Pre-WW2 Slow Motion Dial Admiralty Pattern 8419 In Its Original Box

This 3 3/4" diameter Pre-WW2 Slow Motion Dial Admiralty Pattern 8419 In Its Original Box, is in very good condition and has never been used (New Old Stock). The box has only been opened to photograph the dial.

I've no idea what equipment the dial was used on, other than something in the, pre-WW2, British Navy. I'd be delighted to hear from you if you know.

Beautifully engineered in black painted brass, with a white early plastic tuning dial and black bakelite knob, it comes with its original cardboard box which is scuffed with a torn lid. There is some very slight corrosion on the dial label and of/off switch, which appear slightly blue-green. 

Approximate Size: 

• Base Dial Diameter: (Graduated Marks from 0-100):  9.5 cm (3 3/4")
• Black Bakelite Turning knob Diameter: 5 cm (2") 
• Depth: 5 cm (~2")

Marked on both the metal label and box:

Pattern 8410

Dial, 3 3/4" Dia. Slow Motion

Based marked: S4116

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