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The Great War (1914-1918) Forum

Remembered Today:

Barr & Stroud rangefinder?


Lyffe

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I'm wondering if there is an expert on WW1 range finders who could identify the equipment in the attached photo? The photo was taken in Nov 1923 in the garden of J C P Cave, a 'gentleman of private means'. He was a well-known amateur meteorologist and it has been suggested this piece of equipment might be a Barr & Stroud rangefinder - or something similar.

And before anyone asks, Cave had been meteorologist-in-charge at the Royal Aircraft Factory at South Farnborough, and his successor subsequently conducted a short trial during Jan and Feb 1918 using an 80 cm Mk II Infantry Rangefinder to measure the height of low clouds - apparently successfully. The two men corresponded after the war this method of measuring cloud heights is certainly something that would have interested Cave.

Any suggestions would be most helpful.

Brian

post-42511-1245663460.jpg

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It would be possible to use a modified rangefinder coupled to a device to measure vertical angles, but why go to that trouble when you can use a pilot balloon with a fixed rate of ascent and a Pilot Balloon Theodolite. When the balloon disappears through the cloud its a simple matter using Trigonometery to work out the cloud base.

John

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Thank you John. As I said it was a trial, but there were good reasons for doing it. The pilot balloon method you describe is only valid if there is more or less continuous cloud cover at the same level, but in many cases cloud is well broken and a pilot balloon could quite easily miss the cloud base and ascend through a clear area. The rangefinder technique wouldn't have worked with continuous cloud cover, only in broken cloud situations when the pilot balloon was useless.

I don't know any of the details about the rangefinder technique, but at face value both techniques would be valid depending on the situation.

In fact cloud bases were not recorded during WW1 (at least they weren't written in the Daily Register) so this was a very new field. Another technique trialled was finding cloud height at night using a searchlight shining vertically on to the cloud; standard procedure from about 1934, but totally unique in 1918.

But is it a rangefinder?

Brian

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The image is not the MG WWI No 2 Mk I, II or III INF B & S, however there are much larger Artillery RFs of similar style, that have two tripod fixings - as this one shows, and I would think this is one, although the scale/size may be deceptive even with fence line. I will dig out my British Optics manuals and have a look.

Sorry that this does not immediately help you.

acB

Thank you John. As I said it was a trial, but there were good reasons for doing it. The pilot balloon method you describe is only valid if there is more or less continuous cloud cover at the same level, but in many cases cloud is well broken and a pilot balloon could quite easily miss the cloud base and ascend through a clear area. The rangefinder technique wouldn't have worked with continuous cloud cover, only in broken cloud situations when the pilot balloon was useless.

I don't know any of the details about the rangefinder technique, but at face value both techniques would be valid depending on the situation.

In fact cloud bases were not recorded during WW1 (at least they weren't written in the Daily Register) so this was a very new field. Another technique trialled was finding cloud height at night using a searchlight shining vertically on to the cloud; standard procedure from about 1934, but totally unique in 1918.

But is it a rangefinder?

Brian

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Have you anyway of getting the photo enlarged? Incidentally Barr and Stroud range finders were still being used in the early 1970s and were issued to Armoured Car regiments at that time. Not the quickest means of establishing range but useful all the same in some situations.

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Mark,

Thank you for your offer, you have given me some hope.

Keith,

The image was cropped from a general view. I've cropped it further, but it's becoming rather pixilated. I'd estimate of the tube something like about 7 ft or 200 cm in length.

Brian

post-42511-1245827335.jpg

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