8. Thus radiation is one phenomenon, and (as we shall find) the spectrum of a black body (a conception roughly realized in the carbon poles of an electric lamp) is continuous from the longest possible wave-length to the shortest which it is hot enough to emit. These various groups of rays, however, are perceived by us in very different ways, whether by direct impressions of sense or by the different modes in which they effect physical changes or transformations. The only way as yet known to us of treating them all alike is to convert their energy into the heat-form and measure it as such. This we can do in a satisfactory manner by the thermo-electric pile and galvanometer.

9. Of the history of the gradual development of the theory of radiation we can give only the main features. The apparent concentration of cold by a concave mirror, which had been long before observed by Porta, was rediscovered by Pictet, and led to the extremely important enunciation of the Law of Exchanges by Prévost in 1791. As we have already seen, Prévost's idea of the nature of radiation was a corpuscular one, no doubt greatly influenced in this direction by the speculations of Lesage (see ATOM). But the value of his theory as a concise statement of facts and a mode of co-ordinating them is not thereby materially lessened. We give his own statements in the following close paraphrase, in which the italics are retained, from sect. ix. of his Du Calorique Rayonnant (Geneva, 1809).

"1. Free caloric is a radiant fluid. And because caloric becomes free at the surfaces of bodies every point of the surface of a body is a centre, towards and from which filaments (filets) of caloric move in all directions. "2. Heat equilibrium between two neighbouring free spaces consists in equality of exchange.

3. When equilibrium is interfered with it is re-established by inequalities of exchange. And, in a medium of constant temperature, a hotter or a colder body reaches this temperature according to the law that difference of temperature diminishes in geometrical progression in successive equal intervals of time.

4. If into a locality at uniform temperature a reflecting or réfracting surface is introduced, it has no effect in the way of changing the temperature at any point in that locality.

5. If into a locality otherwise at uniform temperature there is introduced a warmer or a colder body, and next a reflecting or refracting surface, the points on which the rays emanating from the body are thrown by these surfaces will be affected, in the sense of being warmed if the body is warmer, and cooled if it is colder. "6. A reflecting body, heated or cooled in its interior, will acquire the surrounding temperature more slowly than would a non-reflector. "7. A reflecting body, heated or cooled in its interior, will less affect (in the way of heating or cooling it) another body placed at a little distance than would a non-reflecting body under the same circumstances.

"All these consequences have been verified by experiment, except that which regards the refraction of cold. This experiment remains to be made, and I confidently predict the result, at least if the refraction of cold can be accurately observed. This result is indicated in the fourth and fifth consequences [above], and they might thus be subjected to a new test. It is scarcely necessary to point out here the precautions requisite to guard against illusory results of all kinds in this matter.

of heat; and we must also introduce some results of the splendid investigations of Sadi Carnot (1824), which cast an entirely new light on the whole subject of heat.

11. Prévost's leading idea was that all bodies, whether cold or hot, are constantly radiating heat. This of itself was a very great step. It is distinctly enunciated in the term "exchange" which he employs. And from the way in which he introduces it it is obvious that he means (though he does not expressly say so) that the radiation from a body depends on its own nature and temperature alone, and is independent altogether of the nature and temperature of any adjacent body. This also was a step in advance, and of the utmost value. It will be seen later that Prévost was altogether wrong in his assumption of the geometrical rate of adjustment of differences of temperature, a statement originally made by Newton, but true only approximately, and even so for very small temperature differences alone. Newton in the Queries to the third book of his Optics distinctly recognizes the propagation of heat from a hot body to a cold one by the vibrations of an intervening medium. But he says nothing as to bodies of the same temperature.

12. To Carnot we owe the proposition that the thermal motivity of a system cannot be increased by internal actions. A system in which all the parts are at the same tempera ture has no thermal motivity, for bodies at different temperatures are required in order to work a heat-engine, so as to convert part of their heat into work. Hence, if the contents of an enclosure which is impervious to heat are at any instant at one and the same temperature, no changes of temperature can take place among them. This is certainly true so far as our modes of measurement are concerned, because the particles of matter (those of a gas, for instance) are excessively small in comparison with the dimensions of any of our forms of apparatus for measuring temperatures. Something akin to this statement has often been assumed as a direct result of experiment: a number of bodies (of any kinds) within the same impervious enclosure, which contains no source of heat, will ultimately acquire the same temperature. This form is more general than that above, inasmuch as it involves considerations of dissipation of energy. Either of them, were it strictly true, would suffice for our present purpose. But neither statement can be considered as rigorously true. We may employ them, however, in our reasoning as true in the statistical sense; but we must not be surprised if we should find that the assumption of their rigorous truth may in some special cases lead us to theoretical results which are inconsistent with experimental facts,-i.e., if we should find that deviations from an average, which are on far too minute a scale to be directly detected by any of our most delicate instruments, may be seized upon and converted into observable phenomena by some of the almost incomparably more delicate systems which we call individual particles of matter.

