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308 A P P E N D I X .
mus. Sub quo tempestatis infortunio quinqué navigavimus diebus,
demissis omnino vcHs. In quibus quidem quinqué diebus duecntas
ct quinquaginta in mari penetravimus lencas, linea? interdum eqmnoctiali,
necnon mari et auras temperatìori semper appropinquando, per
quod nos à príemissis eripere periculis altissimo Deo placuit. Eratque
hujuscemodi nostra navigatio ad transmontanum ventum et GriECum,
ob id quòd ad ^ t h i o p i » latus pertingere cupiebamus, il quo per mans
Atlajitiei fauces eundo, mille tercentum distabamus leucis. Ad illam
autem per summi tonaiitis gratiam Maij Hs quinta pertigimus die.
Ubi in plaga una ad latus Austri, quo; Serraliona dicitur, quindecim
diebus nos ipsos refrigerando fuimus. Et post hseo cursum nostrum
versus Ínsulas Lyazori dictas arripuimus : quffi quidem insulsi à Serraliona
ipsa septingentis et quinquaginta leucis distabant, ad quas
sub JuHi finem pervenimus, et pariter quindecim inibi nos reficiendo
perstitimus diebus. Post quos inde exiyimus, et ad Lisbon^ nosti'íe
recursum nos accinximus, à qua ad occidentis partem tercentum sepositi
leucis eramus, et cujus tandem deinde portum MDII cum prospera
salvatione et cunctipotentis nutu rursum subivimus cum duabus
duntaxa navibus, ob id quod tertiam in Serraliona, quoniam ampUus
navigare non posset, igni combusseramus. In liac autem nostra tertiò
cursa navigatione, sexdecim circiter menses permansimus ; è quibus
undecim absque transmontaneee stellfe, necnon et majoris urs® minorisve
aspectu navigavimus, quo tempore nosmetipsos per aliam meridionalis
poU stellam regebamus : qua: superius commemorata sunt,
qu!E in eadem nostra tertiò facta navigatione, relatu magis digna
conspexi."
The above is a Uteral extract from pp. 116—126 of the Noves
OBBIS, id est, Navigationes primee in Americam. Koterodami, apud
Johannes Léonard! Berewout. Anno 1616.—an exceedingly scarce
work.
No. 53.
BAROMETRIC OBSERVATIONS IN THE RIVER SANTA CRUZ.
Before leaving the Beagle, to explore part of the river, two
mountain barometers, afterwards carried in the boats, were suspended
on shore, close to the sea, and compared with a barometer on board
the ship, the cistern of wliich instrument was at the level of the sea.
A P P E N D I X . 309
After returning from exploring part of the river, both mountain
barometers were agtiin similarly compared, and the difference betwean
the best instrument and that iixed on board was found to be the
same as before, namely, 0,19 inch. At sunrise on the 5th of May,
at the westernmost station reached by the boats, the mountain baro -
meter which was preferred showed 29,81 (/3'); the thermometers,
attached, and detached, 44° Fahrenheit; and the cistern of the instrument
was one foot above the level of the river. At the same time
(allowing tlie difference of longitude) the barometer on board the
Beagle showed 30,07 (/3); while the attached thermometer showed
44°^ and the detached 43°.
The rise of tide that morning at the ship was twenty-one feet, and
it was high water at thirty minutes past seven, A.M.
By Baily's rule—*
B = 0,00000 (subtract 0,19 from 29,81)
log. H' = 1,47159
1,47159
log. n = 1,47813
D = 0,00654 - - - log ="7,81558
c ="9,99980
Half-tide 10,5 feet. A = 4,79307
— 2,5 405 = 2,60745
+ 7
— 1 412 feet.
Hence the western station appears to be about four hundred and
twelve feet above the level of the eastern—that of the Beagle ;—
but other pairs of observations were made during the previous and
following days (May 4tli and 6th) of which the results, similarly
deduced, were 464, 501, 527, 487, 497, 434, and,436;—each considerably
above 400 feet: and as that part of the river (the western
station) is about two hundred miles from the sea, the fall, on an
average, cannot be less than two feet in each mile.
* Pp. 183 and 263 of Astronomical Tables and Formulse, by Francis
Baily, Esq. F.R.S. Pres. A.S. &c. &c.