The London, Edinburgh and Dublin philosophical magazine and journal of science . n current in the test-coil,and commutating the galvanometer terminals connected withthe induced coil; and the deflexion D, produced by chargingand discharging the disks at the same rate, the galvanometerterminals being commutated as before. The deflexionsactually measured were 2d and 2D (see preceding paper).In each set of readings five determinations of both 2d and2D were made with the disks running in each direction,2d and 2D were determined alternately. In the first fivesets of readings the potential was kept p
The London, Edinburgh and Dublin philosophical magazine and journal of science . n current in the test-coil,and commutating the galvanometer terminals connected withthe induced coil; and the deflexion D, produced by chargingand discharging the disks at the same rate, the galvanometerterminals being commutated as before. The deflexionsactually measured were 2d and 2D (see preceding paper).In each set of readings five determinations of both 2d and2D were made with the disks running in each direction,2d and 2D were determined alternately. In the first fivesets of readings the potential was kept practically constant,and the speed of the disks varied from 99 to 92*4 revolutionsa second, and in the next six sets the speed was kept prac-tically constant, and the potential of the disks varied from905 to 5900 volts. To show how closely the various quan-tities could be determined the following table, giving all the 38 Dr. H. Pender on the Magnetic data for one complete set of observations, is appended. Acomparison of this table with Table III. of the previous paper Fier. will show how greatly the conditions of the experiment havebeen improved. In the latter the greatest deviation fromthe mean of 2D is 42 per cent., while in the table below it isonly 44 per cent. Effect of Electrical Convection. 29 The symbols have the following meanings:—E is the elec-trometer reading, from which is deduced V, the potential ofthe disks in volts, by means of the calibration curve of theelectrometer, 1\ the number of seconds required by the eastdisk to make 1990 revolutions, T2 the same for the disk onthe west side, N the mean number of revolutions of the twodisks per second deduced therefrom, i the test-currentmeasured in amperes, cl and D as described above. Theratio of the two systems of units is calculated from these datain the manner described below. March 25, 1902. Table I. 1 . Direction of rotation: east disk + , west disk — . 2d. 2D. E. Tr T2. i. 73 78 | 59-775 81 61-0 72 j 80 5
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