382 HERSCHEL, JOHN F. W. 



HESS, PETER. 



was subsequently enlarged into the " Outlines 

 of Astronomy," of which several editions 

 have been published. The extensive popular- 

 ity of these " Outlines" is proved by the fact 

 of their being translated into Russian, Arabic, 

 and Chinese. "The Cabinet Cyclopaedia" 

 was projected by the Rev. Dionysius Lardner, 

 and for it Mr. John Herschel wrote " A Pre- 

 liminary Discourse on the Study of Natural 

 Philosophy," which, at the time of its publi- 

 cation, created a remarkable sensation by the 

 graces of its style and frequent eloquence of 

 its language ; and certainly it did much to 

 originate the revival of the study of science in 

 Great Britain and America among the more 

 thoughtful classes, and to convince them that 

 the study of Nature's laws was worthy of the 

 most cultivated minds. This "Preliminary Dis- 

 course " was the work of a philosopher. In 1831 

 he was created a Knight of the Royal Hano- 

 verian Guelphic Order (K. IL), and in 1838 he 

 became a baronet. In 1833, being desirous of 

 carrying out, in the Southern Hemisphere, a 

 similar set of observations to those which he 

 had made in the Northern, he started for the 

 Cape of Good Hope. He was offered for him- 

 self and his instruments a passage in a king's 

 ship ; but he declined to avail himself of this 

 offer, and he himself defrayed the whole cost 

 of the expedition. Four years were spent at 

 Feldhuysen, near Cape ToVn, 1834-'37. The 

 great object of Sir John Herschel was to dis- 

 cover whether the distribution of the stars in 

 the Southern Hemisphere corresponded with 

 the results of his father's labors, prosecuted 

 mainly on the opposite side of the Galactic 

 circle. That the observations might be strict- 

 ly comparable, they were made by the same 

 method as Sir William Herschel adopted, and 

 with a telescope of the same optical power. 

 The whole number of stars counted in the 

 telescope amounted to 68,948, which were in- 

 cluded within 2,299 fields of view. By a com- 

 putation, based on the star-gauges in both 

 hemispheres relative to the Milky "Way, Sir 

 John Herschel found the stars visible in a 

 reflecting telescope of 18 inches aperture 

 amounted to 5,331,572; and, in truth, the 

 number really visible in the telescope was 

 vastly greater than this : for, in some parts of 

 the Milky Way, the stars were found to be so 

 crowded in space as to defy all attempts to 

 count them. The results of this vast labor 

 were published by Messrs. Smith & Elder in 

 1847, the expense being borne by the Duke of 

 Northumberland. The catalogue of the Royal 

 Society informs us that he contributed 131 me- 

 moirs and papers to the Scientific Transactions 

 and journals devoted to science : two other 

 memoirs he wrote in conjunction with Mr. 

 Babbage, and, as we have already stated, 

 one in connection with Sir James South. It 

 must not be supposed that Sir John Herschel 

 devoted all his attention to astronomical and 

 mathematical science. The phenomena of 

 light especially claimed much of his attention ; 



and we find in the "Philosophical Trans- 

 actions," and in those of the Cambridge Philo- 

 sophical Society, numerous papers on the 

 "Polarization of Light," the "Action of Light 

 on Crystals," and on allied subjects, nor should 

 it be forgotten that he contributed to the 

 Encyclopaedia Metropolitans a treatise on 

 "Light," and another on "Sound," which are 

 of the most exhaustive character, and may bo 

 quoted as examples of the highest class of 

 scientific literature. Geological science, too, 

 had attractions for him. The "Proceedings" 

 of the Geological Society of London contains 

 an excellent paper on "Phenomena connected 

 with the Internal Temperature of the Earth," 

 and another " On some Phenomena observed 

 in Glaciers." When Daguerre announced his 

 discovery of the production of pictures by the 

 agency of the sun's rays, Sir John Herschel at 

 once seized upon the subject, and brought all 

 his powers to bear on a careful examination of 

 the chemistry of a sunbeam. The result of 

 this was the publication, in 1840, in the "Phil- 

 osophical Transactions," of an important me- 

 moir "On the Chemical Action of the Rays of 

 the Solar Spectrum on Preparations of Silver 

 and other Substances, both Metallic and Non- 

 metallic, and on some Photographic Processes," 

 and a second memoir " On the Action of the 

 Solar Spectrnm on Vegetable Colors, and on 

 some New Photographic Processes." Besides 

 these, he communicated at the various meet- 

 ings of the British Association several valu- 

 able contributions to this branch of science ; 

 and to him alone is due the discovery of the 

 means of rendering photographic pictures per- 

 manent by dissolving out the unchanged salts 

 of silver by the use of the hyposulphite of 

 soda. His investigations on those salts will be 

 found recorded in the Edinburgh Philosophi- 

 cal Journal as early as 1819 and 1820. When 

 the discovery of the collodion process, by its 

 facility, removed photography from the do- 

 main of science, and placed it, as an art, in 

 he hands of trade, he withdrew, with some- 

 thing like disappointment, from his pursuit of 

 " active chemistry," leaving the record of his 

 labors as the starting-point for others, who will 

 find a vast field, as yet untouched, promising a 

 rich reward in the discovery of truths of the 

 highest character. The reviews which ap- 

 peared from time to time in the Quarterly and 

 Edinburgh Reviews were always elegant ex- 

 amples of that class of literature. These, and 

 his Address to the Royal Astronomical So- 

 ciety and to the British Association, were col- 

 lected into a volume, and published in 1857. 

 In the same volume are also to be found a 

 short series of poetical translations, chiefly 

 from the German, and some original poems, 

 all of which speak of the depth of the love 

 felt by the man of science for the poetical in 

 Nature. 



HESS, PETEK VON", a German painter of 

 genre and battle pieces, born at Dusseldorf, 

 July 29, 1793; died in Munich, in May, 1871. 



