BappickKeR—On the Influence of Magnetism on the Rate of a Chronometer. 33 
A; Nos. 606 and 657 in the same way to magnet B; Nos. 600 and 274 to 
magnet C. 
Soutn Poe. | Nortu Pore. 
Situation. | No. of Days. 
No. 657. No. 615. No. 605. No. 606, 
: | | 
Detached. o= 08°20.) = O= 7-41 |. + 0=09 — 319 7 
| | | 
Magnet to VI at 7 in. | POPOL OS eo OlsO2n utah 4 san) e oa G 5 
a VL +87 31-47 | + 114-68*| +0-66 | -8-14 7 
ae UL |= 530-00 | — 0 4:43 || -1-28 ~ 4-47 7 
EnV Eyal || 
A IDS | + 6388-90 | + 0 7:06 -1-42 | -4-54 5 
| | 
iam RO | + 551-34 | + 0 6:02 | --1-68 | -5-62 5 
Detached. | - 0 6-86 | - 0 6-04 - 1-08 - 5-03 9 
| | 
Arnold and Dent conclude from these experiments that— 
(2) A chronometer’s rate will be accelerated when the north end of the 
balance is exposed to the south pole of the magnet ; 
(4) Its rate will be retarded when the south end of the balance is exposed 
to the south pole of the magnet. 
If we consider, that in the case (a) the attraction of the magnet will tend to 
decrease, and that in case (4) the magnet’s repulsion will tend to increase the ares of 
vibration, we see that these two rules are virtually the same as those given by 
Barlow (cf. p. 16), and that, according to Harvey’s Paper just discussed, they are by 
no means necessary ones. Since, Arnold and Dent continue, either the south or 
the north pole of the balance must lie under figure VI, the effects of the magnet’s 
exposure to XII and to VI must be opposite each other; but by the excentric 
situation of the balance ‘“ the comparison of the effects is rendered uncertain.” At 
III and IX values between those at XII and VI are obtained, which among them- 
selves are ‘‘ quite consistent.” It is surprising, and to be regretted, that Arnold 
and Dent were not induced by these observations to regulate the positions and 
distances of the magnet with reference to the centre of the balance instead of that 
of the chronometer. They think also that Nos. 605 and 606 show traces of mag- 
netic influence, but that in these chronometers the increase and decrease of rates 
are gradual, while they take place quite suddenly in the other chronometers. I do 
* Mean of four days only: during the first three days the axis of the magnet had been lying 
aboye the plane of the balance, which gaye only - 13*2 as daily rate, 
TRANS, ROY. DUB. SOC., N.S. VOL, Ill. F 
