of Natural Philosophy. — 138 
» Book IV. Prop. 1. Scholium. The editer of the Lon- 
don edition of 1799, left the question undecided, as Mr. 
Cavallo had done, whether any other than ferruginous bodies 
are capable of magnetic properties. This scholium has been 
ese although the experiments of ‘Tourte of Berlin,* 
d Lampadius, place it beyond a doubt, that nickel and 
sbi possess the same capacity, in this respect, with iron, 
except in an inferior degree. According to Lampadius, (see 
Thomson’s Annals, 1815,) the “* magnetic energies” of iron, 
nickel, and eobalt: are as: wy apericts 55, 35, and 25, re- 
spectively. - 
Prop. 2. 2. Sehol. a it were worth the while to retain 
ne os = on the variation of the 
magnetic force at all, in place’ a important 
ones of Coulomb, the numbers ought at least to have been 
corrected. Had the editor of the’ oubdnd edition taken 
these experiments from Musschenbroek himself, instead of 
taking them from Cavallo, he would have avoided the error 
of making the distances all ten times too large.+ The de- 
nomination employed in the original statement (see Philos. 
: d. 1744,) is tenths of inches. instead of inches. 
© Prop. 10. . Toillustrate the mode of finding the declina- 
tion of the needle ‘by red acme of the heavenly bodies, 
‘If the magnetic ampli- 
tude is 80° eastward of the 1 north, and the true amplitude i is 
82° towards the same side, then the variation of the le 
is 2° west.” This statement cannot be reconciled to any 
definition of the term “ amplitude ;” and it cannot be re- 
conciled with the usual definition and the one given in 
Astronomy, except by making all the alterations which fol- 
low: oh if the: —— Seem be 10° N, of E. er the 
serra to1-10 
hundred three feet, is 
it is at 20 in. ‘and the thermon- 
* Nicholson's Journal, Vol. 96. fF: i: eae: 
+ If perfect exactness in such a case w of any importance it woald 
be necessary to bo ncen'ed that Musschenbrock’s c Rhin- 
land measure ; wi! are greater than en cangor 3 1,03 to. 
We ncknowiedze 0 ourselves indebted, fot c above remark, to the Saal 
oe of pipes 
wid Peg eae 
