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ing that they might endanger his professionał The surface is a fertile plain, watered by Spring standing, he withdrew the edition from the creek and several of its branches, and ocmarket very soon after its publication. The cupied by corn and cotton plantations, intersame year appeared his “Visit to 13 Asylums spersed with forests of oak and yellow pine. for the Insane in Europe." In 1848 he pub- Scarcely a rock is to be seen in the county. lished the “ History, Description, and Statistics The Chattahoochee is navigable along the borof the Bloomingdale Asylum."' After his re. der of the county by steamboats, and the smallturn from his second European tour, he publish- er streams furnish good water power. On the ed in the “American Journal of Insanity" & bank of Colamoka creek is one of those remarkseries of articles on institutions for the insane able ancient mounds which have been found in in Germany and Austria, which were subse- various parts of the United States. It is 75 feet quently collected in a volume. Another series high, with a level surface on the top 240 by 90 of articles on “ Bloodletting in Mental Dis- feet in extent. The productions of the county orders was also published in book form in in 1850 amounted to 4,354 bales of cotton, 223,1854. His other contributions to the medical 037 bushels of Indian corn, and 76,377 of sweet and psychological journals are very numerous. potatoes. There were 16 churches, 1 newspa-THOMAS, a writer on law, brother of the per office, and 144 pupils attending academies preceding, born in Leicester, Mass., April 21, and schools. Value of real estate in 1856, 1791, died in Philadelphia, July 14, 1849. His $994,031. Named in honor of Peter Early, govearly education was obtained at the academy ernor of Georgia in 1813. Capital, Blakely. of his native town. In 1817 he removed to EARLY, John, a bishop of the Methodist EpisPhiladelphia, and engaged in mercantile pur- copal church south, born in Virginia in 1785. At suits for a few years, and then having studied an early age he joined the Virginia conference, law commenced the practice of the profession and became an itinerant minister. He filled sucin that city, where he was distinguished not cessively the offices of secretary of conference, only for legal ability, but for the large amount presiding elder, and delegate of the general conof time he bestowed without fee or reward in ference. At the general conference of 1846 he defending the cause of the poor, often refusing was elected general book agent, in which office cases offering large pecuniary emolument in he continued until elected bishop in 1854. As order to attend to those who were unable to a traveller, revivalist, and systematic preacher, pay. He edited in succession the “Colum- it is said of him that he has few equals in the bian Observer," "Standard,” « Pennsylvanian," ministry of the southern Methodist church. and “Mechanics' Free Press and Reform Advo- EARTH, the planet upon which we live. (For cate;" and he took an active part in calling & its motions and its relations to the heavenly bodconvention to revise the constitution of Pennsyl- ies, see ASTRONOMY.) The ancients, familiar with vania in 1837, was a prominent member of it, only a small portion of its surface, entertained and is believed to have made the original draft the crudest notions of its form and extent. In of the new constitution. At this time he was so the time of Homer it was regarded as a flat cirpopular that any office in the gift of the people cle, everywhere surrounded by a dark and myswas at his command, but he lost the support of terious ocean. The nations which dwelt upon the party with which he was connected (the its borders were called Cimmerians and describdemocratic) by advocating the extension of the ed as living in perpetual darkness. In every right of suffrage to negroes. In 1840 he was the direction the most distant lands heard of were candidate of the liberty party for the vice-pres- placed on the margin of this ocean, so that as idency. After that period he mingled little in geographical knowledge increased its shores in political affairs, and devoted himself almost en- like manner receded. The strait at the pillars tirely to literary pursuits. His first published of Hercules, leading into the ocean, was for work was an " Essay on Penal Law," written many centuries the boundary of the earth towhile he was a member of the law academy of ward the west. The Black sea appears for a Philadelphia, and published by the library com- time to have been the boundary in the other dipany. This was followed by an “Essay on the rection, and Colchis on the margin of the EastRights of States to alter and annul their Char- ern sea. Ethiopia reached the sea to the south, ters," a work which elicited the approbation and the Riphæan mountains stretched to the of Thomas Jefferson; a “Treatise on Railroads northern verge of the earth. The ancient Heand Internal Communications," published in brews found the same boundary to the west; 1830; & spelling book for schools, which was but in other directions they vaguely spoke of highly approved by eminent teachers in Phila- the “ends of the earth.” Availing themselves delphia and vicinity ; a “Life of Benjamin of the commercial enterprise of the Phænicians, Luudy,” an eminent philanthropist. At the they had in the time of Solomon prosecuted their time of his death he had nearly completed a trading voyages through the straits of Babelhistory of the French revolution and a transla- mandeb into the Indian ocean, bringing home tion of Sismondi's “ Italian Republics." from expeditions of 3 years' duration the pro