1

ments. To this we will recur.) His desire to escape the difficulties of surface-reflexion led him to consider the radiation inside an imperfectly transparent body in the enclosure above spoken of. He thus arrived at an immediate proof of the existence of internal radiation, which recruits the stream of radiant heat in any direction step by step precisely to the amount by which it has been weakened by absorption. Thus the radiation and absorption rigorously compensate one another, not merely in quantity but in quality also, so that a body which is specially absorptive of one particular ray is in the same proportion specially radiative of the same ray, its temperature being the same in both cases. To complete the statement, all that is necessary is to show how one ray may differ from another, viz., in intensity, wave-length, and polarization.

14. The illustrations which Stewart brought forward in support of his theory are of the two following kinds. (1) He experimentally verified the existence of internal radiation, to which his theory had led him. This he did by showing that a thick plate of rock-salt (chosen on account of its comparative transparency to heat-radiations) radiates more than a thin one at the same temperature, surrounding bodies being in this case of course at a lower temperature, so that the effect should not be masked by transmission. The same was found true of mica and of glass. (2) He showed that each of these bodies is more opaque to radiations from a portion of its own substance than to radiation in general. Then comes his conclusion, based, it will be observed, on his fundamental assumption as to the nature of the equilibrium radiation in an enclosure. It is merely a detailed explanation that, once equilibrium has been arrived at, the consequent uniformity of radiation throughout the interior of a body requires the step-by-step compensation already mentioned. And thus he finally arrives at the statement that at any temperature a body's radiation is exactly the same both as to quality and quantity as that of its absorption from the radiation of a black body at the same temperature. In symbolical language Stewart's proposition (extended in virtue of a principle always assumed) amounts to this at any one temperature let R be the radiation of a black body, and eR (where e is never greater than 1) that of any other substance, both for the same definite wave-length; then the substance will, while at that temperature, absorb the fraction e of radiation of that wave-length, whatever be the source from which it comes. The last clause contains the plausible assumption already referred to. Stewart proceeds to show, in a very original and ingenious way, that his result is compatible with the known facts of reflexion, refraction, &c., and arrives at the conclusion that for internal radiation parallel to a plane the amount is (in isotropic bodies) proportional to the refractive index. Of course, when the restriction of parallelism to a plane is removed the internal radiation is found to be proportional to the square of the refractive index. This obvious completion of the statement was first given by Stewart himself at a somewhat later date.

15. So far Stewart had restricted his work to "dark heat," as it was then called; and he says that he did so expressly in order to confine himself to rays "which were universally acknowledged to produce heat by their absorption." But he soon proceeded to apply himself to luminous radiations. And here he brought forward the extremely important fact that "coloured glasses invariably lose their colour in the fire" when exactly at the temperature of the coals behind them, ie., they compensate exactly for their absorption by their radiation. But a red glass when colder than the coals behind appears red, while if it be hotter than they are it appears green. He also showed that a piece of china or earthenware with a dark pattern on a light ground appears to have a light pattern on a

