202 W. A. Burnham—lIncrease of Magnetism im soft tron. 
the supposed mechanism of Stromboli fail as completely to 
account for any such connection as they do to explain the 
rhythmical action of the volcano itself. The only distinct 
relations that can be gathered from the inhabitants of the 
referable to acknowledged meteorological principles. 
Art. XX.—Brief Contributions from the Physical Laboratory 
of Harvard College. No. X1.—Increase of Magnetism in a bar 
of soft iron upon the reversal of the magnetizing current; by 
WitiiaM A. BURNHAM. 
In testing the intensity of the magnetism induced in a bar of 
soft iron which forms the armature common to two electro- 
state of the bar on the first passage of the current through the 
magnetizing helices, after a reversal of the poles of the battery. 
This increase disappears upon subsequent magnetizations of 
the bar. Various observations were taken by placing the 1n- 
duction coil C (see paper by Mr. Sears in the July number of 
this Journal) at different distances on the bar which was mag- 
netized. A bar of soft iron was experimented with in the first 
instance, the coil C being at a distance of five centimeters from 
TABLE I. 
Distances of C from the middle of the 
bar in centimeters. 
Constant deflections on making and) +|—} + ,—| + |—| + |-—| + |— — 
breaking circuit. 40/40) 50 |50| 60 |60! 70 |70| 80 80} 90 | 99 
- + 
Deflection on the first passage of the|/—|+)— |}+| — |+| — |+|— 
current after changing the poles. 
PRatnrn ta PSR i TRY a ile . 
- 3: 
— 
— 
Bned aa eye nea Dae —|+ 
f tk t.'40/40! 56 |50! 60 60! 70 |70' 80 ‘80! 90 | 90 
It will be seen by this table, that when the coil C stands at 
a distance of five centimeters from the zero point on the arma- 
_ ture upon making the cireuit, the galvanometer needle swings 
