I seem to remember that the interval between guns was reduced from 10 seconds to 5 seconds sometime in the late nineteenth century and thereafter the rhyme ceased to be used.

I cannot offer a contemporary authority for the use of the words quoted but it seems to be correct although different versions of this rhyme exist. The following version seems more appropriate to a 10 second interval:

"If I wasn't a gunner, I wouldn't be here. Starboard number two gun, FIRE!
Away from my home and my family so dear. Starboard number three gun, FIRE".

Gun salutes.

Does anyone know of a publication that has information on gun salutes by a British warship in the late 1700's or the early 1800's?

I do know that Samuel Pepys reduced the number of guns fired when rendering honors but this was done in the 1600's in order to conserve gunpowder.

Hi Don,

Try this: Regulations and Instructions Relating to His Majesty's Service at Sea (1808)

Google Books has other editions from the mid- to late-1700s as well.