WW1 Telephone Magnetos

When used in telephony, magnetos are small hand cranked devices that are used to produce a small electric charge. These are used to send a current down the line to ring a bell at the opposite end to inform people that there is a call for them. By rotating an armature inside a set of horse shoe magnets an AC charge of between 50 and 100 volts. These magnetos could be housed inside the telephone itself, or as a separate unit. Tonight we are looking at a pair of telephone magnetos from the First World War:imageAlthough one of these cases magnetos is dated 1918, I cannot find a /|\ mark on either one so it is impossible to say if they are military or civilian in origin; they are however interesting objects from a century ago and worthy of closer inspection. The smaller of the two magnetos is a free standing unit, with rubber feet, a hinged lid secured with a small screw and a large winding handle on the side:imageInside the case is a set of magnets and a large brass cog wheel which is part of the gearing used to spin the armature and generate current:imageThe second magnetos is designed to be mounted on a wall or bulkhead and has a backing plate with a series of brass reinforced screw holes for attaching it vertically:imageTwo large brass screw terminals are fitted to the top of the box to attach the telephone wires to:imageThe front of the box is hinged and this was originally lockable, with a small lock escutcheon visible:imageNext to this is the date 1918 and the maker’s mark for ATM Co. The initials are repeated on the magneto inside the box:imageThese are the initials for the Automatic Telephone Exchange Company of Washington. This company had set up a factory in Liverpool in 1889 but quickly distanced itself from its American parent company. During World War One the company produced shells for the military but continued its core business, manufacturing telephone equipment for both the War Office and Admiralty, producing private exchanges for both. Whether this is one of the pieces of equipment bought by either the Admiralty or War Office is unclear, but I suspect it is likely as investment in 1918 was far more heavily skewed to the military than to civilian infrastructure projects but it is impossible to be certain.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.