| OCR Text |
Show 84 CAUSES OF ERROR IN who possesse d op ti'cal instruments as perfe. ct ash any in mod·e 1rn Europe, t h ey wou ld Probably ' on consultmg t ese memoria1 s, h come to a conclusion that there had been a gre~t revo u- tl.oavne .m t 11 e so 1a r an d sidereal systems. ''Many prtmd a· ry ha nd secon d ary P1 a ne t s, '' they might say ' "are e.n .u merate m .t esde tab l es, w h1. c h ex I'st no lonoo· er • Their pos1t10ns are ass1gne with such precision, that we may assure ourselves that there is nothing in their place at present but the blue ether. Where one star I· S v1·s 1' ble to us ' these documents re. present sev. eral t h ousan d s. Some of those which are now smgled,' Jrc onsisted t11en of two separate bodies, often distinguis11ed by Iuerent co-l ours, , a nd revolvinOo' periodically round. a comm.o n centre of gravity. There is no analogy to them m the umverse at pre-sent, for they were neither fixed stars nor planets, but stood in the mutual relation of sun and planet to each other .. We must conclude, therefore, that there bas occurred, at no distant period, a tremendous catastrophe, whereby thousands of wor~ds have been annihilated at once, and some heavenly bo?ws absorbed into the substance of others." When such doctrmes had prevailed for ages, the discoyery of one of the worlds, supposed to have been lost, by aid of the first rude telescope, would not dissipate the delusion, for the whole burden of P~?of would now be thrown on those who insisted on the stabiltty of the system from the beginning of ti~e, an~ these J)hilosophers would be required to demonstrate the existence of .all .the worlds said to have been annihilated. Such popular preJudices would be most unfavourable to the advancement of astronomy i for instead of persevering in the attempt to improve their instrume~ ts, and laboriously to make and record observations, ~he greater number would despair of verifying the continued existence of the heavenly bodies not visible to the naked. er· Instead of confessing the extent of their ignorance, and stl'lvmg to remove it by bringing to light new facts, they. wou~d be engaged in the indolent employment of framing .1ma~mary theories concerning catastrophes and mighty revolutiOns m the system of the universe. For more than two centuries the shelly strata of the Subapennine hills afforded matter of speculation to the early g.eologists of Italy, and few of them had any suspicion thafsim.tlar deposits were then forminO' in the neighbouring sea. Tncy were as unconscious of the ~ntinued action of causes still pro- GEOLOGICAL THEORIES. 85 clueing similar effects, as the astronomers, in the case supposed by us, of the existence of certain heavenly bodies still giving and reflecting light, and performing their movements as in the olden ti~e. Some imagined that the strata, so rich in organic remains, instead of being due to secondary agents, had been so created in the beginning of things by the fiat of the Almighty; and others ascribed the imbedded fossil bodies to some plastic power which 1·esided in the earth in the early ages of the world. At length Donati explored the bed of the Adriatic, and found the closest resemblance between the new deposits there forming, and those which constituted hills above a thousand feet high in various parts of the peninsula. He ascertained that certain genera of living testacea were grouped together at the bottom of the sea in precisely the same manner as were their fossil analogues in the strata of the hills, and that some species were common to the recent and fossil world. Beds of shells, moreover, in the Adriatic, were becoming incrusted with calc~reous rock; and others were recently enclosed in deposits of sand and clay, precisely as fossil shells '~ere found in the hills. 'l'his splendid discovery of the identi~ y of modern and ancient submarine operations was not made without the aid of artificial instruments, which, like the telescope, brought phenomena into view not otherwise within the sphere of human observation. In like manner, in the Vicentin, a great series of volcanic and marine sedimentary rocks were examined in the cady part of the last centu.ry; but no geologist suspected, before t~1c time of Arduino, that these were . partly composed of ancient submarine lavas. If, when these enquiries were first made, geologists had been told that the mode of formation of such rocks might be fully elucidated by the study of processes then going on in certain parts of the Mediterranean, they would have been as incredulous as geometers would have been before the time of Newton, if any one had informed them that, by making experiments on the motion of bodies on the earth, they might discover the laws which regulated the movements of distant planets . . Tl~e establishment, from time to time, of numerous points of 1?entification, drew at length from geologists a reluctant admisSion, that there was more correspondence between the physical constitution of the globe, and more uniformity in the laws re- |