dark ground when it is taken out of the fire and examined | in a dark room. Hence he concluded that his extension of Prévost's theory was true for luminous rays also. 16. In this part of the subject he had been anticipated, for Fraunhofer had long ago shown that the flame of a candle when examined by a prism gives bright lines (ie., maxima of intensity of radiation) in the position of the constituents of a remarkable double dark line (¿.e., minima of radiation) in the solar spectrum, which he called D. Hallows Miller had afterwards more rigorously verified the exact coincidence of these bright and dark lines. But Foucault went very much farther, and proved that the electric arc, which shows these lines bright in its spectrum, not only intensifies their blackness in the spectrum of sunlight transmitted through it, but produces them as dark lines in the otherwise continuous spectrum of the light from one of the carbon points, when that light is made by reflexion to pass through the arc. Stokes about 1850 pointed out the true nature of the connexion of these phenomena, and illustrated it by a dynamical analogy drawn from sound. He stated his conclusions to Sir W. Thomson,2 who (from 1852 at least) gave them regularly in his public lectures, always pointing out that one constituent of the solar atmosphere is certainly sodium, and that others are to be discovered by the coincidences of solar dark lines with bright lines given by terrestrial substances rendered incandescent in the state of vapour. Stokes's analogy is based on the fact of synchronism (long ago discussed by Hooke and others), viz., that a musical string is set in vibration when the note to which it is tuned is sounded in its neighbourhood. Hence we have only to imagine a space containing a great number of such strings, all tuned to the same note. Such an arrangement would form, as it were, a medium which, when agitated, would give that note, but which would be set in vibration by, and therefore diminish the intensity of, that particular note in any mixed sound which passed through it.

17. Late in 1859 appeared Kirchhoff's first paper on the subject. He supplied one important omission in Stewart's development of the theory by showing why it is necessary to use as an absorbing body one colder than the source in order to produce reversal of spectral lines. This we will presently consider. Kirchhoff's proof of the equality of radiating and absorbing powers is an elaborate but unnecessary piece of mathematics, called for in consequence of his mode of attacking the question. He chose to limit his reasoning to special wave-lengths by introducing the complex mechanism of the colours of thin plates (LIGHT, vol. xiv. p. 608), and a consequent appeal to Fourier's theorem (HARMONIC ANALYSIS, vol. xi. p. 481), instead of to the obviously permissible assumption of a substance imperfectly transparent for one special wave-length, but perfectly transparent for all others; and he did not, as Stewart had done, carry his reasoning into the interior of the body. With all its elaboration, his mode of attacking the question leads us no farther than could Stewart's. Both are ultimately based on the final equilibrium of temperature in an enclosure required by Carnot's principle, and both are, as a consequence, equally inapplicable to exceptional cases, such as the behaviour of fluorescent or phosphorescent substances. In fact (see THERMODYNAMICS) Carnot's principle is established only on a statistical basis of averages, and is not necessarily true when we are dealing with portions of space, which, though of essentially finite dimensions, are extremely small in comparison with the sentient part of even the tiniest instrument for measur ing temperature.

1 L'Institut, 7th February 1849; see Phil. Mag., 1860, i. p. 193. 2 Brit. Assoc., President's address, 1871. Pogg. Ann., or Phil. Mag., 1860.

19. From the extension of Prévost's theory, obtained in either of the ways just explained, we see at once how the constancy of the radiation in an enclosure is maintained. In the neighbourhood of and perpendicular to the surfaces of a black body it is wholly due to radiation, near a transparent body wholly to transmission. A body which reflects must to the same extent be deficient in its radiation and transmission; thus a perfect reflector can neither radiate nor transmit. And a body which polarizes by reflexion must supply by radiation what is requisite to render the whole radiation unpolarized. A body, such as a plate of tourmaline, which polarizes transmitted light, must radiate light polarized in the same plane as that which it absorbs. Kirchhoff and Stewart independently gave this beautiful application.

20. Empirical formulæ representing more or less closely the law of cooling of bodies, whether by radiation alone or by simultaneous radiation and convection, have at least an historic interest. What is called Newton's Law of Cooling was employed by Fourier in his Théorie Analytique de la Chaleur. Here the rate of surface-loss was taken as proportional to the excess of temperature over surrounding bodies. For small differences of temperature it is accurate enough in its applications, such as to the corrections for loss of heat in experimental determinations of specific heat, &c., but it was soon found to give results much below the truth, even when the excess of temperature was only 10° C. 21. Dulong and Petit, by carefully noting the rate of cooling of the bulb of a large thermometer enclosed in a metallic vessel with blackened walls, from which the air had been as far as possible extracted and which was maintained at a constant temperature, were led to propound the exponential formula Aat+B to represent the radiation from a black surface at temperature t. As this is an exponential formula, we may take t as representing absolute temperature, for the only result will be a definite change of value of the constant 4. Hence if to be the temperature of the enclosure, the rate of loss of heat should be A(at - ato), or Aato(at-to-1). The quantity A was found by them to depend on the nature of the radiating surface, but a was found to have the constant value 1.0077. As the approximate accuracy of this expression was verified by the experiments of De la Provostaye and Desains for temperature differences up to 200° C., it may be well to point out two of its consequences. (1) For a given difference of temperatures the radiation is an exponential function of the lower (or of the higher) temperature. (2) For a given temperature of the enclosure the radiation is as (1·0077) - 1, or (1+0·00380+ ...), where is the temperature excess of the cooling body. Thus the Newtonian law gives 4 per cent. too little at 10° C. of difference. 22. Dulong and Petit have also given an empirical formula for the rate of loss by simultaneous radiation and convection. This is of a highly artificial character, the part due to radiation being as in the last section, while that due to convection is independent of it, and also of the

