Okay.
I don't have Kellogg's diary for that date. His diary - which provided the raw material for his book - is at the Connecticut Historical Society in Hartford and I only copied the dates that pertained to the Raiders, so I don't have Aug. 14.
Frederic James was pretty close to dying by this point, and just wrote, "Sunday 14th - Pleasant Lived upon boiled rice today. Read my testament and hymn book.
Fred never mentions the spring, but I've read that it appeared during the storm that washed out part of the stockade fence, and he has that happening on Tuesday, Aug 9: Cloudy most of the forenoon and in the afternoon we had a tremendous shower, which flooded out the camp & made quite a river of our swamp & also washed down 5 large gaps in the stockade, two on the ease side and two on the west side. Our rations were not served out on account of the rain."
Eugene Forbes, who like Fred, would not live to make it home, but left a really detailed diary that was published in 1865 (I don't really trust anything that was published after John McElroy's book came out in 1879). He usually wrote quite a bit, but this seems to have been slow day. "Everything very dull and quiet Drew fresh beef, salt and beans P.M. Thomas Mulvaney died in the hospital come days ago
Charles Hopkins made no entry that day.
George Hitchcock: "Prisoners from Sherman today -- report Atlanta taken by Union forces."
Amos Stearns: "A very warm day. I went to the Surgeon's Call but did not get prescribed for because the Surgeon was not there. I think I have the scurvey [sic]. I went after the ration today. Jennison got supper. I have thought of my friend at home much today. O my darling L. Maria!"
Charlie Mosher: "No entry for that date".
Those are the diaries that I have in this room. The less likely ones are upstairs - those are the ones who didn't go into as much detail or have gaps in the entries where nothing was written for several days or weeks. I also checked the entries for the 13th, since, if a man died after the bodies were collected for the day, they would tote his body over to the South Gate and he wouldn't be picked up or have his death recorded until the following day.
Most of these diaries were written by East coast men - Mass, NY, and NJ. If I were you, my next step would be to take a look at the regimental histories on the 1st Kentucky Cavalry. I found one listed - The First Kentucky Cavalry by Sgt. E Tarrant, who was a member of the regiment, and it was republished in 2013 as "The Wild Riders of the First Kentucky Cavalry: a History of the Regiment in the War of Great Rebellion." and the modern edition is available on Amazon:
https://www.amazon.com/dp/1484953126/?tag=civilwartalkc-20
Good luck!