Page:Encyclopædia Britannica, Ninth Edition, v. 10.djvu/120

110 early, fostered his inclination towards art, and though he had enjoyed no special instruction his ﬁrst attempts at copying nature were so successful that his father was persuaded to permit him to choose a profession which seemed so much to accord with his natural bent. Under his father’s direction he began studies in landscape, and he also diligently copied the works of the chief masters in animal painting which were contained in the academy and court library of Vienna. In the summer he made art tours in the districts of Styria, Tyrol, and Salzburg. Two animal pieces which he exhibited at the Vienna Exhibition of 1824 were regarded as remarkable productions for his years, and led to his receiving commissions in 1825 and 1826 from Prince Metternich and Caraman, the French ambassador. His reputation was greatly increased by his picture The Storm, exhibited in 1829, and from that time his works were much sought after and obtained correspondingly high prices. His Field Labourer was regarded by many as the most noteworthy picture in the Vienna exhibition of 183-4, and his numerous animal pieces have entitled him to a place in the ﬁrst rank of painters of that class of subjects. The peculiarity of his pictures is the representation of human and animal ﬁgures in connexion with appropriate landscapes and in characteristic situations so as to manifest nature as a living whole, and he particularly excels in depicting the free life of animals in wild mountain scenery. Along with great mastery of the technicalities of his art, his works exhibit patient and keen observation, free and correct hand- ling of details, and bold and clear colouring. He died at Vienna, 7th J nly 1862. Many of his pictures have been engraved, and after his death a selection of fifty-three of his works was prepared for this purpose by the Austrian Ii'mzst- tierein (Art Union).  GAUGE, in the mechanical arts, is the name applied to a great variety of instruments, of which the object may be broadly stated to be the affording of in- creased facilities for comparing any two dimensions or distances. Wherever it is necessary for this to be done with a degree of accuracy unattainable by such means as the ordinary measuring rnle aﬁ'ords, or for the same dimensions to be frequently measured with a maximum of speed and certainty, there will the hand-craftsman at once avail himself of some form of gauge. At the present day a due appreciation of the value of gauges is of growing importance to the mechanician, since they enable him greatly to improve the “ ﬁt ” of the several portions of his machinery, whilst at the same time the labour expended in ﬁtting is materially reduced. Indeed the system of making all similar parts “ to gauge,” so that in any number of machines they are interchangeable, is now effecting more than any other single cause for the improvement and cheapening of mechanical substitutes for manual labour. The gauges which come within the province of this article differ in two main particulars, according as they refer the measurements which can be made by them to some deﬁnite and established standard of length, or take cognizance only of an arbitrary or haphazard one. The obvious advantage of being able to record, and at any time again obtain with certainty, the thickness of a plate of metal, or any other gauged dimension, would have led one to sup- pose that for all except mere temporary purposes the gauges used would invariably be of the ﬁrst kind—Standard Gauges, as we shall distinguish them. But the fact is un- happily far otherwise, at least as regards the important manufactures of sheetmetal and wire (which cannot be easily measured without some form of gauge), the result being that the thickness and diameters of these are expressed by vari- ous complicated and irregular series of numbers and letters, which have no reference either to each other or to any standard system of measurement. Of these arbitrary series the B.W.G. or Birmingham Wire Gauge may be taken as the type. The largest size of which it takes account is known as No. 0000, after which come 000, 00, 0, and then the numerals from I to 36, which last is the smallest size. It is frequently used for gauging the thick- ness of sheet metal as well as for wire, in spite of the ex- istence of the Birmingham Plate Gauge, which has an equally arbitrary series of its own, consisting of the some numbers (from 1 to 36) used in the reverse manner, the low numbers being the small sizes. Other arbitrary wire gauges also tend to add to the general confusion, amongst which may be mentioned the Lancashire Gauge, which takes an alphabet and a half, in addition to the numerals up to $0, for expressing the sizes of steel wire which are referred to it, but which nevertheless does not apply to “ music wire," or “needle-wire,” or sundry other special kinds of wire, which are favoured with separate gauges of their own. Of late years careful comparisons have more than once been independently made with a view to ascertaining the standard value of these incongruous systems, but the discrepancies in the results only prove what might have been predicted, viz., that errors have crept in, and that those which profess to be alike differ amongst themselves, whilst there exists no satisfactory means of rectifying these errors. Their gradual and entire abolition therefore seems to be the only chance of real improvement, and it is earnestly to be hoped that the Standard Gauge originally suggestch by Sir J. Whitworth, which is now largely employed, may soon entirely supersede them. In this system the sizes are directly referred to the English imperial standard of length, each being expressed by the number of thousandth parts of an inch which it contains. Thus No. 36 wire means wire '036 of an inch in diameter. Under the old systems this might have been either No. 20, No. 62, No. 3, or N o. 18.

Examples of some of the usual forms of gauges are given below. For wire the simplest gauge consists of a steel plate with a series of holes drilled through it, each hole being numbered according to the series to which the gauge re- fers. By means of the Notched Gauge (ﬁg. 1) sheet metal can be gauged by a similar mode of obtaining a more or less accurate ﬁt. Rough gauges on the same principle are constantly employed also in workshop practice for comparing together internal or external diameters, the. 3 and they serve the purpose well enough so 1 n g a‘; the object is a mere comparison, without taking acronnt of the amount of any minute difference which may exist. When a measure- ment of such differences is required, or direct reference to a standard system, recourse must be had to some form of gauge provided with means for enlarging them sufﬁciently to be readily recognizable. Sliding or Calliper Gauges, such as fig. 3, fulﬁl this requirement by having