12 Bappicker—On the Influence of Magnetism on the Rate of a Chronometer. 
the balance. Finally, Abraham (No. 16) arrived, after many experiments and 
difficulties, at the following method .of neutralising the magnetism in a chronome- 
ter’s steel parts:—-He dipped the apparatus to be deprived of magnetism into 
very fine iron filings, by which the situation of the magnetic poles became visible. 
On approaching a very strong magnet at the distance of from one inch to a quarter 
of an inch to the part covered with iron filmgs, one remarks at once an effect, if 
the magnet’s pole and that of the steel piece are equal: the iron dust is removed 
gradually in the same degree as the magnetic power is neutralised, If the iron 
dust is quite fallen off one dips the steel piece-again into it, in order to see if not 
by too long an exposure it acquired opposite polarity. If this is the case, it will 
be neutralised as before by means of the other pole of the magnet. Abraham states 
that, generally speaking, he performs the above experiment—be it the balance or 
some other steel part—in about one minute, and proves the efficacy of this pro- 
ceeding by testimonies of competent men. 
The above observations of magnetic qualities in a chronometer are sufficient to 
show that the utmost care is necessary in the manufacturing of a chronometer, in 
order to avoid polarity ; and further on they make it highly probable that terres- 
trial and artificial magnetism have some effect upon a chronometer’s rate; but 
they do not give by any means satisfactory information as to the special distribu- 
tion of magnetism in the different steel parts. We do not know anything, for in- 
stance, about the balance spring; and what we know about the balance, especially 
Scoresby’s remark, only shows how interesting further investigation would be. 
These observations could be easily made by chronometer manufacturers ; it would 
be very important if they, by dipping the apparatus into iron filings, would, 
however roughly, indicate and note down the situation of the magnetic poles. 
As to the remedies or prescriptions how to remove the magnetic property, it is a 
matter of experiment and practice alone which of them will be the most effective. 
I think that an equal attention to all of them will be about the only way to 
success. 
IV, 
[S. VarLey.—GerorcE FIsHer. | 
It will now be necessary to reproduce and discuss the observations of the rates 
of chronometers when under the influence of either terrestrial or artificial mag- 
netism. I at first intended to give these two kinds of observations separately; but 
as this could not be done without frequent repetitions, since they continually refer 
to each other, I shall give them all in chronological order: only the methods of 
compensation proposed will be reserved for a special chapter. We have several 
series of observations of changes of rate with changes of position as to the 
