1847.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



133 



wliicli llify have been found; if any person would take the trouble 

 to c( nnpare the time \\liich such dials new show, with that lime whicli 

 they ought to show, they will find that the earth's axis must change in 

 the manner wliich we have described. It may be supposed, because 

 the bearings of natural objects, such as the tops of mountains, do nut 

 charge in txact accoid;aice with the motion of the e;irlli's axis, like 

 the foundations of churches and otiu r sliuclures of man, that such u 

 law has not an tqual influence over lliem : the fact is, that the rigid- 

 n ss of the materials of \\hich they are composed not only prevenis 

 them immediately yifldirg to this moticn, I'Ut also leaves them ele- 

 vated or depressed, either gradually or ^uddinly, above or below the 

 ri St of the surrounding matter. This theory is borne out by many 

 pheni niena, but it is our intention first to test it by those which are 

 capable of being submitted to actual measurement. 



It is borne out by actual measur(ments which were instituted in 

 different places, in order to determine the figure and magnitude of 

 the earth. For this purpose, the lengths of small arcs were measured 

 in ditiere nt places on the surface of tl'e earlh, with the greatest care ; 

 tut, for v\ant of a true theory of the earlh, tlieir measurements, for 

 the purposes for wliich they were irstitnted, were almost useless, and 

 led to \ eiy dissatisfactory conclusions. Although th.ese measurements 

 disappointed the measuiirs, in pointing out the form which they sup- 

 posed the earth to be before they commenced their opeiations, yet 

 their results are of the greatest use in supporting what is here pro- 

 mulgated. We cannot avoid remarking here, that the plans upon 

 which all our great measures of the eartli proceeded were very in- 

 judicious — that is, first supposing the figure to be one form while they 

 were carrying on their optralions, and when finished affirming it to 

 be another: besides, they give way as much as possible in all their 

 measurements and calculations to their preconceived opinions, despite 

 if all the natural exponents which pointed to the contrary. The 

 values of the degrees of latitude found at difiierent places on the 

 earth's surface difftr from each other more than might be expected, 

 considering the great attention that has been paid to ascertain and 

 make allowance for every known cause of en or. In France, the 

 lengths of the degrees were found to go on diminishing from north to 

 south, but not in a regular progression. In England, on the contrary, 

 they were found to dimiuisli from south to noitb : so that if the figure 

 of the eanli were to be deduced from the degrees in the former of 

 llitse counliies akne, it would appear to be oblate ; if from the de- 

 grees in tl'.e latter, it would appear prolate. As might be expected, 

 the lengths of degrees measured in the norlliein lieniispliere of tlie 

 earth deviate, within certain small limits, from the values they should 

 have on the surface of any conjectured figure, except the one which 

 we have described. The degrees measured in corresponding latitudes 

 in the opposite hemispheres also disagree ; — this fact, as a matter of 

 course, must necessarily follow. The proportions between the equa- 

 torial and polar diameters of the earth are, necessarily, stated to be 

 various; the comparison of the arc meiisured in France with that in 

 Peru (in which last, it should be remarked, the observations of Bcu- 

 guer were made use of,) gives, for that proportion, 334 to 333 ; 

 D'Alembert, taking a mean of the observations of Bouguer and La 

 Candamine, afterwards found it to be as 3ll9 ; 30S. The length of a 

 degree in India, compared with that iu England, showed the ratio to 

 be as 329 : 328. 



(•318:317 



The ratios ^ 314 : 313 



(. 289 ; 288, and many others, have been given at differ- 

 ent times from the same sort of measurements. The difTerence in 

 these ratios instead of showing that thty are all wrong, shows the 

 exact contrary, — that they are all very nearly correct : which increases 

 the number of observed facts that support the pliisico-dynamical de- 

 monstration.* 



That the earth is slightly indented or exdented in different places, 

 appears at once from the different magnitudes which actual measure- 

 ments point out : if it were otherwise, no matter whether it was sup- 

 posed to be spheroidal, ellipsoidal, or any other solid, formed under a 

 uniform law, except the form which we have here designated " an 

 indented and exdented evoluted spheroid," the difference could not 

 have been so great;— so that, although the right motion of the earth's 

 axis, or rather the slow but constant change of the position of the 

 excess of this planet above its greatest inscribed sphere, exercise its 

 influence on all the particles of which it is composed, yet some of 



* In tonsequeoce of an Editorial note, annexed to the first part of this article, it is ne- 

 cessary for me to state that the mathematical demODSlralion of this problem is given in 

 my work on the Calculus, which is being printed, and will shonly be published. In due 

 time my analysis shall be published, together with a concluding article db the " Streugth 

 of Materials,*' a subject fully discussed in my forthcoming work, juat mentioned. 



