To the Editors of the Philosophical Magazine and Journal.2
GENTLEMEN,
I FEEL some difficulty in writing this note, and yet I think it requisite to say a closing word upon a subject which has already occupied too much of your space.3 It is nearly ten years since Mr. Adie made his experiments: would not a careful repetition of them at present show more wisdom upon his part than a reliance upon results which have such a mass of scientific evidence against them? With regard to his theory of the metallic cross*,4 I have one request to make of Mr. Adie; and that is, that he would kindly place his pencil on the point C, where he supposes the current to be generated, follow the course of the current, and get back to C, without passing through the battery.5 Some oversight must, I imagine, have occurred in Mr. Adie’s direction of the cross; as the matter stands at present, I frankly confess my inability to understand it.
JOHN TYNDALL. | Queenwood, Jan. 1853.
J. Tyndall, ‘On the Temperatures of Conductors of Electrical Currents’, Phil. Mag., 5:30 (1853), p. 147.
Editor: the editors in 1853 were David Brewster, Richard Taylor, Robert Kane, and William Francis.
To the … Journal: the letter was given the title ‘On the Temperatures of Conductors of Electrical Currents’ by the editors of the Phil. Mag. See Volume 3 for Tyndall’s extensive contributions to the Phil. Mag.
too much of your space: Tyndall was referring to a series of letters published in the Phil. Mag. between Richard Adie and himself in fall of 1852 regarding experiments on the ability of electricity to cause the absorption of heat or reduction of the temperature of conductors. The original letter sparking the discussion was R. Adie, ‘On Some Thermo-electrical Experiments’, Phil. Mag., 3:17 (March 1852), pp. 185–187. See also letters 0663; 0670; 0672; and 0685.
theory of the metallic cross: this is described as the observed effect of heating or cooling at the cross-joint of two metal bars when electricity is applied to one end of each of the bars (often of different metals) and measured through the opposite ends of the same bars by a galvanometer (an instrument for detecting electric current). When the current passes in one direction a current is generated in the adjacent bar suggesting that the cross-joint connected to the source of the current is cooled. However when the current is passed in another direction or varied in tension this leads to different temperature effects. The point at issue, for Adie, appears to be a lack of sufficient time allowed for the metallic cross to exhibit temperature change, thus not allowing Tyndall to adequately observe the cooling effect taking place (R. Adie, ‘On the Temperatures of Conductors of Electrical Currents,’ Phil. Mag., 5:29 [January 1853], pp. 46–49.
pencil on the point C … battery: refers to a diagram of the metallic cross included with Adie’s letter. See n. 3. Adie acknowledged and responded to Tyndall’s objections and lack of understanding in ‘On the Electrical Currents induced in the Metallic Cross’, Phil. Mag., 6:34 (July 1853), pp. 46–50.
Please cite as “Tyndall0711,” in Ɛpsilon: The John Tyndall Collection accessed on