Rare Swiss double dialed phonotelemeter chronograph Circa 1900

Silver chronograph “Breveté SGDG” with two dials by Droz & Cie.
–
An extremely rare Swiss phonotelemeter with two dials, circa 1900.
Comprising fifteen seconds chronograph, ten minutes register, sound telemeter, kilometre gauge and compass.
Silver tiered case with small wheel in the bottom part of the band for the distance gauge. Two dials: front side – enamel with Arabic numerals, outer 15 seconds chronograph, inner 5 kilometer telemeter ring, blued pointer and signature: “Mr le Ministre de la guerre appelle l’attention de M. M. les officiers sur l’emploi de ce Phonotélémètre” (“The Minister of War informs the officers on the use of the sound telemeter“); back side – enamel with radial Roman hours, outer gauge scale calibrated for 20 kilometres, inner gauge scale calibrated for 15 kilometres and blued spade hands. Mechanical bridge movement, nickel-plated, with lever escapement.

This is a device consisting essentially of a stopwatch, for estimating the distance of guns in action by measuring the interval between the flash and the arrival of the sound waves from the discharge.
–
Diameter: 52 mm
–
Weight: 115 g
–
Signed: Droz & Cie., St. Imier, Breveté , S.G.D.G.
–
Breveté SGDG was a French type of patent that ceased to exist in 1968. The name was a common abbreviation for “Breveté Sans Garantie Du Gouvernement“ (patent without government guarantees).
–
Droz & Perret
The roots of Berna Watch Factory SA go back to 1864 . That year, the Droz & Perret company was founded in St. Imier by Alcide Droz and Henry Perret.
Alcide Droz & Fils
In 1883 the name of the company was changed to Alcide Droz & Fils and in 1887 to Droz & Cie. changed. A subsidiary, Droz, Amstutz & Cie., Ran the West End Watch brand in 1885 and exported watches under this brand mainly to India.
Berna Watch Factory SA.
In 1905 the name change from Droz & Cie. in Berna Watch Factory SA. In addition to pocket watches , stopwatches (up to 1/100 of a second), chronographs , watches with repetitions and particularly flat watches were manufactured.