Ending the war-time service of the Sibley tent is like saying that all of the red dresses were worn by ladies of the evening - to-day it's in print but then it just wasn't so.
The late Francis Lord did a lot to advance our understanding of American 1860's military equippage. But like you and me; from time-to-time we don't always land on the correct square. I think if Dr. Lord were with us to-day he'd comment that his decision to imply that the conical shaped Sibley tent was based on the days prior to the woderful advantage of Cyber-surfing and the new facility National Archives II and their marvelous still-picture holdings in College Park, Maryland.
As a signal and telegraph researcher, I wouldn't trade my "Civil War Collector's Encyclopedia" collection for anything in the world. There's a tremendous amount of items identified nowhere else. I truly appreciate the section Lord included which covers the signal corps. I gives a good intro of the service. But then again I wouldn't call a photographer's dark-room lamp a signal lantern or a conical mechanic's light a signal torch either.
Then again, Jack didn't ask my help with the identificationof these items either.
Best Regards to a fellow researcher,