# MIMCO Marconi International Marine Co. Ltd ship's brass compass.



## marconiwireless (Sep 29, 2013)

I recently acquired a number of early Marconi Wireless telegraph Company ships radio equipment from the British School of Telegraphy in Earls Court which has now closed and amongst it is a brass compass measuring 14cm marked Marconi International Marine Co. Does anyone remember using one of these?


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## Ron Stringer (Mar 15, 2005)

A question about this instrument came up on SN a few years back and the item was identified but I can't remember what it was or on which thread it came up. I think it was something to do with direction-finding but I am not sure.

Luckily there are other members with far better recall than mine and you should have an answer shortly.


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## marconiwireless (Sep 29, 2013)

Hello Ron, Thankyou for your quick reply, I thought that was its purpose, hopefully someone can confirm.

Dennis.


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## Ron Stringer (Mar 15, 2005)

Found it!

http://www.shipsnostalgia.com/showthread.php?t=34090

I knew SN had aired this instrument before. Sorry to say that there was no positive identification so we haven't advanced too much in the past couple of years. (Jester)


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## marconiwireless (Sep 29, 2013)

*MIO brass compass.*

Thankyou for replying to my query. Yes, I am aware of the Marconi Belini-Tosi d/f and do in fact have one but the compass dial is built in and made of ebonite so I suspect your second suggestion that it formed part of some land based system is probably crrect


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## gwzm (Nov 7, 2005)

I haven't seen one of these in the flesh. However, it looks to me like a calculator that would be used by a navigating officer to bring together the elements that go with a D/F bearing to arrive at the true bearing relative to the D/F beacon, viz:
1.What is the D/F beacon bearing relative to the ships head?
2.What is the D/F bearing correction +/-for the bearing obtained?
3.What is the compass heading at the time the bearing was taken?
4.What is the compass deviation correction +/-that needs to be applied to the compass heading?
These would all have to be taken into account and manually worked through by the navigating officer who may be under pressure and might possibly make an erroneous calculation with potentially disastrous consequences. This device would simplify the process
As a Radio Officer, I was required to take check bearings during a voyage to confirm the accuracy, or otherwise, of the D/F bearing correction chart. Before the days of gyro compasses, the ship would be swung in a position where there was clear visibility of e.g. a lighthouse, to find the difference between the compass heading and the actual bearing.
I'm sure one of our navigating officers will correct me if I've got this wrong.


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## marconiwireless (Sep 29, 2013)

*MIMCO compass*

Thankyou for your reply and comments. I have now found the identical one in the Powerhouse Museum, Sydney which describes exactly what you suggested, many thanks to all who responded to my question.


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