The Fuller Phone Mk IV

[Brian Wolfe]

It was mid-1915 and the war was not going well for Brittan's "Contemptible Little Army" and her Allies. Every move on the part of the Allies seemed to be known by the Germans ahead of time and thwarted. Raids were met by either artillery or well prepared troops. Relief troops were met with shouts of "welcome" by the Germans as they took over from exhausted front line soldiers. In one case it is said that the Regimental march was played by the Germans for the Scottish troops newly arrived to the trenches.

With trenches only yards apart in some areas this preparedness on the part of the German Army was nothing short of phenomenal. A very efficient espionage organization was suspected by the Allies. An organization that had some how infiltrated their military machine from the highest levels right down to the front line operations. The thoughts of such an organization must have created a great deal of fear and paranoia in the ranks and caused the senior staff to have doubts of any chance to advance until these agents were ferreted out.

Just when this problem of espionage seemed to be insurmountable a British civilian who had been interned by the Germans made it back home with the answer to this conundrum. It turned out not to be espionage at all but simply the Germans listening in to signals passed to them through the earth. After some experimentation it was proven that the problem was indeed due to induction of the signals themselves. The Allies had been using an earth return. Part of the problem was solved through the use of metallic circuits, in this case twisted pairs of wires in place of the earth return previously employed, however, listening in continued to be a problem due to tapping into these lines.

In October 1915 Captain (later Maj. Gen.) A.C.Fuller invented the Fullerphone which prevented "listening in" through any means, with the exception of the use of another Fullerphone. If security during this period was anything like it was in the Second World War every precaution would have been employed, even at the cost of the operator's life, to prevent a Fullerphone from falling into enemy hands. The Fullerphone was tested extensively in the water filled area of Ypres and found to work very well. This was the answer they were looking for.

After the War modifications and improvements were made and in 1939 the Mk IV went into service. This was the most successful model, being easier to use and much more sensitive the the earlier models. The Mk IV carried no telephone set, as they had in WWI, and was used to send Morse Code style signals. While the original set had been designed for static use and WWII was a mobile conflict the Fullerphone continued in use due to its ability to work simultaneously with a telepnone over the same line. The Fullerphone could also work over long or even leaky lines where the telephone or telegraph was useless.

The WWI model Fullerphones (Mk I through III) were housed in wooden boxes while starting with the Mk IV and then including Mk V and VI the Fullerphone could also be found housed in an aluminum case, In 1943 a "tropicalized" version was issued. The last model produced was the Mk VI which was completely "tropicalized" and immersion-proof, when closed, due to a watertight gasket on the lid.

[Brian Wolfe]

Here is a closer view of the headset housed in the lid. The Mk IV in my collection is housed in a wooden box.

[Brian Wolfe]

When used in a situation such as at Headquarters it was common to slide the Fullerphone out of its case and use it in the manner shown below. Note the Morse key to the right of the unit.

I hope you enjoyed this post and a look at the amazing Fullerphone.

For more check out "Wireless for the Warrior" on the internet.

Regards

Brian

[Brian Wolfe]

Here's a photo to compliment the Fullerphone photos. It is of a wiring party going to the trenches. The back of the postcard photo verifies that this is a communications group.

From the equipment - such as the steel helments - in the photo it would suggest a date that would place this well within the time that the Fullerphone was in use, that being late 1915 and after.

Regards

Brian

[Brian Wolfe]

This is photo of a field phone in use. I believe this to be in the earler stages of the War and therefore predates the Fullerphone. The fellow with the headset appears to be holding a pocket watch and is supporting this group that I think is artillery. If this is before the invention of the Fullerphone then there is the likelihood that the Germans were listening in on the conversation. Is there a chance that the field phone operator is waiting for a prescribed time to either make a transmission or change the frequency of the phone?

Regards

Brian

[Tomas]

Very nice phone Brian

Tomas

[joe campbell]

brian!

this is one of the reasons i love this forum.

interesting, well presented, well illustrated.

i learned something today.

my thanks!

joe

[nesredep]

Hello!

Nice Phone.

All the best

Nesredep.

[Roppe]

Hi,

I've got 2 complete Fuller Phone Mk IV.

I sell them. Does someone want to buy one?

Roppe