Burlington free press. [volume] (Burlington, Vt.) 1827-1865, 1846-12-04
Great Circle Sailing

Mr.. Samuel Y. Colt has prepared thorough
work upon this important snl Jet, which is high
Iy recommended both by scientific and practical
men. We find the following notice of it in the
New York Express :--Boston D,iiy Advertiser.
COlT's GREAT CIRCLE SAiLIYG.-,fit were told
to some OF our readers. that ship leaving New
York, and bound for d place in Europe. in exact
ly the same latitude. would not be taking the
shortest pc siblc course by steering due East, the
statement would at first seem somewhat difficult
ct belief, yet such. nevertheless, is the well dem
onstratcd fact. Tho shortest course would be
one. that constantly tended little north of East
until the maximum difference of latitude. be-
tween this course and the parallel had been alta
tanned, and then gradually falling off towards
che South. until it reached the laitn 10 If the
place at the place. This cours wouldhe the arc
off great circle, and it would be for seventy de-
grccs of longitude, in LATITUDE 10, twenty miles
sho ter than course du, Ea { and Wts.-in
l,titude 30, there woild be ii saving Of sixty
three miles in seventy degrees of onpi,u IT, in
latitude 400. cighty-ninc miles, in latitude 5oo,
one hundred and three miles.
When the point of depart r.. and the p'acc
bound for are in different ATTITUDES, the usual
course of ship is ona rhumb, or line of double
curvature. obliquey crossing the mcrlans a,
the same angle, and thus not o ly crossing down
wards with the curvature of the EARTH b { after
ly with the approximation of the meridians to-
wards each other as they approach the p l.. A
ike difference between this rhumb line and rrcat
circle course is TO be found. and IA Ike saving
of time and space would be m de by kec, ing tie
ship upon the arc ot n great circle.
The reason that the rhumb lin, circle is uni
ally adopted. is that naviga'ors have gcncr-
ally known nothing about graf circle sailing.
and even for these few who unlcrslo ID it, prin.
n Is rtv > al
t,ns have bee n hitherto too com Heated or labo-
rious. All these objections have been ohyat ID
by Mr.. Colt in the work before US. b, means
of a few perfectly simrli!icd rule. and elaborate
tables, he has put it in the power OF all ma ter>
~ conduct their vessels across Il e ocean, bv the
hitherto neglected short route. The sa,ing til Il
will thus BE- eli. It'd, to the who'c commerce of
the country, it is not easy to cacuat, bit il
cannot BE- doubted that il will be immense and
that it wi justly cntil, Mr. Colt to lie ranked
among the greatest bencactors of Iii, country
and in fact of the world.
number ofour mot distinguished scientific
man have given thnir tc.tn my in favor of the
value of Mr.. Colts lab,rs. Doctor II icklev
Professor Of Mathematics and Astronomy in
Columbia College says, that hv the method OF
great circle sailing a day or two may b, saved
ina voyage across the Atlantic. and the same in
proportion for longer voyage. and that under
some circumstances in ca. cs of head winds. the
enormous saving Of sixty eight miles in enc hun
drcd. can be made.
"The rules" says Professor IIacklcy "fJr de-
termning the proper courses of the snip and for
solving all problems in great circle sailing O,
simple proportions quickly wrought are 50 Civ
en- by Mr.. Cot, as to be easily int Eligible 10 al
practical men. In order to still further alb pa
the labor, he has added table of double entry
with the two ATTITUDES, that in. and that bound
for, Ivy means of which the operation upon tw
of the three terms of the proportion most used
already performed. so that the calculations of
the course upon which ship ought to sail nj
any time is but the work of a moment. Such
calculations ran rarely be required more than
once in DAY
Professor Loomis. ofthe New York Universe v
Gays, ut appears surprising. that in work like
Bowditch's Navigator the methods of conducting
ship upon an arc OF great circle should MOI
have been clearly pointed out, and Mr.. Colt has
done an important service to the commerce o
this country. in attempting To supply this dc
hcency." Captain Deano of the Patrick Hen
~, says, that every navigator should at once >
copy of Mr.. Colts book. and make himsel
master of its principles. a very sligit know
edge of nautical astronomy and spherical trigo
nomctry." says the Captain. in his letter to tn,
author, "will enable scamen to understand an,
test the truth OF this beautiful theory. ] think
the publication and general distribution of Won
book, will be of the greatest benefit to shp-own
ers and underwriters" Other competent udrc.
have added their testimony in favor of the work
and we sincerely hop, that Mr.. Colts labors vii
be rewarded by the success they merit.