MAG 



MAG 



perpendicular, receive a strong magnetic 

 power, their lower ends repelling the 

 south, but attracting the north poles of 

 magnets applied to them respectively. 

 The direction of the dipping net-die was 

 ascertained hy one Robert Norman, about 

 two hundred and fifty years ago. He 

 suspended a small magnetic needle, by 

 means of a fine thread around ks centre, 

 so as to balance perfectly, over a large 

 magnet : the south pole of the former 

 was instantly attracted by the north pole 

 of the latter. He found that so long as 

 the needle was held exactly centrical, at 

 about two inches above the magnet, it re- 

 mained horizontal : but so soon as with- 

 drawn a little more towards one end than 

 the other of the magnet, the equilibrium 

 was destroyed, and that pole of the nee- 

 dle which was nearest to either pole of 

 the magnet was instantly attracted, and 

 pointed downwards thereto. By the mag- 

 netic equator, we mean a circle passing 

 round the earth at right angles with the 

 magnetic poles, which do not correspond 

 with the geographical poles, as may be 

 fully understood by the indications of all 

 compasses to points differing from the 

 latter;, and as the indications of com- 

 passes vary so much, both at different 

 times and places, we may reasonably 

 conclude, that the magnetic poles are 

 not fixed. The variation of the dipping 

 needle has not, in our latitude at least, 

 varied more than half a degree since 

 its depressive tendency was first disco- 

 vered by Norman. 



The suspension of Mahomet's body, in 

 the temple where it was deposited, is 

 supposed to have resulted entirely from 

 magnetism, with which the Arabians 

 were completely unacquainted. 



MAGNETISM, animal. About thirty 

 years ago, Father Hehl, of Vienna, im- 

 posed on his countrymen, and indeed on 

 the greater part of the civilized world, 

 a pretended mode of curing all kinds 

 of disease, by means of a sympathetic 

 affection between the sick person and 

 the operator. The remedy was supposed 

 to depend upon the motions of the fin- 

 gers, and the features of the latter, he 

 placing himself immediately before the 

 invalid, whose eyes were to be fixed on 

 his, and performing a number of antic 

 and unmeaning changes, accompanied by 

 various grimaces, or inflections of the 

 principal muscles of the visage. This 

 rarely failed to excite a certain degree 

 of apprehension in the mind of the sick; 

 which, by creating a new action of the 

 system, often frightened them into con- 



valescence. That such effects may have 

 been produced among the credulous and 

 timid, we shall not controvert ; but, on 

 the other hand, it is asserted, that num- 

 bers have been so far overcome with 

 terror and fatigue, (for, like Dr. Sangra- 

 do, the operator was never satisfied 

 while any strength to undergo the pro- 

 cess remained) that consequences highly 

 dangerous, and in some instances tatal, 

 were induced. Notwithstanding the ob- 

 vious folly of the pursuit, there were found 

 many gentlemen of great respectability 

 and talents among its followers ; hence 

 a certain degree of credit was establish- 

 ed, and there were not wanting persons 

 foolish enough to certify many cases, 

 and to give a celebrity, which was in a 

 very short time found to be misapplied. 

 It is a lamentable case, that, through- 

 out the world, impositions of this nature 

 are always tolerated lung enough to an- 

 swer the purposes of the fabricator, and 

 to encourage others in similar deceptions. 

 Our readers may recollect many instances 

 of notorious character, among which the 

 metallic-tractors, which were at one time 

 asserted to be allied to metallic-magne- 

 tism, may, perhaps, serve as a proper illus- 

 tration and proof. 



MAGNIFYING, in philosophy, the 

 making of objects appear larger than 

 they would otherwise do ; whence con- 

 vex lenses, which have the power of 

 doing this, are called magnifying glasses; 

 and of such glasses are microscopes con- 

 structed. 



MAGNITUDE, whatever is made up 

 of parts locally extended, or that hath se- 

 veral dimensions ; as a line, surface, solid. 

 The apparent magnitude of a body is that 

 measured by the visual angle, formed by 

 rays drawn from its extremes to the cen- 

 tre of the eye ; so that whatever things 

 are seen under the same or equal angles, 

 appear equal ; and vice versa. Mr. Mac- 

 laurin observes, that geometrical magni- 

 tudes may be usefully considered as ge- 

 nerated or produced by motion. Thus, 

 lines may be conceived as generated by 

 the motion of points ; surfaces, by the 

 motion of lines ; solids, by the motion of 

 surfaces ; angles may be supposed to be 

 generated by the rotation of their sides. 

 Geometrical magnitude is always under- 

 stood to consist of parts ; and to have no 

 parts, or to have no magnitude, are consi- 

 dered as equivalent in this science. There 

 is, however, no necessity for considering 

 magnitude as made up of an infinite num- 

 ber of small parts ; it is sufficient that no 

 quantity can be supposed to be so small, 



