DIONYSIUS DIORAMA. 



683 



Christianity by the apostle Paul, about the middle of 

 the first century, and first bishop at Athens, where 

 he suffered martyrdom, is remarkable for the Greek 

 works which have been ascribed to him, and for be- 

 ing considered the patron saint of France. These 

 writings, composed in an obscure style, and hardly 

 intelligible on account of their mysticism, are, Of 

 the heavenly Hierarchy, Of the Names of God, Of 

 the ecclesiastical Hierarchy, and Of the mystic Theo- 

 logy, with a number of letters, which, by their style, 

 contents, and historical allusions, betray an author 

 who could not have lived before the middle of the 

 fourth century. They appeared, in a very equivocal 

 manner, as the works of Dionysius, as late as the 

 sixth century. Fantastic descriptions of the Deity, 

 and of the orders of angels and blessed spirits, bor- 

 rowed from the New Platonic philosophy ; brilliant 

 representations of the Catholic ceremonies ; exalta- 

 tions of the hierarchy ; praises of the monastic life, 

 and mystic interpretations of the doctrines of the 

 church, gave them such charms, that the absurdities 

 in which they abound did not prevent the ignorant 

 clergy of the seventh century from reading them with 

 delight, and finding in them the clearest proofs of the 

 apostolic origin of many ecclesiastical observances 

 and institutions, which are of a much later date ; for 

 they had no doubt of their genuineness. In France, 

 where a certain Dionysius established the first Chris- 

 tian community at Paris, in the third century, they 

 were readily received in the ninth century ; and this 

 Dionysius, without further inquiry, was taken for the 

 Areopagite, because the origin of the Gallican church 

 could thus be carried back to the first century ; and 

 France gained a patron who was a martyr and the 

 immediate disciple of an apostle. The monastic life, 

 in the Western church, gained new support from 

 these writings, which were frequently translated into 

 Latin ; and mystic theology received its first impulse 

 from them. The convent of St Denis, which was 

 originally dedicated to the first apostle of Christianity 

 at Paris, but is now consecrated to Dionysius the 

 Areopagite, had a remarkable dispute with the con- 

 vent of St Emmeran, at Ratisbon, in the eleventh 

 century, concerning the possession of the genuine 

 bones of the saint. Each maintained that it possessed 

 his earthly remains, and each had its claims confirm- 

 ed by the infallible authority of the pope. In the 

 fourteenth century, another church in Paris claimed 

 the third head of the sainb. The writings attributed 

 to Dionysius the Areopagite, are as spurious as the 

 relics. The pretended author of them neither left 

 such writings, nor ever taught in France, as was put 

 beyond all doubt by the French critics Daille, Sir- 

 inoiul, and Launoi, in the seventeenth century. 



DIONYSIUS the Little (so called on account of 

 his short stature); a Scythian monk, who was abbot 

 of a monastery at Rome in the beginning of the sixth 

 century, and died about the year 545, celebrated as 

 the author of the computation of time from the Chris- 

 tian era. He calculated an Easter cycle in 526, and 

 fixed the birth of Christ, agreeably to the most cer- 

 tain data, in the year 753 after the foundation of 

 Rome. The computation of time from the birth of 

 Christ thus established, and now universal among 

 Christians, was not publicly used until the eighth cen- 

 tury. His collection of ecclesiastical laws, viz. the 

 (so called) Apostolical canons, decrees of councils 

 favourable to the pretensions of the Roman bishops, 

 and official letters written by the Roman bishops 

 since the fourth century, which were called Decretals, 

 had a more rapid success. The placing of the latter 

 by the side of the decrees of councils, and thus at- 

 tributing to them equal authority, was so flattering 

 to the pride of the Roman bishops, and the letters of 

 their predecessors afforded so favourable an oppor- 



tunity for renewing their ancient pretensions, that the 

 collection soon obtained the authority of an acknow- 

 ledged source of canon law. Dionysius was, as his 

 friend Cassiodorus says of him, a good Latin writer, 

 and well acquainted with the Greek language, from 

 which he translated much. Nothing more is known 

 of him, except that he favoured the superstition of 

 the Theopaschites. 



DIOPTRICS ; the science which treats of the re- 

 fraction of the rays of light, or the laws of vision when 

 the rays, before reaching the eye, pass through dif- 

 ferent refracting mediums ; for instance, from the air 

 through the glasses of a telescope. Dioptrics, conse- 

 quently, is a branch of optics, i. e. the science of 

 vision in general. It demonstrates the different direc- 

 tions in which the rays move, according as they are 

 broken on plane or curved surfaces. The principles 

 deduced from these observations determine the nature 

 of the various lenses, explain the manner in which 

 the light is refracted in the human eye, teach the 

 manner of seeing through lenses, and the composition 

 of them, consequently the theory of telescopes, mag- 

 nifying glasses, &c. The ancients were not acquainted 

 with this science. Natural science, in modern times, 

 has been greatly indebted to it. By its aid, or 

 rather by the aid of the glasses which it has taught 

 how to construct, the human eye has been enabled to 

 reach objects previously unknown. Kepler, Snellius 

 of Leyden, Descartes, Newton, &c. , not only extended 

 this science, but founded a great part of their dis- 

 coveries on it. In modern times, the science of diop- 

 trics has been very much enriched by the important 

 invention of the acliromatic telescope commonly at- 

 tributed to Mr Dollond, but which, in fact, was the 

 invention of Mr Hall, of Essex, as was proven to the 

 satisfaction of a jury. The imperfection of the Eng- 

 lish law of patent was clearly exhibited in this case, 

 as Mr Dolland's claim was sustained from his being 

 the first who sold an achromatic telescope. See 

 Achromatic, Refraction of Light, Telescope, Lenses. 



DIORAMA. Under this title a novel and a very 

 beautiful mode of depicting landscape scenery has 

 been, within these few years, exhibited in Paris and 

 London. It appears to be an improvement on an 

 invention of the late M. De Loutherbourg, who 

 made a similar exhibition about forty years ago, 

 which was then much admired and styled Eido- 

 physikon. M. De Loutherbourg's pictures, however, 

 were only shown by lamp light, whereas in this 

 new method, the exhibition takes place by daylight 

 only. The advantage which this mode of represent- 

 ing the face of nature, possesses over any other yet 

 invented, is, that it causes the light to play at will 

 all over the picture, so that the spectator can hardly 

 help imagining himself placed on the very spot, 

 when he perceives the rays of the sun now lighting 

 up one range of mountains, now another, and beholds 

 them peeping out from behind masses of clouds, 

 which gradually become overcast as if with rain, and 

 then the lowering effect giving way in its turn to 

 bright gleams of sunshine which enlighten the bos- 

 soms of the distant lakes, glitter upon the purling 

 brooks, and then die away behind the darker skirts 

 of the surrounding woods and thickets. 



this is produced by a mode of uniting trans- 

 tainting to the usual opaque method, and caus- 

 daylight to fall upon the picture, both from 

 before and behind. At the same time, while by means 

 of coloured transparent bunds, suspended both above 

 and behind the picture, and which are put in motion 

 by means of machinery the rays of light can be 

 intercepted and made to fall at pleasure in 

 graduated tints upon every part of the picture in sue- 

 cession. To understand this more clearly we hav<? 

 annexed the following engraving. 