EARLY, a S. W. co of Ga., bordering on Ala., ducts of tropical regions; while their ships sent bounded W. by the Chattahoochee river, and westward toward the Atlantic returned laden N. by Colamoka creek; area, 864 sq. m.; pop. with the tin, silver, lead, and other metallic in 1852, 8,641, of whom 4,211 were slaves. products of Spain and Great Britain. The expeditions of Alexander into Asia opened new of a degree upon the surface of the earth, and countries in the east, and largely extended the from this to calculate the whole circumference. geography of the Greeks. The Romans by their At Syene, in upper Egypt, was a well, at the conquests added discoveries in the other direc. bottom of which the full disk of the son was tion; but these, while they removed further off, seen at noon of the day of the summer solstice; still served to fix the encircling ocean, the mare at the same time from Alexandria, then taken tenebrosum, as the impassable barrier and limit to be on the same meridian, its angular distance to the land. At a very early period the astron- from the zenith was 7° 12'. This was the omers among the Egyptians, Chaldeans, and measure of the celestial arc between the two Greeks perceived that the heavenly bodies, zeniths, and bore the same relation to the whole while occupying the same positions, stood in dif- circumference as the distance between the two ferent relations to different points upon the sur- points on the surface bore to the circumference face of the earth. In the school of Thales, Anaxi- of the earth. Presuming this distance to be mander, Anaximenes, and Pythagoras, the sun 5,000 stadia, and 7° 12' being zo of a circle, the dial was employed to mark the progress of the total circumference was then 250,000 stadia. sun in its meridional range, and to determine the The world known by the reports of travellers latitude of places, and the division of the year into extended only about 38,000 stadia in a N. and S. 365 days. The length of the longest and shortest direction; and from the pillars of Hercules to days at numerous places was determined by the the city of Thinw upon the eastern ocean, along Egyptians with this instrument, and they first his base line drawn E. and W. across the Mediadded 57 days to the older division of the year terranean, Eratosthenes reckoned a greatly exinto 360 days. Thales (born at Miletus, 640 B. aggerated distance of 70,000 stadia, and yet less C.) perceived the error of giving to the earth a than 1 of the whole circumference. He indulges plane surface, and ascribed to it a spherical fig- only conjectures whether the remainder was ocure and a position at the centre of the universe. cupied entirely by the ocean he called the AtAnaximander believed it was cylindrical; and lantic, or consisted in part of strange continents in the Pythagorean cosmography the extraordi- and islands. Posidonius next attempted a siminary advance was made of placing the sun in lar measurement by observations of the altitude the centre of the system with the earth moving of the star Canopus, when seen on the meridian about it. But this step was soon lost, and the at Rhodes, and again at Alexandria. Finding a knowledge of the extent and form of the earth difference of altitude of 7° 30', and assuming made but slow progress as the limited observa- the meridional distance of the two points to be tions of travellers were gradually accumulated. 5,000 stadia, he made the whole circumference A latitude observation is recorded of Meton and 240,000 stadia. Of the real value of the stadium Euctemon at Athens, 432 B. O. As commercial employed we are entirely ignorant; and it is intercourse was extended among the nations and certain that it was not, as employed at that time, navigation became an important art, the spher- a fixed determinate measure. The great astronical figure of the earth must have become appar- omer Hipparchus of Rhodes, born at Nice, in ent by the same phenomena which are now com- Bithynia, 140 B. O, first determined the longimonly appealed to in proof of it, viz.: the sinking tudes of places upon the earth by the eclipses of distant objects seen upon a level plain, as the of the moon, and produced maps upon which sea below the horizon; the greater or less ele- localities were designated by their latitudes and vation of the circumpolar stars, as the observer longitudes. Thus & means was furnished of is further toward the north or the south; the determining the relative positions of places different angles under which the sun is seen at without the necessity of measurements upon the noon of the same day at different points on the surface between them; and afterward, when same meridian; and other appearances of the suitable instruments should be contrived, of same character. This form being recognized, it finding directly any spot beyond the sea, and was natural to seek the measure of its circum- returning to the starting point. Adopting these ference, and it is extremely probable that at- principles, Ptolemy, the astronomer and geogtempts of this kind were made before any of rapher, prepared the most complete map of the those of which we have account. Some of the world so far as it was known, designating places measures of the most remote antiquity appear by their latitudes and longitudes, and cansing to have relation to the terrestrial circumference; the meridians to approach each other toward and, as stated by Laplace, they seem to indicate the pole. For want of accurate measurement not only that this length was very exactly of the length of a degree, his map, however, was known at a very ancient period, but that it has very imperfect. Still it continued for many also served as the base of a complete system of centuries to be the great authority in geography; measures, the vestiges of which have been found and it was not until 1635, when the difference in Asia and Egypt.” Aristotle states that be- of longitude between Marseilles and Aleppo was fore his time the circumference had been detere found to be only 30° in place of 45°, as repremined by mathematicians at 400,000 stadia. sented upon the map, it became apparent that Eratosthenes, who lived the next century after more perfect observations for longitudes must Aristotle, appears to have been the first to be adopted than those of the ancients. The clearly perceive the true method of applying uncertainty of the results obtained by observing astronomical observations to the measurement eclipses of the moon was soon perceived, and at last the suggestion of Galileo was adopted of the equator and there accumulate them in a observing the eclipses of the satellites of Jupiter. belt, increasing the equatorial diameter. NewIn the 9th century an attempt was made by di- ton calculated that to maintain the hydrostatic rection of the caliph Al Mamun, who reigned equilibrium the proportion of the polar to the at Bagdad from 813 to 833, to determine the equatorial diameter must be as 230 to 231. length of a degree of latitude. His mathema- Richer

