semaphore

Presumably here: maps.osi.ie/publicviewer/#V1,660117,611797,7,9

I don't see any Majors.

derangedlemur That's the one, thanks. ofarrl told us a while back that it no longer exists.

Could the Major be the chap in the middle with the mustache? As I recall officers and NCOs had to have facial hair until the 1930s in the army, one man was court marshaled for shaving his off during WW1!

Ok, Captain, but not Major. Still a person of importance

Another from the May 1908 public field day at Governors Island. The PFC in front has the daytime signal flags. Behind him (and ready for "night work") is a Colt Acetylene Flash Lantern. The acetylene generator and carbide cannister is not yet connected. The signal flags are NOT semaphore flags (the poles are too long). They are used to send morse code. A long sweep overhead was a dash, a short sweep to one side was a dot.

4 of the 6 soldiers are in Signal Corps Uniform. The 2 on the right are in the uniform of the Coastal Artillery - the one in front showing the insignia of a second class gunner.

The tall sergeant in the rear wears the cap insignia and chevrons of a Master Signal Electrician. That flasher is NOT going to malfunction in front of all the VIPs.

No heliograph here, despite the "Tag". As Seuss. says, the displayed device is a signal lantern, specifically a Colt Acetylene Flash lantern, used primarily at night (hence the title at the top of the photograph: "Night Work".). The heliograph used mirrors to reflect sunlight, and were used during the day - there IS a heliograph on display in the accompanying photograph "Day Work", which can be viewed at the Library of Congress, here: www.loc.gov/item/2014680520/ This signal lantern ("Field Lantern" is depicted in Fig. 18 (page 111) of: Manual No. 6, Manual of Visual Signaling of the U.S. Signal Corps, by Captain D. J. Carr, Washington CPO 1905. The heliograph is depicted in Figures 8 & 9 (pp. 76 & 77) of that same manual. There was a Colt Acetylene Flash Lantern on display at the museum at Fort Huachuca, AZ, when I was there last. The 1905 manual gives the brightness of the field lantern as 1,900 candlepower (p. 112), vs. the millions of candlepower from the mirror-reflected sunlight of a heliograph.

Seuss. Here's a photo of a Colt Acetylene Flash Lantern on display at the Fort Gordon Museum. If you click on the thumbnail image below, then scroll down below the photo to the comments, you'll find links to more information about this device. Much of the material is in this thread:
www.treasurebunker.com/forums/index.php?/topic/3804-us-si...

The Seattle was originally the Washington, hence the cross out I've got vertigo looking at how close he is to the edge!

Despite the annotation on the card, this is semaphore flag signaling. Wig-Wag flag signaling uses a single flag. Both were practiced in this era.

Thanks signal mirror for pointing out this error. I'll ask the catalogers to add a note correcting it. I'll also ask that we add a line to this photo and the other two you commented on, saying they are semaphore flag signaling so they will be easier for researchers to find.