194 



NATURE 



{June 28, 1888 



circulated, and expounded in the following year. The 

 precaution was nevertheless insufficient to prevent a claim 

 to priority being put forward. Dr. Wallis, the Savilian 

 Professor of Geometry, prepared on behalf of his friends 

 Wren and Neile, a storage-battery of fame in the shape 

 of a counter-anagram, which — if Huygens's private notes 

 are to be relied upon — he fraudulently interpreted as an 

 announcement similar in purport to that imparted to him 

 from the Hague. Some unexplained circumstance possibly 

 underlies a transaction on the face of it highly discredit- 

 able to our countrymen. The pretensions of the English 

 observers were at any rate quickly and quietly withdrawn, 

 and Huygens was left in undisturbed enjoyment of the 

 credit most justly due to him. 



Shortly after his return from Paris, late in 1655, he 

 constructed a telescope of 23 feet, magnifying one 

 hundred times ; and the comparison of the observa- 

 tions it afforded him with those of the previous year 

 enabled him at once to penetrate the mystery of Saturn's 

 enigmatical appendages. His hypothesis as to their 

 nature, wrapt up in the customary logogryph, was ap- 

 pended to his little tract on the Saturnian satellite, with 

 an accompanying prediction of the future changes of 

 figure to be expected in the planet. Its verification, how- 

 ever, falls outside the limits of the publication we are at 

 present concerned with. Nor does it include any mention 

 of the novel sight disclosed to Huygens by his improved 

 instrument in the constellation of Orion, where a certain 

 " hiatus " in the firmament permitted (as he supposed) 

 the pure, faint splendour of the empyrean to shine through 

 on his amazed vision. 



Huygens .had an eminently sane and sagacious mind. 

 His fortunate intuitions were numerous, and the inves- 

 tigations they suggested were singularly solid and com- 

 plete. A great part of his work was thus fitted to be, and 

 has actually become, the substructure of the modern 

 scientific edifice. He was, however, less happy in the 

 few cases in which, relaxing his habitual prudence, he 

 gave the rein to speculation. His prevision that the 

 measure of discovery in the solar system was filled by the 

 disclosure of Titan, was belied with scarcely civil haste 

 by Cassini's further detections hopelessly overthrowing the 

 numerical balance between six primary and six second- 

 ary bodies. And the surmises which constituted the bulk 

 of his " Cosmotheoros " were, for the most part, infelicitous. 

 Yet he reprehended, as woven out of figments, the Car- 

 tesian theory of the origin of the universe, and concluded 

 with the wise and memorable words :— "To me it would 

 be much if we could understand how things actually are, 

 which we are far enough from doing. How they were 

 brought about, what they are, and how begun, I believe 

 to be beyond the range of human ingenuity to discover, 

 or even by conjectures to approach/' 



A. M. Clerke. 



NORWEGIAN GEOLOGY. 



BbmmeWen og Karmocn med Omgivelser. Geologisk 



beskrevne af Dr. Hans Reusch. (Kristiania : Published 



by the Geological Survey of Norway, 1888.) 



'THE attention of geologists in all parts of the world 



- 1 - has for some years been concentrated upon the 



crystalline schists, which have so long presented insuper- 



able difficulties to those who would explore their origin. 

 Little by little the darkness has been rising from these 

 ancient foundation stones of the earth's crust ; and 

 though a long time must probably still elapse before their 

 history can be even approximately sketched, there can 

 be no doubt that we are now at last on the right road of 

 investigation. Fresh evidence is continually being ob- 

 tained from the rao:t widely-separated regions, and each 

 additional body of facts goes to support the view that the 

 schistose rocks are the records of gigantic terrestrial 

 displacements, whereby portions of the crust have been 

 pushed over each other, and so crushed and deformed as 

 to acquire new internal rock-structures. Out of these 

 mechanical movements, with their accompanying che- 

 mical transformations, a true theory of metamorphism 

 will no doubt eventually be evolved. In the meantime 

 it is too soon to generalize ; what we need is a far larger 

 mass of observations. The subject is a wide one, for it 

 involves the labours of the field-geologist, the petro- 

 grapher, the mineralogist, the chemist, and the physicist. 

 And only by the united exertions of these fellow-workers 

 can we hope for good progress and solid results. 



The most recent contribution to the question of the 

 origin of the crystalline schists has just appeared in the 

 form of a handsome volume, by Dr. Hans Reusch, on 

 the Bommel and Karm Islands off the mouth of the 

 Hardanger Fjord. It consists of a mass of detailed ob- 

 servations on the structure of the crystalline rocks of that 

 part of the Scandinavian coast, and furnishes an admir- 

 able array of fresh data for the study of the problems 

 of regional metamorphism. Dr. Reusch's previous re- 

 searches on the compressed conglomerates and meta- 

 morphosed fossiliferous rocks of the same district were 

 of the utmost value in the discussion of the question, 

 and he now augments these by new details from the 

 surrounding region. 



Especially important are the numerous illustrations of 

 the effects of pressure and stretching in the production 

 of the well-known structures of the crystalline schists. 

 The strangely deceptive resemblance to stratification 

 resulting from these processes is exhibited in many ex- 

 amples. Excellent instances are likewise given of the 

 production of foliation in dykes. Eruptive diabases and 

 gabbros are shown to pass into dioritic rocks, and horn- 

 blendic schists and granite mto various foliated com- 

 pounds. More novel features of the essay are the 

 careful studies of the deformation and foliation of what 

 were unquestionably at one time ordinary sedimentary 

 deposits — sandstones, conglomerates, and limestones. It 

 is shown, for instance, that in a mass of still recognizable 

 conglomerate the planes of stratification are cut across, 

 almost at right angles, by those of foliation, while the 

 lines that mark the direction of stretching or deformation 

 slant upwards across the latter. 



Dr. Reusch brings forward some remarkable observa- 

 tions regarding the connection between conglomerates 

 and granitic rocks. He thinks that in some places what 

 is now granite has resulted from the metamorphism of 

 what was originally a breccia or conglomerate composed 

 of fragments of granite, gneiss, quartzite, and quartz. 

 The quartzite and quartz, being less liable to change, 

 remain still visible, while the granite and gneiss have 

 passed into common granite. In another locality he 



