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    wave-like form in the sand is not a ripple mark , but a ripple ; if it is the mark of any thing it is a ' current mark / and as such I have always preferred to speak of it . Just as a current in the air produces a ripple in the surface of the water below it , so a current in the water produces a ripple in the sand below it . It makes no difference indeed whether the sand be acted upon by air or water . Whenever the circumstances are favourable , wind , will cause a ripple ( or eurreht .-mark ) on the surface of blown sand , as I observed frequently under very favourable circumstances at Sandy Cape in Australia , and as has been observed by Sir Charles Lyell near Calais . ( Lyell ' $ Elements , p . 20 , 4 th edition . ) In each case the moving fluid propels the grains of sand forward , piling them up into ridges , which are perpetually advancing by the rolling of particles over the crest of each ridge into the hollow beyond , where they are for a time sheltered from the current , but soou buried under the advancing ridge , to be again torn up and rolled onward perhaps as their site becomes exposed to the force of the stream .

    " The ripple or ' current mark' on the surface of a bed therefore ia no trustworthy guide as to the depth at which the bed was formed , as has sometimes been supposed , for as the water is rippled by the wind or current of air at the bottom of the atmosphere , so may mud or sand be rippled at the bottom , of the sea by the current of the water , whatever be its depth , provided the force of that current be sufficient to overcome the pressure of its weight to the necessary extent , and gently propel forward the sand or silt that lies below it . " Or this : — STETTCTttBE AND FOBMATION OF AQUEOUS BOCKS . "A group or series of beds , which in one place consists entirely of one set of materials , may in another consist of an entirely different set .

    " For example , a series of beds of almost pure limestone , say 800 or 1000 feet in thickness , may , by the gradual interposition of shale and sandstone and their increase in thickness , and the simultaneous thinning of the limestone beds , pass—in the course , say , of fifty miles—into a group of shales and sandstones , with few or no calcareous beds . " Similarly , a great group of beds , in one place consisting of sandstones , marls , and conglomerates , in another place may be composed entirely of clay-slate and limestone . "Again , a set of beds , in one part of the world composed entirely of soft white chalk , in another may be entirely hard black marble , and in a third may be clay-slate and sandstone .

    " These may seem to be rather dry and barren statements ; they are not entirely so . They have an interpretation : a story , if only a fragmentary one , may be deduced from them . We saw that from the structure of the aqueous rocks we could reason back to the nature and to the varied play of the agencies that produced them . The grouping of these rocks gives us similar information . " Take the case of the two beds of limestone or sandstone mentioned at p . 56 . "We learn that , after the first was deposited , there was a very considerable interval before the formation of the second , although when we first found them resting one on the other , there was nothing- to tell us of that interval . The first-formed

    or lowest bed rested at the bottom of the water , and into that water was swept on one side a quantity of silt , mud , and sand , that was carried a certain distance , and then fell to the bottom ; some of it , especially of its finer portion , was carried further than the other , but none of it reached so far as the place where we first found the beds . At that place , during the whole of that interval , the water remained unsullied with mechanical detritus , and not sufficiently impregnated with mineral matter to cause a deposition to take place . After that interval , perhaps after a s till longer one , another deposition took place , and the upper bed was formed , resting in one part directly on the lowest , and in the other , on the interposed materials .

    " In the case of great groups of rocks changing entirely their mineral character , we learn , among other things , that at the time those groups were deposited , Nature acted much as she now does ; that the surface of our globo was not one uniform sea , but broken by land and water ; and that the refuse and detritus washed from the land into the water , was of as various a character as it is now . While in some wide-spread and tranquil seas chemical precipitations were taking place , in other parts of the sa me seas mechanically suspended and transported materials were being brought in , just as we know must now be taking place in our present seas . ' We arc thus shown that these rocks wore not formed by any mysterious or inscrutable agency , acting by means or on n plan which we cannot discover or cannot unders tand , and are therefore left to guess at or conjecture about ; but by » c simple action of those natural agencies which surround us continually on every 81 do , and are o pen to our observation in our daily walks . lo the

