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PHIPPs’s JOURNAL, 569
well as the degree of attention paid to thofe made by us, I have fet down every cir-
cumftance that I thought material, giving every part of each obfervation, with each
feparate refult, and the mean of every fet, with the weather at the time. Whenever I
mention its blowing frefh, it was only comparatively with refpect to the reft of the
voyage, no obfervation having been made in any weather which might not generally
{peaking be called fine.
Having faid fo much of the inaccuracy of the inftrument, I muft add, that I think
fome-general and rather curious inferences may fafely be drawn from thefe obferva-
tions. One is, that the variation near the latitude of eighty, if it alters at all with time,
does not alter in any degree as it does in thefe latitudes: the variation having been
found by Poole in 1610 to be 22° 30’ W. in latitude 78° 37’; 18° 16’ W. in Crofs
Road in latitude 79° 15’ N.; and 17° oo’ within the foreland in latitude 78° 24’. By
Baffin in 1613, in Horne Sound, latitude 76° 55’, the variation from the meridian was
42° 14’ W.3; but by his compafs 17°: his compafs “‘ was touched 5 and a half
eafterly,” that being the variation in London at that time: in Green Harbour, lati-
tude, 77° 40’, he obferved the variation 13° 11’ W. Fotherby in 1614, made the va-
yiation in Magdalena Bay, latitude 79° 34’ N. 25? oo’ W.; and in latitude 79° 8’, two
points. Neither Poole nor Fotherby mention whether their variations are reckoned
from the meridian, or whether their compaffes, like Baffin’s, were fitted to the varia-
tion at that time in London. If Fotherby’s were taken with a compafs in which a
correction was made for the variation at London, his obfervation agrees exactly with
thofe made by me in Vogel Sang and Smeerenberg; and thofe of Poole and Baffin
differ fo little from mine, that the difference need not be regarded. But the variation
in London now differs from what it was at that time above twenty-fix degrees.
The other inference is, that, in going to the eaftward in the latitude of eighty, the
welterly variation decreafes very confiderably from a difference in the longitude.
Account of the Inftruments made ufe of for keeping the Meteorological Journal.
Tue marine barometer was made by Mr. Nairne, from whom I received the fol-
lowing defcription :
«« The bore of the upper part of the glafs tube of this barometer, is about threé
tenths of an inch in diameter, and four inches long. To this is joined a glafs tube,
with a bore about one twentieth of an inch in diameter. The two glafs tubes being
joined together, form the tube of this barometer; and, being filled with mercury, and
inverted into a ciftern of the fame, the mercury falls down in the tube till it is counter-
balanced by the atmofphere.
<¢ In a common barometer, the motion of the mercury up and down in the tube is
fo great at fea, that it is not poflible to meafure its perpendicular height ; confequently
cannot fhew any alteration in the weight of the atmofphere: but in this marine baro-
meter, that defeét is remedied. The inftrument is fixed in gimmals, and kept in a
perpendicular pofition by a weight faftened to the bottom of it.
«¢ The perpendicular rifing or falling of the mercury is meafured by divifions, on a
plate divided into inches and tenths, and by a vernier divifion into hundredths of an
inch, which is fixed to the fide of the tube.’
The Hygrometer I was favoured with by M. De Luc; and the following Account is a
"© literal Tranflation of that which he gave me in French,
Yue part of M. De Luc’s Hygrometer which is affected by the imprelfiions of the
moilture of the air, is a hollow cylinder of ivory, two inches eight lines long, and in-
VOL- I. 4d ternally
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