BappicKkEr— On the Influence of Magnetism on the Rate of a Chronometer. 11 
while another chronometer, ‘‘ which had been frequently, for many months, em- 
ployed in inquiries connected with magnetism,” led to the following result :— 
Coulomb's Apparatus (the Oscillating Bar) one inch above the Crystal. 
North. Intensity. Deviation from Mean. 
XI. 100-18 + 1:27 
IX. 99°75 } “- +0:89 
VI. 97°54 — 1°32 
Ill. 98-03 — 0°83 
Mean 98°86 — 
which proves, as Harvey remarks, that the application of magnets does not in all 
cases produce magnetic qualities of a very powerful kind. 
If we look now over the suggestions which have been made for the removal 
of the magnetic qualities of the steel parts, the following are to be mentioned, 
besides the general and natural idea, to avoid steel in the fabrication of a chrono- 
meter, and to replace it by some other unmagnetic metal. We find gold (for the 
spiral), platinum, and brass, mentioned for this purpose. It is well known, also, that 
glass was tried by Arnold and Dent for the balance-spring. These experiments 
have, however, not been finally successful. Peter Lecount (No. 7) proposes to 
remove the magnetic properties by the action of fire, and to let the steel part cool 
carefully in a direction at right angles to the dippimg needle or magnetic meridian, 
and to subject every steel part—not only the balance with its spring, but also the 
steel spindles of the fusee, of the barrel, &c.—to this manipulation. Similar is 
Scoresby’s (No. 8) idea. He recommends “that the flat surface of the balance be 
the last part that is finished, and that it be ground and polished in the plane of the 
magnetic equator.” And again, ‘‘as the balances are now generally, I believe, 
wrought out of a solid piece of soft steel, encompassed by a rim of brass,” that 
they should be turned and blued (after polishing) in the same plane. He found 
that a sensible diminution of magnetism took place after grinding chronometer 
balances in the plane of the magnetic equator, or striking them in the same plane 
with a small smooth-faced hammer, while resting upon a hard flat substance. All 
these remarks of Scoresby seem to apply to small balances of pocket chronometers 
only. Harvey (No. 9) thinks Scoresby’s method would be effective then only, 
when it could be applied to the other steel parts also; but the chain alone would be 
capable of imparting, in a short time, any magnetic qualities it might possess to 
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