, who was sent by the academy of ticians assembled on the plain of Shinar, and, sciences of Paris to Cayenne in 1672, observed taking the altitude of the polar star, separated that the pendulum which vibrated seconds in in two parties, travelling in opposite directions Paris lost about 24 minutes daily at Cayenne. till they found a difference of altitude of one This fact, as Newton explained in his Princidegree. They made the distance upon the sur- pia, must be a consequence of the reduction face the same as that given by Ptolemy, prob- of the force of gravity, either by effect of the ably adopting his conclusion, which they were centrifugal force or of increased distance from set to verify. From this time to the middle of the centre. The deductions of Newton and the 16th century no further attention was given Huyghens that the earth was a spheroid like that to ascertaining the dimensions and true figure already observed of Jupiter, flattened at the of the earth by astronomical observations; but poles, conflicting with the opposite conclusions vast accessions of geographical knowledge were of the first Cassini, induced the academy of made by the enterprise of the navigators of this sciences to cause exact measurements of meriperiod. They at last solved the mystery of the dional arcs to be made both near the equator mare tenebrosum. The next attempt to deter- and the polar circle. The celebrated commismine the circumference was made by Fernel, a sion of their members left Paris in 1735, BouFrench physician, who died in 1558. In the want guer, La Condamine, and Godin to join in Peru of exact surveys, by which the true distance be- the officers appointed by Spain, Antonio d'Ultween places might be known, he measured the loa and Jorge Juan; and Maupertuis with 4 space between Paris and Amiens by the number others to proceed to the gulf of Bothnia, where of revolutions of his carriage wheel, and mak- they were joined by the Swedish astronomer ing his observations for latitude he made the Celsius. . Ten years were spent by the party in length of a degree 57,070 French toises; a re- Peru in the measurement of an arc of over 3° markably close approximation to the actual in length, extending from lat. 2' 3" N. to 3° 4 length. Willebrord Snell, a mathematical teacher 32" s. In 2 measurements of the original of Holland, made in 1617 a similar attempt base the difference was hardly 24 inches; and between Alkmaar and Bergen-op-Zoom ; and a second base of 5,259 toises differed when he was the first to apply a system of triangu- measured less than a toise from its length as lation to expedite his geodetic measurements. calculated from the triangles. The length of His instrument for observing angles was a quad- the degree at the equator, reduced to the level rant of 54 feet radius. As afterward corrected of the sea, was calculated by Bouguer at 56,753 by Muschenbroek, the length was 57,033 toises. toises, or 362,912 feet; by La Condamine, at In 1635 Norwood in England repeated the ex- 56,749 toises ; and by Ulloa, at 56,768 toises. periment, measuring along the road the distance The northern party found a place for their between London and York, making the degree operations between Tornea in Lapland and the 367,176 feet, or 57,800 toises. Toward the close mountain of Kittis, 57' 29.6" further north, in of the same century Picard first applied the tele- lat. 66° 48' 22". The difference of latitude scope attached to a quadrant, and furnished with being determined, they measured a base line cross wires, to observe the angles for his tri- upon