23. Our knowledge of the numerical rate of surfaceemission is as yet scanty, but the following data, due to Nicol,1 may be useful in approximate calculations. Loss in heat units (1 b water raised 1° C. in temperature) per square foot per minute, from Bright copper Blackened copper.

.1.09 .2.03

0.51 1.46

0.42 1.35.

The temperatures of body and enclosure were 58° C. and 8° C., and the pressure of contained air in the three columns was about 30, 4, and 0'4 inches of mercury respectively. The enclosure was blackened.

24. Scanty as is our knowledge of radiation, it is not at all surprising that that of convection should be almost nil, except as regards some of its practical applications. Here we have to deal with a problem of hydrokinetics of a character, even in common cases, of far higher difficulty than many hydrokinetic problems of which not even approximate solutions have been obtained.

25. What is called Döppler's Principle (LIGHT, vol. xiv. p. 614) has more recently2 led Stewart to some curious speculations, which a simple example will easily explain. Suppose two parallel plates of the same substance, perfectly transparent except to one definite wave-length, to be moving towards or from one another. Each, we presume, will radiate as before, and on that account cool; but the radiation which reaches either is no longer of the kind which alone it can absorb, whether it come directly from the other, or is part of its own or of the other's radiation reflected from the enclosure. Hence it would appear that relative motion is incompatible with temperature equilibrium in an enclosure, and thus that there must be some effect analogous to resistance to the motion. We may get over this difficulty if we adopt the former speculation of Stewart, referred to in brackets in § 13 above. For this would lead to the result that, as soon as either of the bodies has cooled, ever so slightly, the radiation in the enclosure should become that belonging to a black body of a slightly higher temperature than before, and thus the plates would be furnished with radiation which they could at once absorb, and be gradually heated to their former temperature.

26. A very recent speculation, founded by Boltzmann3 upon some ideas due to Bartoli, is closely connected in principle with that just mentioned. This speculation is highly interesting, because it leads to an expression for the amount of the whole radiation from a black body in terms of its absolute temperature. Boltzmann's investigation may be put, as follows, in an exceedingly simple form. It was pointed out by Clerk Maxwell, as a result of his electro-magnetic theory of light, that radiation falling on the surface of a body must produce a certain pressure. It is easy to see (most simply by the analogy of the virial equation, MECHANICS, vol. xv. p. 719) that the measure of the pressure per square unit on the surface of an impervi ous enclosure, in which there is thermal equilibrium, must be one-third of the whole energy of radiation per cubic unit of the enclosed space. We may now consider a rcversible engine conveying heat from one black body to another at a different temperature, by operations alternately of the isothermal and the adiabatic character (THERMODYNAMICS), which consist in altering the volume of the en1 Proc. R. S. E., vii. 1870, p. 206.

2 Brit. Assoc. Report, 1871. 3 Wiedemann's Ann., 1884, xxii.

Hence it follows at once that, if the fundamental assumptions be granted, the energy of radiation of a black body per unit volume of the enclosure is proportional to the fourth power of the absolute temperature. It is not a little remarkable that Stefan had some years previously shown that this very expression agrees more closely with the experimental determinations of Dulong and Petit than does their own empirical formula.

27. It would appear from this expression that, if an impervious enclosure containing only one black body in thermal equilibrium is separated into two parts by an impervious partition, any alteration of volume of the part not containing the black body will produce a corresponding alteration of the radiation in its interior. It will now correspond to that of a second black body, whose temperature is to that of the first in the inverse ratio of the fourth

