1CI 
M AG N 
backward and forward three or four times over the whole 
length of the bar, and, removing them from the middle of 
this, place them on the middle of the other bar, as before 
direfted, and go over that in the fame manner; then turn 
both the bars with the other fide upward, and repeat the 
former operation: this being done, take the two from be¬ 
tween the pieces of iron, and, placing the two outermolt 
of the touching-bars in their room, let the other two be 
the outermolt of the four to touch thefe with ; and this 
procefs being repeated till each pair of bars has been 
touched three or four times over, which will give them a 
confiderable magnetic power, put the half dozen together 
after the manner of the four, as at fig. 17. and touch with 
them two pair of the hard bars, placed between the irons 
at the diftance of about half an inch from each other. 
Then lay the foft bars afide ; and with the four hard ones 
let the other two be impregnated, in the manner Ihovvn 
at fig. 18. holding the touching-bars apart at the lower 
end near two-tenths of an inch, to which diltance let them 
be feparated after they are fet on the parallel bar, and 
brought together again after they are taken off; this being 
obferved, proceed according to the method already de- 
fcribed, till each pair has been touched two or three times 
over. But, as this vertical way of touching a bar will net 
give it quite fo much of the magnetic virtue as it will re¬ 
ceive, let, each pair be now touched once or twice over, 
in their parallel polition between the irons, with two of 
the bars held horizontally, or nearly l'o, (fig. 19 ) by draw¬ 
ing at the fame time the north of one from the middle 
over the fouth end, and the fourh of the other from the 
middle over the north end of a parallel bar ; then,- bring¬ 
ing them to the middle again without touching the pa¬ 
rallel bar, give three or four of thefe horizontal Itrokes to 
each fide. The horizontal touch, after the vertical, will 
make the bars, as Itrong as they can poflibly be made; as 
appears by their not receiving any additional Itrength, 
when the vertical touch is given by a greater number of 
bars, and the horizontal by thofe of a iuperior magnetic 
power. This whole procefs may be gone through in 
about half an hour; and each of the larger bars, if Well 
hardened, may be made to lift twenty-eight troy ounces, 
and fometimes more. When thefe bars are thus im¬ 
pregnated, they will give to a hard bar of the fame fize 
its full virtue in lefs than two minutes; and will, there¬ 
fore, anfwer all the purpofes of magnetifm, in navigation 
and experimental philosophy, much better than the load- 
ltone, which is well known not to have fufficient power to 
impregnate hard bars. The half dozen being pur into a 
cafe, as at fig. 20, in fuch a manner as that two poles of 
the fame denomination may not be together, and their 
irons with them as one bar, they will retain the virtue 
they have received; bur, if their power Ihould, by making 
experiments, be ever lb far impaired, it may be reftored, 
without any foreign afliltance, in a few minutes. And if, 
out of curiolity, a much larger fet of bars fnould be re¬ 
quired, thefe will communicate to them a fufficient power 
to proceed with, and they may in a Ihort time, by the 
fame method, be brought to their full firength. Mr. Can. 
ton, by the fame procefs, communicated magnetic virtue 
to two large bars, each half an inch fquare, io| inches in 
length, and weighing nearly ten ounces and twelve penny¬ 
weights, to fuch a degree, that one of them lifted by one 
of its ends feventy-nine ounces and nine pennyweights; 
and a flat femicircular magnet, weighing an ounce and 
thirteen pennyweights, was made to lift, by applying its 
two ends together to an iron wedge, ninety troy ounces. 
The fame ingenious gentleman could alfo readily deprive 
his bars of their virtue; and'change tiie poles of a natural 
loadftone, by placing it in an inverted direction, between 
the contrary poles of his larger bars, laid down at fome 
diftance from each other, in the fame Itraight line conti¬ 
nued at the diltance of about a quarter of an inch from 
either of the poles, without touching the Itone with either 
of the bars. 
V0L.X1V. No. 961. 
E T I S M. 