the frozen rivers, 2 measurements giving angulation, and twice measured between Amiens a difference of only about 4 inches. The aro and Malvoisine with wooden perches a base of being then determined, it was found to give 57,5,663 toises, or nearly 7 m. in length, employ- 422 toises to the degree. With this result they ing also at the other extremity a base of verifi- returned to France, being absent only 16 months. cation of 3,902 toises. The celestial arc of The greater length of the degrees as they ap1° 22' 55" was measured by a sector of 10 feet proach the poles was thus established, and radius. He made the degree 57,060 toises, a consequently the greater equatorial than polar result very nearly accurate, attained by a for- diameter of the earth. Multiplied measurements tunate compensation of errors in his method in different parts of the earth now became imand in his standard of measure. In 1718 the portant to determine its true figure. They have second Cassini published a work upon the mag. been made in various countries, and confirm nitude and figure of the earth, with an account the general conclusions of Huyghens and Newof measurements further north and south on ton. La Caille's measurement at the cape of Picard's line made by La Hire and himself. Good Hope in 1751, the only one in the southAbout the time of Picard's observations the ern hemisphere, presented anomalies, or showed question began to be agitated, whether the form great irregularity in the figure of the earth, of the earth was really that of a true sphere. which were not explained till, nearly a century The tendency of the centrifugal force of bodies afterward, the arc was remeasured with great revolving upon their axis, established by Hay- care under the auspices of the British governghens and Newton, must evidently be to throw ment, and it was shown that the discrepancy was their movable particles from the poles toward owing principally to the deviation of the plumb line of La Caille by attraction of the mass of the by means of another the line was made to reach mountain near by. In North America the first Formentara, distant 12° 22' 13.39" from Dunmeasurement of this character was by Mason kirk, its northern extremity. The result of this and Dixon in 1764–5, on the peninsula between extension affected the quadrantal arc before Delaware and Chesapeake bays. The arc was obtained so little, that the standard unit, the measured throughout with wooden rods, and mètre

