The Washington union. [volume] (City of Washington [D.C.]) 1857-1859, 1859-01-14

kRIaArE LALcEsrE,
ROAD or Rio DIX JANEIRo, October 80, lSs

ROAD OF RIO Dx JASEmo, October 49, 1858.
Sh have frequently had occasion to recognise the
utility OF the Wind Charts that the British Admiralty has
published, and which nothing than recast Of
the Pilot Charts that contained In your admirable
work of tho Sailing Directions.
have made of them chiefly the coast OF Brazil
and have at the time recognised LIST, that the
squares Of 70 long by A. lat. contain spaces too
extended, especially for navigation within 100 leagues
from the coast I'd that the tciad being traced with
different scales for the diversquares inspection OF the chart
alone does not suffice Tor the obtaining Of a sufficiently
appreciation of the duration OF the Winds and that
ii is necessary to make proportion before attaining
comparative results 3d. that the distribution OF winds
by ess is not sufficiently detailed for the navi
cation. These remarks have led me to seek the
of extending the work of the British Admiraltys Wind
Charts of the Coast Of Brazil by bringing observations to
bear squares 10 of long. by 10 of at and for each
month separately you have done in your ingenious
Pilot Charts.
take the liberty, sir to submit my project TO YOU
with the hope that you will aid with your advice
The great example you have given to the world by the
elevated tone of your views by the immensely of your
abors and by the multiplicity of your researches has
stimulated the aror of all those who interested In
the periectng OF navigation and should be fortunate
it, TO slight extent and in small portion OF
the globe, should be able add anything to the data
you have given to sailors OF all nations who traverse the
oceans.
Ny intention is to determine what are the winds that
prevail from Cape st. Rogue to La Plata extending to
hundred leagues from shore every month of the
squares OF IL long. and IL lat. i shall
not adopt eight hours the unit Of time, but one
ur aud will seek how many hours during each month
the different winds blow The results which shall find
will be inscribed ia tables which will contain every month
Of the year for each square SO, shall have many
tables as there squares that is to say nearly two
hundred for the portion OF the Atlantic which wish
explore; and The whole Will form pamphlet which the
navigator will lind easy to consult and WHICH will ndi
cate which route he should follow to obtain the best
chances for favorable wind and make his the short
est passage chart accompanying the pamphlet will
indicate the position OF each square.
Such sir is the work have undertaken and for which
need large number of observations. 1 have already
commenced by means Of the logs that / have been
able to procure here. The BRAZILIAN Admiralty has
placed ut my disposal all those Of the vessels of the Inn
peria navy which have ciuised these coasts during
the last twenty five years. wish to obtain many us
possible of other nayies and it, amidst the innumerabe
documents you have had TO consult In the construction
of your Pilot Charts should be enabled to get
those which relate to the location / have indicated
You would render great service by procuring me
this means of multiplying the observations. Perhaps it
might be possible TO have them sent to by the Com
'nder-in chief of the United States naval forces. will
employ the same medium to return them. My stay
this station being extended to 1860 will have ample
time for receiving these documents which would be
precious for the completion Of my work.
take the liberty sir, of indicating to you the manner
in which proceed to abstract information from the logs
well their discussion and shall be highly pleased
if the method meets your appreciation.
trace every ships track on chart of large scale
l
with send you a sketch.
remark that have only made squares OF Il to about
200 miles from the shore, outside of which they are
squares of 20 In searching the logs, note forms
prepared for this work. the number Of hours of the diff
ferent winds in each crossed by the track with the
day and the month this scrutiny is held all the logs
This preparatory work will furnish at its completion
for each Of the squares certain number Of obser
yations in hours of different Winds which heng separated
by columns it will be easy add the hours Of each and
which will produce totals OF hours which will reduce to
proportion to the hours contained in month An
ample will suffice 70 make understood. Let us sup
pose that for the square No. 1880 to ace long. w Of
Paris 60 to ~ lat s. n have 10000 hours Of obser
vations for the month Of April. which 600 s r.
Winds 1000 Il. 5. f., 1000 N. T., and 1000 variable
Winds I will thence conclude that for the month of
April which contains T20, there will be 432 hours Of
wind from the s. L ii4 L S. T., ~ n f., and "
rabies This same process applied TO each month will
furnish me with the necessary elements wherewith to fill
the tables above mentioned, and Of which enclose
specimen. / have detailed in it all the winds of the
compass from two points to two points but there would
be great simpication of the matter If limited my
self to the prevailing winds, making sum total of
the winds that blow but a few days in the month
would be much obliged to you for your advice this
head,
The union of all these tables will make pamphlet
which intend emitting Tables indicating the prevail
ing winds each month and for each square of one de-
gree atera the Eastern Coast of South America and
forming supplements to AIaury pharts-N. II.
The No. placed at the head Of each table indicates
the the chart the No the LETT OF the mouth
the number Of observations made and the No. to the
right the number OF hours Of calm.
The comparing of these divers tables will show the
navigator the best route follow and their viii be
simple and practical
What have undertaken 10 do sir, is merely the ex-
tension very small extent OF the very important la
bos that you have done for all seas and which have so
greatly helped the art Of navigation to the extent of di
minshng by nearly onehalf certain voyages II such
researches made in all quarters ireaHeased hy yes
ses there is no doubt that many suggestions would he
found to shorten their passages the ocean aud il
will always be 10 You, sir TO whom the honor will be
due because i was you who enlightened the world 10
these new views
shall Join 70 She observations the directions OF the
winds some indications the currents. should have
been pleased also 10 nate Che force Of the wind the
peture Of the water and air and the barometc height
but ships logs ia general wanting the records neoess
W for this purpose and IL will only bs when captains
shall have learnt the Importance of these data by conform
Ing to the form of the log which you have given that we
shall be able to obtain these interesting details.
end this letter sir, by begging you 10 excuse il
length and to accept the expression my high conse
ton
The Yce-Admral Commanded In hie( of tue French
Naval Division Of R,agil and Ia Plata =
~" +. SCI ~ O. DE cHABANNEs