The method in which the fteel lie made ufe of was 
hardened is as follows : Having cut a fufficient quantity 
of the leather of old flioes into very fmall pieces, an iron 
pan is provided, which a little exceeds the length of a bar, 
is wide enough to admit of two bars fide by fide without 
touching each other on the pan, and at leaff an inch deep. 
This pan is nearly half filled with the bits of leather, upon 
which are laid the two bars, having fattened to the end of 
each a fmall wire for taking them out; the pan is then 
quite filled with the leather, and placed on a gentle flat 
fire, being covered 1 and furrounded with charcoal. The 
pan, being brought to fomewhat more than a red heat, is 
kept about half an hour, and the bars are fuddenly 
.quenched in a large quantity of cold water. Mr. Horne, 
in his Eflays on Iron and Steel, p. 147, claims-the merit 
of di reCling this procefs for hardening Mr. Canton’s bars. 
In order to communicate the magnetic virtue to a fteel 
bar, to the needle of a compafs, &c. by means of two mag¬ 
netic bars, place the bar or needle, AB,flg. 21, Plate iff, 
upon a table ; then place the two magnetic bars CD, EF, 
ftraight up upon AB, at a little and equal diltance from 
the middle of the bar A B, and in fuch manner, that ths 
fouth pole, D, of one of the bars, may be neartit to that 
end of the bar, A B, which is required to become the 
north pole, See. then thefe two bars mult be Aid gradually 
towards one extremity of the bar, keeping them conllantly 
at the fame diltance from each other; and, when one of 
the magnetic bars, for inftance C D, is arrived at A, then 
they mult be Aid the contrary way, till EF arrives at B • 
and thus the bar, A B, mult be rubbed a greater or fmaller 
number of times, till it will be found by'"trial to have ac¬ 
quired a confiderable power. When the magnetic bars 
are powerful, and the bar, AB, is of very good Iteel, and 
not very large, a dozen of Itrokes are fully fufficient. 
When the magnetic bars are to be removed from the bar 
AB, care mult be had to bring them to the fame fituatioii 
where they were firlt placed, viz. at a little and equal dif¬ 
tance from the middle of the bar A B, and then they may 
be lifted up. 
In this operation, the effect of the bars may be im¬ 
proved feveral ways, which will be found neceflary when 
the bar, A B, is proportionably large, and it is required 
to give it the greatelt poffible power. This may be ef¬ 
fected, firlt, by joining the magnetic bars at top, inter- 
pofing a piece of wood or other i'ubltance, except iron, to 
keep them apart, as fhown in fig. 22 ; for in this manner, 
the upper poles of the bars, being contiguous, will tend to 
It re ng then each other, and, of courfe, their lower poles 
will alfo be ftrengthened. Secondly, by placing the bar 
to be rendered magnetic, between two bars of foft iron* 
or two other magnets, in the manner before directed * 
Thirdly, the magnetic bars may be inclined the contrary- 
way, after the manner ufed by Mr. ./Epinus; fo that the 
magnets CD, E F, may make an angle of about fifteen 
degrees with the bar A B, as at fig. 23. 
The bar may, in the fame manner, be rendered magne¬ 
tic by means of an armed magnet, or by a horfe-Jkoe mag¬ 
net, placing botli the poles of the magnet in contaft with 
the bar, A B, as in fig. 24. 
As artificial magnets are frequently thus made in the 
fhape of a femicircle, or like a horfe-fhoe, for the hike of 
bringing both poles in the fame plane, the crooked (tee! 
bars of which they are conftrmfted are made magnetic in 
the fame manner as the ftraight bars, excepting only, that 
the magnetic bars which are ufed for it mull follow the 
curvature of the fteel bar; thus, if it be required to ren¬ 
der magnetic the piece ABC, fig. 25, place it flat upon 
a.table, and to its extremities apply the magnets DF 
E G ; joining their extremities F, G, wirh the conductor 
or piece of foft iron F G. Then apply the magnetic bars 
H, I, to the middle of the piece ABC, and llroke it with 
them, from end to end, following the direction of the bent 
fteel, fo that on one fide of it the magnetic bars may Hand 
in ths direction indicated by the dotted representation LK 