; equal to the T6.0pt.ooo of the quadrant, the degree in mean lat. 39° 12' was found to be would differ scarcely 730.007 of the value before 363,771 feet, or 68.896 English miles. It has given it. A singular anomaly was noticed upon never been supposed that this was a very ex- some portions of this arc, and the same was obact measurement, but its accuracy has not been served in the English surveys, that where these disproved. In 1784 measurements were com- portions were considered separately, the length menced larger than any ever before undertaken of the degrees appears to increase toward the for the purpose of accurately determining the equator. This is supposed to be owing to some difference of longitude between the observato- disturbing cause, as, possibly, inequalities in the ries at Paris and Greenwich. Instruments of density of the strata which affected the instrogreat size and improved construction were pre- ments in use upon them. The effect is to produce pared expressly for this work, and the base line a slight uncertainty in the exactness of the reof 27,404 feet upon Hounslow heath was meas- sult obtained, and in the calculated proportion ured once with wooden rods of 20 feet length, of the polar to the equatorial axis of the earth. and once with glass rods of the same length in The length of the quarter of the meridian was frames. The junction of the triangles on the found to be 5,130,740 toises. Of the other two sides was completed in 1788; but the oper- measurements which have been made of an arc ations on the English side were regarded only as of the meridian, the most important are those a portion of the full survey of the island to be conducted in Hindostan by Col. Everest, in conafterward carried out. Still more extensive sur- tinuation of the work commenced by Col. Lambveys were commenced in France in 1791, with ton in the early part of the present century; the object of obtaining the exact length of the and those by Struve and Tenner in Russia (the quadrant of the meridian, in order to make use latter commenced in 1817 and completed in of a definite part of this natural and permanent 1853). A small arc of 1° 35' was measured quantity as a standard for all linear measures. near Madras by Col. Lambton; and another was The pendulum vibrating seconds in some de- commenced from Punnæ in the southern extermined latitude had been proposed as a means tremity of the peninsula, in lat. 8° 9' 32.51", of furnishing an unchangeable measure, but it and extended to Damargida, lat. 18° 3' 15". was given up because of its dependence upon After Lambton's death in 1823, Col. Everest the element of time, the measure of which is carried the work on further north for some time. arbitrary, and its sexagesimal divisions are in- In 1832, after an interruption, it was resumed admissible as the foundation of a system of and continued till 1840, when it reached Kalidecimal measures. Local causes also, as the ana, lat. 29° 30' 48', thus including 21° 21' geological structure of the locality, affect the (1,477 m.). Every precaution was taken, and rate of its vibrations. The length of the quad- the most perfect instruments were provided, to rant of the meridian, not being liable to these insure the utmost accuracy; and notwithstandobjections, was adopted instead, and a new meas- ing the natural obstacles of the climate, the urement was carried out on the meridian of heat, rains, and thick atmosphere, the malaria Paris under the distinguished astronomers De- of the plains, and the impenetrability of the lambre and Mechain, and the work was not in- jungles, the results obtained from the bases of terrupted by the political disorganizations of verification indicate as great exactness as has the years 1792, 1793, and 1794. The line was been attained in the best European measureextended across France from Dunkirk to Barce- ments. The whole extent of the Russo-Scandilona, making an arc of about go, and every navian arc is from Ismail near the month of precaution was taken to insure the most per- the Danube, in lat. 45° 20', to Fugeloe ip Fin. fect accuracy in the measurements. The base mark, lat. 70° 40'. The portion extending N. line near Paris was more than 7 m. in length from Tornea (4° 49') was measured by the (6,075.9 toises), and another of verification of Swedish and Norwegian engineers. The ground 6,606.25 toises near the southern extremity of throughout the whole extent of the line is rethe arc differed by measurement less than a foot markably favorable for the execution of this in length from its extent calculated from the work, on account of its freedom from great irtriangles extending from the first base more regularities of surface; but in the southern part than 436 m, distant. Though this arc thus forests spreading over a level country have determined was sufficient for the purpose re- rendered it necessary to raise many temporary quired, the French astronomers in 1805, after elevated stations; and in the north the ese an interval of 3 years, began to carry the meas- traordinary refractions of that region have addurement still further south, Biot and Arago ed to the difficulties of the work. This arc, directing the work after the death of Mechain. and that of Hindostan, give the measure of a The island of Ivica in the Mediterranean was large portion of the quadrant of the meridian, connected with the system by a triangle, one leaving only the degrees between 29° 30' and side of which exceeded 100 m. in length; and 45° 20' unmeasured from lat. 8° 9' to 70° 40'.

