1823.] Subterr anean Heat . — Improved System of Road- Making. 121 



view, if not an equal portion of inter- 

 esting matter or superior talent, the 

 siirae fearless and consistent spirit of 

 freedom, the same unshrinking ad- 

 vocacy of liberal principles, and the 

 same correct discrimination on literary 

 subjects, which have so long recom- 

 mended it to those Avlio have formed 

 their taste upon classical models, and 

 their political principles on the basis 

 of true patriotism. 



To the Editor of the MmUhly Magazine. 



SIR, 



THE question, as to whether the 

 earth contains within itself any 

 general source of heat, increasing 

 downwards from the surface, as those 

 crude and sceptical philosophers have 

 maintained, who contended for a 

 central furnace, out of which nearly 

 all the solid superficial parts of the 

 globe have been vomited in a molten 

 state, — has of late been much enquired 

 into and contested amongst the Cor- 

 nish geologists and miners ; by which 

 the fact of apparent increase of tem- 

 perature downward s, in the open spaces 

 of deep mines in work, has been esta- 

 blished, and some few isolated feeders 

 of water have been found to enter 

 these deep workings in a warmer 

 state than more superficial springs ; 

 but Mr. P. Moyle, by his excellent 

 observed facts and reasonings, insert- 

 ed in some late numbers of the " An- 

 nals of Philosophy," appears to have 

 nearly set the question at rest, by 

 showing the utmost probability, that 

 adventitious causes, like respiration of 

 the miners, combustion of the candles, 

 oxidation of the newly-exposed mine- 

 rals and rocks, friction of the machi- 

 nery, and probably other unknown 

 local causes of heat, have occasioned 

 the variably high temperatures ob- 

 served in deep mines whilst in work ; 

 and that these same mines, when dis- 

 «ised, and allowed to become full of 

 water, as numbers are, into which 

 IVlr. Moyle has simk properly-con- 

 trived thermometers, to a series of 

 different depths, from 60 to more than 

 10(X> feet under water ; all of them 

 concur in showing an almost uniform 

 temperature, something below the 

 mean heat of the surface. 



licrland mine, one of the deepest of 

 tJu; disused mines on which Mr. M. 

 has thus experimented, is fortunately 

 about to be emplifd of its water, and 

 again wrought; and, on the other 



Monthly Mao. N<>. ,'J79. 



hand, Huet Abraham, one of the 

 deepest mines now in work, whose 

 temperature has been well observed 

 and recorded as amongst the hottest 

 of the mines, is about to be disused, 

 and become full of water ; and on the 

 results of the cross or counter experi- 

 ments, to be hereafter made in these 

 two mines, Mr. Moyle appears very 

 properly willing to rest, for the proof 

 of his assertions, that there is no na- 

 tural increase of temperature down- 

 wards. As to the hot-springs which 

 occur, he says, "While these prove 

 the existence of causes sufficient to 

 give them their high degree of tempe- 

 rature, they prove at the same time, 

 by their rarity, the local and adventi- 

 tious nature of those causes;" and, as 

 to volcanoes, we may add, that theli 

 sources of heat are still more local and 

 rare of occurrence. Y. 



To the Editor of the Monthly Magazine. 



SIR, 



AT a time like the present, when, 

 owing to diminished prices of all 

 commodities, the depressed house- 

 keepers are casting their eyes on every 

 side, some to divert attention from 

 the cause, and some others to evade the 

 overwhelming pressure of the direful 

 effects of proceedings not now to be 

 recalled ; it is with real earnestness 

 that I solicit your aid in the furtherance 

 of an object calculated not only to 

 diminish parish -burthens by furnishing 

 ample employment to an infinite num- 

 ber; but, in its prosecution, tending 

 greatly towards the national advantage, 

 as well as happiness. The comprehen- 

 sive view which the Monthly Magazine 

 has ever taken of every means which 

 is suggested for the general good, 

 together with the notice, a few months 

 back, of some efforts relative to my 

 present subject, induce me to endea- 

 vour, through your medium, to more 

 widely diffuse the immense advan- 

 tages some districts enjoy by the adop- 

 tion of a system of road-making and 

 improving, upon the plan of John 

 Loudon M'Adam, esq. general sur- 

 veyor of the Bristol district. The 

 roads, under the above superintend- 

 ance, have, in the proceedings of a 

 Select Committee of the House of 

 Commons, sitting in March and April 

 last, been decided as superior in every 

 point to any ever travelled, by the 

 evidence of the greatest coach-masters 

 in the kingdom, with the further advan- 

 \i ta-e 



