October 18.

Jack McLean, in considering why the Lake of Menteith is called a lake

and not a loch, states that the appropriate entry in Moray McLaren's

Shell Guide to Scotland contains ''not a breath of explanation''

(October 16).

If Jack McLean will refer to the New Shell Guide to Scotland, that is

Donald Lamont Macnie's revision of Moray McLaren, he will discover the

explanation that the lake (of Menteith) is a corruption of laich(t)

meaning low-lying land. I also understand that some early maps indicate

the Loch of Menteith as part of the Laicht of Menteith.

Further, the Lake of Menteith is not the only lake in Scotland,

although I understand that two of the other Scottish lakes -- at

Pressmennan (East Lothian) and at The Hirsel (Berwickshire) -- are

probably artificial and not natural sheets of water.

As to the question which side spoke Scots (as, originally, a northern

dialect of Anglo-Saxon) during the ''saltire'' Battle of Athelstaneford

-- with August 10, 756, as the only possible date for the battle -- the

answer must be the Northumbrian Angles, as both the leading contingents

on the other side, the Picts and the Gaels (Scots) of Dalriada, would

have spoken their own Celtic languages.

Incidentally, the name Athelstaneford has no connection whatsoever

with the southern Anglo-Saxon name Athelstan. ''Staneford'' is simply a

translation of the Gaelic ''ath-ail''.

Alexander S. Waugh,

27 Wilson Road,

Banchory.