220 Miscellaneous Intelligence. 
Art. XIV.—MISCELLANEOUS. INTELLIGENCE. 
I. MecHANicars SCIENCE. 
1. On the Fabrication of Artificial Magnets.—Professor Stein- 
hauser has ascertained, that if by the process of Canton, we 
unite, in the form of a square, two steel bars, and two contacts 
of iron, it is better to operate by the double touch in a circle, 
than by a motion backwards and forwards. Again, when we 
combine these bars in a square, the force of that which we wish 
to magnetize, ought to increase in proportion as the other mag- 
net has become more energetic; that in magnetizing horse-shoe 
magnets, it is much more advantageous to place two of these 
bent bars, with their friendly poles so situated as that the mag- 
netic circle be completed ; and that we should then touch cir- 
cularly, with the magnet destined to communicate the power. 
When the two horse-shoe bars are separated, they lose usually 
a considerable part of their force, if we do not previously de~ 
compose the great circuit into two smaller ones, by applying 
each contact to its curved magnet before the separation. In 
this way, the two separated magnets lose little or nothing of 
their power; and two may be touched in the same time that 
one is, on the usual plan. By conforming to these rules, Pro- 
fessor Steinhiuser has succeeded in making magnets of extra- 
ordinary power, in the least possible time. He also lays the 
bar to be magnetized on others previously made, and arranged 
_ in a horse-shoe form. 
2. Retrograde Movement of the Magnetic Needle.—M. Arago, 
in commenting on Colonel Beaufoy’s observations, inserted in 
the Annals of Philosophy for May, remarks that the numbers, 
given for its mean declinations in March, 1822, compared with 
those of March, 1819, give for the retrograde movement of the 
north point of the compass in three years— 
By the observations of the morning 5’ 40” 
By those of 14 hour after noon . 5’ 06” 
And by those of the evening . . 6/32” 
Mean . . 546” 
Whence the mean annual retrogradation is 1’ 55” 
More than 15,000 observations of the needle, made at Paris, 
by night and day, confirm this diminution of the declination. 
3. Comparison of British and French Canals, by M. Huerne de 
Pommeuse, Member of the Chamber of Deputies.—This gentleman 
has just published a 4to volume on the above subject. ‘‘ Vauban,” 
