"Tally-ho" is the traditional cry made by the huntsman to tell others the quarry has been sighted. It may also be used with directions, including "away" and "back".
First used in fox-hunting, it was adapted in the 19th century to describe some horse-drawn vehicles and in the 20th century to advise of enemy aircraft and space junk.
Etymology Tally-ho dates from around 1772, and is probably derived from the French taïaut, a cry used to excite hounds when hunting deer."Merriam-Webster Dictionary - Tallyho". Merriam-Webster Dictionary. Referenced May 19, 2008.
Taïaut may have originated in the second half of the 13th century by the concatenation of a two-word war-cry: taille haut, where "taille" is the cutting edge of a sword and "haut" means high or 'raised up'. So the original meaning might be something close to "Swords up!".cnrtl.fr, Centre National de Ressources Textuelles et Lexicales, "Taïaut"
Usage
Fox-hunting The cry was made by the huntsman on catching sight of the fox to alert other members of the hunt. It has been used in similar circumstances for quite different quarries:
Dog Sports In lure coursing AKC events, a cry of "tallyho!" signals the beginning of the chase. After hearing the "T" in "tallyho," a handler is permitted to release the dog.
Royal Air Force It was used by RAF fighter pilots in the Second World War to tell their controller they were about to engage enemy aircraft.
It was also used to announce to the squadron leader (or other person of command in the flight) the spotting of an enemy aircraft.
Royal Navy The British T-class submarine HMS Tally-Ho was named after the hunting cry. It is the only vessel to bear the name. It was launched in 1942 and scrapped in 1967.
NASA "Tally-ho" is also used by NASA astronauts in audio transmissions to signify sightings of other spacecraft, space stations, and unidentified objects.
Horse-drawn coaches
References