    unobservant the world is a , riddle , a heap of wonders , a conjuror ' s > 0 *; to the observant , an admirable and beautiful piece of mechanism , for ever » work for his instruction and delight ; the agencies and tbo action for ever varyin g ' , like the strains of a . piece of music or tho harmony of a poem , but all co mbining' to one end , all obeying the impulse of ono law , all tending to one great system of order and arrangement . " Again : — HOW W 15 RE MINHHAL KOC . K 8 FUSED ? , question may here bo risked , porhnps , which we ought to endeavour to wvver , namely , How oiune minerals and rocks in a state of fusion ? in other words , > at is the ciiuHo or tho origin of si heat sufficient to molt tho most refractory rocks , ont ^ ni aml I ) 0 "r imt } l iioodif ° f malted "tone , to pile up great mountain-manses p ' /¦ lnoro < lust uml rofuHo of its safety-valves , and to shake and lift up whole u mtuiouts nfc onco ?

    « l > re J la ' S < i ( : luU )(; or wo briefly described tho extent to which volcanoes wore Prodi < ° ' V "' : RlOl ) 0 ' "U ( 1 < llC win"llirit y . "of- to «« y identity , of their elleds and train '" latitml ° H . If wo wore to examine " tho other igneous rocks , tho Onmit "" granitic , wo hIiouUI find an equal identity , throughout tho globe , nt . lh << '" Kmuito everywhere , throughout Ainorien , throughout Europe- and Asia ; * UMo l \ ° ° ( ? ( M ) d H ° ' ' llm ) IIKllout AuHtrulin , in the Indian ' Arahipoliigo . The » n < l lin l ' H ' of K re (! listolle ftndlwwnlfc , feldspar-trap and porphyry ; they occur whoUi » mUl ° ° nond <; baiaetoristies over the whole globe . This heat , then , MMinif « ' t ' r linciont or > " ° « 1 «™» ''» " «» . whether in its superficial or most deep-seated oflcvtH ti ° - > hnS 1 ) OOn ov"r 3 'where the name , and evorywhero produced the hiiiiio l »« rtiiif l HtttU " noufc a ( i onc 0 I » 'o « l «« lo 8 tbo possibility of its arising- from any ' AVo iii ,. n i arthH aml ulI"llic ^ H »« b hb Hilicon , aluminium , > yotnssuun , &c ., &c ., whon oxygon ( whether it bo derived from an-or wntcr )

    gams access to them at a proper temperature , unite with it so fiercely , as to produce vivid combustion and generate great heat . It ia supposed therefore that these metallic bases exist in large quantities in the interior of the globe , and that they are continually combining with oxygen somewhere or other , and this combustion taking place on a grand scale . This hypothesis is one that is sufficient to account for the facts of individual cases , and may . perhaps be-so . modified as to account for the similarity in the igneous rocks over the whole globe . Objections that were raised to it on purely chemical grounds , have since been shown to be untenable . " The other supposition is that the earth was originally , or at one period of its history , entirely in a fluid state , a globe of molten matter ; that a cooled crust then formed on it , which would at first be formed entirely of igneous rocks ; that after water had been formed and had existed for some time on it , the aqueous rocks were commenced , but that the molten matter of the interior occasionally forces its way to the surface , either along great cracks or at weak spots , and that , in its uneasy throes and pulsations , it has formerly , and still does occasionally , squeeze or inject yet molten matter into parts of the cooled external crust .

    "A modification of the latter hypothesis is supported by some ( partly on astronomical grounds and considerations of general physics ) , namely that whether the earth was ever entirely fluid or not , its interior is not now so , but that great subterranean lakes of molten matter exist in the interior at no great comparative depth in the earth , and not sufficiently extensive to at all resemble a central fluid nucleus . " Under the latter hypothesis or its modifications , the essential unity of the igneous rocks is fully allowed for and accounted for . We have seen in this chapter how intimately connected they all are , how they graduate and pass into each other ,

    how even they are all composed of the same substance—Silica—for at least half their mass , and how few are the other ingredients essential to their existence . The hypothesis of original fluidity accounts in the fullest way for their sameness in all pai'ts of the globe , and for the similarity of the composition of even their most striking varieties . Accepting it , we should view them all as springing from the same mass of matter , their varieties resulting either from substances added to their composition in their passage towards the surface , from the re-arrangement of their constituents in various parts , according to accidents not known to us , or from the different conditions to which they have been subjected , as to pressure , rate of cooling , or subsequent alteration .

