. There is also a distinction which we may have in every kind of meter. They may be either non-recording, as merely exhibiting the variations to the eye; or recording, or marking them per manently on paper. The wind-vane, or weather-cock, is simply a flat sheet of thin metal, or two sheets in the shape of a thin wedge, at the end of a metal rod, the whole turning freely on a vertical axle. Besides serving to show the direction of the wind itself, the vane is often used to turn the gauge, so as to present the pressure-surface with its face always direct to the wind. Of all the gauges that have been invented or proposed it would be impossible to give even the names. The primi tive statical forms of anemometer that is, such as set against the force of the wind a gradually increasing re sistance, with some means of indicating the point of balance have been divided by Dr Robinson (Trans. Eoy. Irish Acad., vol. xxii. p. 150) into three classes : First, vertical windmills, kept facing the wind by a vane, and acting by winding on their axle a string against some form of gradu ated resistance. Of this nature were Dr Hooke s anemo meter (which is generally considered the first practical attempt in wind-measuring), and those of Wolfius and Martin. The second class consists of those in which the wind acts on a flat plate, usually a foot square, pressing it against the elasticity either of a metallic spring or of a mass of confined air, a previous graduation of the elastic force having been made for each instrument. The first gauge of this type was invented by the celebrated Bouguer about the middle of last century ; and since his time there have been many attempts at improvement of this principle, the apparent simplicity of the spring- measure being its recommendation. Modified forms of Bouguer s wind-pressure gauge are in use even at the present day ; and about a quarter of a century ago a self- registering adaptation of it was constructed by Osier, and very generally employed. The third class measures the wind-force by the difference of level it is capable of pro ducing in an inverted syphon, or U tube, containing water or some other liquid. Lincl s anemometer, invented in 1775, is the best known of this type, and is still in common use. It is simply a U tube, with one leg bent at right angles towards the upper end, and attached to a vane, so as to have its mouth constantly facing the wind. It is about half-filled with water, and a scale gradu ated to hundredths of an inch is attached. The difference of level in the legs of the syphon indicates the force of the wind; but it is only by experiment that the pressures corresponding to these differences can be laid down. Thus each instrument requires a carefully-constructed reference table of pressures and velocities corresponding to its read ings. According to Lind, a difference of level of 1 inch indicates a pressure of 5 2 fl&gt; on the square foot, and that corresponds to a velocity of about 32| miles an hour, which is in common language a high wind. A difference of 3 inches would indicate a storm, and one of G inches a