BappickEr—On the Influence of Magnetism on the Rate of a Chronometer. 27 
sented in his fig 13, which I reproduce on Plate I., Fig. 9. Two other chrono- 
meters, F and G, were also observed when standing on the dise, the figure XII 
pointing successively towards S., W., N., E. And, finally, chronometer F was ex- 
posed to the north pole, the figures X, VII, IV. being successively in contact with it. 
Chronometer B showed an increase of rate by 10°-3 before the north, and of 1°:9 be- 
fore the south pole ; chronometer EK changed its detached rate of + 8°°5 into + 27°:2 
before the south pole, after which the free rate became again + 8*°3. This rate was 
then changed into — 2*6, when the chronometer was placed on the disc, so that its 
centre coincided with the centre of the plate, and the radius passing through the 
balance centre was at right angles to the magnetic axis. Harvey remarks :—‘‘ The 
great effect of the middle of the plate on the rates of the chronometer will not be 
regarded as remarkable when it is considered that only a single point of the chro- 
nometer could be applied to the equator of the magnet; and that both the balance 
and the main-spring were in each case beyond the centre of the plate, and conse- 
quently under the influence of an attractive force, less powerful than that deve- 
loped by the poles of the magnet, but much superior to the effect of the actual 
equator of the plate.” It is to be regretted that these observations did not induce 
Harvey to bring the centre of the balance into coincidence with the centre of the 
plate, nor to observe the rate of the chronometer when in the same position as to 
the equator, as the drawing shows it to be with reference to the poles. 
The observations of the chronometers F and G led to the following daily rates, 
which are the results of six days’ exposure on the average :— 
Situation of Chronometer F. Daily Rate. | Situation of Chronometer G. Daily Rate. 
Detached. + 2*-0 Detached. — 45-1 
XII pointing 8. | + 7:3 XII pointing N. + 0:1 
O-€1 0 bial =a W.| — 38°6 XII o K. -8°6 
On the dise. ‘ 
Xi ea. N. | +24:°8 | XII A s. -3°7 
On the disc, 
XII - K.} + 5:0 XII fe W. -4:4 
X in contact with north pole. | — 6:8 XII "3 N. +22 
Vil ” ” ” ” + 7 9 XII ” W. - 4 “7 
IV ” ” ” ”) ot 2 3 
| 
which show that by turning the chronometer— 
From N. to E. the alteration of rate was losing, 
”) EK. ” S. ) ) 9 ) 9) gaining, 
) S. ) W. ) ”) oP) ) ” losing, 
Diaw Was th ote ” 299 ” gaining. 
E 2 