O. B. 



them for a time remain unaltered, from their rigidness, — but, ulti- 

 mately, all must give way, or be covered by the ocean, which is always 

 ready to obey this general law of nature. 



The late trigonometrical surveys show, either that the latitude of 

 places have changed, or that they were greatly misplaced by former 

 surveyors. Kow, it is more likely that the places have changed their 

 positions with respect to the true north anii south points, than that 

 errors of such magnitude could be committed ; one of the principal 

 objects of trigonometrical surveying being to determine the geogra- 

 phical positions of principal or noted places, whether on coasts or 

 inland, in islands or on continents, in order to give accuracy to maps, 

 and for the purpose of accommodating navigators with the true lati- 

 tudes and longitudes of principal promontories, lighthouses, havens, 

 and ports. It is well known that these have, till lately, been require- 

 ments even in this country : the positions of some important points, 

 as the Lizard, not being known within seven minutes of a degree ; 

 and the last survey found the best country maps in many cases to 

 exhibit differences of more than three miles in distances of not more 

 than twenty or thirty miles. The late surveyors may attribute all this 

 to blunders made by their predecessors; bnt this is not at all likely, 

 as the rudest instruments or the most careless observations could not 

 so far mislead : in one hundred years from the present time, the same 

 apparent blunders will be again detected. There is nothing which 

 might be named that baffles the observer more, in determining the 

 longitude either on land or at sea, than the erroneous opinion that the 

 latitudes of places remain always unchanged. The whole face of 

 nature points out this universal change; — geologists not having re- 

 cognised it is astonishing : their conflicting and contradictory theories 

 respecting the formation and structure of the earth, by this theory 

 are set at rest for ever. 



The chemical influence of heat and cold, combined with the gradual 

 change of all matter, at once accounts for the several observed phe- 

 nomena attributed to so many causes. By the right motion of the 

 earth's axis, or rather the change of the excess so often alluded to, 

 we have, among others, the following natural consequences: — Rivers 

 appear to bury themselves in the earth, or rather, the places rise 

 through which they flow. Mountains, which do not immediatply give 

 way to this change of surface, from the rigidness of the substance of 

 which they are composed, ultimately, often without the slightest 

 warning, decrease in altitude many fee't. As this protuberance shifts 

 its position, it only disturbs the particles, but in a very slight degree 

 changes their respective distances; — for instance, it is not to be ima- 

 gined that the particles of one valley co-mingle with those of another. 

 In the ocean, islands appear and disappear from the same cause. 

 Continents, as well as islands, are increased in some parts and dimin- 

 ished in others, and that iu such a regular m.anner that the influence 

 of this general law is at once recognised. The structures of man, as 

 well as those of nature, are often instantly elevated or depressed. 

 Countries, which were once fruitful and thickly inhabited, have be- 

 come barrtn; and, on the contrary, those which were barren, become 

 fruitful. This motion not only changes the beds of rivers, but those 

 of oceans and seas, so as not to show the same levels in places only a 

 few miles distant— that is, with respect to what is erroneously called 

 the mean level of the sea. Mr. Whewell has fallen into errors in his 

 account of the theory of the tides, from his not having observed this 

 general law of nature. In fact, the true cause of the motion of the 

 waters on the surface of the earth, is mainly to be attributed to this 

 motion. The sea-worn pebble obtrudes through the caverns of the 

 deep and appears on the surface of the earth many miles from the sea, 

 mixed with marine substances and remains of shell-fish. Fossil remains 

 aie found many feet from the surface, and in different climates from 

 those to which they belonged, — often imbedded in substances which are 

 evidently deposits, assuming different appearances from pressure, 

 position, and being submitted in the great laboratoiy of nature to the 

 different changes of temperature, and other local causes. It is not 

 dithcult to conceive how transformation can take place, for in the 

 laboratory of the chemist the most durable substance is easily made 

 to pass from a dense to an aeriform st.ite, and the contrary ; — water 

 on the surface of the earth affords us daily a familiar instance of this, 

 in its three separate states of rock, fluid, and vapour. The varying 

 spinning motion of the earth on its axis, which is continually changing 

 the excess so often mentioned, has this effect on t!ie particles that 

 comjiose the ocean ; they are daily and hourly obliged to accommo-* 

 date themsevles to ihe behaviour of this motion, and also to the con- 

 stant change of the less pliable substances over which they are com- 

 pelled to move : therefore, to imagine that the ocean can have a 

 mean or uniform level, as Mr. Whewell and many others do, is ab- 

 surd. But this is satisfactorily shown by a comparison of the ob- 

 servations made on the tides in different ports and places. Slow as 

 the right motion of the earth's axis appears to the shoitsightedness of 



