Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . enhagen, in the year 1819, that a magnet, freelysuspended, tends to assume a position at right anglesto the direction of a current of electricity passingnear it. This may be shown by the followingexperiment: — 149. Let N S (Fig. 50) be a magnetic needlepoised upon a pivot so as to allow of a free hori- Pig, 50. zontal motion, and W R _ a wire passing directlyover and parallel to course, the directionof the wire must be northand south, as the nee
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . enhagen, in the year 1819, that a magnet, freelysuspended, tends to assume a position at right anglesto the direction of a current of electricity passingnear it. This may be shown by the followingexperiment: — 149. Let N S (Fig. 50) be a magnetic needlepoised upon a pivot so as to allow of a free hori- Pig, 50. zontal motion, and W R _ a wire passing directlyover and parallel to course, the directionof the wire must be northand south, as the needlewill necessarily assumethat direction, by the in-fluence of the earth. If,now, the extremities ofthe wire are put in con-nection with the poles of a galvanic battery, in sucha manner as to cause a current of electricity to passthrough it, the needle, N S, will be deflected, andwill turn towards the position a b or c d, accordingto the direction of the current of positive electricity,whether from W to R, or from R to W. If the wireIS placed in the same direction below the needle, thedeflections will be the reverse of those produced by. DEFLECTION OF NEEDLE. 95 the same current when flowing above. If the posi-tive current is passing from south to north in thewire, as shown by the arrow in the cut, the northpole of the needle will turn to the west if it bebelow the wire, and to the east if above it. 150. In these cases, the needle will not be de-flected so far as to assume a position exactly at rightangles with the wire, on account of the influence ofthe earth, which still acts upon the magnet, andtends to draw it to its original position. Itwill accordingly come to rest in a state of equilib-rium between the two forces, in a direction inter-mediate between a line at right angles to the wireand that of the needle when controlled by the mag-netism of the earth alone. 151. The same experiment may be performedwith the dipping needle, the wire being placed par-allel with th
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
