GREAT CIRCLE SAILING.

New Zealander, Volume 6, Issue 460, 11 September 1850, Page 2

GREAT CIRCLE SAILING.

Extraordinary Quick Passage from England to Australia.—The Devenport Telegraph «tate 3) — The emigrant-ship Constance, from Devenport, commauded by Captain Godfrey, of Dartmouth, has made the shortest voyage to Adelaide ever known ; having reached that port in the unprecedented short period of seventy-seven days, the average length of that voyage being about a hundred-and-ten daya. This is one of the beneficial results of the great circle table constructed by our townsman, Mr. Towson, and published by the Adnairaliiy about eighteen months since, and by the age of which Capt. Godfrey shaped his course, by which means be effected a saving of 934 miles, and obtained the additional advantage of more favourable winds. The following more detailed and scientific account of the manner in which this remarkable voyage was performed is given by the London Standard. Jt V'vill doubtless be deeply interesting to our nautical readers. Our account of Captain Godfrey's unprecedented short passage to Australia, in the emigrant-ship Constance, having produced a greater sensation among those interested in Australia and New Zealand than any voyage ever before made, we are induced to publiih the following additional details of the track Captain Godfrey pursued by the aid of Mr. Towson's value able tables:—We may state that about 12 months since Captain Godfrey underwent a voluntary examination at the port of Plymouth, and obtained a firstclass certificate. During his examination he became first acquainted with great circle sailing, and iti modifications, and the consequent value to navigators of the Admirality " tables to faciliute the practice of great circle tailing," especially to those engaged in voyages such as he was about to undertake. He immediately resolved to make what the author has termed the composite track, which is thus described in the work alluded to :—" To follow the great circle track rigidly would sometimes lead through latitudes so high as to be impracticable; this generally happens, too, when the greatest amount of distance would be saved ; but though in such casss it would be unwise to attempt the great circle yet there is a very simple application of these tables, which will give the shortest possible route consistent with a restricted maximum latitude." The mariner is then directed to choose hia maximum latitude, and Captain Godfrey chose the pa'iallel of 55 deg. This voyage disappointed the expectations of Captain Godfrey; although far shorter than the average time, it was not the shortest voyage ever made. He discovered that in latitude 55 the winds were light and unsteady, he was therefore obliged to return to the parallel of 50 degrees. Although, however, he failed in the object he had in view, lie acquired experience which to himself and the commercial world it ot the highest importance. He has ascertained that the composite track on the parallel of 50 degrees is the shortest practicable route to Australia ; for Although the route of the parallel of 55 maximum latitude is 160 miles shorter in distance, the advantage of wind gives the unquestionable preference to tl.at of 50 degrees* The next voyage he brought this knowledge into practicable operation, and has astonished the men of mercantile pursuits by making the shortest voyage ever known. The composite route to Australia does not differ from other voyages until the mariner has reached about the latitude of 24 S. Having cleared the trade winds, he then shapes his route on the arc of a great circle, Tarying his course by compass according as the latitude of the ship varies, as shown below; or he sails as near to these courses as the direction of the winds will permit. The courses are as follows :—

This part of the voyage is about 3,480 miles, and brings the ship 68 degrees of longitude nearer her destination. She then runs due east on the parallel 50, about 72 deg. 40 mm. of longitude, being about 4,360 miles, and then leaves that parallel by the route of a great circle for her destination. This last-named part of her voyage is 1,865 miles, and about 43 degrees longitude—making altogether, from the commencement of the composite track, 8,145 miles; whereas the same voyage by the Cape, and thehce to Adelaide, by Mercator's sailing, is 9,080, making a saving of distance to tne amount of 935 miles, besides an equal saving of time, from the uniform favourable winds that blow in these latitudes.

Lmt. !50 .... >00 .... I4'O .... 17-0 .... J9-30 .... 1:1-30 13-0 .... 4-30 .... Course. SE SE i E SEfE SE | E SE by E ESEf S ESEfS ESE*S Lat. 46-0 .... 47-0 .... 480 .... 48-30 .... 490 .... 49 30 .... 49 45 .... 49-57 .... Course. ESE ESE \ E ESE |E ESE | E Eby S EJS E 4 S E i S