roots of the volumes of the detached part of the enclosure. 28. Lecher 2 has endeavoured to show that the distribution of energy among the constituents of the radiation from a black body does not alter with temperature. Such a result, though apparently inconsistent with many wellknown facts, appears to be consistent with and to harmonize many others. It accords perfectly with the notion of the absolute uniformity (statistical) of the energy in an enclosure, and its being exactly that of a black body, even if the contents (as in § 25) consist of a body which can radiate one particular quality of light alone. And if this be the case it will also follow that the intensity of radiation of any one wave-length by any one body in a given state depends on the temperature in exactly the same way as does the whole radiation from a black body. Unfortunately this last deduction does not accord with Melloni's results; at least the discrepance from them would appear to be somewhat beyond what could fairly be set down to error of experiment. But it is in thorough accordance with the common assumption (§ 14) that the percentage absorption of any particular radiation does not depend on the temperature of the source. The facts of fluorescence and phosphorescence, involving the radiation of visible rays at temperatures where even a black body is invisible, have not yet been dealt with under any general theory of radiation; though Stokes has pointed out a dynamical explanation of a thoroughly satisfactory character, they remain outside the domain of Carnot's principle. (P. G. T.) RADIOMETER. See PNEUMATICs, vol. xix. p. 249. RADISH. See HORTICULTURE, vol. xii. pp. 286, 287. RADNOR, an inland county of South Wales, is situated between 52° 5' and 52° 25′ N. lat. and between 2° 57'

and 3° 25′ W. long., and is bounded E. by Hereford and Shropshire, N. by Montgomery, W. by Cardigan, and S. by Brecknock. Its greatest length from north to south is about 30 miles, and its greatest breadth from east to west about 33 miles. The area is 276,552 acres, or 432 square miles.

The greater part of the surface of the county is hilly, and the centre is occupied by a mountainous tract called Radnor Forest, running nearly east and west, its highest summit reaching 2163 feet. Towards the south and south-east the hills are much less elevated and the valleys 1 Sitzungsber, d. k. Ak, in Wien, 1879. Wiedemann's Ann., 1882, xvii.

| widen out into considerable plains, abounding with small rivulets. The hills for the most part present smooth and rounded outlines, but the valley of the Wye is famed for its beauty. The higher ranges are covered with heath, but there is good pasturage on the lower slopes. The smaller elevations are frequently clothed with wood. The prevailing strata are the Lower Silurian rocks; but in the east there is a considerable area occupied by Old Red Sandstone, and throughout the county felspathic ash and greenstone are found, while near Old Radnor there is a large patch of Silurian limestone. Lead and copper are said to exist, but not in quantities sufficient to pay the working. There are saline, sulphurous, and chalybeate wells at Llandrindod. The Wye enters the county in the north-west, 18 miles from its source in Plinlimmon, and flowing in a south-easterly direction divides it from Brecknock, until it bends north-east and reaches Hay, after which it for some distance forms the boundary with Hereford. Its principal tributary is the Ithon, which flows south-west and joins it 7 miles above Builth. The Teme, flowing southeast, forms the northern boundary of the county with Shropshire. The Llugw, rising in the northern part of the county, flows south-east into Hereford, a little below Presteigne.

Agriculture. The climate is somewhat damp, and in the spring for pasturage, but there is some good arable land in the valleys in cold and ungenial. The greater part of the county is suitable only the southern and south-eastern districts, which produces excellent crops of turnips, oats, and Welsh barley, the soil being chiefly open shaly clay, although in the east there is an admixture of red sandstone soils. In 1884 there were 156,628 acres, or about fiveninths of the total area, under cultivation, and of these 114,242 acres, or about four-fifths, were in permanent pasture. Of the 21,356 acres under corn crops 12,245 acres, or more than half, were under oats, whilst wheat occupied 5200 acres and barley 3853. Green crops occupied only 7100 acres, of which 1107 were under potatoes and 5682 under turnips. Horses numbered 9249 (3755 used solely for agricultural purposes), cattle 30,917 (10,223 cows and heifers in milk or in calf), and sheep as many as 244,771. The inhabitants are dependent almost solely on agriculture, the manufactures being confined chiefly to coarse cloth, stockings, and flannel for home use.

Railways.-The county is intersected by several lines: the Central Wales Railway runs south-west from Knighton to Llandovery; another line runs south-eastwards by Rhayader and Builth and joins the Hereford line, which passes by Hay and Talgarth; while another branch line passes by Kineton to New Radnor. Administration and Population.-Radnor comprises six hundreds, but contains no municipal borough. It has one court of quarter sessions and is divided into six petty and special sessional divisions. The ancient borough of Radnor (population 2005) is governed by the provisions of an old charter, and has a commission of the peace. The county contains sixty civil parishes with part of one other, and is partly in the diocese of St David's and partly in that of Hereford. It returns one member to the House of ComThe population in 1871 was 25,430 and in 1881 it was 23,528, of whom 11,939 were males and 11,589 females. The number of inhabited houses was 4775. The average number of persons to an acre was 0.09 and of acres to a person 11.75.

mons.