370

The French arc, extending from lat. 38° 40' city thus obtained is generally sor or gør, differto 51°, fills up a portion of this gap, and they ent values being allowed for the rate of increase all together afford abundant data for an exact in the density of the earth from the surface to. computation of the curvature of the meridian; ward the centre. Degrees of longitude might be and this is rendered the more certain from the ineasured instead of latitude for determining the standards of length used in India and Rus- figure of the earth ; but the difficulty would be sia having been directly compared. Other arcs in the precise estimation of differences of longihave been measured by Bessel and Bayer in tude in the celestial arc. The close approach of Prussia ; Schumacher in Denmark; Gauss in the earth in its general form to the figure of hyHanover; beside a few others of less import drostatic equilibrium forcibly suggests the probThe longest arc measured in the progress of the ability of the particles which compose its mass U. S. coast survey is one of 33°, extending from having been in condition to move freely togeNantucket to Mount Blue in Maine. Great ther under the influence of the centrifugal force confidence is felt in the accuracy of this meas- and their mutual attractions. The conditions urement, from the extreme care with which the that now obtain upon the outer portion of the triangulation is conducted. The work is not earth in the mobility and transporting power of yet quite completed. An arc of parallel will its waters, which cover of its surface, may be also be measured along the Mexican gulf.—From regarded as sufficient to give, in long periods of the various measurements that have been al- time, the observed external form; but the indiready made, different values have been calcu- cations afforded by the pendulum of regularly lated for the ellipticity of the earth, or the pro- increasing gravity from the equator toward the portions between the polar and equatorial diam- poles, fand hence of symmetrical arrangement eters. Prof. Airy, before the completion of of the layers throughout, imply the existence the recent surveys, found the ellipticity zis, and of similar conditions during the entire period of Bessel afterward made it zoo. The French and the construction of the earth.-The form and Indian ares give a smaller ellipticity, as stobut dimensions of the earth being

obtained, calculathe Russian, it is thought, will be about The tions respecting its density or weight may be following statement presents the average of sev- made by several distinct methods. The one first eral of the measurements : Equatorial diameter, applied was originally suggested by Bouguer—a 41,843,330 feet, or 7,924.873 miles ; polar di- comparison of the attractive power of a mounameter, 41,704,788 feet, or 7,898.634 miles; tain of known dimensions and density with that difference of diameters, or polar compression, of the earth of known dimensions, whence its 138,542 feet, or 26.239 miles; ratio of diam- density might be computed. Newton had aleters, 302.026 : 301,026 ; ellipticity, gonzo ; ready estimated that á hemispherical mountain length of degree at equator, 362,732 feet; 3 m. high and with a base of 6 m. diameter length of degree at lat. 45°, 364,643.5 feet. would cause a plummet to be deflected 1' 18" Profs. Airy and Bessel, calculating from different from the vertical. In making the trial the sets of measurements, obtained the following plummet is attached to a delicate astronomical results:

instrument, with which observations are made to determine the meridian altitudes of stars near

the mountain, and on the same parallel at a disEquatorial diameter..... 7,925.643

tance accurately determined and sufficiently far 7,899.170 7,899.114 off to be beyond its influence. The difference Polar compression..

299.15 to 298.10

in the 2 altitudes shows the power of attraction.

Observations are sometimes made from stations The ellipticity of the earth is always expressed on opposite sides of the mountain, and the reby a larger fraction than the above when com- sult is then obtained by a different plan from puted from observations upon the vibrations of the above. Bouguer, in 1738, observed the inthe pendulum in different latitudes. It is vari- fuence of Chimborazo in deflecting the plummet, ously given from jobs to 206.5. These observa- and unsuccessfully endeavored to compute its tions have been made at so large a number of amount from observations made at 2 stations on places, that the effects of local causes of irregu- the S. side only. In 1772 Dr. Maskelyne prolarity would be expected to disappear ; yet posed to the royal society to try the experiment there is an unexplained discrepancy with the upon some mountain in Great Britain; and the results of the geodetic method. This is per- society thereupon appointed a committee of haps owing in part to the variable resistance attraction,”_including in it, with Maskelyne, opposed by air of different densities, the effect Cavendish, Franklin, and Horsley. Mr. Charles of which can be obviated by conducting the ex- Mason was intrusted with the selection of a periments in a vacuum. The ellipticity has also proper hill, and

finally Schehallien in Perthshire, been calculated from some irregularities in the Scotland, was fixed upon. The primary measmotions of the moon, caused by the equatorial urements were made by Mason in 1774, to deprotuberance; and it may well be remarked as termine the distance apart of the stations to be an extraordinary fact that from this source a used, one on the N. and the other on the S. side strong confirmation should be afforded of the of the hill, under similar slopes. By triangucorrectness of the results obtained from the lating, Dr. Maskelyne found this distance to be measures of the meridional arcs. The ellipti- 4,364.4 feet, corresponding in that latitude to a

1

Airy, miles.

Bessel,

7,925.604

Polar diameter.

26.471

26.478 299.83 to 298.83

Ratio of diameters..

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