72 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[March 



the qualities of the component soil, in every perforation^ into the boJy of 

 the earth the temperature increases regularly with the depth of perforation, 

 and that the water when reached has always a warmth proportionate to 

 its depth under the incumbent soil, thus natural rivers have at their original 

 springs (if constant) a warmth which in the coldest weather prevents their 

 freezing, and it has been ascertained that the well at Paris, the deepest 

 we believe ever executed, gave a high temperature much above the heat 

 of any other artificial spring. 



Let me endeavour to explain my views by observing, that admitting as 

 a llieory, that the attraction or condensation of the materials of the earth, 

 and simply sea sands, I conceive that at some enormously great pressure I 

 believe they would be vitrifipd, I placed under Bramah's Hydrostatic 

 engine, a short square column of Portland stone, viz. 2ft. Tin. high, and 

 1ft. by 1-2 at bottom and top ; this piece of stone burst asunder with the 

 pressure 173J tons, the fragments being then quite hot, and the fracture 

 was attended with a report as loud as that of a pistol. Now admitting 

 that tlie pressure of each portion of the surface of the earth 1-2 by 1ft., 

 superficies, produced a heat such as described under the pressure of a 

 column equal to the weight of 1737 tons, an increased height may 

 reasonably be supposed to generate heat in the same progression until at 

 length such heat would be produced, that expansion would follow, and 

 at length a volcano takes place in some place of the west of the globe, 

 probably where as at sea there is the least incumbent weight, or in some 

 district of country where the nature of their constituent materials opposed 

 the least resistance to expansion. 



With respect to the heat of water, the reflection on the most considerable 

 geissers gives the same infeieuce, for let us admit that water shall perco- 

 late the fissures of the earth to a great depth, and that its incumbent 

 weight produces heat to such an extent that it boils over, and that after the 

 heat escapes a temporary subsidence takes place, thus the exceptions of 

 the geisser does not re-occur until heat has been again regenerated by the 

 same pressure ^hich before produced it. 



Possibly it may be opposed, that the regularity of Buxton, Baths, and 

 other overflowing hot springs does notlead to this conclusion!; I am inclined 

 to think that where there are natural cavities in mountains which are 

 recipients of water, and when the incumbent pressure is not excessive, and 

 where there are oriticesj which discharge the superabundant water, it is 

 not irrational to suppose that the vents just referred to perforin the office of 

 geissers, and as there is no obstruction to them by the narrowness of their 

 orifices, or vast height of columns or water, violent discharges do not 

 take place. 



A further observation on volcanoes, and earthquakes may perhaps deserve 

 attention, namely, that in the districts where they have more particularly 

 been attended to, the component soils are in themselves of a nature liable 

 to the action of fire. Sulpliur abounds near Etna. 



It may be said, that admitting this doctrine of the generation of heat and 

 the self-discharge thereof by its escape by volcanoes, and the invasion of 

 hot water, and hot vapours, yet there must be some portions of the earth 

 where these efforts of nature do not appear to take place. To this I reply 

 that we are so ignorant of the lowermost structure of the earth, as to the 

 inclination of their various beds, that it is possible Hecia the great vent of 

 the North, may serve as the chimney of a great region, and that the other 

 volcanoes mentioned in the remainder of the article first referred to, may 

 discharge the superabundant heat of other portions of the Globe, for it is 

 notorious that earthquakes are felt 20 or 30 degrees of longitude distant 

 from the places where such eruptions have taken place. 



It is therefore, I trust, no presumption to entertain those ideas that so 

 long as gravitation exists, there will be a generatiou of heat, and conse- 

 ([uently that this discharge of heat, is an important dispensation in main- 

 taining this Globe, and that although sometimes dreadful vi>itations are 

 witnessed, yet they are not without their benefits to the great bulk of 

 mankind. 



John White. 



Paddle Box Boats Abandoned — The Rdributmi steam-frigate, Cap- 

 tain Lhshington, ha\in^' retnmefl her pa(i(ile-bo.v bouts to Ihe Portsnioulh dockyard on 

 account of their great vrelght(12 tons,) will not have any more paddle-box boats litted, and 

 the padule-box is accordingly already built up in the usual way, it being apparent that the 

 vessel can carry conveniently as many boats as are necessary on board and upon her 

 quarters, without encumbering herself with such heavy appurteuanccs. The removal of 

 the paddle-box boats has given this fine vessel a much more sightly and light appear- 

 ance, and no doubt will ease her in sea-going. She is being fitted with a connecting beam 

 u> strengtbea her paddle, boxes. 