History and Antiquities.-During the Roman occupation the district was included in the province of Siluria. The Roman road from Chester to Caermarthen entered the northern extremity of the county near Newtown and, following the valley of the Ithon, crossed the Wye and entered Brecknockshire near the town of Builth. There are remains of a Roman station at Cym near Llandrindod, and at Wapley Hill near Presteigne there is a very good example of a British camp. The district was afterwards included chiefly in Powis, but partly in Gwent and partly in Feryllwge. It was made a county by Henry VIII. Anciently it was called Maesy. fedd. The name Radnor is also of very great antiquity, and occurs in the Cambrian annals as early as 1196. There are no ancient castles claiming special notice, and the only ecclesiastical ruin of importance is that of the abbey of Cwm-Hir, founded for the Cistercians in 1143, and occupying a romantic situation in the vale of Clywedog. A considerable portion of the ancient building has been used as materials for the adjoining modern mansion.

RADOM, a government of Poland, occupying a triangular space between the Vistula and the Pilica and bounded on the N. by Warsaw and Siedlce, on the E. by Lublin, on the S. by Austrian Galicia and Kielce, and on the W.

by Piotrków. The area is 4765 square miles. Its southern part stretches over the hilly plateau of Poland, which consists of short ridges of hills from 800 to 2000 feet in height, intersected by deep valleys, and is known as the Sandomir Heights. These heights are thickly wooded; the valleys, running west and east and watered by several tributaries of the Vistula, are excellently adapted for agriculture. Farther north in its central portion the contour of the government is level, the soil fertile, and the surface, which is diversified here and there with wood, is further broken up by occasional spurs, 800 feet in height, of the Lysa Góra Mountains. The northern districts, where the Pilica joins the Vistula, consist of low flat tracts with undefined valleys, exposed to frequent floods and covered over large areas with marshes; the basin of the Pilica, notorious for its unhealthiness, is throughout a low marshy plain. Devonian, Carboniferous, Permian, and Triassic deposits appear in the southern plateau, Chalk and Jurassic in the middle, and Tertiary in the north. Wide tracts are covered with Glacial deposits, the Scandinavian erratics reaching as far south as Ilza; these last in their turn are covered with widely spreading post-Glacial lacustrine deposits. The Vistula skirts the government on the south and east and is an important means of communication, several hundreds of light boats (galary) descending the river every year, while steamers ply as far up as Sędomierz. The Sędomierz district is occasionally exposed to disastrous inundations of the river. The tributaries of the Vistula (Radomka, Kamienna, and several others) are but short and small, while those of the Pilica are mere streams sluggishly flowing amidst marshes.

The population (644,830 in 1882) is Polish for the most part, oneseventh being Jews. According to creed the proportions areRoman Catholic 840 per cent., Jewish 14-6, Protestant 1.3, and Greek 0-1 per cent. The chief occupation of the inhabitants is agriculture, the principal crops being wheat, oats, rye, potatoes, and beetroot (for sugar). Corn is exported and potatoes largely used for distillation. In 1879 there were 148 manufacturing establishments (197 in 1883), employing 1708 hands, with an aggregate production of 2,121,000 roubles (£212,000), the more important being tanneries, flour-mills, sugar-works, and several machinery and iron-works. These last are suffering, however, from want of wood-fuel, and many of them have recently been closed. Trade is not very extensive, the only channel of commerce being the Vistula. There is no lack of philanthropic institutions within the government (most of them founded early in this century), but nevertheless the sanitary condition of the people is deplorable. Plica polonica, which is endemic in the government of Radom as well as in that of Kielce, is widely diffused, no fewer than 15,000 persons suffering from it, and cognate maladies, such as goitre, scabies, and tinea capitis, are also widely prevalent.

The educational institutions include two lycées or gymnasia and two progymnasia (all at Radom), with 813 male and 287 female pupils, a normal school, a theological seminary at Sandomir, and 170 primary schools (112 in villages), with 8465 scholars.

