G24 



DEGREE. 



circle being considered as dixided into U(j() parts, 

 culled degrees, which are marked by u small near 

 the top of the figure ; thus, 45" is 45 degrees. The 

 degree is subdivided into sixty smaller parts, called 

 minutes ; the minute into sixty others, called teconds ; 

 the second into sixty thirds, &c. Thus 45 12' 20" 

 is forty-five degrees, twelve minutes, twenty seconds. 

 Tin- magnitude or quantity of angles is estimated in 

 degrees ; for, because of the uniform curvature of a 

 circle in all its parts, equal angles at the centre are 

 subtended by equal arcs, and by similar arcs in peri- 

 pheries of different diameters ; and an angle is said 

 to be of so many degrees as are contained in the arc 

 of any circle comprehended between the legs of the 

 angle, and having the angular point for its centre. 

 Thus we say "an angle of 90," or " of 45 24'." 

 It is also usual to say, " such a star is elevated so 

 many degrees above the horizon," or " declines so 

 many degrees from the equator ;" or " such a town 

 is situated in so many degrees of latitude or longi- 

 tude." A sign of the ecliptic or zodiac contains 

 thirty degrees. The French divide the circle into 

 400 degrees; each degree containing 100 minutes, 

 each minute 100 seconds, &c. 



Degree of Latitude is the space or distance, on the 

 meridian, through which an observer must move to 

 vary his latitude by one degree, or to increase or 

 diminish the distance of a star from the zenith by 

 one degree ; and which, on the supposition of the 

 perfect sphericity of. the earth, is the 360th part of 

 the meridian. The length of a degree of a meridian, 

 or other great circle, on the surface of the earth, is 

 variously determined by different observers, and the 

 methods made use of are also various ; and, there- 

 fore, without entering into the history of all attempts 

 of this kind, we shall present our readers with the 

 following 



TaUf of the different Length* of a Degree, al meanred in \ 

 Eaih, the Time of ill Measurement, the Latitude ofiti i 



uriMii Parti of tlu 

 iddle Point, 4>c. 



Degree of Longitude is the space between the two 

 meridians that make an angle of 1 with each other 

 at the poles, the quantity or length of which is 

 variable, according to the latitude. The following 

 table expresses the length of a degree of longitude 



Degrees, Measurement of. After the immortal 

 Newton had taught that the earth, on account of 

 its motion round its axis, must be highest near the 

 equator, and that the diameter of the equator must 

 3e longer, by one 230th part, than the diameter 

 from pole to pole, the French wished to investi- 

 gate the subject further by actual measurement. 

 Newton gave them warning tliat the difference 

 between a degree at Bayonne and one at Dun- 

 kirk was so trifling that it could not be detected 

 at all with the imperfect instruments then in use 

 and was, in fact, afraid that they might come to a 

 result directly opposite to what he conceived to be 

 correct, and bring confusion into science. But his 

 warnings were of no avail. The measurement was 

 begun, and the fear of the great philosopher was 

 realized ; for the result was, tliat the axis of the poles 

 was longer than a diameter of the equator, and tliat 

 the earth was, in form, more like a lemon than an 

 orange. For forty years, disputes were maintained 

 on this point, without settling the question ; and, at 

 last, the academy of sciences resolved, on the propo- 

 sition of Condamine, to have a degree measured at 

 the equator (the expedition went to South America 

 in 1735), and one in Lapland (Kittis and Tornea 

 being the extreme stations to which the expedition 

 was sent in 1736). It was found that the northern 

 degree was greater than that under the equator, 

 and that Newton's conjecture was right. But 

 the question still remained, How great is the flat- 

 tening of our planet ? The theory said, one 230th 

 part, if the earth had been in a perfectly liquid state, 

 when it began its rotation. The calculations, how- 

 ever, always gave different results, varying according 

 to the different measurements adopted as the basis 

 of them ; for measurements had been made, not only 

 in America and Lapland, but also in France, England, 

 Hungary, and Italy. It was concluded, that the 

 earth was not a regular body, but had great local 

 inequalities. Though this was possible, yet the con- 

 clusion was too hasty, because these supposed ine- 

 qualities might be caused by the insufficiency of the 

 instruments, and by the smallness of the arcs mea- 

 sured. When the French established their new and 

 admirable system of measures and weights upon the 

 basis of the metre, which was to be the ten millionth 

 part of the distance from the equator to the pole 

 (S^Kj'jj^j English feet ; see Measures), it was neces- 

 sary to know, with accuracy, the circumference and 

 the flattening of the earth. A measurement, there- 

 fore, took place in France, not of one degree, but of 

 ten degrees, from Dunkirk to Formentera. (See 

 Delambre.) In Sweden, in 1802, the degree, which, 

 eighty years before had been measured by Mauper- 

 tuis, was now measured again, with better instru- 

 ments, and thus the circumference and flattening of 

 the earth were pretty well ascertained. After the 

 peace, the measurements of degrees, which were 



in different' latitudes, supposing the earth to possess made in England, under general Roy, by lieutenant- 

 a perfect sphericity : [ colonel Mirage, were connected with those in France ; 



