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PHIPPS’S JOURNAL» 563
behaviour both of the officers and feamen. In one of thefe gales on the twelfth of Sep-
tember, Dr. Irving tried the temperature of the fea in that ftate of agitation, and found
it confiderably warmer than that of the atmofphere. This obfervation is the more in-
terefting, as it agrees with a paflage in Plutarch’s Natural Queftions, not (I believe) be-
fore taken notice of, or confirmed by experiment, in which he remarks, “that the fea
becomes warmer by being agitated in waves.”
The frequent and very heavy gales at the latter end of the year, confirmed me in
the opinion, that the time of our failing from England was the propereft that could have
been chofen. ‘Thefe gales are as common in the {pring as in autumn: there is every
reafon to fuppofe therefore, that at an early feafon we fhould have met with the fame
bad weather in going out as we did on our return. The unavoidable neceflity of car-
rying a quantity of additional ftores and provifions, rendered the fhips fo deep in the
water, that i heavy gales the boats, with many of the ftores, mult probably have been
thrown overboard ; as we experienced on our way home, though the fhips were then
much lightened by the confumption of provifions, and expenditure of ftores. Such ac-
cidents in the outfet muft have defeated the voyage. At the time we failed, added to
the fine weather, we had the further advantage of nearly reaching the latitude of eighty
without feeing ice, which the Greenlandmen generally fall in with in the latitude of
feventy-three or feventy-four. There was alfo moft probability, if ever navigation
fhould be practicable to the Pole, of finding the fea open to the northward after the
folftice; the fun having then exerted the full influence of his rays, though there was
enough of the fummer {till remaining for the purpofe of exploring the feas to the north-
ward and weftward of Spitfbergen.
APPENDIX.—Obfervations on different Methods of meafuring a Ship’s Way.
THE degree of accuracy with which the diftance run by a fhip can be meafured, is
athing of great importance, but unfortunately not eafily to be afcertained from the
great variety of circumftances which may occafion errors in the reckoning, and which,
though not depending upon the meafure of the fhip’s way, may in voyages not nearly upon
a meridian be confounded with thofe that do. ‘The circumitances of the prefent voyage
gave me the faireft opportunity of trying this experiment, the weather being fine, and
the courfe very nearly upon a meridian ; fo that an error of one point could not make
more than the difference of one mile in fifty in the diftance. When the difference of
latitude is the fame as the diftance, it gives frequent opportunities of comparing the
reckoning with the obfervation, and whatever error is found muft be attributed to the
imperfections in the manner of meafuring the diftance. Mott of the writers on this
fubject have attributed the errors toa faulty divifion of the log-line.
Before Norwood meatured a degree, the length of a minute had been erroneoufly fup-
pofed five thoufand feet ; in confequence of which, the log-line, from the firft ufe of that
inftrument about the year 1570, was invariably marked forty-two feet to thirty feconds.
Norwood, when he publifhed his Seaman’s Practice, {tated the true meafure to be fifty-
one feet to thirty feconds; but, asthe fhip would really run more than is given by the
log, and it is right to have the reckoning ahead of the fhip, he recommended marking
the log-line fifty three feet to thirty feconds. It does not appear at what time an alter-
ation cither in the marking the log, or the length of the glafs, took place in confequence
of thefe obfervations : Sir Jonas Moore in his Navigation which was publithed in the
reign of Charles Il. mentions, that the feamen, having found the old log not to anfwer,
had fhortened the glafs to twenty-five feconds, which was equal to a line marked fifty
4c 2 feet
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