d out by Robert Norman,
Hydrographer." In the third chapter we are told "by what meanes the rare
and straunge declyning of the needle from the plaine of the horison was
first found."

"Having made many and diuers compasses, and using always to finish and end
them before I touched the needle, I found continually that after I had
touched the yrons with the stone, that presently the north point thereof
would bend or declyne downwards under the horison in some quantity,
insomuch that I was constrained to putt some small piece of waxe in the
south parts thereof, to counterpoise this declyning, and to make it equal
againe. Which effecte hauing many times passed my hands without any greate
regarde thereunto, as ignorant of any such properties in the stone, and
not before hauing heard or read of any such matter, it chanced at length
that there came to my handes an instrument to be made with a needle of
sixe inches long, which needle, after I had polished, cutt off at full
length, and made it to stand leuel upon the pinn, so that nothing rested
but only the touching of it with the stone. When I hadde touched the same,
presently the north part thereof declyned down in such sort, that being
constrained to cut away some of that part to make it equall againe in the
end, I cut it too short, and so spoiled the needle wherein I had taken so
much paines.

"Hereby being straken into some cholar, I applyed myself to seek farther
into this effecte; and making certain learned and expert men, my friends,
acquainted in this matter, they advised me to frame some instrument to
make some exact triall how much the needle touched with the stone would
declyne, or what greatest angle it would make with the plaine of the
horison."

The author then proceeds to give a number of experiments which he made
with his instrument, and which may be regarded as the dipping-needle in
its first and rudest form. By it he found the inclination or dip to be 71 deg.
50'.

It is remarkable, that until within the last seventy years, it appears to
have been the received opinion that the intensity of terrestrial magnetism
was the same at all parts of the earth's surface; or, in other words, that
in all countries the needle was similarly affected. And yet few things are
more inconstant; for, not only is the magnetic force widely different in
various parts of our globe, but the magnetic condition itself is one of
swift and ceaseless change.

The first person who atte