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well as in function, and illustrating his positions by a variety of ex- 

 periments, which, with their results, are given at length in this 

 paper ; and after showing the practical applications of which the 

 investigations contained in it are susceptible, he concludes by ob- 

 serving, that a just estimate of their importance can scarcely be 

 formed, till an analogous account of the nerves of the throat, neck, 

 and chest shall be laid before the Society, which will show that in 

 them also there are the same distinctions of structure and functions, 

 and that the nerves of respiration may be distinguished and separated 

 amidst the apparent intricacy of the general system, and that by 

 dividing them, the motions of the several parts, which unite in the 

 act of respiration, may be successively stopped ; while their other 

 functions, dependent upon their other nerves, are continued. 



By pursuing this investigation, the remaining parts of the nervous 

 system are also much simplified, and the apparent confusion arising 

 out of the crossing and re-union of nerves is thus shown to be for 

 the purpose of associating the muscles into different classes, for 

 combining them in subserviency to different organs, and placing 

 them under the guidance of a sensibility more certain in its operation 

 than the will. 



Further Researches on the Magnetic Phenomena produced by Electri- 

 city ; with some New Experiments on the Properties of Electrified 

 Bodies in their Relations to Conducting Powers and Temperature. 

 By Sir Humphry Davy, Bart. P.R.S. Read July 5, 1821 . [Phil. 

 Trans. 1821, p. 425.] 



In this paper Sir Humphry Davy adds to his former details upon 

 the subject of electro-magnetism, by tracing the general effects of 

 the action of electricity on conductors, in their relation to this new 

 property and to heat. 



The magnetic phenomena he found the same, whether the electri- 

 city was small in quantity, and passing through good conductors of 

 great magnitude, or whether the conductors were so imperfect as 

 only to convey a small quantity of electricity. That these magnetic 

 powers are not affected by the mobility of the parts of fluids, Sir 

 Humphry proved by the electrization of mercury and fusible metal, 

 in glass tubes, which were thus made to attract iron filings and mag- 

 netic needles, while imperfectly conducting fluids did not, under si- 

 milar circumstances, give any polarity to steel. Electricity passed 

 through air, however, produces this effect ; and Sir Humphry has 

 succeeded in affecting the arc of fire by the approximation of a 

 magnet. 



In investigating the relative conducting powers of substances for 

 electricity, Sir Humphry found that a wire kept cool is a better con- 

 ductor than when heated ; and the knowledge of this fact led to the 

 explanation of a very singular result, namely, that by applying heat 

 to one part of a wire in the circuit, its other parts become colder, 

 and that by applying cold they become hotter ; thus, when one part 



