Clubs and Balls

Teeing Ground
Order of play
Falling off tee

Playing the Ball
Unplayable
Wrong, Substitute
Lifting, Dropping
Moved, Deflected

Provisional, Lost,
Out of bounds

Putting Green
Flagstick
Marking, lifting
Stymie

Hazards, Penalty Areas
Water hazards
Lateral water hazards

Abnormal Conditions
GUR
Casual water, Temporary water
Hole, cast, or runway

Obstructions,
Loose impediments

Ground under Repair
1744 First mention of an area from which free relief is granted in - Trench, ditch, dyke, the Scholars' holes and the Soldiers' lines. Tee behind, but play with an iron club. (I have a theory on the 'iron club' requirement.)

1775 HCEG. Relief 'when the cut of the spade appears where the ball lyes'. The player had two relief options: drop behind, play with an iron, no penalty; or tee and play with any club, penalty one stroke.
This option was removed in 1809.

1812 No relief from a rabbit scrape, but for a ball in a burrow the player had a free drop behind, and play with an iron club.

1858 Relief from any of the 'short holes made for golfing'; changed to any holes other than one being played in 1875 the beginnings of holes made by the greenkeeper and wrong putting green relief.
Drop behind and play with an iron in 1858; iron club requirement dropped in 1875.

1882 First use of the term, 'ground under repair'

1891 In any golf hole; lift and drop within 1 club length.

1899 Reference to hole made by greenkeeper, a golf hole and a flag hole. Drop as near as possible, not nearer hole

From 1902 'Ground under repair' was included in the rules on obstructions, but not defined.

1947 USGA included a hole made by the greenkeeper and material piled for removal, under 'artificial obstructions', and required the Committee to accurately define ground under repair. Relief: drop within two club lengths of the margin of the GUR.

1950 R&A separated GUR and defined it for the first time as any portion of the course so marked by the Committee. Play from GUR was prohibited, but became optional from 1952. Relief also available if the ball is within two club lengths of the GUR.

1952 Rules defined GUR as it is today. Relief: drop as near as possible to where the ball lay, avoiding the condition.

Casual Water
Casual water was not distinct in the 1744 rules, it costs the player a stroke to take relief from any water, or 'wattery filth'.

1758 HCEG amendment to relief from water if the ball is at least half covered

Royal Wimbledon 1883 first use of the term 'casual water.'

1899 First recognised as separate from water hazard. Relief: drop behind no penalty; on the putting green, place behind.

1902 Defined as a temporary accumulation of water, not one of ordinary or recognised hazards of the course. Can drop behind, or to the side. For casual water within a hazard, player must drop in the hazard.

1908 Relief changed to within 2 club lengths of the margin, and the player's stance is included in casual water interference. On the putting green, can place 2 club lengths behind, or where the interference is avoided. Re-drop if the ball rolls into water.

1933 Drop 'on dry ground' as near as possible to where the ball lay.

1950 Definition re-written, casual water is now not within the margin of a water hazard, and snow and ice can be casual water if they cannot be treated as loose impediments.

1956 Add 'which is visible before or after the player takes his stance' to the definition.

From 1964, snow and ice are CW or LI at the player's option. Dew specified as not being casual water in 1988, and frost added 1992.

2019 Casual water now know as 'Temporary Water'.

Hole, Cast or Runway
1812 and 1829 No relief for the ball in a rabbit scrape, the player 'must play it as from any common hazard'; however, from a burrow the player could drop behind and play with an iron. It was inevitable that such occasions should be prominent in the rules of this time, as the Old Course golfers battled for control of the links with rabbit farmers until around the 1820s.

No mention of rabbit scrapes or burrows then until 1891 when rabbit scrapes were included in the list of hazards.

From 1908, rabbit scrapes, hoof marks and other damaged caused by animals was consigned to Local Rules

Holes, casts and runways made by a burrowing animal, a reptile or a bird first appeared in the 1947 USGA Rules. Interference and relief as for ground under repair.

1952 Rules used 1947 wording, with added 'but not rabbit scrapes'

Play with an 'Iron Club'
Rule 5, 1744 and other examples up to 1829 (e.g. St Andrews 1754, 1812 Rules 5 and 7, 1829; HCEG 1775, 1809; Montrose 1830) specify that the next stroke must be played with an iron club. Each time when free relief is granted, the use of an iron club is specified.

My theory is that it was a kind of 'half-stroke' penalty. Edinburgh Golfers 1775 Rule 6, a player apparently could choose to play with any club for the loss of a stroke, but avoided the penalty by dropping and playing with an iron.

From mid-1700s up to around the mid 1800s, most clubs were long-nosed woods. Irons were 'trouble' clubs - rut irons, sand irons etc., and would only hit the ball a relatively short way. Players would not like to use them too often as they also damaged their expensive featheries.

Clearly, a player would choose to use a wooden club if possible. Restricting the player to an iron club for the next stroke after such relief was a noticeable disadvantage.
Along with the introduction of the gutta percha ball around 1848, iron clubs became more popular among players. The disadvantage of having to play an iron, and the Rules requiring players to do so, quickly disappeared.