The Philosophical magazine; a journal of theoretical, experimental and applied physics . osite direction. This experimentwas repeated with three different pairs of wires and with thesame results. It has been mentioned in Experiment I. that as soon as thetemperature reached a bright red the deflection of the galva-nometer frequently altered by fits and starts, and was even attimes strongly reversed in direction. This circumstance con-stituted a difficulty in all the experiments, and was presentlyfound to be due to slight shiftings of the flame of the burnerfrom slight draughts in the room. Hot
The Philosophical magazine; a journal of theoretical, experimental and applied physics . osite direction. This experimentwas repeated with three different pairs of wires and with thesame results. It has been mentioned in Experiment I. that as soon as thetemperature reached a bright red the deflection of the galva-nometer frequently altered by fits and starts, and was even attimes strongly reversed in direction. This circumstance con-stituted a difficulty in all the experiments, and was presentlyfound to be due to slight shiftings of the flame of the burnerfrom slight draughts in the room. Hot iron at any tempera-ture is thermoelectrically negative to cold iron ; but when thetemperature reaches a bright red there is such a suddenaccession of negativeness that if we lay a piece of iron atthis temperature upon another piece of cool iron there isdeveloped an electromotive force which, thermoelectricallyconsidered, is very large. Experiment III. In fig. 2 A is a piece of the same iron wire connected withone terminal of a condenser C having a capacity of one third Fio-. 2. hat/. of a microfarad ; B is a second piece of the same iron wireconnected by insulated copper wire with one terminal of areflecting-galvanometer G having a resistance of about 6, units; the other terminals of the condenser and galvano-meter are connected together with insulated copper free end of B was heated in a burner nearly to a whiteheat, and then, having first been removed from the flame, wasquickly placed on the free end of A; immediately there was adeflection of the spot of light on the galvanometer-scalePhil Mag. S. 5. Vol. 25. No. 152. Jan, 1888. E 50 Mr. H. Tomlinson on the Thermoelectrical Properties through 10 divisions, showing that the condenser was beingcharged. Ahiiost iniiiictliately after B had touched A, it wasremoved, and after allowing isufficient time lor the wires tocool B was again placed on A, when a deflection througli 10divisions of the scale in the o])j)Osit
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