Upper pole of magnet south:-Galvanometer key rai>ed, deflection-24 divs. depressed, ,-42 divs. Net deflections clue to current (subtracting effect of the magnet on the galvanometer needle) :-Upper pole north (Io2-25 =) + 77 clivs. south (-42 + 24=)-IS divs. Sum of opposite deflections due to transverse current, (77 + 18=)95, or deflection on each side ofzero =47"5 divs. The , Jits therefore had the effect of reducing the amount of the Hall deflections ; the d irectiou was unaffected. Experiment 3.-The galvanometer contacts were now moved from the edges to the pomt< D, E, about 5 mm. from the line, and the experiment was repeated with the following result:-Upper pole of magnet north :-Key raised, deflection + IS divs. , depressed, , + 165 divs. Upper pole south :-Key raised, cit flection-35 divs. , depressed, , + 180 divs. Net deflections due to current:-U]'per pole north (I65-I8=).,. 147 divs. , south (180+35=)+2I5 divs. Sum of deflections rue to transverse current (215-I47=) 68. Deflection on each side of zero=34 divs. Thus "hen the galvanometer cnntacts were near the nliddle of the plate the deflections were almost as great as when the galvanoweter was connected to the edges. But they 71Je>•e in tlze opposite direction, sh o wing that the lJ all effect was reversed. Expe riment 4.-A repetition of the last. Upper pole Lorth :-Key raised, deflection + 28 rliv;. , depressed, , + Ij"O divs. Upper pole south:-Key raistd, deflection-24 divs. depressed, , +I 70 divs. Net deflections due to current:-Upper pole nor th (I 70 •-28=) I32 divs. south (I70 +24=) I94 divs. Sum of deflectir, ns due to tram verse current, (I94-132 =) 62. Dt!lection on each side of zero = 3I divs.
