382 



H U T T O N. 



Mutton, alkali had been found in a stony mineral. He con- 

 """Y"" 1 * tinned to make tours to various parts of the island, in 

 prosecution of his geological inquiries, which assumed 

 greater and greater consistency. In 1777, Dr Hutton 

 published a pamphlet entitled, Considerations on the Na- 

 ture, Qualities, and Distinctions of Coal and Culm, with 

 a view to throw light on a disputed point, whether the 

 Mnall coal of Scotland was liable to the duty on F.ng- 

 lish coal, or to that on English culm. On this sub- 

 ject he displayed great accuracy of observation ; and 

 his discussion led to a satisfactory decision of the ques- 

 tion. From the time of fixing his residence in Edin- 

 burgh, Dr Hutton had been a member of the Philoso- 

 phical Society, known by the three volumes of literary 

 and physical essays which it published. In i.hat Society 

 he read several papers, none of which have been pub- 

 lished, with the exception of one which appeared in the 

 second volume of the Transactions of the Royal Society 

 of Edinburgh, " On certain natural appearances of the 

 ground on the hill of Arthur's Seat." The institution 

 of the Royal Society, which happened in 1783, called 

 forth from Dr Hutton the first sketch of his Theory of 

 the Earth, which he had matured in his own mind, but 

 communicated only to his friends Dr Black and Mr 

 Clerk of Eklin, both of whom approved of it. For an 

 account of this theory, see the article MINERALOGY. The 

 distinguishing feature of it was, the universal agency 

 of heat in consolidating the rocky strata, after the ma 

 terials of which they were formed had been collected 

 by the subsiding of loose earthy materials at the bottom 

 of the sea. This heat he conceived to be seated in the 

 central parts of the earth. To the expansive power of 

 this agent, acting on water or other bodies, he ascribed 

 the elevation of the strata from the bottom of the sea 

 to the higher situations which they have since occupied. 

 He thus accounted for the present appearances. He 

 supposes the earth to have undergone many revolutions 

 *t very distant intervals of time, and to be subjected to 

 a law which produces a general and sudden convulsion 

 as a stage in certain cycles of changes, which at all other 

 times are slowly yet incessantly advancing. This theory 

 has been defended by the author and his followers \vith 

 much learning and ingenuity ; and in a particular man. 

 ner by his zealous and enlightened admirer Professor 

 Playfair. It has however met with a formidable com- 

 petitor in that of Werner ; the leading feature of which 

 is, to account for consolidation by crystallization from a 

 State of aqueous solution, rejecting the hypothesis of a 

 central heat, whether as concerned in the fusion of the 

 rocks, or in the elevation of the strata. It supposes the 

 materials of the strata to have subsided at their present 

 elevation ; and its chief embarrassment consists in the 

 difficulty of accounting for the retiring of the waters. 

 The illustration of these opposite general views includes 

 a vast variety of discussion on the constitution of the 

 rocky strata. The controversy has eminently promoted 

 the investigation of the mineral kingdom. A great 

 part of the world content themselves with a smile bor- 

 dering on contempt, when they casually listen to these 

 speculations ; and a superficial observer is generally 

 struck with the character of extravagance which ap- 

 pears so prominent in the hypotheses assumed. No hy- 

 pothesis, however, within the limits of possibility is too 

 extravagant for the subject. The disposition of the 

 strata is itself an extravagant fact, if we may be allowed 

 to apply this epithet to any thing in nature. It points 

 to causes so different in their general character from any 

 that we see in actual operation, that no hypothesis is to 

 he rejected for its strangeness ; and hypotheses of this 



kind are unavoidable to those who attempt to explain Huttou. 

 the phenomena before them. A wish of thi.s sort 1 *^"Y"~ 1 " 

 cannot be reasonably condemned. There can scarce- 

 ly be a more sublime speculation in physics, th:m to 

 attempt the resolution of problems which nature sug- 

 gests on so magnificent a scale. We may indeed 

 sometimes wonder to see a particular theory so tena- 

 ciously adhered to ; and it may be regarded as a cu- 

 rious fact, that in the present age the one or the other 

 of tlie theories now mentioned should be adopted by 

 all geologists. It might be supposed, that the sub- 

 ject would afford several others equally plausible ; but 

 it is probably not so much a satisfaction with their 

 own theory as a simple prrfi-rence of it to its oppo- 

 nent, that is indulged in by the greater part of ge- 

 ologists. The unexplained phenomena of mngnetitm, 

 particularly the fluctuating variations of the needle, and 

 the supposition of interchanges of materials among the 

 different planets, (countenanced in some measure by 

 the well authenticated instances of stones which have 

 fallen from the atmosphere,) will perhaps at some fu- 

 ture period lead to a modification of our geological 

 theories, or to the formation of others. 



A paper of Dr Hutton " On the Theory of Rain,-" 

 was published in the first volume of the Edinburgh 

 Transactions. It forms the only scientific explanation 

 of the phenomena that we have. The discovery of it 

 evinced profound genius and accurate infomiation, and 

 it will probably always be retained by meteorologists. 

 Two portions of air of different temperatures, both sa- 

 turated with humidity when mixed, and thus reduced 

 to a medium temperature, have not the power of retain- 

 ing the same quantity in a state of vapour. The reason 

 of this is, that the quantities of humidity retained in 

 this state proceed in a geometrical ratio, while those of 

 temperature increase arithmetically. A larger quantity 

 of water is retained by that heat which had kept the 

 one portion of air above the reciting medium, than 

 when the same heat is employed in raising to that me- 

 dium the temperature of the coldest portion. The con- 

 sequence of this is, that a part of the water is precipi- 

 tated. This theory was opposed by Monsieur de Luc, 

 who maintained, that the heat was communicated from 

 one part of the atmosphere to another without the ac- 

 tual intermixture of different portions of air. Dr Hut- 

 ton made several other acute improvements in meteoro- 

 logy, which were afterwards published in his " Physi- 

 cal Dissertations," in which his theory of rain was again 

 given. It was by the theory of the earth, however, that 

 the greatest portion of his interest was absorbed. The 

 journeys which he made to Glen Tilt, to Galloway, the 

 isle of Arran and St Abb's Head, supplied him with 

 fHCts which afforded him exquisite delight, especially 

 those which elucidated his peculiar views of the nature 

 of granite, and the circumstances under which it assu- 

 med its present situation in relation to the other rocks. 

 He supposed it to have been forced up in a state of ig- 

 neous fusion by the expansive power of the central heat, 

 and injected in that state into the rents produced in the 

 superincumbent strata, which had previously formed the 

 exterior crust of the globe. It was the continuation of 

 the granite upward into these rents or veins that so much 

 delighted Di- Hutton. This is a fact which still fur- 

 nishes one of the strong points of the Huttonian the- 

 ory. 



This philosopher also turned his attention to another 

 subject suggested by his chemical pursuits, viz. the ge- 

 neral nature of matter. His doctrines on this subject, 

 are given in his " Dissertations on different subjects in 



