462 Magnetism.—Letter from Mr. Ivory. 
mal, as it may be supposed, feeling iame, made his way out of 
the field by unhanging the gate with his mouth, and went straight 
to the same farrier’s shop, a distance of a mile and a half. The 
farrjer had no sooner opened his shed, than the horse, which had 
been evidently standing there some time, advanced to the forge, 
and held up his ailing foot. The farrier instantly began to ex- 
amine the hoof, discovered the injury, took off the shoe, and re- 
placed it more carefully ; on which the horse immediately turned: 
about, and set off at a merry pace for his well-known pasture. 
Whilst Mr. Lane’s servants were on the search, they chanced to 
pass by the forge ; and on mentioning their supposed loss, the’ 
farrier replied, ‘‘ Oh! he has been here and shod and gone home 
again ;” which on their return they found to be actually the case. 
—Cheltenham Chronicle. 
MAGNETISM. 
The Prussian StateGazette mentions a highly important dis- 
covery, which Dr. Seebeck had communicated to the Academy of 
Sciences at Berlin, in three different sittings. It was on the 
magnetic properties inherent in all metals and many earths, (and 
notin iron only as was supposed,) according to the difference of the 
degrees of heat. This discovery, it is added, opens an entirely 
new field in this department of natural philosophy, which may 
lead to interesting results with respect to hot springs, connected 
with the observations made by the Inspector of Mines (M. Von 
Trebra) and others, relative tothe progressive increase of warmth 
in mines in proportion to their depths. According to M. Von 
Trebra’s observations, the heat at the depth of 150 feet below 
the surface of the earth is one degree ; at 300 feet deep, two 
degrees ; at 600 feet four degrees, &c. 
LETTER FROM MR, IVORY TO THE EDITOR, 
Srr,—I find in your last Number, a letter from my late an- 
tagonist, which would not have required any immediate notice 
from me, if he had not said that his veracity was called in ques- 
tion. Now I am not conscious that I used any words or mode 
of expression that can be so interpreted; at least, I certainly 
never intended to insinuate any thing of the kind. 
He also says that he was attacked upon his own ground ; 
which is somewhat strange; for, on the other hand, J always 
thought that I was defending myself from an attack made upon 
me without any ground at all. I am, sir, 
Your obedient servant, 
Dec. 20, 1821. James Ivory. 
