Page:Encyclopædia Britannica, Ninth Edition, v. 13.djvu/862

828 K A L K A L of both mirrors, first, because in that position only the direct and reflected sectors are all at the same distance from the eye, and, in consequence, no want of symmetry is introduced by the foreshortening of one sector more than another ; and, secondly, because in that position the maximum amount of light is reflected to the eye by the mirrors, and, in consequence, the various sectors appear as nearly as possible equally illuminated. Of course a certain amount of light is necessarily lost at each reflexion, and hence there is always a slight difference between the luminosity of the various sectors. However, this is found not to introduce any serious want of symmetry when the instrument is properly constructed. A modification of the simple kaleidoscope was introduced by Sir David Brewster, whereby the images of large and distant objects can be introduced into the picture. This is effected by removing the object box and replacing it by a tube carrying at its outer end a double convex lens, represented by LL in fig. 5. By a screw adjustment the lens can be so placed as to focus the distant object Fig. 5. exactly in the plane of the sector AOB, and so bring its image into the very best position for producing symmetrical patterns. When this instrument is directed towards a tree in full foliage, or towards an arrangement of flowers in full bloom, a very beautiful effect is produced, which can be varied by gradually moving the instrument. This form was called by Brewster the telescopic kaleidoscope. Another form is called the polyangular kaleidoscope. (fig. 6). The only essential difference in it is that the mirrors are so ar ranged that the angle between them can be varied at pleasure. This, being very use ful for illustrating the theory of the instru ment, is the form usually found in col lections of philosophi cal apparatus. In all the instruments above described only two mirrors have been employed; but obvious ly we may have more than two. Suppose we wish to employ three mirrors enclosing a tri angular opening, and that we also wish to produce perfectly sym metrical pictures. We arc here limited in our choice of angles by the following conditions first, the sum of the three angles which the mirrors make with each other must be equal to 180, and, secondly, each angle must be an even submultiple of 360. By trial it is easily found that the only angles which satisfy these con ditions are 60, 60, 60; 90, 60, 30 ; and 90, 45, 45. Hence with three mirrors we must choose one or other of these three sets. The first is that usually chosen. Suppose similarly we wish to use four mirrors ; then, we must put them either in the form of a square, when all the mirrors are of equal breadth, or in the form of a rectangle, when the opposite mirrors are of equal breadth. It is obvious that in these two cases only will the angle between each pair of mirrors be an even sub- multiple of 360. With more than four mirrors kaleidoscopes cannot be constructed so as to give symmetrical forms, since each of the interior angles of a regular polygon of more than four sides must exceed an even sub- multiple of 360. See Harris s Optics ; Wood s Optics ; Parkinson s Oiitics ; Brew- ster s Treatise on the Kaleidoscope. The last-mentioned contains an account of the application of the instrument to the art of designing. (J. BL.) KALGAN", or CHANG-KEA-KOW, a large city of China, in the province of Chih-li, with a population estimated at from 70,000 to 100,000. It lies in the line of the Great Wall, 137 miles north-west of Peking, "commanding one of the most important passes between China and Mongolia and the main road of the overland route between China and Russia" (Bushell). Fritsche gives its position as in 40 50 X. lat. and 114 54 E. long., and its height above the sea as 2810 feet. The valley amid the mountains in which it is situated is under excellent cultivation, and thickly studded with villages. Kalgan consists of a walled town or fortress and suburbs 3 miles long. The streets are wide, and excellent shops are abundant ; but the ordinary houses have rather an odd appearance, from the fact that, like those of Erzeroum, they are usually roofed with earth and become covered with green sward. Large quantities of soda are manufactured ; and the position of the town renders it the seat of a very extensive transit trade. In early autumn long lines of camels come in from all quarters for the conveyance of the tea-chests from Kalgan to Kiakhta ; and each caravan usually makes three journeys in the winter. There is an excellent inn in the town frequented by the Russian merchants, some of whom have permanent residences and warehouses just outside the gate. On the way to Peking the road passes over a beautiful bridge of seven arches, ornamented with marble figures of monkeys, lions, tigers, and other animals. The name Kalgan is Mongolian, and means a barrier or "gate-beam." KALIDASA is the most illustrious name among the writers of the second epoch of Sanskrit literature, which, as contrasted with the age of the Vedic hymns, may be characterized as the period of artificial poetry. Owing to the utter absence of the historical sense in the Hindu race, it is impossible to fix with chronological exactness the life time of either Kalidasa or any other Sanskrit author. Native tradition places him in the 1st century B.C. ; but the evidence on which this belief rests has been shown to be wholly worthless. The works of the poet have been found to contain no allusions by which their date can be directly determined ; yet the extremely corrupt form of the Prakrit or popular dialects spoken by the women and the subor dinate characters in his plays, as compared with the Prakrit in inscriptions of ascertained age, has led the chief authori ties, Weber and Lassen, to agree in fixing on the 3d century of our era as the approximate period to which the writings of Kalidasa should be referred. The richness of his creative fancy, his delicacy of senti ment, and his keen appreciation of the beauties of nature, combined with remarkable powers of description, which are conspicuous throughout his works, place Kalidasa in the first rank of Oriental poets. The effect, however, of his productions as a whole is greatly marred by extreme artificiality of diction, which, though to a less extent than in other Hindu poets, not unfrequently takes the form of puerile conceits, and plays on words, the matter being treated merely as a means for displaying dexterity in the manif ulation of the language. In this respect his writings contrast very unfavourably with the more genuine poetry of the Vedas. Though a true poet, he is wanting in that artistic sense of proportion so characteristic of the Greek mind, which exactly adjusts the parts to the whole, and combines form and matter into an inseparable poetic unity. Kalidasa s fame rests chiefly on his dramas, but he is also distinguished as an epic and a lyric poet.