Can anyone tell me anything about this instrument? I believe it’s an inclinometer, used to measure elevation or depression, but am not sure if this is correct. As you’ll see in the photos, the case is marked "G. Battle & Co.", with the year 1915 and pheon. The instrument itself is marked "R. J. Hopgood & Co. London", with the serial No.1897 and year 1915.

I’d especially like to know if these were used with artillery and, if so, if they were intended for use with a specific type of gun. Also, was this a common item throughout the war? This is the first one of its type I’ve seen.

Here are some photos:

Thanks!

Click to enlarge the picture