The government is divided into eight districts, the chief towns of which are Radom, Ilza (2750), Konsk (6275), Kozienice (5690), Opatow (5200), Opoczno (5585), and Sędomierz or Sandomir (6265, or 14,710 including suburbs). Zavihvost (3700) is an important custom-house. Ostrowiec (5290), Staszów (6910), Przedborz (6345), and Szidlowiec (5290) have municipal institutions.

RADOM, capital of the above government, situated on the Mleczna, a tributary of the Radomka, 65 miles south from Warsaw, is one of the best-built provincial towns of Poland. Lublin Street has a number of fine shops, and there are two well-kept public gardens. The permanent population in 1882 was 12,970, half of whom were Jews, and the town is rapidly growing towards the south-east. Though an old town, Radom has no interesting antiquities. The church of St Wlaclaw, contemporary with the foundation of the town, was transformed by the Austrians into a storehouse, and subsequently by the Russian Government into a military prison. The old castle is in ruins, and the old Bernardine monastery is now used as barracks. The manufactures are unimportant, but trade has been lately increasing.

Radom, which is mentioned in historical documents of the year 1216, at that time occupied the site of what is now Old Radom. Jadwiga was elected queen of Poland in 1882, and here too in New Radom was founded in 1340 by Casimir the Great. Here 1401 the first act relating to the union of Poland with Lithuania was signed; the "seim" of 1505, where the organic law of Poland was sworn by the king, was also held at Radom. Several great fires, and still more the Swedish War, were the ruin of the old city. After the third partition of Poland it fell under Austrian rule; later on, in 1809, it became capital of the Radom department of the grand-duchy of Warsaw. In 1815 it was annexed to Russia and became chief town of the province of Sandomir.

RAEBURN, SIR HENRY (1756-1823), portrait-painter, was born at Stockbridge, a suburb of Edinburgh, on the 4th of March 1756, the son of a manufacturer of the city. He was early left an orphan. Being placed in Heriot's Hospital, he received there the elements of a sound education, and at the age of fifteen was apprenticed to a goldsmith in Edinburgh. Here he had some little opportunity for the practice of the humbler kinds of art, and various pieces of jewellery, mourning rings and the like, adorned with minute drawings on ivory by his hand, are still extant. Soon he took to the production of carefully finished miniatures; and, meeting with success and patronage, he extended his practice to oil-painting, being all the while quite self-taught. The worthy goldsmith his master watched the progress of his pupil with interest, gave him every encouragement, and introduced him to David Martin, who had been the favourite assistant of Allan Ramsay junior, and was now the leading portraitpainter in Edinburgh. Raeburn received considerable assistance from Martin, and was especially aided by the loan of portraits to copy. Soon the young painter had gained sufficient skill to render it advisable that he When in his should devote himself exclusively to art. twenty-second year he was asked to paint the portrait of a young lady whom he had previously observed and admired when he was sketching from nature in the fields. She was the daughter of Peter Edgar of Bridgelands and widow of Count Leslie. The lady was speedily fascinated by the handsome and intellectual young artist, and in a month she became his wife, bringing him an ample fortune. After the approved fashion of artists of the time, it was resolved that Raeburn should visit Italy, and he accordingly started with his wife. In London he was kindly received by Sir Joshua Reynolds, who gave him excellent advice as to his study in Rome, especially recommending to his attention the works of Michelangelo. He also offered him more substantial pecuniary aid, which was declined as unneeded; but Raeburn carried with him to Italy many valuable introductions from the president of the Academy. In Rome he made the acquaintance of Gavin Hamilton, of Batoni, and of Byers. For the advice of the last-named he used to acknowledge himself greatly indebted, and particularly for the recommendation that "he should never copy an object from memory, but, from the principal figure to the minutest accessory, have it placed before him." After two years of study in Italy he returned to Edinburgh in 1787, where he began a most successful career as a portrait-painter. In that year he executed an admirable seated portrait of the second Lord President Dundas.

Of his earlier portraiture we have interesting examples in the bust-likeness of Mrs Johnstone of Baldovie and in the three-quarter-length of Dr James Hutton, works which, if they are somewhat timid and tentative in handling and wanting in the trenchant brush-work and assured mastery of subsequent productions, are full of delicacy and character. The portraits of John Clerk, Lord Eldin, and of Principal Hill of St Andrews belong to a somewhat later period. Raeburn was fortunate in the time in which he practised portraiture. Sir Walter Scott, Blair, Mackenzie,