Maximum Magnetiem of Iron, Steel, etc. 425 
It is, of course, independent of the length of the iron bar 
forming the magnet and depends only on the section. 
Joule* has made many experiments on the maximum sus- 
taining-power of magnets, and has collected the following table, 
which I give complete, except that I have replaced the result 
with his large magnet by one obtained later. 
Ma; t “ , 
(EN cone end mo idl hyo gil Realy tna Q. 
1 10°00 2775 277. 154700 
2 196 49° 250° 147000 
Mr. Joule, +5 0436 12° 275 154100 
4 0012 -202 162° 118300 
Mr. Nesbit, 45 1428° 317° 165500 
Prof. Henry, 3-94 750° 190° 128200 
Mr. Sturgeon, 196 50° 255° 148500 
obtained, thus giving an experimental proof that my estima 
of 854 Ibs. cannot be far from correct, and illustrating the 
+ il. Mag., 1851, 
tioh vd order to facilitate the reduction of my units to others, I here give the rela- 
veo the letters used by me and those used in Prof. Maxwell’s Treatise on 
ism. 
‘icity and M 
Ps in this Paper = 3$ (Maxwell) = magnetic induction. Art. 605. _ 
Ee eae: <8 = gurface integral of magnetic induction. 
4nM 4 . 402, 
eo ®  elaee = magnetic force. Art. 605. 
>. fee Tee = intensity of magnetization. Art. 605. 
ets i k, are the same as in Maxwell’s Treatise. 
for a ve, throughout spoken of lines of force, &c. in the sense used by Faraday ; 
‘it uote On the interpretation of these terms see Maxwell's Treatise on Elec- 
Ticity ang Magnetism, ye 404, ; 
