20 Bappicker—On the Infiuence of Magnetism on the Rate of a Chronometer. 
Taste VI.—Box Chronometer (Parkinson AND Fropsuam), assumed Detached Rate 
— 0°39 losing. 
Chronol. | No, of Days. | Temperature.| Intensity. position Rate. age Remarks. 
o 2 : Detached Rate. 
10 4 55 38 S. -1°2 - 08 N. of ball. 
11 4 51 33 N. -1-0 -0°6 Nee 
7 3 58 iol S -1:9 -1°5 Se 55, 
2 5 51 97 S. =ice -0°9 ae aoe 
3 | 5 54 97 s. = 195 = ill We a 
1 4 57 100 a. +02 =a = 
5 5 61 100 at -0°6 a ae 
6 7 = 100 as -0°5 Ee = 
4 3 60 127 Ss. = 16 = 1-2, N. of ball} 
9 4 54 169 8. -1:4 = 1:0 Nee 
8 4 58 183 S. a he! Si S53 
From these Tables Barlow draws the following ‘ practical deductions” :— 
1. The rate of a chronometer is undoubtedly altered by its proximity to iron 
bodies. 
2. It does not appear to be by any means a general case that iron necessarily 
accelerates the rate, as five out of the six instruments used were obviously 
retarded, and only one showed indications of accelerations in one position (No. II.), 
and this case is more doubtful than the retardation in the other five. 
3. It is very obvious (cf. Nos. IV. and V.) that much depends on the direction 
of the balance with respect to the iron. 
4. Generally speaking, it appears that the greatest effect is produced in those 
instances where the change in the magnetic intensity is the greatest, but there 
does not seem to be that uniformity of relation that we should naturally have 
anticipated. 
5. As a practical conclusion, it is obvious that a chronometer on board ship 
ought to be kept as carefully at a distance from any partial mass of iron as the 
compass itself, and that it should not be placed in a situation where experiments 
with a compass show any considerable degree of magnetic deviation. 
6. Lastly, Barlow proposes a way of eliminating the influence of the ship’s 
iron, which will be discussed later on, together with similar suggestions of other 
observers (cf. p. 44). 
