A CLEVER INVENTION.

Dominion, Volume 2, Issue 336, 24 October 1908, Page 6

A CLEVER INVENTION.

HENNAH AND RISSEL'S COURSE RECORDER. " TO PREVENT DISASTER. Herewith wo publish a facsimile of a section of tho course-steered by the Manuka on her trip from Sydney this week, as recorded on the chart of the Patent Automatic Course Indicator' and Recorder, which has been invented by Captain Hennah and Mr. ltissel, of Wellington. The inventors claim, apparently with every reason, that tho instrument will record faithfully. when a vessel is out of her course, and will' sound an alarm to say so if tho alarm gauge .is set. This, of course, is a most essential feature of the indicator, and it is claimed that had the Union Company's steadier Wairarapa, the more recent,Kia Ora, and the Aeon carried such an instrument and set.it each time tho course was altered, -in each of those cases—and in many others where vessels.,have been lost in thick weather through getting off their course—disaster would have been averted. A dotailed .description ,of the instrument appeared in Thursday's Dominion.

In explaining the above diagram, it'must'be imagined that it represents part of chart wound round a drum, which revolves by .clockwork in strict accord with the, time :kept by the, clock contained in tls°]iiistr(i--,mont. ' As' it revolves a pencil sot '"dead" on the course begins'to trace tho coiirs,e|"the vessel is pursuing, being guided in''its'work by an electrical connection with a Kelvin compass." If the vessel is being steered jwr-. fectly' straight a straight line would be-' shown]" but even-' the slightest deviation' is l recorded, in minutes' and' seconds, f in' tho' l above chart the true courso is marked by a' double line, and each lino' on either side 1 .represents a minute. Hero the steersman' who has gone on duty on the Ma.nuka at 8 p.m. (see the time numerals in tho side!mar-' gin) has kept a very straight course for the 'first hour, but in the next he has allowed the vessel to pay off a little, but he lms straightened her lip for the last two hours of his 'watch. At midnight ho had heen_ relieved'by another helmsman,'and the lines .traced on the above chart between midnight and 2 a.m. are more eccentric. Assuming that the instrument' had been 'set with a'five minutes']. range "while course reproduced above- wag, being 'steeredy the alarm bell would never liavo sounded, •but supposing, for the sake of argument,' that only a four minutes' range had :been given, the boll would have rune three times between 1 a.m. and 2 a.m. While tho recorder is an accurate judge of the capabilities of the man at the helm, it is. also a first-class critic of the steering capabilities of a vessel.