    " It has been well remarked by Professor John Phillips , that the two hypotheses are not incompatible , and may be both entertained and united . " In conclusion it should be observed that Mr . Jukes confines himself to Physical Geology , leaving Palaeontology to be treated by another hand . He has done wisely in thus limiting his subject ; wisely , because Physical Geology is the subject peculiarly his own , and because , from an occasional glimpse we get , we suspect him of profoundly erroneous views with respect to the great biological question of the successive and progressive forms of life in anterior epochs . Thus , at p . 204 he says : —

    " It has been proposed to cut off the Cambrian rocks , considered as marked by the absence of all organic remains , from the rest of the Palaeozoic rocks , and to form a separate class , called Azoic , ( or destitute of animals ) , for all the rocks below those of the Silurian system . This appears to me to be premature , to say the least of it . It rests on the assumption , not only that no fossils have been found in rocks below the Silurian , but that no animals existed before the lowest Silurian rocks were deposited . It would suppose Lingulse and Trilobites to be the first of all created beings—a hypothesis that , to say the least of it , seems a very singular one , and for which it is difficult even to imagine any reason , fitness , or congruity with what we know of the laws and order of Nature . ' Do non apparentibus et de non cxistentibus eadem ost ratio / is doubtless a sound legal

    maxim , but in science it only holds good as forbidding any reasoning at all about the things in question : to argue that things do not exist because we cannot find any traces or remains of them , is to estimate by the deficiencies of our own powers and faculties tho omnipotence and superabundance of Nature * So little credit do I personally attach ( if I may be allowed to speak of myself ) to negative evidence in the matter of organic remains , that , to take up extreme ground at once , I hold myself perfectly prepared , if I live long enough , to hear of the discovery of the Silurian Mammalia , and of course of all those of the more recent periods . I am therefore individually quite prepared to hear sometime of the discovery of fossils older than Silurian forma , but certainly not at sill inclined to amuse myself and others by endeavouring to prophesy what they will be like . "

    In the iirst place , as a matter of logic , if it be not legitimate to argue from the absonco of any remains , that therefore no animals existed , surely the convorsSia not a more legitimate argument ? If I am far from justified in concluding there wore no animals because I cafc find no traces of them , surely you are not justified to concluding there were animals because we can rind no traces P In tho second place Mr . Jukea ' a declaration of being prepared to hear of Silurian mammalia , implies a wilful disregard of positive evidenco in favour of mere speculation !

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    SPANISH DRAMAS , OLD ANJ ) NEW . Six Dramas of Caldcron . I'Veely Translated by Edward Fitzgerald . Pickering Tho Flower of a Day . A Driunn . Translated from tho { Spanish of Don . Frunewco Ciunprodon . By William Uiddulpli Purkor . •) . W . Parker niul Son . A not uninstrucbivo contrast ; may evolve itsolf from the study of the . so two small volumes . Oalderon ia tho greatest name in tho annals of tho ancient ; Spanish drama , and Cmnprodon linn a name in his own country , though probably not moro than a hundred iJlngliahrncn have any acquaintance with it . Mr . Parker during his residence in Spain seems to have caught tho national ewjouement . He says : — " On my return to England , after some years absence in Spain , I was mirprisod by hearing- it frequently asserted , that ; both the national dranin and poetry ot that country were ivt tho lowest possible ebb . Now , us I bad boon n constant attendant at the Spanish theatre , and particularly interested by tho plays of Zorilla , Ciuunrodon , ltubi , Uroton de los Herreros , and other author ' s , I wus most anxious to refute

    tins , in my opinion , undeserved calumny . " I therefore selected and translated three plnys : The Flower of a Day , by Ciunprodon ; Traitor , Martyr , and Unshrhen , tho last and , I think , tho best dramatical production of Zorilla ; nnd tho Tempests of tho Heart , by Jtubi ; considering them fair Hpoeiinens of tho modern ? Spanish drama . " On Bonding thorn , bowover , to n publisher , I wan informed , to my grievous disappointment , that in hia opinion , not fifty copies would bo sold ; that Engliim people

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    September 3 , 1853 . ] THE LEADER . 859

• Citation
  • Leader (1850-1860), Sept. 3, 1853, page 859, in the Nineteenth-Century Serials Edition (2008; 2018) ncse-os.kdl.kcl.ac.uk/periodicals/l/issues/vm2-ncseproduct2002/page/19/