REV1E\VS. 



An Essay on an Improved Method of Construction for Viaducts, Bridges, 

 and Tunnels, being an .ipplication of the Principle of Universal Gravitation, 

 as illustrated in the Solar System. By Messrs. Blair and Phillips, .\rchitects 

 and Civil Engineers. London : Weale, 1845. 8vo. pp. 10. 



We are constantly called upon to criticise opinions which evince incorrect 

 conceptions of mechanics, but we seldom or never have criticised any dissert, 

 ation in which the laws of nature are so gloriously confounded together as 

 in the pamphlet before us. To most (we hope, all) of our readers its title 

 will sufficiently explain its merits : the laws of motion and those of equili- 

 brium are throughout ttiken as identical ; the equilibrium of arches, &c. is 

 referred to the " principle of gravitation as illustrated in the Solar System .'" 

 Risum teneatis amici ? 



We will not attempt anything like serious argument respecting the views 

 propounded in the pamphlet. It is necessary to a satisfactory discussion 

 that the disputants should have some similar views : we should imagine, 

 however, that Messrs. Blair and Phillips have not one idea in common with 

 us respecting the theory of the arch. Dissimilarity of opinion may reach a 

 point beyond which argument is fruitless. It is possible to diverge so far 

 from the highway of received opinions as to render a return to it absolutely 

 hopeless. Our authors seem in this predicament. However, that the reader 

 may judge for himself as to tl)e possibility of their hereafter returning to the 

 paths of orthodoxy, we give one or two short extracts. 



" If an arch be turned over any opening, and a wall be built upon it, the 

 arch supports very little besides itself. There is no weight for it to support, 

 because the position which a regular wall takes is that of a continued series 

 of corbels, which corbels meet in the centre, and form a direct line from the 

 centre to each pier. This reminds us of a general law of gravitation by which 

 all bodies, when unimppded, fall directly to the earth^s centre, and, if im- 

 peded, take a direct line tending in some degree toxcards that centre. 



With this law of nature before our eyes, let us examine — 1st, the semi- 

 circular arch. This form of arch is used very much, and is by many con- 

 sidered of great strength. Now we wish to show- that of itself this arch is 

 very weak. It is weak, because, when a weight is placed on any one part of 

 it, there is great danger of it becoming deformed." 



The remarks are illustrated by absurd diagrams in which arches are re- 

 presented as distorted by a superincumbent pressure into all kinds of im- 

 possible shapes. The authors seem to think that when an arch fails it is by 

 the slipping of the voussoirs on each other ; whereas in practice it is uni- 

 versally found that the friction of the voussoirs is so great that they cannot 

 slide, and that the arch can only fall by the opening of the joints. The point 

 endeavoured to be elucidated by these diagrams is that all curved arches 

 must be distorted by pressure upon them, and that a perfectly flat arch is 

 alone free from this danger. The reasoning is as follows : — 



" Why is this ? The reason is evident. The line of the arch is curved, 

 and as curved (and in proportion to its curve) liable to bend. 



" Ve come then to our great point, namely, that weight falls in direct 

 lines, and not in curves, as is supposed ; and the nearer our supports ap- 

 proach to a straight hne, the more strength we obtain. If this is true and 

 it cannot be denied, the elliptical arch is of all arches the weakest." 



It really is no more than charitable to inform the writers that the strength 

 of an arch depends not only on its curvature but also on that which they 

 have altogether neglected to consider — the depth of its voussoirs. 



We are informed by our authors that they take no credit to themselves for 

 the plan of building arches flat, but they pronounce the whole body of civil 

 engineers blockheads for not having previously thought of it. 



" It may, however, and, we doubt not, will be said, that what we advance 

 is plain and easy, and that we need not claim to ourselves any credit for in- 

 troducing it. \Ve acknowledge that it is both plain and easy; indeed we 

 stated this at the commencement of our description. Cut who is he that 

 has apjiliid this plain and easy method.' If we cannot claim any credit, 

 surely they that have overlooked what we have now taken up may be set 

 down as ignoramuses, and not df. serving the name and title of civil engineers. 

 For why should the best method of construction be set aside, and an inferior 

 one adopted .= Why should thousands and tens of thousands of pounds be 

 thrown away in that which is worse than useless — injurious ? And why 

 should we praise men trho, directly in face of the laws of the universe, would 

 erect a fabric whose stability they doubted, or which would not stand the 

 test of time and the researclies of science.'" 



After this the least that the Institution of Civil Engineers and the Institute 

 of British Architects can do, is to ordain a fast and go into mourning. 



